Human RME-8 Is Involved in Membrane Trafficking through Early Endosomes

Cell Structure and Function

Masashi Yamada⁸  Akemi Fujibayashi⁸  Koji Takio³  Satoshi Waguri⁶  Tomohiko Taguchi⁵  Jianguo Gu¹  Ryo Misaki⁵  Megumi Yamakami⁴  Masashi Ohtani⁸  Naoshi Dohmae⁹  Kiyotoshi Sekiguchi⁸  Yasuo Uchiyama⁷  Tamotsu Yoshimori⁴  Mitsunori Fukuda² 

[1] Division of Regulatory Glycobiology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Pharmaceutical University;Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University;Biometal Science Laboratory, RIKEN Spring-8 Center;Department of Cell Regulation, Research Institute for Microbial Diseases, Osaka University;Department of Biochemistry, Osaka University Graduate School of Medicine;Department of Anatomy and Histology, Fukushima Medical University School of Medicine;Department of Cell Biology and Neuroscience A1, Osaka University Graduate School of Medicine;Division of Protein Chemistry, Institute for Protein Research, Osaka University;Biomolecular Characterization Team, RIKEN

关键词: early endosome;    endocytosis;    membrane trafficking;    Rab5;   

DOI  :  10.1247/csf.07045

学科分类：分子生物学，细胞生物学和基因

来源: Japan Society for Cell Biology

【 摘 要 】

References(39)Cited-By(14)Supplementary materials(3)RME-8 is a DnaJ-domain-containing protein that was first identified in Caenorhabditis elegans as being required for uptake of yolk proteins. RME-8 has also been identified in other species, including flies and mammals, and the phenotypes of their RME-8 mutants suggest the importance of this protein in endocytosis. In the present study, we cloned human RME-8 (hRME-8) and characterized its biochemical properties and functions in endocytic pathways. hRME-8 was found to be a peripheral protein that was tightly associated with the membrane via its N-terminal region. It partially colocalized with several early endosomal markers, but not with late endosomal markers, consistent with observations by immunoelectron microscopy. When cells were transfected with a panel of dominant-active Rab proteins, hRME-8 was confined to large vacuoles induced by expression of Rab5aQ79L, but not by Rab7Q67L. Expression of C-terminally-truncated hRME-8 mutants led to the formation of large puncta and vacuoles, and compromised endocytic pathways through early endosomes, i.e., recycling of transferrin and degradation of epidermal growth factor. Taken together, these results indicate that hRME is primarily involved in membrane trafficking through early endosomes, but not through degradative organelles, such as multivesicular bodies and late endosomes.

【 授权许可】

Unknown