Polyunsaturated fatty acids (PUFAs) are fatty acids with two or more unsaturations. They are essential components of membrane phospholipids and it is well-known that under physiological conditions, PUFAs have a big impact in the human health. There exist two major series of PUFAs, i.e., omega-3 (or n-3 PUFA) and omega-6 (or n-6 PUFA), depending on the positions of the first double bond. The balance between n-6 PUFA and n-3 PUFA, is critical and associated to pathological conditions such cardiovascular and neurodegenerative diseases , which might pave the way for their understanding and to uncover new therapeutical directions.In this research topic we have gathered together 10 articles which contribute to the comprehension of the effects of fatty acids (PUFAs and other bioactive lipids) on ion channels and ionic pumps properties. The focus is put not only in the molecular interactions, but also on the systemic effects of their alterations in pathological conditions, as for example in the bipolar disorder , potassium (KV), calcium (CaV), and proton (HV) channels, as well as calcium-activated potassium (KCa), and transient receptor potential (TRP) channels. In this very interesting work they propose that the effect of PUFAs on voltage gated ion channels can be grouped into three main categories (1) those causing alterations in voltage dependence, (2) those causing changes in the maximal conductance and (3) those causing changes in the gating kinetics. They also propose five molecular mechanism by which PUFAs can exert these effects: (1) by binding to amino acids located at the ion-conducting pore, (2) by binding to amino acids at the extracellular side of the channel forming an open-channel block, (3) by binding at the voltage sensor domain (VSD) linker close to the intracellular gate, (4) at the interface between the extracellular part of the channel and the external leaflet, from where they can electrostatically affect the S4 VSD and (5) by electrostatic effects on the pore domain. In agreement, in the article by Moreno et al. on K+ channels, the mechanism of modulation involves an electrostatic effect of PUFAs on VSD. These authors explain in detail that the negative charge of the carboxyl group of the fatty acid is crucial for the electrostatic interaction between PUFA and the VSD (at the bilayer/channel interface close to the S3-S4 segment). Similarly, in the original research article by Oliván-Viguera et al., the effects of omega-3 fatty acids on the calcium/calmodulin-gated KCa3.1 properties expressed in murine and human fibroblasts were analyzed. KCa3.1 channel function has been linked to abnormal cell proliferation, pathological tissue remodeling and fibrosis of a variety of organs, chronic inflammation, and autoimmune diseases. They found that α-linolenic acid and docosahexanenoic acid (DHA) inhibit KCa3.1 currents and strongly reduce fibroblast growth in a dose-dependent way. The association between KCa3.1 and PUFA as well as the link between KCa3.1 and human diseases, led them to suggest that reduced fibroblast KCa3.1 functions might be a feature and a possible biomarker of cell dysfunction in Lysosomal Storage Disorders.In this Research topic, + channels, cystic fibrosis transmembrane conductance regulators, ATP-sensitive K+ channels, Ca2+-activated anion channels, pannexin 1 hemichannels, and canonical subtype of TRP channels (TRPCs). In this RT, Choi and Hwang review the effects of various pro-resolving lipids on the functions of four sensory TRP channels and NMDA receptors and discussed their beneficial effects on inflammation and pain. Nowadays, the physiological significance of bioactive lipids is expanding and new roles in their signaling properties are growing rather slowly, perhaps, the main reason for this, is that these molecules are usually found in very small quantities and often they are co-extracted with other lipophilic molecules, making their detection and identification a hard task. In this RT, Divito et al. discuss on the fact that common analytical methodologies are usually ineffective due to the unsuccessful separation of bioactive lipids in complex biological samples, and show that novel multidimensional separation techniques are very useful separation strategies for these elusive molecules.PUFAs can also modulate ion channels activity through generation of bioactive lipids. In particular pro-resolvins have been shown to modulate different types of ion channels, including epithelial NaRetamal presents evidence supporting the hypothesis that carbon monoxide inhibits Cx46 hemichannels through a lipid peroxide-dependent process. Hemichannels are ion channels composed of six protein subunits known as connexins (Cxs). Under physiological conditions they present a low open probability however, massive and/or prolonged hemichannel opening induces or accelerates cell death. It is known that carbon monoxide (CO) modulates many cellular processes through the activation of guanylate cyclase and/or inducing direct carbonylation of proteins by mechanisms that are either sensitive or insensitive to reducing agents. Additionally, in the article by Puebla et al. the effects of PUFA on Cx hemichannels, gap junction channels (GJCs), and channels formed by Pannexins (Panx) are reviewed. Panx as Cxs channels are permeable to large molecules such as ATP and glutamate. The authors show that PUFAs can act as either inhibitors or activators of Cxs and Panxs, and these opposing effects can be mediated by different post-translational modifications that affect these two types of proteins.Several articles are included in this RT showing different forms of regulation of Cx46 hemichannels by lipid molecules. In this Research Topic, Diaz et al. have analyzed the effect of diets containing different PUFAs composition on the thermodynamic properties of Na+-K+-ATPase and on the lipid composition of gill epithelia and isolated enterocytes from euryhaline teleost fish. They demonstrate not only that branchial cells and enterocytes have different lipid composition, but also that they differently respond to severe PUFAs-deficient diets, unraveling powerful lipostatic mechanisms protecting membrane lipids in branchial cells. Paralleling these results, the thermodynamic properties of the Na+-K+-ATPase were modified in enterocytes but not in branchial cells. They discuss on direct and specific interactions of different fatty acid-containing phospholipids and cholesterol within the Na+-K+-ATPase molecular framework, determining the thermodynamic traits and enzyme activity within a given lipid microenvironment.Using a different strategy, The original idea of this Research topic was to broaden the interest of the scientific community in studying the relationship between fatty acids (and derivatives) and integral membrane proteins. We expect this compilation may stimulate scientists to endeavor research aimed at uncovering the molecular mechanisms underlying their interaction and how it is involved in regulation/dysregulation of cell function under normal and pathological conditions.MD and MAR have edited the research topic and have written and drafted this editorial.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


It also plays an important role in regulation of mitochondrial metabolism in response to exercise. Recent studies have shown that SIRT4 is involved in a wide range of mitochondrial metabolic processes, including depressing insulin secretion in pancreatic beta cells, promoting lipid synthesis, regulating mitochondrial adenosine triphosphate (ATP) homeostasis, controlling apoptosis and regulating redox. SIRT4 also appears to have enzymatic functions involved in posttranslational modifications such as ADP-ribosylation, lysine deacetylation and lipoamidation. However, the effects on SIRT4 by metabolic diseases and changes in metabolic homeostasis such as during exercise, along with the roles of SIRT4 in the regulation of metabolism during disease, are not well understood. The main goal of this review is to critically analyse and summarise the current research evidence on the significance of the SIRT4 as a metabolic regulator and in mitochondrial function and its putative roles in relation to metabolic diseases and exercise.NAD The sir20 years . SIRT3, 20 years . Mitocho20 years . These m20 years .SIRT3 has been a subject of intensive research as a mitochondrial fidelity protein, and its roles in mitochondrial substrate metabolism, protection against oxidative stress and cell survival pathways have been identified . SIRT5 hExercise has been found to increase activities and protein levels of SIRT1 and SIRT3, decrease the level of lysine acetylation, increase the turnover rate of proteins, decrease the accumulation of carbonyl groups and improve cellular function . HoweverBased on the background information above, this review is focused on a critical analysis of the known and potential roles of SIRT4 in regulation of cellular metabolic and energetic state, mitochondrial energy transfer, mitochondrial survival, redox regulation and metabolic diseases. In addition, the reports on the effects of exercise or physical activity on energy metabolism and mitochondrial homeostasis in relation to SIRT4 are also examined.