OPA1 regulates respiratory supercomplexes assembly: The role of mitochondrial swelling

Mitochondrion. 2020 Mar;51:30-39. doi: 10.1016/j.mito.2019.11.006. Epub 2019 Dec 20.

Abstract

Optic atrophy type 1 protein (OPA1), a dynamin-related GTPase, that, in addition to mitochondrial fusion, plays an important role in maintaining the structural organization and integrity of the inner mitochondrial membrane (IMM). OPA1 exists in two forms: IMM-bound long-OPA1 (L-OPA1) and soluble short-OPA1 (S-OPA1), a product of L-OPA1 proteolytic cleavage localized in the intermembrane space. In addition to OPA1, the structural and functional integrity of IMM can be regulated by changes in the matrix volume due to the opening/closure of permeability transition pores (PTP). Herein, we investigated the crosstalk between the PTP and OPA1 to clarify whether PTP opening is involved in OPA1-mediated regulation of respiratory chain supercomplexes (RCS) assembly using cardiac mitochondria and cell line. We found that: 1) Proteolytic cleavage of L-OPA1 is stimulated by PTP-induced mitochondrial swelling, 2) OPA1 knockdown reduces PTP-induced mitochondrial swelling but enhances ROS production, 3) OPA1 deficiency impairs the RCS assembly associated with diminished ETC activity and oxidative phosphorylation, 4) OPA1 has no physical interaction with phospholipid scramblase 3 although OPA1 downregulation increases expression of the scramblase. Thus, this study demonstrates that L-OPA1 cleavage depends on the PTP-induced mitochondrial swelling suggesting a regulatory role of the PTP-OPA1 axis in RCS assembly and mitochondrial bioenergetics.

Keywords: Mitochondria; Mitochondrial swelling; Optic atrophy type 1 protein; Permeability transition pore; Respiratory supercomplexes.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Cell Line, Tumor
  • Electron Transport / physiology
  • Energy Metabolism
  • GTP Phosphohydrolases / genetics
  • GTP Phosphohydrolases / metabolism*
  • HeLa Cells
  • Humans
  • Male
  • Mitochondria, Heart / metabolism*
  • Mitochondrial Membranes / physiology*
  • Mitochondrial Swelling / physiology*
  • Oxidative Phosphorylation
  • Phospholipid Transfer Proteins / metabolism
  • Proteolysis
  • RNA Interference
  • RNA, Small Interfering / genetics
  • Rats
  • Rats, Sprague-Dawley
  • Reactive Oxygen Species / metabolism

Substances

  • PLSCR3 protein, human
  • Phospholipid Transfer Proteins
  • RNA, Small Interfering
  • Reactive Oxygen Species
  • GTP Phosphohydrolases
  • OPA1 protein, human