Evaluation of hypothalamic murine and human melanocortin 3 receptor transcript structure

The melanocortin 3 receptor (MC3R) is involved in regulation of energy homeostasis. However, its transcript structure is not well understood. We therefore studied initiation and termination sites for hypothalamic murine Mc3r and human MC3R transcripts. Rapid Amplification of cDNA Ends (RACE) was performed for the 5′ and 3′ ends of murine and human hypothalamic RNA. 5′ RACE experiments using hypothalamic murine RNA indicated mouse hypothalamus expresses two major Mc3r transcription start sites: one with a 5′ UTR approximately 368 bases in length and another previously unknown transcript with a 5′ UTR approximately 440 bases in length. 5′ RACE experiments using human hypothalamic RNA identified a 5′ UTR beginning 533 bases upstream of the start codon with a 248 base splice. 3′ RACE experiments using hypothalamic murine RNA indicated the 3′ UTR terminates approximately 1286 bases after the translational stop codon, with a previously unknown 787 base splice between consensus splice donor and acceptor sites. 3′ RACE experiments using human MC3R transcript indicated the 3′ UTR terminates approximately 115-160 bases after the translational stop codon. These data provide insight into melanocortin 3 receptor transcript structure.