+-dependent deacetylase activity but to affect its targets mainly through NAD+-dependent ADP-ribosylation  in mitochondria . Fatty adiseases . SIRT4 hdiseases . Moreovediseases . In shordiseases , it shou+ and NADH play important roles in energy metabolism, cell death and various cell functions , that is, opening mPTP will lead to the release of mitochondrial NAD+ from matrix space to intermembrane space which is subsequently hydrolysed by NAD+ glycosylase  transporter  and sirtuins, and further affect the signalling cascades and gene expression  ligands.NADunctions . Mitochotions  have been extensively discussed elsewhere . SIRT4 h+ homeostasis and pyrimidine nucleotide synthesis in mitochondria  and decreasing ROS from mitochondrial sources in podocytes under hyperglycaemic conditions , providing evidence for the application of exercise in the prevention and treatment of type 2 diabetes . Laurentvia the mitochondrial pathway, accompanied by increased mitochondrial membrane potential and reduced ROS production  . In thiss fusion . Togethes fusion . Howevers fusion .The relationship between exercise and oxidative stress is very complicated due to the different mode, intensity and duration of exercise . RegularIt is known that SIRT4 has effects on substrates metabolism, therefore been speculated to be associated with pathological conditions and diseases . RepressIn addition to the regulation of mitochondrial metabolic functions, deregulated metabolism is tightly connected with the development of various cancers . SIRT4 sSIRT4 is also involved in the development of brain astrocytes. SIRT4-dependent inhibition of GDH is believed to regulate the development of glial cells . A recenAccumulated experimental data have shown that exercise can increase oxygen consumption and rebuild the balance of intracellular pro-oxidant-antioxidant homeostasis . The mitTwo studies have reported that a 12-week treadmill training significantly decreased SIRT4 level in gastrocnemius muscle of rats that were selectively bred as low-capacity runners (LCRs) and high-capacity runners (HCRs), respectively, suggesting decreased SIRT4 level resulted in increased free fatty acid utilisation that is a key element for elevating endurance capacity ,b. TheseDrosophila melanogaster has found that loss of mitochondrial SIRT4 shortened the insects’ lifespan and decreased their physical activity (activity .+-dependent SIRT4 is very sensitive to metabolic challenges and may be modulated by physical exercise, although there have been debates about the expression of SIRT4 depending on the cell type (In summary, these reports suggest that NADell type . It is oResearch on animal models at the cellular level together with the data obtained from human studies suggest that SIRT4 is a master regulator of a wide range of mitochondrial metabolic processes in mammalian cells, such as depressing insulin secretion, promoting lipid synthesis, regulating mitochondrial ATP homeostasis, controlling apoptosis and regulating redox. SIRT4 could be on both sides of redox regulation and is the only sirtuin shown to induce ROS production. Exercise can activate a number of pathways that contribute to metabolic reprogramming and result in an increased generation of ROS that can modulate muscle contraction, antioxidant protection, and oxidative damage repair. The adaptations induced by exercise are typically expected to protect against metabolic and age-related diseases and improve health, making it important to identify proteins involved in this reprogramming for treatment of metabolic diseases. Although the effects of exercise on SIRT4 have not been thoroughly investigated, it appears that SIRT4 might play a role in metabolic regulation and control during exercise. Further research is thus required to elucidate the roles of SIRT4 in relation to the benefits of exercise in prevention and treatment of metabolic diseases.YH and SZ were the primary authors who were responsible for the design and writing of the manuscript. SC and AC assisted with writing and editing the manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Dynamic metabolic changes occurring in neurons are critically important in directing brain plasticity and cognitive function. In other tissue types, disruptions to metabolism and the resultant changes in cellular oxidative state, such as increased reactive oxygen species (ROS) or induction of hypoxia, are associated with cellular stress. In the brain however, where drastic metabolic shifts occur to support physiological processes, subsequent changes to cellular oxidative state and induction of transcriptional sensors of oxidative stress likely play a significant role in regulating physiological neuronal function. Understanding the role of metabolism and metabolically-regulated genes in neuronal function will be critical in elucidating how cognitive functions are disrupted in pathological conditions where neuronal metabolism is affected. Here, we discuss known mechanisms regulating neuronal metabolism as well as the role of hypoxia and oxidative stress during normal and disrupted neuronal function. We also summarize recent studies implicating a role for metabolism in regulating neuronal plasticity as an emerging neuroscience paradigm. Regulation of tissue metabolite supply and cellular energy metabolism is essential to maintain healthy cellular and systemic function. This regulation is especially critical to the central nervous system (CNS) where energy consumption is highly dynamic. Within the brain, increased neuronal activity drives increased energy consumption and compensatory metabolic and vasculature changes in turn enhance neuronal function , blood volume, glucose consumption and oxygen metabolism are all increased within localized regions of activity following neuronal stimulation. Neurovascular coupling, first postulated by Roy and Sherrington  forms th2+ release within astrocytic end feet and inducing various downstream Ca2+ signaling pathways known to control vasodilation  produced in neurons. Vasodilation is strongly stimulated by •NO through activation of the enzymatic •NO receptor, soluble guanylate cyclase (sGC), producing cGMP and leading to vasodilation by cGMP-dependent kinase signaling , causing attenuation of postsynaptic activation , supports shuttling of lactate from astrocytes to neurons. The lactate efflux transporter MCT4 is expressed primarily in astrocytes while MCT2, an isoform that allows for rapid substrate uptake of lactate, is primarily expressed in neurons  fMRI which relies on neurovascular coupling to measure regions of brain activity based on measurements of oxyhemeoglobin and deoxyhemeoglobin consistently generates signals with a post-stimulus undershoot  at which hypoxic damage will occur in neurons, in rat cortex a PtO2 value between 6.8 mm Hg and 8.8 mm Hg has been estimated as a PtO2 where oxidative metabolism will be disrupted  and from 1 mm Hg to 60 mm Hg across all brain regions with proximal structures displaying large variations in oxygen tension  complexes I or III during normal oxidative respiration. This causes conversion of 1%–2% of oxygen into the superoxide anion, a precursor to hydrogen peroxide and hydroxyl free radicals. Within the brain, a high neuronal oxidative rate heightens the potential for ROS production and neurons are especially vulnerable to oxidative damage due to low levels of antioxidant enzymes such as glutathione  occurring in around 1:10 people aged over 65. AD principally affects short-term working memory and is classified by the presence of two hallmark neuropathologies; extracellular amyloid plaques, formed from aggregation of amyloid (Aβ) peptide, and intraneuronal neurofibrillary tangles formed from aggregation of hyperphosphorylated tau. In AD patients, regional hypometabolism in the brain is a predictor for progressive cognitive decline and reduced cerebral metabolism is associated with carriers of the AD risk allele of the APOE-4 gene  and Huntington’s disease (HD). PD is thought to be caused by both genetic and environmental factors and primarily impacts patient motor function. PD involves the formation of protein aggregates consisting mainly of α-synuclein and affects the dopaminergic neurons of the midbrain substantia nigra. HD is an inherited neurodegenerative disorder caused by expanded CAG repeats in the Huntingtin (HTT) gene causing progressive neuronal