Abstract
Melanocytes are neural crest-derived, melanin-producing pigment cells. They provide for pigmentation of the skin and its appendages, including feathers and hairs, and play critical roles in sensory organs. In the inner ear of mammals, they regulate the endocochlear milieu that enables auditory hair cells to function properly, and in the eye they influence organogenesis, light penetration, and image quality. The precursors to melanocytes, called melanoblasts, are segregated from other neural crest derivatives through interactions between signaling pathways and transcription factors, notably between the Wingless/Int family of protein/β-catenin signaling pathway, the KIT ligand/KIT-mediated mitogen-activated protein kinase signaling pathway, and the melanoblast/melanocyte transcription factor MITF (microphthalmia-associated transcription factor). In conjunction with a variety of other factors, including cell adhesion molecules, cell cycle regulators, and cytoskeletal components, extracellular signaling and MITF together control melanoblast survival, proliferation, migration, homing into distinct tissues, and ultimately regeneration of melanocytes from undifferentiated precursors. Hence, melanocytes are cells with multiple functions in the body, including essential functions in eye and inner ear, and they serve as an excellent model system to elucidate the fundamental principles of cell lineage development in the neural crest.
Bismuth, K