Structure and function of human prepro-orexin gene

Orexin-A and -B are recently identified potent orexigenic peptides that are derived from the same precursor peptide and are highly specifically locali zed in neurons located in the lateral hypothalamic area, a region classical ly implicated in feeding behavior. We cloned the whole length of the human prepro-orexin gene and corresponding cDNA. The human prepro-orexin mRNA was predicted to encode a 131-residue precursor peptide (prepro-orexin). The h uman prepro-orexin gene consists of two exons and one intron distributed ov er 1432 base pairs. The 143-base pair first exon includes the 5'-untranslat ed region and a small part of the coding region that encodes the first seve n residues of the secretory signal sequence. The second exon contains the r emaining portion of the open reading frame and 3'-untranslated region. The 3.2 kilobase pairs of the 5'-upstream region from a cloned human prepro-ore xin gene promoter is sufficient to direct the expression of the Escherichia coli beta-galactosidase (lacZ) gene in transgenic mice to neurons in the l ateral hypothalamic area and adjacent regions. The lacZ-positive neurons we re positively stained with anti-orexin antibody but not with anti-melanin-c oncentrating hormone antibody. These findings suggest that this genomic fra gment contains all the necessary elements for appropriate expression of the gene and will be useful for the targeted expression of the exogenous gene in orexin-containing neurons. These mice might also be useful for examining the molecular mechanisms by which orexin gene expression is regulated.