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Updated: Mar 1, 2026

In Vitro and In Vivo Detection of Mitophagy in Human Cells, C. Elegans, and Mice
Published on: November 22, 2017
ER-mitochondria signaling regulates autophagy.
Patricia Gomez-Suaga1, Sebastien Paillusson1, Christopher C J Miller1
1a Department of Basic and Clinical Neuroscience , Institute of Psychiatry, Psychology and Neuroscience, Kings College London , London , UK.
Endoplasmic reticulum-mitochondria tethers regulate autophagy. Loosening these contacts via VAPB/RMDN3 knockdown stimulates autophagosome formation, while tightening inhibits it, involving calcium signaling.
Area of Science:
- Cell Biology
- Organelle Communication
Background:
- Endoplasmic reticulum (ER) and mitochondria form crucial functional contacts regulated by tethering proteins.
- VAMP associated protein B and C (VAPB) and regulator of microtubule dynamics 3 (RMDN3/PTPIP51) form ER-mitochondria tethers.
- These tethers are implicated in regulating cellular processes, including autophagy.
Purpose of the Study:
- To investigate the role of VAPB-RMDN3 tethers in regulating macroautophagy/autophagy.
- To elucidate the mechanisms by which ER-mitochondria contacts influence autophagosome formation.
Main Methods:
- Small interfering RNA (siRNA) knockdown of VAPB and RMDN3.
- Overexpression of VAPB and RMDN3.
- Utilizing a synthetic linker protein for artificial ER-mitochondria tethering.
- Assessing autophagosome formation.
- Investigating the role of inositol 1,4,5-trisphosphate receptor (ITPR)-mediated calcium signaling.
Main Results:
- siRNA-mediated knockdown of VAPB or RMDN3, which loosens ER-mitochondria contacts, stimulates autophagosome formation.
- Overexpression of VAPB or RMDN3, which tightens contacts, inhibits autophagosome formation.
- Artificial tethering reduces autophagy, and this effect is rescued by VAPB/RMDN3 siRNA.
- ER-mitochondria contact-mediated autophagy regulation involves ITPR-dependent calcium delivery to mitochondria.
Conclusions:
- VAPB-RMDN3 tethers play a critical role in modulating autophagy.
- The extent of ER-mitochondria contact influences autophagosome formation.
- Calcium signaling via ITPR is a key mechanism linking ER-mitochondria contacts to autophagy regulation.
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