MSG1(Melanocyte-Specific Gene 1): Mapping to Chromosome Xq13.1, Genomic Organization, and Promoter Analysis

Abstract

MSG1(melanocyte-specific gene 1) is a recently isolated gene predominantly expressed in cultured normal melanocytes and pigmented melanoma cells.MSG1encodes a 27-kDa nuclear protein that has strong intrinsic transcriptional transactivating activity. In this report, the humanMSG1gene was mapped to chromosome Xq13.1 using X chromosome-specific somatic cell hybrids, and the mouseMsg1gene was mapped 1.9 ± 1.3 cM proximal toXistusing an interspecific backcross panel. Both the human and the mouseMSG1genes consist of three exons and two introns within 5 kb of genomic DNA, and their genomic structures are highly conserved. Southern blot analysis suggests the existence ofMSG1homologues in chicken, zebrafish, andDrosophila.A 2.0-kb fragment of the 5′-flanking region of the mouseMsg1gene contains a TATA box and potential binding sites for several transcription factors including USF, Brn-3, Brn-2, TFE3, Oct-1, AP-2, and Spl. This promoter fragment activates transcription of a reporter gene in pigmented melanoma cells, but not in amelanotic melanoma cells or nonmelanocytic cells, indicating thatMsg1expression is at least partially regulated at the transcriptional level.