Irregular RNA splicing curtails postsynaptic gephyrin in the cornu ammonis of patients with epilepsy.
Anomalous hippocampal inhibition is involved in temporal lobe epilepsy, and reduced gephyrin immunoreactivity in the temporal lobe epilepsy hippocampus has been reported recently. However, the mechanisms responsible for curtailing postsynaptic gephyrin scaffolds are poorly understood. Here, we have investigated gephyrin expression in the hippocampus of patients with intractable temporal lobe epilepsy. Immunohistochemical and western blot analyses revealed irregular gephyrin expression in the cornu ammonis of patients with temporal lobe epilepsy and four abnormally spliced gephyrins lacking several exons in their G-domains were isolated. Identified temporal lobe epilepsy gephyrins have oligomerization deficits and they curtail hippocampal postsynaptic gephyrin and GABA(A) receptor α2 while interacting with regularly spliced gephyrins. We found that cellular stress (alkalosis and hyperthermia) induces exon skipping in gephyrin messenger RNA, which is responsible for curtailed postsynaptic gephyrin and GABA(A) receptor α2 scaffolds. Accordingly, we did not obtain evidence for gephyrin gene mutations in patients with temporal lobe epilepsy. Cellular stress such as alkalosis, for example arising from seizure activity, could thus facilitate the development of temporal lobe epilepsy by reducing GABA(A) receptor α2-mediated hippocampal synaptic transmission selectively in the cornu ammonis.
FU-Berlin, Fachbereich Biologie, Chemie, Pharmazie, Takustr. 3, 14195 Berlin, Germany.
Benjamin
B
Förstera
Abdel Ali
AA
Belaidi
René
R
Jüttner
Carola
C
Bernert
Michael
M
Tsokos
Thomas-N
TN
Lehmann
Peter
P
Horn
Christoph
C
Dehnicke
Günter
G
Schwarz
Jochen C
JC
Meier
D017398:Alternative Splicing / Q000235:genetics*; D000818:Animals; D015153:Blotting, Western; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000235:genetics* / Q000302:isolation & purification; D002478:Cells, Cultured; D003067:Coenzymes / Q000378:metabolism; D004247:DNA / Q000235:genetics; D004569:Electroencephalography; D055724:Electrophysiological Phenomena; D004833:Epilepsy, Temporal Lobe / Q000235:genetics* / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D049452:Green Fluorescent Proteins / Q000096:biosynthesis; D006624:Hippocampus / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics* / Q000302:isolation & purification; D008667:Metalloproteins / Q000378:metabolism; D018613:Microscopy, Confocal; D000090006:Molybdenum Cofactors; D018408:Patch-Clamp Techniques; D011621:Pteridines / Q000378:metabolism; D051381:Rats; D011963:Receptors, GABA-A / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012640:Seizures / Q000378:metabolism; D013569:Synapses / Q000378:metabolism*; D014162:Transfection
D002352:Carrier Proteins; D003067:Coenzymes; D004247:DNA; D049452:Green Fluorescent Proteins; D008565:Membrane Proteins; D008667:Metalloproteins; D000090006:Molybdenum Cofactors; D011621:Pteridines; D011963:Receptors, GABA-A; C484841:GABRA2 protein, human; C073441:gephyrin; C022261:molybdopterin