NGF enhances depolarization effects on SNAP-25 expression: induction of SNAP-25b isoform

The 25 kDa synaptosomal associated protein (SNAP-25), which is implicated i n neuronal plasticity and neurosecretion, exists as two isoforms generated by alternative splicing of exons 5a and 5b. The aim of the present study wa s to characterize factors influencing isoform expression. We report that ch ronic depolarization of PC12 cells alone or in the presence of NGF induces the expression of isoform-b, in addition to a 1.8- to 3-fold increase in SN AP-25 mRNA and protein as determined by immunoblotting and combined RT-PCR and Southern blot analysis. When cerebellar granule neurons were cultured i n elevated K+, the predominant isoform switched from SNAP-25a to SNAP-25b. Taken together these results suggested that chronic depolarization regulate s the transcription and processing of SNAP-25 mRNA. NeuroReport 12:673-677 (C) 2001 Lippincott Williams & Wilkins.