Oligomeric CHMP7 mediates three-way ER junctions and ER-mitochondria interactions
Qingzhu Chu1, Jingru Wang1, Yuanjiao Du1
1Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Cell Death and Differentiation
|August 12, 2022
Summary
CHMP7 protein mediates membrane contact sites between the endoplasmic reticulum (ER) and mitochondria. This discovery reveals a new role for CHMP7 in organelle tethering during non-mitotic stages.
Area of Science:
- Cell Biology
- Molecular Biology
- Membrane Trafficking
Background:
- The endoplasmic reticulum (ER) undergoes significant remodeling during the cell cycle.
- CHMP7, a component of the endosomal sorting complexes required for transport (ESCRT) machinery, is known to coordinate nuclear envelope reformation.
- The function of ER-associated CHMP7 during non-mitotic stages is not well understood.
Purpose of the Study:
- To investigate the role of CHMP7 in non-mitotic cellular processes.
- To explore potential functions of CHMP7 beyond its known role in nuclear envelope reformation.
- To elucidate the mechanisms by which CHMP7 mediates membrane contact sites.
Main Methods:
- Immunofluorescence microscopy to determine CHMP7 localization.
- Biochemical assays to analyze protein interactions and membrane binding.
- In vivo tethering assays to assess organelle interactions.
- Mitochondrial division assays.
Main Results:
- CHMP7 localizes to the ER, mitochondrial-associated membranes (MAMs), and outer mitochondrial membrane (OMM).
- CHMP7 dynamically assembles at three-way ER junctions and ER-mitochondrial contact sites, mediated by hydrophobic interactions.
- CHMP7 facilitates the formation of three-way ER junctions in conjunction with Atlastins (ATLs).
- CHMP7 regulates ER-mitochondrial interactions and influences mitochondrial division independently of the ESCRT complex.
Conclusions:
- CHMP7 plays a direct role in establishing ER membrane contact sites during interphase.
- CHMP7 mediates the tethering of the ER with mitochondria.
- CHMP7 has functions independent of the canonical ESCRT pathway in regulating organelle dynamics.
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