ASCL2/Mash2: Proteins and Enzymes

ASCL2 (Achaete-scute like 2; also HASH2, bHLHa45 and Mash2) is a class II member of the HLH family of transcription factors. Its predicted MW is 20 kDa. ASCL2 shows restricted expression, being limited to intestinal Lgr5⁺ stem cells and first trimester placental cytotrophoblasts. In the intestine, ASCL2 is under the control of Wnts and serves to maintain an epithelium stem cell pool. In the placenta, ASCL2 acts to maintain the pool of cytotrophoblasts at the expense of synctiotrophoblasts, thus promoting placental growth. Human ASCL2 is 193 amino acids (aa) in length. It contains one poly-Arg motif (aa 36-39), a DNA binding sequence (aa 53-63) and an HLH domain (aa 64-103). ASCL2 forms heterodimers with daughterless homologs (E22, E2A and HEB). Over aa 1-49, human ASCL2 shares 59% aa identity with mouse Mash2.