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Ataxia-Telangiectasia Mutated is located in cardiac mitochondria and impacts oxidative phosphorylation

Marguerite Blignaut1, Ben Loos2, Stanley W Botchway3,4

  • 1Division of Medical Physiology, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg, 7505, South Africa. 13813412@sun.ac.za.

Scientific Reports
|March 20, 2019
PubMed

Insights

Ataxia-Telangiectasia mutated protein kinase (ATM) is located in cardiac mitochondria, impacting oxidative phosphorylation. Its inhibition affects the electron transfer chain, crucial for energy production in cardiomyocytes.

Area of Science:

  • Cell Biology
  • Mitochondrial Biology
  • Cardiovascular Research

Background:

  • Ataxia-Telangiectasia mutated protein kinase (ATM) absence causes neurological, metabolic, and cardiovascular issues, linked to mitochondrial dysfunction.
  • ATM is activated by mitochondrial oxidative stress, mediating antioxidant responses via the pentose phosphate pathway (PPP).
  • The precise mitochondrial localization and role of ATM in oxidative phosphorylation remain unclear.

Purpose of the Study:

  • To investigate the endogenous localization and function of ATM within cardiac mitochondria.
  • To determine ATM's role in oxidative phosphorylation and its interaction with the mitochondrial electron transfer chain.

Main Methods:

  • Immunodetection of endogenous ATM in cardiac myocyte mitochondria.
  • Ex vivo inhibition of ATM kinase activity and assessment of mitochondrial respiration.
  • Inhibition of ATM in H9c2 cardiomyoblast cells and measurement of NAD(P)H autofluorescence lifetime.

Main Results:

  • ATM is found endogenously in cardiac myocyte mitochondria, associated with the inner mitochondrial membrane.
  • ATM inhibition significantly reduced the electron transfer chain complex I-mediated oxidative phosphorylation rate.
  • ATM inhibition decreased NAD(P)H autofluorescence lifetime, indicating altered mitochondrial redox state.

Conclusions:

  • ATM is present in cardiac mitochondria and interacts with the electron transfer chain.
  • ATM plays a role in regulating oxidative phosphorylation in cardiomyocytes.
  • These findings suggest ATM's importance in energy metabolism of terminally differentiated cardiac cells.

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