AKIP1 Expression Modulates Mitochondrial Function in Rat Neonatal Cardiomyocytes

Yu, Hongjuan; Tigchelaar, Wardit; Koonen, Debby P. Y.; Patel, Hemal H.; Boer, Rudolf A. de; Gilst, Wiek H. van; Westenbrink, B. Daan; Silljé, Herman H W

doi:10.1371/journal.pone.0080815

Cited by 19 publications

(24 citation statements)

References 33 publications

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“…3, A and B), indicating that at least half of the observed OCR in E10.5-E11.5 mouse hearts was dependent on mitochondrial respiration. The remaining portion likely reflects other oxidation reactions within the cells, as has been commonly observed in other systems (9,28,60).…”

Section: Resultsmentioning

confidence: 78%

Impaired cardiac energy metabolism in embryos lacking adrenergic stimulation

Baker

Gidus

Price

et al. 2015

American Journal of Physiology-Endocrinology and Metabolism

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As development proceeds from the embryonic to fetal stages, cardiac energy demands increase substantially, and oxidative phosphorylation of ADP to ATP in mitochondria becomes vital. Relatively little, however, is known about the signaling mechanisms regulating the transition from anaerobic to aerobic metabolism that occurs during the embryonic period. The main objective of this study was to test the hypothesis that adrenergic hormones provide critical stimulation of energy metabolism during embryonic/fetal development. We examined ATP and ADP concentrations in mouse embryos lacking adrenergic hormones due to targeted disruption of the essential dopamine β-hydroxylase (Dbh) gene. Embryonic ATP concentrations decreased dramatically, whereas ADP concentrations rose such that the ATP/ADP ratio in the adrenergic-deficient group was nearly 50-fold less than that found in littermate controls by embryonic day 11.5. We also found that cardiac extracellular acidification and oxygen consumption rates were significantly decreased, and mitochondria were significantly larger and more branched in adrenergic-deficient hearts. Notably, however, the mitochondria were intact with well-formed cristae, and there was no significant difference observed in mitochondrial membrane potential. Maternal administration of the adrenergic receptor agonists isoproterenol or l-phenylephrine significantly ameliorated the decreases in ATP observed in Dbh-/- embryos, suggesting that α- and β-adrenergic receptors were effective modulators of ATP concentrations in mouse embryos in vivo. These data demonstrate that adrenergic hormones stimulate cardiac energy metabolism during a critical period of embryonic development.

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Section: Resultsmentioning

confidence: 78%

Impaired cardiac energy metabolism in embryos lacking adrenergic stimulation

Baker

Gidus

Price

et al. 2015

American Journal of Physiology-Endocrinology and Metabolism

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“…To determine the oxidative consumption rate (OCR) in cardiomyocytes, a Seahorse metabolic flux analyzer (Seahorse Biosciences) was used as previously described (24). Neonatal cardiomyocytes were seeded at a density of 100,000 cells/well in special Seahorse 24-well plates.…”

Section: Methodsmentioning

confidence: 99%

“…Mitochondrial membrane potential (⌬⌿m) was assessed by tetramethylrhodamine ethyl ester (TMRE), as described before (24). In brief, cells were seeded at a density of 40.000 cells/well in black 96-well plates and cultured as described above.…”

Section: Methodsmentioning

confidence: 99%

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Loss of mitochondrial exo/endonuclease EXOG affects mitochondrial respiration and induces ROS-mediated cardiomyocyte hypertrophy

