Tohoku University has revealed that Varp, known as a molecule essential for transport of melanogenic enzymes, promotes dendrite formation of melanocytes. This research result has been acquired by Assistant Professor Norihiko Ohbayashi and Professor Mitsunori Fukuda at Graduate School of Life Sciences, Tohoku University.

 Melanin pigments, sources of our skin color and hair color, are synthesized by melanogenic enzymes in melanocytes, and are stored in specialized organelles called melanosomes. Mature melanosomes are transported within melanocytes and are eventually transferred from dendrites of melanocytes to neighboring keratinocytes and hair matrix cells. This process makes skin and hairs black. For efficient transfer of melanosomes from melanocytes to keratinocytes, dendrite formation had been considered to be important. However, the mechanism of dendrite formation has remained to be fully elucidated.

 In this study, the research group has revealed that the activation of Rab21 by Varp is required for dendrite formation, by using cultured mouse melanocytes. Varp was known to be required for transport of melanogenic enzymes to melanosomes in melanocytes by the Rab38 effector function. In addition, this study has found that melanocytes in which the Rab21 activation by Varp was specifically impaired markedly lost their ability to form dendrites. Thus, it is elucidated that the Rab21 activation by Varp is involved in supplying new membranes and/or proteins to the tips of dendrites for dendrite outgrowth.

 Since Varp is related to the two important processes for darkening skin and hairs, that is, transport of melanogenic enzymes and dendrite formation, screening of medical agents inhibiting or stabilizing Varp functions will lead to keep our skin white and prevent our hairs from becoming gray.

 The research result has been published online in Molecular Biology of the Cell. The paper's title is "the Rab21-GEF activity of Varp, but not its Rab32/38 effector function, is required for dendrite formation in melanocytes".

More information (Japanese)

[Contact] (About the research)

Professor Mitsunori Fukuda

Graduate School of Life Sciences, Tohoku University

TEL: +81-22-795-7731

E-mail: nori*m.tohoku.ac.jp (Replace * with @)

(Public relations)

Associate professor Fuji Nagami

Tohoku Neuroscience Global COE

Tel: +81-22-717-7908 Fax: +81-22-717-7923

E-mail: f-nagami*med.tohoku.ac.jp (Replace * with @)