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Mitf contributes to melanosome distribution and melanophore dendricity

Authors

  • Akiha Kawasaki,

    1. Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
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  • Mayuko Kumasaka,

    1. Developmental Genetics of Melanocytes, Institute Curie, Orsay Cedex, France and Present address: Unit of Environmental Health Sciences, Department of Biomedical Sciences, College of Life and Health Sciences, Chubu University, Kasugai-shi, Aichi, Japan
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  • Akira Satoh,

    1. Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
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    • Present address: School of Biological Sciences, University of California, Irvine, Irvine, CA 92697-1450, USA

  • Makoto Suzuki,

    1. Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
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    • Present address: Division of Morphogenesis, National Institute for Basic Biology, 38 Nishigonaka, Myodaiji, Okazaki 444-8585, Japan

  • Koji Tamura,

    1. Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
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  • Toshiyasu Goto,

    1. International Cooperative Research Project (ICORP), Japan Science and Technology Agency (JST), Tokyo, Japan
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  • Makoto Asashima,

    1. International Cooperative Research Project (ICORP), Japan Science and Technology Agency (JST), Tokyo, Japan
    2. Department of Life Sciences (Biology), Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
    3. Organ Development Research Laboratory, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, Japan
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  • Hiroaki Yamamoto

    Corresponding author
    1. Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
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Address correspondence to Hiroaki Yamamoto, e-mail: hyamamot@mail.tains.tohoku.ac.jp

Summary

Mitf is a transcription factor of the basic/helix-loop-helix/leucine-zipper family which is indispensable for development of melanocytes and the retinal pigment epithelium. Our previous work using Xenopus laevis as a model system suggested that Mitf regulates melanosome dispersal in vivo though whether this was via melanosome transport or melanophore dendricity was not obvious. To better understand the role of Mitf, we have now characterized neural tube cultures from wild-type Mitf-injected or a dominant-negative Mitf-injected embryos and compared them with controls. In vitro, lower levels of Mitf activity induced less dendritic melanophores with aggregated melanosomes, whereas melanophores overexpressing Mitf had an extensive dendritic morphology with dispersed melanosomes. Moreover, immunorfluoresence assays reveal that expression of a dominant-negative Mitf leads to decreased Rab27a expression. These results suggest that Mitf is involved in the regulation of melanosome transport and the level of dendricity in melanophores.

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