| Research Abstract |
Brain-derived neurotrophic factor (BDNF), a member of the neurotrophin family, plays an important role in promoting neuronal survival, neuronal diffrentiation and synaptic plasticity. The BDNF gene consists of four short 5'-exons (exons I, II, III and IV) and a common 3'-exon V encoding a prepro-BDNF protein and four promoters, BDNF promoter I, II, III and IV (BDNF-PI, -PII, -PIII and -PIV) are located upstream of the 5'-exons, respectively. Using DNA transfection in primary culture of rat cortical neurons, we assigned the promoter sequences responsible for the Ca^<2+> signal-mediated activation of BDNF-PI and found that not only the CREB but also the upstream stimulatory factor (USF) bound to the responsive site, in which the CRE and the USF-binding element overlap each other, and contributed to the activation. Quite recently, we have detected the formation of heterodimer between CREB and USF2b molecules, using a co-immunoprecipitation method. On the other hand, the Ca^<2+> signal-mediated activation of PACAP gene promoter was controlled only by the CRE located at around nucleotide position -200, where CREB predominantly bound. The maximum activation of promoters induced by Ca^<2+> signals was detected at lower KCI concentration with the BDNF-PI and -PIII than with the PACAP promoter, suggesting a higher sensitivity of BDNF-PI and -PIII to Ca^<2+> signals than PACAP promoter. We are now investigating which cis-elements account for the different sensitivity of promoters to Ca^<2+> signals between the BDNF-PI (or -PIII) and PACAP promoter. In addition, we are now trying to establish a multi-sample screening system for surveying some chemicals which are effective on preventing neurodegenerative disorders.
|
