The identification and characterization of human Sister-of-Mammalian Grainyhead (SOM) expands the grainyhead-like family of developmental transcription factors

摘要

pThe iDrosophila/i gene igrainyhead/i is the founding member of a large family of genes encoding developmental transcription factors that are highly conserved from fly to human. The family consists of two main branches, with igrainyhead/i as the ancestral gene for one branch and the recently cloned iDrosophila/iiCP2/i as the ancestral gene for the other. We now extend this family with the identification of another novel mammalian member, Sister-of-Mammalian Grainyhead (SOM), which is phylogenetically aligned with igrainyhead/i. SOM is closely related to the other mammalian homologues of igrainyhead/i, including Mammalian Grainyhead (MGR) and Brother-of-MGR, sharing a high degree of sequence identity with these factors in the functional DNA-binding, protein dimerization and activation domains. Protein interaction studies demonstrate that SOM can heterodimerize with MGR and Brother-of-MGR, but not with the more distant members of the family. Like igrainyhead/i, the SOM gene too produces several distinct isoforms with differing functional properties through alternative splicing. The tissue distributions of these isoforms differ and all display highly restricted expression patterns. These findings indicate that SOM, like its family members, may play important roles in mammalian development./p