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Updated: Sep 24, 2025

Detection of Mitochondria Membrane Potential to Study CLIC4 Knockdown-induced HN4 Cell Apoptosis In Vitro
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Detection of Mitochondria Membrane Potential to Study CLIC4 Knockdown-induced HN4 Cell Apoptosis In Vitro

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Novel roles of RTN4 and CLIMP-63 in regulating mitochondrial structure, bioenergetics and apoptosis

Rachel J Carter1, Mateus Milani1, Alison J Beckett2

  • 1Departments of Molecular and Clinical Cancer Medicine, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, L69 3GE, UK.

Cell Death & Disease
|May 4, 2022
PubMed

Insights

Endoplasmic reticulum (ER) proteins RTN4 and CLIMP-63 influence mitochondrial dynamics. Their downregulation causes mitochondrial hyperfusion and impaired function, revealing distinct roles in cell death regulation.

Area of Science:

  • Cell Biology
  • Mitochondrial Dynamics
  • Endoplasmic Reticulum Function

Background:

  • Endoplasmic reticulum (ER) membrane wrapping facilitates DRP1 recruitment for mitochondrial fission.
  • ER shaping proteins RTN4 and CLIMP-63 are crucial for ER architecture and mitochondrial interactions.

Purpose of the Study:

  • To investigate the roles of ER shaping proteins RTN4 and CLIMP-63 in ER-mitochondria interplay.
  • To understand their impact on mitochondrial structure, DRP1 recruitment, and function.

Main Methods:

  • Downregulation of RTN4 and CLIMP-63 in cellular models.
  • Analysis of mitochondrial morphology, ER-mitochondria contacts, and DRP1 localization.
  • Assessment of mitochondrial function including mtDNA-encoded translation, respiratory capacity, and apoptosis.

Main Results:

  • Downregulation of RTN4/CLIMP-63 led to mitochondrial hyperfusion and reduced ER-mitochondria contacts.
  • Mitochondrial recruitment of DRP1 was unaffected, but mitochondrial function (translation, respiration, apoptosis) was impaired.
  • CLIMP-63 is essential for cristae remodeling and DRP1-mediated fission; RTN4 and CLIMP-63 regulate BAX recruitment for apoptosis.

Conclusions:

  • RTN4 and CLIMP-63 play distinct and novel roles in regulating mitochondrial structure and function.
  • These ER proteins are critical for maintaining mitochondrial integrity and executing apoptosis.
  • CLIMP-63 is specifically required for OPA1 proteolysis and mitochondrial fission.

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