degeneration and cell death throughout the brain, affecting mood, cognition and motor skills. Inclusions are also found in the HD brain from aggregation of mutant HTT (mHTT) protein. Like AD, both PD and HD are associated with increased oxidative stress as well as decreased activity of the KGDHC enzyme  also produces deficits in acquisition of spatial memory in adult rats that could be prevented by administration of antioxidant (Row et al., Although it has been well established that metabolic regulation is critical to neuronal function and that metabolic dysfunction is a major pathology in diseases affecting behavior and cognition, there is little known regarding how regulators of metabolism may be involved in neuronal plasticity. A number of studies, however, support a direct role for metabolic regulation and metabolically linked genes in influencing learning and memory. One of the best examples of this is exposure of hypoxia as a modulator of cognitive performance. In +/K+ ATPase, Glut1, Glut3 and, most prominently, lactate transporters MCT1 and MCT4 detected, suggesting transcriptional modulation of neurometabolic coupling occurs following learning (Yao et al., In learning and memory studies using an inhibitory avoidance paradigm, changes in metabolic gene expression were observed at 24 h, with increased expression of NaDrosophila found that neuron-specific, but not glia-specific knockdown of the complex I gene ND20-like, significantly increased aggressive lunging behavior in flies (Li-Byarlay et al., Altered expression of ETC oxidative phosphorylation genes is also associated with altered behavior in the honeybee. In a study exploring molecular profiles in aggressive honeybee behavior, oxidative phosphorylation was most significantly enriched in association with increased aggression. This was found to be true for aged bees that display increased aggressive behavior as well as following environmentally enhanced aggression by alarm pheromone exposure and genetic-related aggression occurring in the Africanized honeybee population (Alaux et al., APOE as well as the NMDA-R, GRINA, and the human actin homolog, ACTB (Watts et al., Also involved in learning and memory are non-coding miRNA genes which are regulated during neuronal activity by various mechanisms and able to regulate translation of various downstream target genes. A number of miRNAs have been associated with plasticity including the hypoxia-regulated, HIF-1 target, miR-210 that is known to be involved in metabolic regulation. miR-210 is significantly upregulated 24 h after long-term memory formation in the honeybee using an olfactory conditioning paradigm. Upregulation of miR-210 correlated with downregulation of a number of metabolically linked protein-coding genes including Gapdh2, Glucose dehydrogenase, Laccase2 and Aldose reductase-like. Inhibition of miR-210 by treatment of honeybees with miR-210 antogmiR also resulted in reduced memory retention in the olfactory conditioning assay indicating a functional role in learning and memory (Cristino et al., While neurovascular coupling mechanisms appear to maintain steady-state oxygen levels in the brain, it is becoming evident that neurovascular uncoupling may in fact have a physiological role in regulating plasticity via oxygen depletion and induction of downstream hypoxia response pathways. Disruptions to hypoxia and oxidative metabolism have also been extensively attributed to neurodegeneration pathology albeit, there is a lack of understanding, as to how these disruptions are triggered and how they may be therapeutically targeted to halt disease progression and improve cognitive and motor functions. Altered behavior, including learning and memory, associated with dysregulation of metabolic genes highlights the importance of understanding the role of oxygen metabolism in neuronal plasticity. Further elucidation of how the hypoxia response pathway and other metabolic genes are involved in neuronal function will be critical in determining the molecular links between cognitive function and oxidative metabolism. This in turn will help elucidate how disrupted metabolism can lead to cognitive deficits and neurodegenerative disease.MW wrote the manuscript. RP and CC edited the manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Previous reviews have generally reported cognitive//behavioral improvements after cognitively oriented treatments (COTs) in persons with MCI. However, comparatively little is known about the neural mechanisms associated with such cognitive improvement. . Methods. An extensive literature search was conducted up to August 2018. Inclusion criteria were (1) studies that evaluated the effects of the COTs in patients with amnestic single- or multiple-domain MCI using fMRI, (2) the MCI patient sample having met Petersen's or Jack/Bond's criteria, (3) randomized and/or controlled trials, (4) fMRI and cognitive assessments completed pre- and post-intervention, and (5) articles available in English.  The primary aim of the current review was to examine neurophysiological changes measured by functional magnetic resonance imaging (fMRI) and possible cognitive changes following COTs in those with MCI Amongst the 26 articles found, 7 studies were included according to the above inclusion criteria. A total of 3 studies applied rehearsal-based strategies as the primary intervention, all of which used computerized cognitive training. Four studies used fMRI to investigate the neurophysiologic and cognitive changes associated with memory strategy training. The majority of the studies included in this review showed evidence of improved objective cognitive performance associated with COTs, even in tasks similar to everyday life activities. In addition, there were significant changes in brain activation associated with interventions, in both typical and atypical brain areas and networks related to memory.  Although additional studies are needed given the small sample size, these initial findings suggest that cognitive improvement after COTs is generally associated with both compensatory  and restorative  mechanisms. The recent growth of interest in nonpharmacologic cognitively oriented treatments (COTs), particularly cognitive training, in those with mild cognitive impairment (MCI) has been fueled by a combination of data showing limited benefits of existing pharmacologic agents , 2 and rA critical first step in understanding such neurophysiological changes is to recognize the heterogeneity that exists in both treatment and fMRI methods. In our previous methodological COT review , we clasThe second important source of heterogeneity is the type of fMRI used to evaluate COT effects. While task-based fMRI paradigms were the standard for the first decades of fMRI research, recent years have seen a shift toward methods that use “resting-state” fMRI (rs-fMRI) to evaluate within- and between-network connectivity. While task-based paradigms identify patterns of BOLD signal directly arising from task performance, rs-fMRI relies on inherent low-frequency oscillations and is dependent on correlations with cognitive/behavioral performance. However, task-based paradigms differ markedly across studies and may yield different patterns of activation due to nothing more than the nature of the stimuli used . In contrast, rs-fMRI can be easily implemented and standardized across sessions and locations but, again, analytic methods vary widely. These relative strengths and weaknesses are critical to consider when examining the effects of COTs and reinforce the need for a more nuanced review of the available literature.With the above noted caveats in mind, the current review specifically addressed the following questions: (1) Which types of COT have been applied to MCI patients? (2) Can COT effects in persons with MCI be generalized/transferred to objective cognitive measurements? (3) Do the observed changes represent evidence of compensation  and/or restoration ?Studies focusing on the main objective of this systematic review published up to August 2018 were included. We selected only those studies that fulfilled the following criteria: (1) studies that primarily evaluated the effects of the cognitive training in patients with amnestic single- or multiple-domain MCI using fMRI, (2) the MCI patient sample having met Petersen or Albert's criteria   or Jack/Databases included were PubMed, Medline, and Google Scholar. The search terms were specified to be found in the title of the studies and were (1) mild cognitive impairment, (2) cognitive training, (3) attention training, (4) executive training, (5) memory training, (6) and fMRI. The search terms combinations in the database were (1) + (6) + (2), (1) + (6) + (3), (1) + (6) + (4), and (1) + (6) + (5).A summary of the study selection is shown in Key details