Biological function and molecular mechanism of Twist2.

Twist2, one of the basic helix-loop-helix protein (bHLH) family members, is responsible for the transcriptional regulation in mesenchymal cell lineages during its development. Twist2 functions as a molecular switch to activate or repress target genes by direct or indirect mechanisms. Twist2 can directly bind with conserved E-box on DNA sequence, to recruit co-activators or repressors, and interfere with the activation or inhibition function through protein-protein interactions with E-protein modulators. Nonsense mutations of Twist2 cause Setleis syndrome. Early research on Twist2 focused on osteogenesis, and then expression differences were found in a wide variety of tumors. Further studies showed that Twist2 plays an important role in cancer epithelial-mesenchymal transition (EMT). Regulation function of Twist2 is controlled by temporal and spatial expression, phosphorylation, dimerization and cell positioning adjustment. The involvement of Twist2 in a broad spectrum of regulatory pathways highlights the importance of understanding its role in normal development, homeostasis and disease. In this review, we summarize the role of Twist2 in osteogenesis differentiation, tumor formation and EMT, and its molecular mechanism. It is helpful to have a thorough understanding of the biological functions of Twist2, and facilitate the transformation and application in diagnosis, development and therapy.