Regulatory role of neuron-restrictive silencing factor in the specific expression of cocaine- and amphetamine-regulated transcript gene.

Cocaine- and amphetamine-regulated transcript (CART) peptide is an endogenous peptide which is widely expressed in the CNS and PNS as well as in endocrine cells. Despite the functional knowledge about CART, the mechanisms that regulate CART gene transcription are poorly characterized. Here, we showed that neuron-restrictive silencer factor (NRSF) functions as a negative regulator of CART gene expression in neuroendocrine cells. A putative neuron-restrictive silencer element (NRSE) conserved between the rodent and human CART promoter was identified and demonstrated to bind to NRSF in sequence-specific manner by the electrophoretic mobility shift and chromatin immunoprecipitation assays. Ectopic expression of NRSF in pheochromocytoma cells (PC12) and insulin-secreting cells (INS-1) induced a marked reduction in the level of CART mRNA and the activity of CART promoter or NRSE reporter. The CART promoter showed very low activity in endogenous NRSF-expressing HeLa cells. When expression of NRSF was down-regulated in HeLa cells using a RNA interfering technique, the transcriptional activity of the CART promoter or a NRSE reporter was significantly increased. Taken together, our data suggested that CART gene expression in neuroendocrine cells is strictly controlled by NRSF, via a mechanism dependent upon the CART NRSE.