for the selected COT studies are presented in A total of 3 studies applied rehearsal-based strategies as the primary intervention, all of which used computerized cognitive training. One randomized controlled trial  investigAnother study of 21 patients with MCI adopted the vision-based speed-of-processing (VSOP) training from the INSIGHT computerized program  with five training tasks: (1) eye for detail, (2) peripheral challenge, (3) visual sweeps, (4) double decision, and (5) target tracker . These tRecently, 23 MCI patients underwent a computerized cognitive training and a separate group of 14 MCI patients underwent a regime of intense social engagement as a control condition . The comFour studies used fMRI to investigate the neurophysiologic changes associated with MST. In the first, Belleville et al.  trained Hampstead et al.  investigIn a subsequent single blind randomized controlled study, Hampstead et al.  used theBalardin et al.  investigp = 0.136). The authors argued that this lack of significant difference was due to possible insufficient power and reduced exposure to the training regimen ; however, this stands in contrast with the above note MST studies that found effects with substantially fewer sessions. Another important factor is the type of outcome measure used in clinical trials of cognitive training  on episodic memory tasks including the RBANS  and worOverall, although the majority of the studies in this review found evidence of improvement in objective cognitive measures, there is still a lack of studies showing generalization effects to everyday life activities. Hampstead et al. , 20 showUp to the present time and to the best of our knowledge, only seven randomized or controlled group fMRI studies have investigated the brain regions or networks systems underlying the effects of COTs in persons with MCI. In the last decade, there has been a marked advance in the neuroimaging methods of analyses from comparing the patterns of brain activation through fMRI before and after cognitive intervention to functional brain connectivity. The majority of the studies included in this review showed significant changes in brain activation associated with cognitive training, in typical and atypical brain areas and networks related to memory, suggestive of compensation. Some studies reported functional normalization and possible restoration processes. Changes on brain activation and connectivity related to cognitive intervention reported by these studies are displayed in Rosen et al.  and HampIn Belleville et al. , 15 MCI Balardin et al.  examinedn = 10; INSIGHT online program from Posit Science, San Francisco, CA), and the control group Mental Leisure Activities Control . The experimental group showed reduced central executive network connectivity possibly related to reduced frontal lobe–oriented dependence and better efficiency of information processing. They also reported maintenance of DMN connectivity, which was viewed as a positive outcome since progressive decrease was expected in MCI.Lin et al.  investigDe Marco et al.  includedOverall, the results of studies evaluating the efficacy of COTs indicate that persons with MCI benefit from COTs, with evidence of direct training gains and some transfer effects. In addition, MCI individuals are able to systematically practice cognitive tasks and learn several strategies to optimize cognitive functioning. The neuroimaging findings showed that COTs frequently led to an increase in brain activation  and either an increase or maintenance in connectivity. The available evidence suggests that the brain remains highly plastic in those with MCI and that neuroimaging is sensitive to change after COTs, thereby suggesting that neuroimaging can reasonably serve as an outcome measure for interventional studies.Based on our previous methodological review , we cateAll the studies related to the MST-based approach reported significant cognitive improvement and increased activation in lateral frontoparietal regions. This finding is in line with the fact that MST requires the user to actively hold and manipulate to-be-learned information, a process that engages cognitive control mechanisms such as working memory. Moreover, critical areas relevant to memory processing  also showed increased activation after training . TogetheThe current literature suggests that changes after COTs can represent both restoration and compensation. This conclusion is consistent with the Interactive model proposed by Belleville and colleagues  that sugLimitations of this review include the following. First, all of the studies classified the MCI individuals based on clinical/cognitive criteria but none included biomarker data . While beneficial for general clinical practice, it is difficult to know whether these groups represent a uniform etiology . This aspect is particularly relevant given the longitudinal nature of intervention trials and neuroimaging-related changes that are attributable to the development and worsening of Alzheimer's disease versus other processes . Second, although the majority of the studies in this review found evidence of improvement in objective cognitive measures, there is still a lack of measures specifically designed to evaluate the cognitive process trained, and, critically, transfer effects to everyday life activities. Future research should develop and validate new tools that better emulate real-world problems that patients experience. We believe that technologies such as virtual reality hold promise in this regard. Third, most of the studies included are based on small sample sizes, since the range of MCI participants in the experimental group was 6 to 17 individuals. Although the current evidence is encouraging, the fact that there are only 7 studies limits definitive conclusions.In conclusion, this review provides some initial understanding of the impact of COTs on cognition and brain mechanisms in individuals with MCI. The efficacy of the COTs will be enhanced if future studies replicate the current methodologies in larger samples and/or apply the same programs in different samples and sites.


Recent evidence indicates that translational control of gene expression plays a major role in determining protein levels, and is intricately involved in different forms of intrinsic and synaptic plasticity. In this review, we summarize findings supporting a key role for translational control in spinal cord-dependent mechanisms of chronic pain, and present recent approaches to reverse persistent pain by targeting these mechanisms.Chronic pain is a pathological condition characterized by long-lasting pain after damaged tissue has healed. Chronic pain can be caused and maintained by changes in various components of the pain pathway, including sensory neurons, spinal cord and higher brain centers. Exaggerated sensitivity and responsiveness of spinal nociceptive circuits, representing maladaptive plasticity, play key roles in the amplification of peripheral signals in chronic pain conditions. This spinal amplification mechanism profoundly contributes to the development and maintenance of chronic pain hypersensitivity in response to peripheral injury, and in some cases occurs independently of the peripheral stimulus. Long-lasting changes in the activity of spinal neurons are caused by alterations in their cellular proteome, which relies on  Peripheral injury causes acute pain, which is essential for an organism’s survival by ensuring quick withdrawal from harmful or potentially harmful stimuli. Under most circumstances, pain resolves shortly after damaged tissue heals. However, in some cases, the pain does not subside and persists after full tissue recovery. This type of pain, called chronic pain, does not serve any protective function and is likely driven by pathological changes that can arise in different components of the pain pathway. Long-lasting sensitization of primary sensory neurons and spinal nociceptive circuits, and plastic changes in brain regions, have all been associated with enhanced transmission and sensation of pain. In this review, we will focus on the spinal cord dorsal horn, which integrates inputs from peripheral and descending pathways to generate an output that is transmitted up to the brain. First, we will briefly describe the mechanisms underlying the sensitization of spinal pain circuits, and then present evidence for the role of translational control in the regulation of these processes.In chronic pain conditions, repeated or intense noxious stimuli lead to maladaptive plastic changes along the pain pathway, including a sensitization of spinal nociceptive circuits, a phenomenon known as central sensitization . CentralLong-lasting modulation of intrinsic excitability and synaptic functions relies on new gene expression. Gene expression