Investigation of de novo mutations in a schizophrenia case-parent trio by induced pluripotent stem cell-based in vitro disease modeling: convergence of schizophrenia- and autism-related cellular phenotypes.
BACKGROUND
De novo mutations (DNMs) have been implicated in the etiology of schizophrenia (SZ), a chronic debilitating psychiatric disorder characterized by hallucinations, delusions, cognitive dysfunction, and decreased community functioning. Several DNMs have been identified by examining SZ cases and their unaffected parents; however, in most cases, the biological significance of these mutations remains elusive. To overcome this limitation, we have developed an approach of using induced pluripotent stem cell (iPSC) lines from each member of a SZ case-parent trio, in order to investigate the effects of DNMs in cellular progenies of interest, particularly in dentate gyrus neuronal progenitors.


METHODS
We identified a male SZ patient characterized by early disease onset and negative symptoms, who is a carrier of 3 non-synonymous DNMs in genes LRRC7, KHSRP, and KIR2DL1. iPSC lines were generated from his and his parents' peripheral blood mononuclear cells using Sendai virus-based reprogramming and differentiated into neuronal progenitor cells (NPCs) and hippocampal dentate gyrus granule cells. We used RNASeq to explore transcriptomic differences and calcium (Ca2+) imaging, cell proliferation, migration, oxidative stress, and mitochondrial assays to characterize the investigated NPC lines.


RESULTS
NPCs derived from the SZ patient exhibited transcriptomic differences related to Wnt signaling, neuronal differentiation, axonal guidance and synaptic function, and decreased Ca2+ reactivity to glutamate. Moreover, we could observe increased cellular proliferation and alterations in mitochondrial quantity and morphology.


CONCLUSIONS
The approach of reprograming case-parent trios represents an opportunity for investigating the molecular effects of disease-causing mutations and comparing these in cell lines with reduced variation in genetic background. Our results are indicative of a partial overlap between schizophrenia and autism-related phenotypes in the investigated family.


LIMITATIONS
Our study investigated only one family; therefore, the generalizability of findings is limited. We could not derive iPSCs from two other siblings to test for possible genetic effects in the family that are not driven by DNMs. The transcriptomic and functional assays were limited to the NPC stage, although these variables should also be investigated at the mature neuronal stage.
['Hathy|Edit|E|', 'Szabó|Eszter|E|', 'Varga|Nóra|N|', 'Erdei|Zsuzsa|Z|', 'Tordai|Csongor|C|', 'Czehlár|Boróka|B|', 'Baradits|Máté|M|', 'Jezsó|Bálint|B|', 'Koller|Júlia|J|', 'Nagy|László|L|', 'Molnár|Mária Judit|MJ|', 'Homolya|László|L|', 'Nemoda|Zsófia|Z|', 'Apáti|Ágota|Á|', 'Réthelyi|János M|JM|0000-0002-3641-012X']
D001321:Autistic Disorder D006801:Humans D057026:Induced Pluripotent Stem Cells D007963:Leukocytes, Mononuclear D008297:Male D009154:Mutation D010641:Phenotype D016601:RNA-Binding Proteins D012559:Schizophrenia D012795:Sialoglycoproteins D015534:Trans-Activators
Schizophrenia DNM iPSC LRRC7 KHSRP RNASeq Proliferation Glutamate Autism Disease-modeling Mitochondrial function