Pumilio2-deficient mice show a predisposition for epilepsy.
Epilepsy is a neurological disease that is caused by abnormal hypersynchronous activities of neuronal ensembles leading to recurrent and spontaneous seizures in human patients. Enhanced neuronal excitability and a high level of synchrony between neurons seem to trigger these spontaneous seizures. The molecular mechanisms, however, regarding the development of neuronal hyperexcitability and maintenance of epilepsy are still poorly understood. Here, we show that pumilio RNA-binding family member 2 (Pumilio2; Pum2) plays a role in the regulation of excitability in hippocampal neurons of weaned and 5-month-old male mice. Almost complete deficiency of Pum2 in adult Pum2 gene-trap mice (Pum2 GT) causes misregulation of genes involved in neuronal excitability control. Interestingly, this finding is accompanied by the development of spontaneous epileptic seizures in Pum2 GT mice. Furthermore, we detect an age-dependent increase in Scn1a (Nav1.1) and Scn8a (Nav1.6) mRNA levels together with a decrease in Scn2a (Nav1.2) transcript levels in weaned Pum2 GT that is absent in older mice. Moreover, field recordings of CA1 pyramidal neurons show a tendency towards a reduced paired-pulse inhibition after stimulation of the Schaffer-collateral-commissural pathway in Pum2 GT mice, indicating a predisposition to the development of spontaneous seizures at later stages. With the onset of spontaneous seizures at the age of 5 months, we detect increased protein levels of Nav1.1 and Nav1.2 as well as decreased protein levels of Nav1.6 in those mice. In addition, GABA receptor subunit alpha-2 (Gabra2) mRNA levels are increased in weaned and adult mice. Furthermore, we observe an enhanced GABRA2 protein level in the dendritic field of the CA1 subregion in the Pum2 GT hippocampus. We conclude that altered expression levels of known epileptic risk factors such as Nav1.1, Nav1.2, Nav1.6 and GABRA2 result in enhanced seizure susceptibility and manifestation of epilepsy in the hippocampus. Thus, our results argue for a role of Pum2 in epileptogenesis and the maintenance of epilepsy.
['Follwaczny|Philipp|P|', 'Schieweck|Rico|R|', 'Riedemann|Therese|T|', 'Demleitner|Antonia|A|', 'Straub|Tobias|T|', 'Klemm|Anna H|AH|', 'Bilban|Martin|M|', 'Sutor|Bernd|B|', 'Popper|Bastian|B|0000-0003-1517-695X', 'Kiebler|Michael A|MA|0000-0002-8850-6297']
D000200:Action Potentials D000818:Animals D056547:CA1 Region, Hippocampal D003712:Dendrites D004827:Epilepsy D005786:Gene Expression Regulation D055785:Gene Knockdown Techniques D020022:Genetic Predisposition to Disease D008297:Male D008810:Mice, Inbred C57BL D017966:Pyramidal Cells D012333:RNA, Messenger D016601:RNA-Binding Proteins D011963:Receptors, GABA-A D012640:Seizures D015222:Sodium Channels
Epilepsy Pumilio2 PUM2 Risk factor Epileptogenesis RNA-binding protein