Anti-SNAP25 monoclonal antibody, clone 5D7

Schizophrenia is considered a neurodevelopmental disorder. Recent reports relate synaptic alterations with disease etiology. The inbred Roman High- (RHA-I) and Low- (RLA-I) Avoidance rat strains are a congenital neurobehavioral model, with the RHA-I displaying schizophrenia-related behaviors and serotonin 2A (5-HT2A) and metabotropic glutamate 2 (mGlu2) receptor alterations in the prefrontal cortex (PFC). We performed a comprehensive characterization of the RHA-I/RLA-I rats by real-time qPCR and Western blotting for 5-HT1A, 5-HT2A, mGlu2, dopamine 1 and dopamine 2 receptors (DRD1 and DRD2), AMPA receptor subunits Gria1, Gria2 and NMDA receptor subunits Grin1, Grin2a and Grin2b, as well as pre- and post-synaptic components in PFC and hippocampus (HIP). Besides corroborating decreased mGlu2 (Grm2) expression, we found increased mRNA levels for Snap25, Synaptophysin (Syp), Homer1 and Neuregulin-1 (Nrg1) in the PFC of the RHA-I and decreased expression of Vamp1, and Snapin in the HIP. We also showed alterations in Vamp1, Grin2b, Syp, Snap25 and Nrg1 at protein levels. mRNA levels of Brain Derived Neurotrophic Factor (BDNF) were increased in the PFC of the RHA-I rats, with no differences in the HIP, while BDNF protein levels were decreased in PFC and increased in HIP. To investigate the temporal dynamics of these synaptic markers during neurodevelopment, we made use of the open source BrainCloud (TM) dataset, and found that SYP, GRIN2B, NRG1, HOMER1, DRD1 and BDNF expression is upregulated in PFC during childhood and adolescence, suggesting a more immature neurobiological endophenotype in the RHA-I strain.

Background: The Coloboma mouse carries a similar to 2 cM deletion encompassing the SNAP25 gene and has a hyperactive phenotype similar to that of ADHD. Such mice are 3 fold more active compared to their control littermates. Genetic association studies support a role for allelic variants of the human SNAP25 gene in predisposing to ADHD. Methods/Principal Findings: We performed association analysis across the SNAP25 gene in 1,107 individuals (339 ADHD trios). To assess the functional relevance of the SNAP25-ADHD associated allele, we performed quantitative PCR on postmortem tissue derived from the inferior frontal gyrus of 89 unaffected adults. Significant associations with the A allele of SNP rs362990 (chi(2) = 10, p-corrected = 0.019, OR = 1.5) and three marker haplotypes (rs6108461, rs362990 and rs362998) were observed. Furthermore, a significant additive decrease in the expression of the SNAP25 transcript as a function of the risk allele was also observed. This effect was detected at the haplotype level, where increasing copies of the ADHD-associated haplotype reduced the expression of the transcript. Conclusions: Our data show that DNA variation at SNAP25 confers risk to ADHD and reduces the expression of the transcript in a region of the brain that is critical for the regulation of attention and inhibition.