can be modulated at different steps: transcription, mRNA translation, mRNA and protein stability, and post-translational modifications of protein. Translational control allows for the modulation of the cellular proteome by regulating the efficiency by which mRNA is translated into proteins. It provides neurons with a mechanism to quickly and locally respond to intracellular stimuli and extracellular cues by modifying their cellular or synaptic proteome.7Gppp), termed the “cap”. This structure facilitates ribosome recruitment to the mRNA . A critical member of this group is eIF4F, which is a three-subunit complex  composedeIF4E activity is also regulated via phosphorylation at serine 209 by MNK1/2 (mitogen-activated protein kinase (MAPK) interacting protein kinases 1/2) downstream of ERK  . This phiMet) and the GTP-bound eIF2. At the end of each round of ribosome recruitment, there is a recycling of inactive GDP-bound eIF2ɑ to active GTP-bound eIF2 by the guanine nucleotide exchange factor (GEF), eIF2B  , via pho), eIF2B . Phospho), eIF2B . PhosphoCamkIIα and Nr2a mRNAs  at their 3′ UTR is regulated by the cytoplasmic polyadenylation element-binding protein (CPEB) . CPEB bi2a mRNAs .Synaptic plasticity refers to the ability of the synapse to strengthen or weaken in response to experience or stimuli. The predominant cellular model for synaptic plasticity is long-term potentiation (LTP), which is thought to underlie learning and memory . Co-actiMost of the current knowledge on the role of translational control in neuroplasticity has been derived from experiments in the hippocampus, however recent studies show that similar mechanisms regulate activity-dependent long-term modification of synaptic strength in other brain areas including cortex, amygdala, and spinal cord .Studies of spinal LTP and central sensitization have demonstrated a significant overlap with underlying mechanisms known in hippocampal LTP and memory formation . LTP of −/−Eif4ebp1 mice lacking the translational repressor 4E-BP1 show a reduced threshold for the induction of spinal LTP as well as an increased extent of potentiation  phase . Thus, sntiation . These rNumerous studies have documented increased activity in signaling pathways upstream of mRNA translation in spinal neurons following acute noxious peripheral stimulation and also in chronic pain conditions. Intraplantar capsaicin  or carraThe functional role of the stimulation of protein synthesis in spinal neurons following peripheral injury has been extensively studied using various pharmacological approaches. Subcutaneous injection of formalin elicits a biphasic pain response. The early phase pain behaviour (0–10 min) is mediated by activation of nociceptors, whereas the second phase (10–50 min) is thought to result from sensitization of spinal pain circuits. Intrathecal administration of the protein synthesis inhibitor anisomycin, or mTORC1 inhibitor rapamycin, profoundly reduces nocifensive behaviour in the second phase of the formalin test but not the first phase . ConsistInhibition of mTORC1 also efficiently alleviates hypersensitivity in chronic models of pain including chronic inflammation-induced pain , bone caAnother important phenomena in which translational control in the spinal cord plays a central role is “hyperalgesic priming” . PeripheSensitization of spinal circuits can be caused not only by peripheral tissue damage and subsequent activation of C fibers, but also by aberrant spinal plasticity in response to drugs. Opioid-induced tolerance and hyperalgesia are two examples of such plasticity, which is commonly observed in both animal models and human patients . Opioid-in vitro finding was confirmed in an in vivo mouse study showing that repeated intrathecal morphine injections strongly induce mTORC1 signaling, and increase eIF4F complex formation and mRNA translation via activation of the μ-opioid receptor (Repeated intrathecal administration of morphine is sufficient to cause tolerance and hyperalgesia, suggesting that spinal cord plasticity plays a central role in these phenomena. Interestingly, a selective μ-opioid agonist, DAMGO, stimulates the AKT/mTORC1 axis and its downstream effectors 4E-BP1 and p70 S6 in non-neuronal cell lines stably expressing the μ-opioid receptor . This inreceptor . Remarkareceptor . A recenreceptor . IntrathNew gene expression is required for the induction phase of spinal sensitization, but not for its maintenance. As soon as sensitization is established, it is no longer sensitive to the inhibition of protein synthesis . Likewis1/D5 receptors coupled with anisomycin reversed persistent sensitization in primed animals (The central role of synaptic plasticity in the reconsolidation phenomenon is further supported by LTP experiments . The ful animals .The results of pain reconsolidation studies provide a potential novel therapeutic avenue to abolish established sensitization of nociceptive circuits in the spinal cord in chronic pain states. Reactivating the pain memory trace and transforming it into the labile state might allow for erasure of persistent pain via blocking reconsolidation using protein-synthesis inhibitors. Notably, the re-opening of the reconsolidation window by spinal application of AMPA and NMDA could be used for a variety of chronic pain states, where the sensitisation-inducing stimulus is unknown or may no longer be relevant.Maladaptive plasticity in the spinal cord is a key mechanism for sensitization of pain circuits and the subsequent development of pain. A central role of translational control in the regulation of synaptic and intrinsic neuronal plasticity in the spinal cord provides an opportunity to target translation control mechanisms to reverse the sensitization state. Recently discovered approaches to open the reconsolidation window by peripheral or central reactivation of nociceptive circuits or activation of dopaminergic pathways provide a promising therapeutic avenue. To fully understand the role and mechanisms of action of translation control in pathological pain states, it is essential to identify the subsets of differentially translated mRNAs in different cell types, pain states and phases of spinal cord sensitization. This information would provide an invaluable resource for better understanding the molecular mechanisms underlying the sensitization of spinal pain circuits and chronification of pain.The authors declare that they have no conflicts of interest.


Streptomyces chartreusis consists of 14 genes (tunA to tunN) with a high degree of apparent translational coupling. Transcriptional analysis revealed that all of these genes are likely to be transcribed as a single operon from two promoters, tunp1 and tunp2. In-frame deletion analysis revealed that just six of these genes (tunABCDEH) are essential for tunicamycin production in the heterologous host Streptomyces coelicolor, while five (tunFGKLN) with likely counterparts in primary metabolism are not necessary, but presumably ensure efficient production of the antibiotic at the onset of tunicamycin biosynthesis. Three genes are implicated in immunity, namely, tunI and tunJ, which encode a two-component ABC transporter presumably required for export of the antibiotic, and tunM, which encodes a putative S-adenosylmethionine (SAM)-dependent methyltransferase. Expression of tunIJ or tunM in S. coelicolor conferred resistance to exogenous tunicamycin. The results presented here provide new insights into tunicamycin biosynthesis and immunity.The tunicamycin biosynthetic gene cluster of  Streptomyces species, including Streptomyces chartreusis (N-acetylglucosamine (GlcNAc), and variable fatty acyl moieties  and resulting in severe toxicity. While the bacterial  and human (DPAGT1) targets are similar, in principle, it may be possible to design tunicamycin variants that specifically inhibit the bacterial proteins. A better understanding of tunicamycin biosynthesis and of the genes responsible for the individual steps in its production could play an important role in the delivery of such analogues. In an earlier work, we cloned and sequenced the tunicamycin biosynthetic gene cluster (tun) from S. chartreusis, expressed it heterologously in Streptomyces coelicolor, and proposed a biosynthetic pathway based largely on homology of the encoded gene products with proteins of known function . Amplification of cDNA spanning each of the gene junctions  experiments were carried out using the S. coelicolor RNA preparation, and also RNA from S. chartreusis using five different primers, RACE1 to RACE5 (Table S1). Two putative transcriptional starts sites (tunp1 and tunp2) were identified in RNA isolated from S. chartreusis and located within the SacI fragment; while the tunp2 transcript was not observed in RNA from S. coelicolor/pIJ12003a, transcription initiation