Abstracts

Molecular determinants which modify activity synaptogenesis may form the core mechanistic components of cortical reorganization after brain injury. Semaphorin 3F (Sema 3F) signaling has been identified as a putative molecular determinant of activity dependent synaptogenesis in the mouse kainic acid model of epileptogenesis. The Sema 3F receptor is a multi-subunit complex composed of at least two proteins, Plexin A3, and Neuropilin 2 (NPN2)., The activity dependent regulation and structure of the mouse NPN2 promoter is detailed here., We have identified a 1.7 kb putative NPN2 promoter from the FVB/NJ (epileptogenic sensitive) and C57BL/6J (epileptogenic resistant strain) mouse strains. The distinct NPN2 promoters, in addition to common putative transcription factor binding sites, have six different single nucleotide polymorphisms (SNPs) that specify distinct putative transcription factor binding sites. The FVB/NJ NPN2 promoter has distinct activity dependent methylation sites, whereas these are absent in the C57BL/6J promoter. When the FVB/NJ nucleotide is substituted for C57BL/6J nucleotide, at least two sites, SNP site 2, and SNP site 6, reduce the activity of the C57BL/6J NPN2 promoter by 90%. These putative strain specific-enhancer sites may explain why NPN2 transcription is maintained in C57BL/6J hippocampal neurons but not FVB/NJ hippocampal neurons after kainic acid status epilepticus (KA-SE). In addition to regulation of the NPN2 transcription by glutamate receptors, we also report the NPN2 promoter may be regulated by reactive oxygen species. We have also determined the sequence of the human NPN2 promoter contains important SNPs distinguishing temporal lobe epilepsy patients from controls, which might be a biomarker or perhaps a causal factor in epilepsy. Promoter activity is an important determinant of NPN2 mRNA levels and thus sema 3F signaling; selective deletion of Sema 3F in the mature forebrain greatly facilitates epileptogenesis via PTZ kindling., This data provide preliminary support for the hypothesis that distinct alleles of synaptic plasticity genes may confer susceptibility for acquired epilepsy after brain injury., (Supported by NIH/NINDS, KSCHIRT, and PREP grant program.)