The key points are:

Transporting melanogenic enzymes to melanosomes is important to synthesize melanin pigments.

A protein called Varp transports melanogenic enzymes (Trp1).

Melanogenic enzymes disappear in Varp-deficient cells, and the amount of melanin pigment decreases.

 

Tohoku University succeeded in identifying a new molecule that transports melanogenic enzymes. These enzymes synthesize melanin pigments to darken the skin and the hair. The research results have been done by a group of Professor Mitsunori Fukuda with Ms. Kanako Tamura (a master course student), and Assistant Professor Norihiko Ohbayashi at Tohoku University Graduate School of Life Sciences.

Melanogenic enzymes synthesize melanin pigments that are an origin of our skin and hair color in cells called melanocytes, and vesicles called melanosomes in melnaocytes contain melanin pigments. Melanosomes are eventually transferred to cells that build the skin and the hair, and darken the color of them. Transporting properly melanogenic enzymes to melanosomes is necessary to synthesize melanin pigments and store them in melanosomes. However, it has not been elucidated as clearly how the enzymes are transported to melanosomes as how actin fibers, cytoskeleton, transfer melanosomes.

 

In this study, the research group found that Rab38-binding protein called Varp is involved in the process of transporting Trp1, one of the melanogenic enzymes, using cultured mouse melanocytes. The group shows that Varp and Rab38 colocalize with Trp1 in melanocytes, and that knockdown of Varp by specific siRNA causes melanogenic enzymes to disappear in melanosomes, and the amount of melanin pigment significantly decreases. It is cleared for the first time that Varp binds Rab38 to be involved in the transport of melanogenic enzymes to melanosomes.

The research results can be applied to drug screening to damage or stabilize Varp’s functions. Regulating melanogenic enzymes transporting is expected to help keep the skin white, or prevent white hair.

The research results will be published in the journal “Molecular Biology of the Cell” soon.

 

[Contact]

Professor Mitsunori Fukuda

Tohoku University Graduate School of Life Sciences

Tel: +81 22-795-7731

E-mail: nori@mail.tains.tohoku.ac.jp

 

Associate Professor Fuji Nagami

Tohoku Neuroscience Global COE

Tel: +81 22-717-7908

Fax: +81 22-717-7923

E-mail: f-nagami@mail.tains.tohoku.ac.jp