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Functional involvement of TMF/ARA160 in Rab6-dependent retrograde membrane traffic

Junko Yamane1, Akiharu Kubo, Kazuhisa Nakayama

  • 1Department of Cell Biology, Faculty of Medicine, Kyoto University, Kyoto, Japan.

Experimental Cell Research
|August 19, 2007
PubMed

Insights

TMF/ARA160 is crucial for retrograde membrane transport, regulating Rab6-dependent movement between the Golgi and ER. Its absence disrupts Shiga toxin transport and causes missorting of specific Golgi enzymes.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Membrane Trafficking

Background:

  • The small GTPase Rab6 controls retrograde membrane transport pathways.
  • TMF/ARA160 is a known Rab6-binding protein involved in cellular processes.

Purpose of the Study:

  • To investigate the role of TMF/ARA160 in Rab6-mediated retrograde membrane traffic.
  • To elucidate the specific mechanisms by which TMF/ARA160 influences transport between endosomes, Golgi, and ER.

Main Methods:

  • High-resolution immunofluorescence and immunoelectron microscopy to visualize TMF and Rab6 localization.
  • RNA interference (RNAi) to knock down TMF and Rab6 expression.
  • Shiga toxin uptake and trafficking assays.
  • Analysis of Golgi resident proteins using chimeric constructs.

Main Results:

  • TMF localizes to Rab6-positive Golgi structures and budding sites.
  • Knockdown of TMF or Rab6 impairs retrograde transport from endosomes to the Golgi, leading to lysosomal missorting of Shiga toxin.
  • TMF knockdown causes Rab6-dependent displacement of GalNAc-T2, but not GalT, from the Golgi.
  • The cytoplasmic region of GalNAc-T2 is critical for TMF-dependent Golgi retention.

Conclusions:

  • TMF/ARA160 plays essential roles in two distinct Rab6-dependent retrograde transport pathways.
  • These pathways include transport from endosomes to the Golgi and from the Golgi to the ER.
  • TMF influences the localization of specific Golgi enzymes like GalNAc-T2 through its cytoplasmic domain.

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