Identification of neuronal enhancers of the proopiomelanocortin gene by transgenic mouse analysis and phylogenetic footprinting.
The proopiomelanocortin (POMC) gene is expressed in the pituitary and arcuate neurons of the hypothalamus. POMC arcuate neurons play a central role in the control of energy homeostasis, and rare loss-of-function mutations in POMC cause obesity. Moreover, POMC is the prime candidate gene within a highly significant quantitative trait locus on chromosome 2 associated with obesity traits in several human populations. Here, we identify two phylogenetically conserved neuronal POMC enhancers designated nPE1 (600 bp) and nPE2 (150 bp) located approximately 10 to 12 kb upstream of mammalian POMC transcriptional units. We show that mouse or human genomic regions containing these enhancers are able to direct reporter gene expression to POMC hypothalamic neurons, but not the pituitary of transgenic mice. Conversely, deletion of nPE1 and nPE2 in the context of the entire transcriptional unit of POMC abolishes transgene expression in the hypothalamus without affecting pituitary expression. Our results indicate that the nPEs are necessary and sufficient for hypothalamic POMC expression and that POMC expression in the brain and pituitary is controlled by independent sets of enhancers. Our study advances the understanding of the molecular nature of hypothalamic POMC neurons and will be useful to determine whether polymorphisms in POMC regulatory regions play a role in the predisposition to obesity.
de Souza
Flávio S J
FS
INGEBI-CONICET, Vuelta de Obligado 2490, 1428 Buenos Aires, Argentina.
Santangelo
Andrea M
AM
Bumaschny
Viviana
V
Avale
María Elena
ME
Smart
James L
JL
Low
Malcolm J
MJ
Rubinstein
Marcelo
M
D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000166:cytology / Q000378:metabolism*; D001483:Base Sequence; D017124:Conserved Sequence; D004252:DNA Mutational Analysis; D004742:Enhancer Elements, Genetic / Q000235:genetics*; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000032:analysis / Q000235:genetics; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D009474:Neurons / Q000737:chemistry / Q000378:metabolism; D009765:Obesity / Q000235:genetics; D010802:Phylogeny; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000378:metabolism; D011110:Polymorphism, Genetic; D011333:Pro-Opiomelanocortin / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D017384:Sequence Deletion
C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D011333:Pro-Opiomelanocortin