at the promoter, aprp, of the apramycin resistance gene present in the cloning vector was detected (in vivo (as opposed to mRNA processing or degradation), PCR fragments were generated that contained each individual putative promoter element, inserted into the β-glucuronidase reporter plasmid pGUS  of this likely detected . To assemid pGUS  and intror tunp2 , consistS. coelicolor under conditions of nitrogen limitation is dependent on the intracellular signaling molecular ppGpp  agar containing X-gluc; no differences in promoter activity were observed between the two strains (data not shown).Antibiotic production in ar ppGpp . To assetunB abolished tunicamycin production and provided new insights into its likely role in tunicamycin biosynthesis  analyses of culture supernatants obtained from the individual tunFGKLMN mutants confirmed retention of tunicamycin biosynthesis (very low for tunF), while supernatants from the mutants lacking antimicrobial activity failed to show the typical characteristic tunicamycin mass spectrum of the wild-type gene cluster  or in pSET152 (tunF) under the control of the constitutive ermE* promoter and introduced into the S. coelicolor derivative containing the corresponding mutated tun gene cluster. With the exception of tunA (see Discussion), antimicrobial activity against B. subtilis was restored in the nonproducing strains and was markedly increased in the tunFGK mutants . A comparative untargeted metabolomics analysis  in which antibiotic activity had been lost. Bioactivity was assessed by overlaying the cross-feeding and coculture plates with a lawn of B. subtilis cells. In no case was antibiotic production restored (data not shown).An attempt was then made to identify the production of tunicamycin biosynthetic intermediates by cross-feeding and coculture experiments, using all possible pairwise combinations of mutants  and a complete loss of activity (the ΔtunIJ-B phenotype). Introduction of pIJ12551::tunIJ into each of the mutants had no significant effect on their phenotypes  that would result in the production of a TunGH fusion protein. While earlier deletion of tunG reduced tunicamycin production, mutation of tunH, which encodes a putative UDP-tunicaminyl-uracil pyrophosphatase, abolished it. Thus, the frameshift mutation may have resulted in a fusion protein with little or no TunH activity and may have also markedly reduced or abolished translation initiation at the natural tunH start codon, thus resulting in markedly reduced levels of tunicamycin production.Sequencing of the tun gene cluster in the ΔtunIJ-B mutant revealed a frameshift mutation in tunD, which is predicted to encode the glycosyltransferase required for addition of an N-acetylglucosamine moiety to tunicaminyl-uracil. The insertion of a G after the codon for threonine 279, while leaving glycine 280 and proline 281 unchanged, would replace the C-terminal 191-aa residues of the 472-aa TunD protein with 107 residues of presumably nonfunctional protein , likely accounting for the lack of bioactivity and failure to complement the mutation.Sequencing of the tunI alone yielded the same two mutant phenotypes  observed as when tunI and tunJ were deleted simultaneously; introduction of pIJ12551::tunI into each of the mutants had no significant effect on their phenotypes  was confirmed by sequencing and introduced into S. coelicolor M1152, whereupon it gave the same phenotype as the tunI-A mutant, i.e., a much-reduced level of antimicrobial activity . Sequencing of the tun gene cluster in the ΔtunI-B mutant revealed a G to A missense mutation in tunC that would result in a Gly to Asp substitution at position 70 of the putative 318-aa N-acyltransferase, presumably resulting in loss of enzyme function and lack of tunicamycin production.In-frame deletion of enotypes . SequenctunJ alone resulted in loss of antibiotic production that could not be complemented by introduction of pIJ12551::tunJ  that must have occurred when pIJ12003a was passaged through E. coli for mutant construction. Insertion of IS10 occurred after nucleotide 12871 of GenBank accession number HQ172897 and resulted in the duplication of residues 12863 to 12871. The time taken for the emergence of the S. coelicolor M1152 exconjugants containing the tunJ deletion was normal for an E. coli-Streptomyces conjugation, in contrast to the prolonged period required for emergence of the tunI suppressor mutants, and was consistent with insertion of IS10 into tunD in E. coli.In-frame deletion of 51::tunJ ; subsequtunIJ mutants with wild-type copies of the genes.In all five cases, the unexpected mutations were presumably not only responsible for the lack of bioactivity, but also for the failure to complement the tunIJ also played a role in conferring immunity to the antibiotic in the producing organism, and that their deletion resulted in lethality or the selection of mutations that abolished or markedly reduced the level of tunicamycin production. To assess the potential role of these genes in immunity, S. coelicolor derivatives containing the wild-type tun gene cluster and derivatives from which tunIJ, tunK, tunL, tunM, or tunN had been deleted were plated as lawns on R5 agar, and their susceptibility to tunicamycin was assessed. While the wild-type gene cluster conferred complete immunity to exogenous tunicamycin, deletion of tunIJ and, surprisingly, of tunL and tunM, resulted in increased sensitivity, although all three deletion mutants were noticeably more resistant than the strain containing the empty vector (pRT802)  . DeletiotunIJ, tunL, or tunM alone could confer immunity to tunicamycin in S. coelicolor, the pIJ12551 expression constructs containing each of the genes that had been used in the earlier complementation assays were introduced into S. coelicolor M1152 by conjugation, and the resulting strains were used in tunicamycin susceptibility assays. Expression of either tunIJ or tunM from the ermE* promoter conferred complete immunity, while expression of tunL resulted in the same level of susceptibility as that of the vector control .Although the presence of promoter elements within the cluster cannot be excluded, the results presented in this paper suggest that all of the genes in the tunicamycin biosynthetic gene cluster are cotranscribed in tunA mutant using both the ermE* and native tunA promoter (data not shown) failed. Similar observations were made for mibA, the 5′ gene in a polycistronic mRNA that is essential for microbisporicin biosynthesis in Microbispora corallina . It is conceivable that this reflects an essential element of posttranscriptional control that operates on the 5′ end of the tun operon transcript that is absent in the tunA deletion mutant.Repeated attempts to complement the tun gene cluster just six (tunABCDEH) are essential for tunicamycin production in S. coelicolor, each of which can be assigned a likely biosynthetic role tunI and tunJ are required for immunity. Of the others, tunFGKLN all have putative roles also carried out by homologues involved in primary metabolism, potentially explaining their nonessentiality. This would require that the primary metabolic enzymes were capable of substituting for their Tun counterparts if the latter were indeed present in the hypothetical tunicamycin biosynthetic complex (see above); alternatively, the complex might only contain the essential enzymes, TunABCDEH. The presence of tunFGKLN within the tun gene cluster may be to ensure adequate precursor supply and/or flux at the onset of tunicamycin production, feeding the likely critical C-C bond-forming step (tunFGN) and efficient acylation from the endogenous fatty acid pool during biosynthesis (tunKL)  that are likely involved in primary metabolism, it is conceivable that this disparity reflects differences in the heterologous hosts and growth conditions used in the two studies. Given the very low level of tunicamycin production in the tunF mutant, it is also possible that a homologous host epimerase  is responsible for partial suppression of tunF oblation. The deletion analysis reported here rules out the previously assigned role for TunM in tunicamycin biosynthesis  targets of the antibiotic (or indeed by modification of one of their substrates in a manner that would afford sufficient substrate protection to prevent tunicamycin from binding to any corresponding complex).The deletion analysis reported here and previously  has demoactivity . The abin et al. , where tEscherichia coli strains were grown and manipulated following standard methods  and subjected to PCR, using the primer pairs listed in Table S1. pIJ12003a was used as a positive control, and RNA that had not been treated with reverse transcriptase was used as a negative control. The 5′ ends of the tun transcripts present in both RNA samples were identified by using