Uncovering cis- and trans-acting code regulating proopimelanocortin transcription in the brain

NASIF S; DE SOUZA FS; LÓPEZ LEAL RA; RUBINSTEIN M

Congreso; XLV Reunión anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2009

The proopiomelanocortin gene (POMC) encodes a prohormone that is expressed mainly in the pituitary and the arcuate nucleus of the hypothalamus, playing a central role in the stress response and energy balance, respectively. We have showed that hypothalamic expression of POMC is driven by two upstream enhancers, nPE1 and nPE2. To identify the critical secuences of nPE1 (630 bp) we performed a bioinformatic analysis coupled with an expression study in transgenic mice. Using this strategy we unraveled a functionally critical 144 bp central region within nPE1 that is necessary and sufficient to drive reporter gene expression to POMC neurons in transgenic mice. Comparison of this critical nPE1 region with those previously identified in nPE2 evidenced a number of short conserved sequences that are present in both enhancers, suggesting that the transcriptional activity of nPE1 and nPE2 might be conferred by a similar set of homeodomain containing transcription factors (HDTF). Data from the literature and from a UNIPROBE search led us to test the ability of several recombinant HDTF candidates to bind to the enhancers’ regions in gel shift assays. Our results represent a step forward to elucidate the transcriptional code of POMC in the brain and the understanding of the overlapping functions of nPE1 and nPE2.