Tohoku University has elucidated a mechanism for "microtubule-dependent retrograde melanosome transport", that is, reversed transport of melanin pigments along the microtubules. 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 to the plasma membrane, along two kinds of cytoskeletal networks, microtubules and actin filaments. First, melanosomes are delivered to the peripheral area in the cell by long-distance and bidirectional (anterograde and retrograde) microtubule-dependent transport. Next, melanosomes are conveyed close to the plasma membrane by short-distance one-way actin-dependent transport. Melanosomes are eventually transferred to neighboring keratinocytes and hair matrix cells, which produce skin and hairs, respectively. This process makes skin and hairs black. Although the mechanism of actin-dependent melanosome transport by small GTPase Rab27A had been revealed, long-distance microtubule-dependent melanosome transport has not been elucidated at all.

 In this study, the research group has uncovered that a transport complex including melanoregulin (Mreg) is involved in the process of microtubule-dependent retrograde melanosome transport, by using cultured mouse melanocytes. It has been revealed that Mreg on mature melanosomes forms a complex with dynein, a kind of motor protein, via Rab interacting lysosomal protein (RILP) and transports melanosomes in a retrograde fashion, that is, from near the plasma membrane to the perinuclear area in the cell.

 This study has revealed that Mreg deficiency nearly restores melanosome distribution from perinuclear melanosome aggregation in Rab27A-deficient melanocytes. Hence, screening of medical agents inhibiting Mreg functions will lead to prevent our hairs from becoming gray.

 The research result has been published online in The Journal of Cell Science. The paper's title is "Melanoregulin regulates retrograde melanosome transport through interaction with the RILP•p150^Glued complex 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 @)