Tigchelaar

Jong

et al. 2015

American Journal of Physiology-Cell Physiology

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Tigchelaar W, Yu H, de Jong AM, van Gilst WH, van der Harst P, Westenbrink BD, de Boer RA, Silljé HH. Loss of mitochondrial exo/endonuclease EXOG affects mitochondrial respiration and induces ROS-mediated cardiomyocyte hypertrophy. Am J Physiol Cell Physiol 308: C155-C163, 2015. First published November 5, 2014 doi:10.1152/ajpcell.00227.2014.-Recently, a locus at the mitochondrial exo/endonuclease EXOG gene, which has been implicated in mitochondrial DNA repair, was associated with cardiac function. The function of EXOG in cardiomyocytes is still elusive. Here we investigated the role of EXOG in mitochondrial function and hypertrophy in cardiomyocytes. Depletion of EXOG in primary neonatal rat ventricular cardiomyocytes (NRVCs) induced a marked increase in cardiomyocyte hypertrophy. Depletion of EXOG, however, did not result in loss of mitochondrial DNA integrity. Although EXOG depletion did not induce fetal gene expression and common hypertrophy pathways were not activated, a clear increase in ribosomal S6 phosphorylation was observed, which readily explains increased protein synthesis. With the use of a Seahorse flux analyzer, it was shown that the mitochondrial oxidative consumption rate (OCR) was increased 2.4-fold in EXOG-depleted NRVCs. Moreover, ATP-linked OCR was 5.2-fold higher. This increase was not explained by mitochondrial biogenesis or alterations in mitochondrial membrane potential. Western blotting confirmed normal levels of the oxidative phosphorylation (OXPHOS) complexes. The increased OCR was accompanied by a 5.4-fold increase in mitochondrial ROS levels. These increased ROS levels could be normalized with specific mitochondrial ROS scavengers (MitoTEMPO, mnSOD). Remarkably, scavenging of excess ROS strongly attenuated the hypertrophic response. In conclusion, loss of EXOG affects normal mitochondrial function resulting in increased mitochondrial respiration, excess ROS production, and cardiomyocyte hypertrophy.cardiomyocytes; hypertrophy; mitochondria; mitochondrial respiration; ROS THE HEART IS ONE OF THE MOST energy-consuming organs in the human body. This energy, in the form of ATP, is used to maintain proper contractile function and is mainly produced by cellular respiration, in particular by oxidative phosphorylation (OXPHOS) in the mitochondria. There is a strict correlation between energy production (supply) and energy utilization (demand). As the heart has limited energy storage capacity, ATP-generating systems must respond proportionally to fluctuations in demand. This energetic status of the heart is a delicate balance and is often disturbed in cardiovascular diseases, including heart failure.As a byproduct of oxidative phosphorylation, the mitochondria produce reactive oxygen species (ROS). Low levels of ROS may be protective (7, 23) and affect signaling pathways that may stimulate growth (5). However, an imbalance between ROS production and the normal cellular antioxidant defense system will lead to oxidative stress and potentially in DNA damage (10). Therefore, cells have develo...

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“…To determine oxygen consumption rate (OCR) in cardiomyocytes, a Seahorse metabolic flux analyzer (Seahorse Bioscience, North Billerica, MA, USA) was used as previously described [21].…”

Section: Seahorse Mitochondrial Flux Analysesmentioning

confidence: 99%

In EXOG-depleted cardiomyocytes cell death is marked by a decreased mitochondrial reserve capacity of the electron transport chain

et al. 2016

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Depletion of mitochondrial endo/exonuclease G-like (EXOG) in cultured neonatal cardiomyocytes stimulates mitochondrial oxygen consumption rate (OCR) and induces hypertrophy via reactive oxygen species (ROS). Here, we show that neurohormonal stress triggers cell death in endo/exonuclease G-like-depleted cells, and this is marked by a decrease in mitochondrial reserve capacity. Neurohormonal stimulation with phenylephrine (PE) did not have an additive effect on the hypertrophic response induced by endo/exonuclease G-like depletion. Interestingly, PE-induced atrial natriuretic peptide (ANP) gene expression was completely abolished in endo/exonuclease G-like-depleted cells, suggesting a reverse signaling function of endo/exonuclease G-like. Endo/exonuclease G-like depletion initially resulted in increased mitochondrial OCR, but this declined upon PE stimulation. In particular, the reserve capacity of the mitochondrial respiratory chain and maximal respiration were the first indicators of perturbations in mitochondrial respiration, and these marked the subsequent decline in mitochondrial function. Although pathological stimulation accelerated these processes, prolonged EXOG depletion also resulted in a decline in mitochondrial function. At early stages of endo/exonuclease G-like depletion, mitochondrial ROS production was increased, but this did not affect mitochondrial DNA (mtDNA) integrity. After prolonged depletion, ROS levels returned to control values, despite hyperpolariza-tion of the mitochondrial membrane. The mitochondrial dysfunction finally resulted in cell death, which appears to be mainly a form of necrosis. In conclusion, endo/exonuclease G-like plays an essential role in cardiomyocyte physiology. Loss of endo/exonuclease G-like results in diminished adaptation to pathological stress. The decline in maximal respiration and reserve capacity is the first sign of mitochondrial dysfunction that determines subsequent cell death.

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AKIP1 Expression Modulates Mitochondrial Function in Rat Neonatal Cardiomyocytes

Cited by 19 publications

References 33 publications

Impaired cardiac energy metabolism in embryos lacking adrenergic stimulation

Impaired cardiac energy metabolism in embryos lacking adrenergic stimulation

Loss of mitochondrial exo/endonuclease EXOG affects mitochondrial respiration and induces ROS-mediated cardiomyocyte hypertrophy

In EXOG-depleted cardiomyocytes cell death is marked by a decreased mitochondrial reserve capacity of the electron transport chain

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