a 5′ rapid amplification of cDNA ends (RACE) kit  following the manufacturer's instructions. Briefly, first-strand cDNA synthesis was carried out using 5 μg of RNA, reverse transcriptase and the oligonucleotide primer RACE1 (Table S1). cDNA was purified using the SNAP columns provided in the kit, and poly(dC) tails were added to the 3′ ends using terminal deoxynucleotidyl transferase. PCR amplification of the tailed cDNA was initially carried out using the 5 ′ RACE abridged anchor primer with the first-strand primer RACE2 or RACE4 (Table S1). A dilution of the PCR mixture was then subjected to a second amplification using the abridged anchor primer with the second nested primer RACE3 or RACE5 (Table S1). The PCR product was gel-purified and a portion sequenced directly using the oligonucleotide RACE3 or RACE5 as primer.RNA was prepared from lawns of mycelium approximately 30 mm in diameter of DNA agar , 24, resS. coelicolor M1152, M145, and M571  was determined by plating the exconjugants on R5 and SMMS agar medium (H-indol-3-yl beta-d-glucopyranosiduronic acid) .The DNA fragments to be assessed for promoter activity were cloned individually as XbaI-KpnI PCR fragments in pGUS  and clear medium  containitunACDEGHIJKLMN mutants, the 12.9-kb SacI fragment of pIJ12003a, a derivative of pRT802 (apr) replacement cassettes generated using the PCR primers listed in Table S1 and pIJ773 as the template DNA, and the cassettes were subsequently deleted using FLP recombinase to give in-frame deletion mutants; in all cases, the ribosome-binding site of the downstream gene was retained in the mutant construct. The SacI fragments from the resulting plasmids were subcloned into pRT802, and those with the fragment inserted in the same orientation as in pIJ12003a (determined by restriction enzyme digestion) were selected for further study. To construct the tunF mutant, pIJ12003a was targeted in the same manner (see Table S1 for the primers used) to yield the mutant derivative pIJ12542. Each of the mutated plasmids was introduced into E. coli ET12567/pR906 . The PCR products for tunACDEGHIJK were cleaved with NdeI and PacI and inserted into pIJ12251  was melted, cooled to 55°C, and inoculated with a one-tenth volume of a mid-logarithmic growth culture of B. subtilis EC1524. Cylindrical plugs (approximately 8 mm in diameter) were cut from the Streptomyces lawns using a cork borer and were either set into or laid on top of 40 ml of the SNA inoculated with B. subtilis EC1524 in a 10-cm2 plastic petri dish, which was then incubated overnight at 30°C.Lawns of the strains to be assayed were made by spreading approximately 107 spores in 100 μl of water onto R5 plates, which were allowed to dry for 20 min. Filter paper discs with various amounts of tunicamycin (dissolved in DMSO) were laid onto the lawns, and the plates were incubated at 30°C for 48 h.Lawns of the strains to be assayed were made by spreading approximately 10


One of the greatest challenges facing the field of organ transplantation is the shortage of donor organs for transplantation. Renal transplantation increases quality of life and survival of patients suffering from end-stage renal disease. Although kidney transplantation has evolved greatly over the past few decades, a not insignificant amount of injury occurs to the kidney during recovery, preservation, and implantation and leads to the loss of function and loss of years of dialysis-free living for many patients. The use of kidneys from expanded criteria donors (ECD) and donation after circulatory determination of death (DCDD) has been adopted partly in response to the shortage of donor kidneys; however these kidneys are even more susceptible to ischemic injury. It has been shown that matrix metalloproteinases (MMPs) and reactive oxygen species (ROS) are involved in mechanisms of injury to the transplant kidney. There is also some evidence that inhibition of MMP activity and/or ROS production can protect the kidney from injury. We review possible pharmacological strategies for protection of kidney graft from injury during recovery, preservation, and implantation. Kidney transplantation increases quality of life and life expectancy in patients suffering from end-stage renal disease compared to renal dialysis. In an effort to increase the number of kidneys available for transplantation in the face of ongoing donor organ shortage, the use of kidneys from more marginal donors has been increasing. This includes kidneys from older donors and those with cardiovascular diseases, such as hypertension (expanded criteria donors (ECD)), as well as donation after circulatory determination of death (DCDD). Both ECD and DCDD kidneys are associated with poorer initial function, a higher rate of delayed graft function (DGF) and poorer function at one year after transplantation . FurtherAlthough kidney transplantation has evolved greatly over the past few decades, the fact remains that, in the process of removing a kidney from a donor, flushing, and cooling it, then rapidly rewarming it once its blood vessels are connected in the recipient, significant injury occurs to the kidney and leads to loss of function as well as loss of years of dialysis-free living of these patients.Ischemia-reperfusion injury (IRI) is an inevitable relevant outcome of kidney transplantation. Kidneys from DCDD are highly sensitive to IRI, a complex pathophysiological process involving hypoxia and following reoxygenation, ionic imbalance, oxidative stress, and mitochondrial uncoupling, as well as a coagulation and endothelium activation associated with a proinflammatory immune response. The main consequences of renal IRI are kidney graft primary nonfunction and delayed graft function or chronic graft dysfunction, all of which involve a mandatory patient's return to dialysis. The incidence of delayed graft function varies greatly, ranging from 10% when using living donor kidneys to more than 50% for DCDD kidneys . In addiMinimizing kidney injury would be a tremendous benefit to patients who are waiting for kidney transplant. By potentially broadening the pool of kidneys that could be acceptable for transplantation purposes, the optimization of kidney preservation and reduction of injury is of great importance in kidney transplantation.During the process of transplantation from one person to another, the kidneys are subjected to ischemic injury, when the blood flow supply is either interrupted or severely disturbed as well as reperfusion injury become as a consequence of the blood flow reconstruction. Injury occurs first time during the procurement , then a second time during the preservation , and a third time at the time of reperfusion and reoxygenation.Warm ischemic time lasts from stopping of blood flow through the donor organ until cold perfusion is commenced (WIT I). WIT I differs regarding type of donors: it lasts just a few minutes for living donors, much longer for DCDD donors and it is minimal for donation after neurological determination of death (DNDD) donor kidneys. A period of relative ischemia between withdrawal of life supporting treatments and asystole can last from a few minutes to one and a half hours or even 2 hours depending on the program and factors specific to each DCDD donor. Prolonged time of warm ischemia in DCDD leads to greater damage of transplanted kidney compared to donation after brain death (DBD) with all the consequences: poorer initial as well as long-term functions, DGF, and higher risk of rejection , 13. ThiWIT II relates to vascular anastomosis   and thisCold ischemia time also has an impact on the graft outcome after transplantation. Prolongation of CIT may predispose to DGF and lead to reduced graft survival and even patient survival , 16. UnfStatic cold storage in which the preservation solution is infused into the organ to flush out the blood and then the organ is immersed in the preservation solution for storage remains the most often used method for kidney preservation. Numerous preservation solutions have been developed to prevent the biochemical and structural changes that occur during the process of graft cooling and reperfusion. However, the amount of time that ECD or DCDD kidneys can be safely preserved in this manner remains limited, highlighting the need for novel strategies to improve kidney preservation and recovery .via the artery). Machine cold perfusion of transplant kidneys has shown benefit in terms of both early and long-term function [ Regardless, the 4 to 36 or more hours' period when a kidney is “on the pump” seems to be a strategic time for pharmacological interventions to help in protecting the kidney from IRI.Machine cold perfusion allows preservation solution to circulate continuously through the kidney for 4 to 48 hours  concentration, while reperfusion results in reoxygenation, and