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Biochim Biophys Acta. 2015 Mar;1852(3):529-40. doi: 10.1016/j.bbadis.2014.12.012. Epub 2014 Dec 20.

Mitochondrial dysfunction in primary human fibroblasts triggers an adaptive cell survival program that requires AMPK-α.

Author information

1
Department of Biochemistry, Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, 6500 HB Nijmegen, The Netherlands; Department of Pediatrics, Nijmegen Center for Mitochondrial Disorders, Radboud University Medical Centre, 6500 HB Nijmegen, The Netherlands; Department of General Pediatrics, Neonatology and Pediatric Cardiology, University Children's Hospital, Heinrich-Heine-University, 40225 Düsseldorf, Germany.
2
Department of Biochemistry, Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, 6500 HB Nijmegen, The Netherlands; Department of Pediatrics, Nijmegen Center for Mitochondrial Disorders, Radboud University Medical Centre, 6500 HB Nijmegen, The Netherlands.
3
Department of Biochemistry, Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, 6500 HB Nijmegen, The Netherlands.
4
Nencki Institute of Experimental Biology, 02-093 Warsaw, Poland.
5
Department of Pediatrics, Nijmegen Center for Mitochondrial Disorders, Radboud University Medical Centre, 6500 HB Nijmegen, The Netherlands.
6
Department of Human and Animal Physiology, Wageningen University, 6708 WD Wageningen, The Netherlands.
7
Department of Cell Biology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, 6500 HB Nijmegen, The Netherlands.
8
The Hakubi Project, Kyoto University, 606-8501 Kyoto, Japan.
9
Department of General Pediatrics, Neonatology and Pediatric Cardiology, University Children's Hospital, Heinrich-Heine-University, 40225 Düsseldorf, Germany.
10
Institut Cochin, NSERM U1016, Université Paris Descartes, 75014 Paris, France.
11
Department of Stereotactic Neurosurgery, Otto-von-Guericke-Universität, 39120 Magdeburg, Germany.
12
Department of Biochemistry, Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, 6500 HB Nijmegen, The Netherlands. Electronic address: w.koopman@ncmls.ru.nl.

Abstract

Dysfunction of complex I (CI) of the mitochondrial electron transport chain (ETC) features prominently in human pathology. Cell models of ETC dysfunction display adaptive survival responses that still are poorly understood but of relevance for therapy development. Here we comprehensively examined how primary human skin fibroblasts adapt to chronic CI inhibition. CI inhibition triggered transient and sustained changes in metabolism, redox homeostasis and mitochondrial (ultra)structure but no cell senescence/death. CI-inhibited cells consumed no oxygen and displayed minor mitochondrial depolarization, reverse-mode action of complex V, a slower proliferation rate and futile mitochondrial biogenesis. Adaptation was neither prevented by antioxidants nor associated with increased PGC1-α/SIRT1/mTOR levels. Survival of CI-inhibited cells was strictly glucose-dependent and accompanied by increased AMPK-α phosphorylation, which occurred without changes in ATP or cytosolic calcium levels. Conversely, cells devoid of AMPK-α died upon CI inhibition. Chronic CI inhibition did not increase mitochondrial superoxide levels or cellular lipid peroxidation and was paralleled by a specific increase in SOD2/GR, whereas SOD1/CAT/Gpx1/Gpx2/Gpx5 levels remained unchanged. Upon hormone stimulation, fully adapted cells displayed aberrant cytosolic and ER calcium handling due to hampered ATP fueling of ER calcium pumps. It is concluded that CI dysfunction triggers an adaptive program that depends on extracellular glucose and AMPK-α. This response avoids cell death by suppressing energy crisis, oxidative stress induction and substantial mitochondrial depolarization.

KEYWORDS:

Respirometry; calcium homeostasis; glycolysis; metabolic regulation; mitochondrial dynamics; redox signaling

PMID:
25536029
DOI:
10.1016/j.bbadis.2014.12.012
[Indexed for MEDLINE]
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