Oral communication, iL11

Official XXIst International Pigment Cell Conference website - 21-24 Sept 2011, Bordeaux - France | updated: September 04 2011

A role for inner ear melanocytes in anti-stress responses

Melanocyte precursors differentiate from the neural crest (NC), which is now considered a fourth germ layer (Hall, 2009), then they migrate and target a wide variety of tissues and organs. During the migration, melanophores⁄melanocytes and the cell⁄tissue microenvironment interact continuously. Therefore, it is not difficult to suppose that the developmental and localizing processes of these cells makes each of their local populations different in functions while retaining common lineage signature(s) such as melanin pigment synthesis and expression of other pigment cell-specific genes. It is well known that a group of melanocyte populations localized in the stria vascularis of the mammalian inner ear cochleae are essential for hearing ability, but peculiarly enough, they do not necessarily need to produce melanin pigment. Marcus et al. (2002) reported that knockout of the Kcnj10 gene, which encodes the inwardly rectifying K+ channel Kir4.1 and is expressed in intermediate cells (melanocytes) of the cochleae, abolishes the endolymphatic potential and reduces K+ concentration in the endolymph, resulting in deafness. Is this the only role for cochlear melanocytes? Gratton and Wright (1992) reported that noise stimulates melanin synthesis in inner ear melanocytes. We recently found that cochlear melanocytes in the stria vascularis (but not in hair follicles) specifically express Gsta4, which is deeply involved in anti-stress responses (Uehara et al., 2009). Considering the facts that melanin works both as an energy transducer and as a radical scavenger, we now hypothesize that melanocytes have evolved to execute a variety of functions depending on their localization but still have common signature functions in which melanin synthesis could essentially contribute. We will discuss studies on the functions of such interesting pigmented cells, especially of the non-classical (non-cutaneous (Yajima and Larue, 2008)) melanocytes scattered across the body.

Advertisement from our sponsor: