title: Status epilepticus-induced somatostatinergic hilar interneuron degeneration is regulated by striatal enriched protein tyrosine phosphatase.
abstract: Excitotoxic cell death is one of the precipitating events in the development of temporal lobe epilepsy. Of particular prominence is the loss of GABAergic hilar neurons. Although the molecular mechanisms responsible for the selective vulnerability of these cells are not well understood, activation of the extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) pathway has been implicated in neuroprotective responses to excitotoxicity in other neuronal populations. Here, we report that high levels of the striatal-enriched protein tyrosine phosphatase (STEP), a key regulator of ERK/MAPK signaling, are found in vulnerable somatostatin-immunoreactive hilar interneurons. Under both control conditions and after pilocarpine-induced status epilepticus (SE), ERK/MAPK activation was repressed in STEP-immunoreactive hilar neurons. This contrasts with robust SE-induced ERK/MAPK activation in the granule cell layer of the dentate gyrus, a cell region that does not express STEP. During pilocarpine-induced SE, in vivo disruption of STEP activity allowed activation of the MAPK pathway, leading to immediate-early gene expression and significant rescue from cell death. Thus, STEP increases the sensitivity of neurons to SE-induced excitotoxicity by specifically blocking a latent neuroprotective response initiated by the MAPK pathway. These findings identify a key set of signaling events that render somatostatinergic hilar interneurons vulnerable to SE-induced cell death.
authors.affiliation: Department of Neuroscience, Ohio State University, Columbus, Ohio 43210, USA.
authors.forename: Yun-Sik
authors.initials: YS
authors.lastname: Choi
authors.forename: Stanley L
authors.initials: SL
authors.lastname: Lin
authors.forename: Boyoung
authors.initials: B
authors.lastname: Lee
authors.forename: Pradeep
authors.initials: P
authors.lastname: Kurup
authors.forename: Hee-Yeon
authors.initials: HY
authors.lastname: Cho
authors.forename: Janice R
authors.initials: JR
authors.lastname: Naegele
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Lombroso
authors.forename: Karl
authors.initials: K
authors.lastname: Obrietan
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D018891:Dentate Gyrus / Q000201:enzymology* / Q000473:pathology; D007395:Interneurons / Q000201:enzymology* / Q000473:pathology; D020935:MAP Kinase Signaling System / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009410:Nerve Degeneration / Q000201:enzymology* / Q000473:pathology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D017027:Protein Tyrosine Phosphatases / Q000502:physiology; D054558:Protein Tyrosine Phosphatases, Non-Receptor; D051381:Rats; D017207:Rats, Sprague-Dawley; D013004:Somatostatin / Q000502:physiology*; D013226:Status Epilepticus / Q000201:enzymology* / Q000473:pathology
chemical_list: D047428:Protein Kinase Inhibitors; D013004:Somatostatin; D017027:Protein Tyrosine Phosphatases; D054558:Protein Tyrosine Phosphatases, Non-Receptor; C082101:Ptpn5 protein, mouse