2. Academic Validation
  3. A Novel Class of ER Membrane Proteins Regulates ER-Associated Endosome Fission

A Novel Class of ER Membrane Proteins Regulates ER-Associated Endosome Fission

  • Cell. 2018 Sep 20;175(1):254-265.e14. doi: 10.1016/j.cell.2018.08.030.
Melissa J Hoyer 1,  Patrick J Chitwood 1,  Christopher C Ebmeier 1,  Jonathan F Striepen 1,  Robert Z Qi 2,  William M Old 1,  Gia K Voeltz 3
Affiliations

Affiliations

  • 1 Department of Molecular, Cellular, and Developmental Biology, University of Colorado-Boulder, Boulder, CO 80309, USA.
  • 2 Division of Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
  • 3 Department of Molecular, Cellular, and Developmental Biology, University of Colorado-Boulder, Boulder, CO 80309, USA; Howard Hughes Medical Institute, University of Colorado-Boulder, Boulder, CO 80309, USA. Electronic address: gia.voeltz@colorado.edu.
PMID: 30220460 DOI: 10.1016/j.cell.2018.08.030
Abstract

Endoplasmic reticulum (ER) membrane contact sites (MCSs) mark positions where endosomes undergo fission for cargo sorting. To define the role of ER at this unique MCS, we targeted a promiscuous biotin Ligase to cargo-sorting domains on endosome buds. This strategy identified the ER membrane protein TMCC1, a member of a conserved protein family. TMCC1 concentrates at the ER-endosome MCSs that are spatially and temporally linked to endosome fission. When TMCC1 is depleted, endosome morphology is normal, buds still form, but ER-associated bud fission and subsequent cargo sorting to the Golgi are impaired. We find that the endosome-localized actin regulator Coronin 1C is required for ER-associated fission of actin-dependent cargo-sorting domains. Coronin 1C is recruited to endosome buds independently of TMCC1, while TMCC1/ER recruitment requires Coronin 1C. This link between TMCC1 and Coronin 1C suggests that the timing of TMCC1-dependent ER recruitment is tightly regulated to occur after cargo has been properly sequestered into the bud.

Keywords

endoplasmic reticulum; endosome fission; endosome recycling; membrane contact site.

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