Authentic Cell-Specific and Developmentally Regulated Expression of Pro-Opiomelanocortin Genomic Fragments in Hypotalamic and Hindbrain Neurons of Transgenic Mice

YOUNG J; CERDAN M; OTERO V; FALZONE T; CHEN CHANG E; LOW M; RUBINSTEIN M,

JOURNAL OF NEUROSCIENCE

HighWire Press

Lugar: Washington, DC; Año: 1998 vol. 18 p. 6631 - 6640

0270-6474

The pro-opiomelanocortin (POMC) gene is expressed in a subset of hypothalamic and hindbrain neurons and in pituitary melanotrophs and corticotrophs. POMC neurons release the potent opioid b-endorphin and several active melanocortins that control homeostasis and feeding behavior. POMC gene expression in the CNS is believed to be controlled by distinct cis-acting regulatory sequences. To analyze the transcriptional regulation of POMC in neuronal and endocrine cells, we produced transgenic mice carrying POMC27*, a transgene containing the entire 6 kb of the POMC transcriptional unit together with 13 kb of 59 flanking regions and 8 kb of 39 flanking regions. POMC27* was tagged with a heterologous 30 bp oligonucleotide in the third exon. In situ hybridization studies showed an accurate cell-specific pattern of expression of POMC27* in the arcuate nucleus and the pituitary. Hypothalamic mRNA-positive neurons colocalized entirely with b-endorphin immunoreactivity. No ectopic transgenic expression was detected in the brain. Deletional analyses demonstrated that neuron-specific expression of POMC transgenes required distal 59 sequences localized upstream of the pituitary-responsive proximal cis-acting elements that were identified previously. POMC27* exhibited a spatial and temporal pattern of expression throughout development that exactly paralleled endogenous POMC. RNase protection assays revealed that POMC27* expression mimicked that of POMC in different areas of the CNS and most peripheral organs with no detectable ectopic expression. Hormonal regulation of POMC27* and POMC was identical in the hypothalamus and pituitary. These results show that distal 59 sequences of the POMC gene located between 213 and 22 kb target expression into the CNS of transgenic mice in a precise neuronspecific, developmentally and hormonally regulated manner. Key words: pro-opiomelanocortin; transgenic mice; gene expression; b-endorphin; melanocortin; neuron-specific expression; arcuate nucleus; hypothalamus; pituitary