a return to aerobic metabolism. The disorders triggered during ischemia cause injury or death of tubular epithelial cells and the following reperfusion further enhances this damage as large amount of deleterious reactive oxygen species is generated . ROS are+/K+ ATPase and accumulation of its metabolites: adenosine, inosine, and hypoxanthine. Under nonischemic conditions, the latter one is a substrate of xanthine dehydrogenase but ionic imbalance during ischemia causes a calcium-triggered proteolytic conversion of xanthine dehydrogenase to xanthine oxidase which at the moment of reperfusion generates the superoxide free radical (O2•−) as a by-product of its action. Superoxide free radical generates secondary, more toxic reactive oxygen species: hydrogen peroxide (H2O2) and hydroxyl radical (•HO) [Prolonged ischemia increases metabolic demand and energy failure. As a consequence of anaerobic metabolism, decrease in cell pH is observed. Progressive depletion of ATP leads to inactivation of Naal (•HO) . Furtheral (•HO) .Mitochondria also play an important role in the cascade of organs' damage as a result of ischemia-reperfusion. An increase of membrane permeability and thus calcium overload in the cell are observed. That triggers in turn the reduction of mitochondrial membrane potential and further inhibition of oxidative phosphorylation by impaired ATP production .Finally, ischemia-reperfusion injury is associated with neutrophil infiltration. Leukocytes mediate microvascular injury by release of proteolytic enzymes and reactive oxygen species generation. Moreover peroxynitrite, which has strong oxidizing properties, is generated during IRI. It is an additional agent triggering damage of molecules in cells including DNA and proteins .The main factors contributing to kidney's damage during IRI are (a) oxidative stress, (b) accumulation of calcium in the cytosol, (c) mitochondrial uncoupling, and (d) a release of iron ions and inflammatory immune response .Ischemia All above-mentioned factors contribute to necrosis or apoptosis of tubular epithelial cells. As renal tubular atrophy occurs, progressive deterioration of kidney graft function is observed .Matrix metalloproteinases (MMPs) are a family of more than 25 structurally related proteolytic enzymes, which play important roles in a variety of physiological processes, including morphogenesis, cartilage and bone repair, wound healing, cell migration, and angiogenesis .2+ bond can be induced by ROS, such as peroxynitrite (ONOO−) and its derivatives. MMPs might be also regulated by naturally occurring protein inhibitors  [2+ [MMPs activity is regulated at multiple levels including transcription, modulation of mRNA half-life, secretion, localization, activation, and suppression by specific and nonspecific proteinase inhibitors . They ar, TIMPs) . Among sMPs) [2+ . HoweverMPs) [2+ . Many diMMPs have long been implicated in fibrotic renal diseases. MMP-2 is involved in renal ischemia-reperfusion injury in an animal model whereby warm ischemia was induced on MMP-2 deficient transgenic mouse model . The deg ex vivo rat model of cold perfusion confirmed that doxycycline protects the kidney from injury during cold preservation [ In conclusion, it has been shown that inhibition of MMPs may be a novel strategy for protection of the transplant kidney. The addition of pharmacological agents, as doxycycline, during preservation might reduce the damage of the kidneys .MMPs play an important role in the injury of the transplanted kidney as well. Since MMPs are increased in patients with chronic antibody mediated rejection and in the fibrotic renal diseases, MMPs have been suggested to be a common pathway for chronic allograft nephropathy in the transplanted kidney . On the ervation . What iservation , supportDuring ischemia, cell swelling caused by ATP depletion increases the osmotic gradient that drives water into the mitochondrial matrix to causes matrix swelling . Thirty 2•−) and hydroxyl radical (HO•) and certain nonradicals that either are oxidizing agents or are easily converted into radicals, such as hydrogen peroxide (H2O2) and hypochlorous acid (HOCl). ROS generation triggers a cascade of reactions starting with the production of O2•− which can be further converted to H2O2 by superoxide dismutases (SOD), manganese superoxide dismutase (MnSOD) in mitochondria, and copper-zinc superoxide dismutase (CuZnSOD) in cytosol. The main sinks for H2O2 are catalase (CAT) and glutathione peroxidase (GPx). The latter uses glutathione (GSH) which is oxidized to GSSG and recycled by glutathione reductase. There are other enzymes that can remove H2O2, such as peroxiredoxin/thioredoxin/thioredoxin reductase (Prx/Trx/TrxR) system. However, CAT activity is about three orders of magnitude higher compared to Prx/Trx/TrxR system which is essential under physiological settings for keeping low levels of mitochondrial H2O2 emission and for normal redox signaling via regulation of thiol redox switches on different proteins [Oxidative stress results from an imbalance between the formation and the neutralization of prooxidants, such as superoxide radical anion .Increased ROS production causes activation of p38 mitogen-activated protein kinase (MAPK) signaling which participates in gene regulation of MMPs, especially MMP-2 and MMP-9 . It was ∙) and peroxynitrite (ONOO−), are produced in kidney IRI by inducible NO synthase (iNOS) in tubule cells. Its activity leads to producing NO in high concentration. Then, NO rapidly interacts with O2•− to form ONOO− which trigger cell damage, oxidant injury, and protein nitrosylation [Besides ROS, reactive nitrogen species (RNS), such as nitric oxide  have been shown to protect against ischemic AKI in animals, but human studies have been inconclusive [Hence due to increased ROS/RNS production over the course of cold preservation and reoxygenation the inhibition of H studies . Studiesnclusive .The relatively unsatisfactory efficiency of conventional antioxidants may be the consequence of their low penetrance to the mitochondria interior, which suffer from oxidative stress as other cellular compartments. The inner mitochondrial membrane is highly impermeable and rich in cardiolipin and maintains a strong negative internal potential that is required for the function of electron transport chain . To over2S) treatment. Supplementation of standard organ preservation solution with H2S decreased the severity of graft injury associated with prolonged cold ischemia time in rat models of kidney transplantation. H2S significantly reduced the graft inflammation, expression of proinflammatory markers and progression of tissue necrosis compared to kidneys stored in standard solution. Additionally, H2S limits renal cellular oxidative damage through preservation of mitochondrial membrane integrity [ To sum up, treatment of donor kidneys with gasotransmitters (H2S or CORM-3) during prolonged cold storage might improve survival and recovery of allograft function during the acute posttransplant period.To effectively improve clinical outcomes of kidney transplant, gasotransmitters has recently been identified as a potential therapeutic strategy to minimize renal IRI during transplantation . Gasotrantegrity . To sum Renal injury during the process of transplantation is a complex issue which has become an important topic in transplantation research in recent years. The shortage of donor organs has necessitated the use of kidneys from marginal donors such as DCDD and ECD donors. However, these organs are more sensitive to injury and DCDD or ECD transplantations result in inferior outcomes compared with living donor kidneys and DNDD kidneys. Therefore, the ability to minimize of graft injury would be a tremendous benefit to patients who are waiting for a kidney transplant by helping with initial function, by potentially increasing the longevity of kidney transplants, and by broadening the donor pool of kidneys that could be acceptable for transplant purposes. In the case of ECD and DCDD donor kidneys, the optimization and reduction of WIT and CIT have become an important topic in transplantation.Machine cold perfusion of transplant kidneys has shown benefits in terms of both early and long-term function of the organ . The useOxidative stress is an element of the cascade of processes participating in IRI. What is more, an excessive production of ROS and RNS not only directly participates in tissue damage but also has an influence on MMPs activity . The oxiPharmacological prevention of renal IRI can result in the ability to use some of marginal donor kidneys that normally would be rejected during qualification for transplantation and help to decrease the gap between the numbers of patients on the wait list and the number of donor organs that are able to be transplanted.