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

Access this Article

Author(s)

    • Fujibayashi Akemi
    • Division of Protein Chemistry, Institute for Protein Research, Osaka University
    • Fukuda Mitsunori
    • Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University
    • Waguri Satoshi
    • Department of Anatomy and Histology, Fukushima Medical University School of Medicine
    • Uchiyama Yasuo
    • Department of Cell Biology and Neuroscience A1, Osaka University Graduate School of Medicine
    • Yoshimori Tamotsu
    • Department of Cell Regulation, Research Institute for Microbial Diseases, Osaka University
    • Taguchi Tomohiko
    • Department of Biochemistry, Osaka University Graduate School of Medicine
    • Misaki Ryo
    • Department of Biochemistry, Osaka University Graduate School of Medicine
    • Ohtani Masashi
    • Division of Protein Chemistry, Institute for Protein Research, Osaka University
    • Takio Koji
    • Biometal Science Laboratory, RIKEN Spring-8 Center
    • Yamada Masashi
    • Division of Protein Chemistry, Institute for Protein Research, Osaka University
    • Gu Jianguo
    • Division of Regulatory Glycobiology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Pharmaceutical University
    • Yamakami Megumi
    • Department of Cell Regulation, Research Institute for Microbial Diseases, Osaka University

Abstract

RME-8 is a DnaJ-domain-containing protein that was first identified in <i>Caenorhabditis elegans</i> 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.<br>

Journal

  • Cell Structure and Function

    Cell Structure and Function 33(1), 35-50, 2008

    Japan Society for Cell Biology

Codes

  • NII Article ID (NAID)
    130004053865
  • Text Lang
    ENG
  • ISSN
    0386-7196
  • Data Source
    J-STAGE 
Page Top