bims-hafaim 2022-11-27 papers

Issue of 2022–11–27
six papers selected by
Kyle McCommis, Saint Louis University

JMA J. 2022 Oct 17. 5(4): 407-415

Mitochondrial Quality Control Mechanisms during Diabetic Cardiomyopathy.

Melis Ketenci, Daniela Zablocki, Junichi Sadoshima.

One of the major complications of diabetes mellitus is diabetic cardiomyopathy. One of the mechanisms that initiates the irreversible deterioration of cardiac function in diabetic cardiomyopathy is mitochondrial dysfunction. Functionally impaired mitochondria result in greater levels of oxidative stress and lipotoxicity, both of which exacerbate mitochondrial damage. Mitochondrial health is constantly monitored by mitochondrial quality control mechanisms. Mitophagy selectively degrades damaged mitochondria, thereby maintaining the healthy pool of mitochondria and preserving myocardial function. Mitophagy in diabetic cardiomyopathy is mediated by multiple mechanisms in a time-dependent manner. Potential targets for the treatment of diabetic cardiomyopathy include increased oxidative stress, mitochondrial dynamics, and mitochondrial clearance. Thus, stimulation of mitophagy represents a promising strategy for the alleviation of diabetic cardiomyopathy.

Keywords: Autophagy; Diabetes Mellitus; Diabetic Cardiomyopathy; Heart Failure; Mitochondria; Mitophagy

DOI: https://doi.org/10.31662/jmaj.2022-0155

Front Cardiovasc Med. 2022 ;9 1033457

PERM1 regulates energy metabolism in the heart via ERRα/PGC-1α axis.

Aims: PERM1 is a striated muscle-specific regulator of mitochondrial bioenergetics. We previously demonstrated that PERM1 is downregulated in the failing heart and that PERM1 positively regulates metabolic genes known as targets of the transcription factor ERRα and its coactivator PGC-1α in cultured cardiomyocytes. The aims of this study were to determine the effect of loss of PERM1 on cardiac function and energetics using newly generated Perm1-knockout (Perm1 -/-) mice and to investigate the molecular mechanisms of its transcriptional control.
Methods and results: Echocardiography showed that ejection fraction and fractional shortening were lower in Perm1 -/- mice than in wild-type mice (both p < 0.05), and the phosphocreatine-to-ATP ratio was decreased in Perm1 -/- hearts (p < 0.05), indicating reduced contractile function and energy reserves of the heart. Integrated proteomic and metabolomic analyses revealed downregulation of oxidative phosphorylation and upregulation of glycolysis and polyol pathways in Perm1 -/- hearts. To examine whether PERM1 regulates energy metabolism through ERRα, we performed co-immunoprecipitation assays, which showed that PERM1 bound to ERRα in cardiomyocytes and the mouse heart. DNA binding and reporter gene assays showed that PERM1 was localized to and activated the ERR target promoters partially through ERRα. Mass spectrometry-based screening in cardiomyocytes identified BAG6 and KANK2 as potential PERM1's binding partners in transcriptional regulation. Mammalian one-hybrid assay, in which PERM1 was fused to Gal4 DNA binding domain, showed that the recruitment of PERM1 to a gene promoter was sufficient to activate transcription, which was blunted by silencing of either PGC-1α, BAG6, or KANK2.
Conclusion: This study demonstrates that PERM1 is an essential regulator of cardiac energetics and function and that PERM1 is a novel transcriptional coactivator in the ERRα/PGC-1α axis that functionally interacts with BAG6 and KANK2.

Keywords: ERRα; PERM1; heart; metabolism; metabolomics; proteomics; transcription control

DOI: https://doi.org/10.3389/fcvm.2022.1033457

Nat Cardiovasc Res. 2022 Sep;1(9): 855-866

Mitochondrial interactome quantitation reveals structural changes in metabolic machinery in the failing murine heart.

Arianne Caudal, Xiaoting Tang, Juan D Chavez, Andrew Keller, Jared P Mohr, Anna A Bakhtina, Outi Villet, Hongye Chen, Bo Zhou, Matthew A Walker, Rong Tian, James E Bruce.

Advancements in cross-linking mass spectrometry (XL-MS) bridge the gap between purified systems and native tissue environments, allowing the detection of protein structural interactions in their native state. Here we use isobaric quantitative protein interaction reporter technology (iqPIR) to compare the mitochondria protein interactomes in healthy and hypertrophic murine hearts, 4 weeks post-transaortic constriction. The failing heart interactome includes 588 statistically significant cross-linked peptide pairs altered in the disease condition. We observed an increase in the assembly of ketone oxidation oligomers corresponding to an increase in ketone metabolic utilization; remodeling of NDUA4 interaction in Complex IV, likely contributing to impaired mitochondria respiration; and conformational enrichment of ADP/ATP carrier ADT1, which is non-functional for ADP/ATP translocation but likely possesses non-selective conductivity. Our application of quantitative cross-linking technology in cardiac tissue provides molecular-level insights into the complex mitochondria remodeling in heart failure while bringing forth new hypotheses for pathological mechanisms.

Keywords: cardiac hypertrophy; heart failure; interactome; mass spectrometry; mitochondria; protein interactions; quantitative cross-linking; systems structural biology

DOI: https://doi.org/10.1038/s44161-022-00127-4

Biochem Biophys Res Commun. 2022 Nov 13. pii: S0006-291X(22)01554-6. [Epub ahead of print]637 170-180

Sirtuin 1 aggravates hypertrophic heart failure caused by pressure overload via shifting energy metabolism.

Tran Ngoc Van Le, Linda Ines Zoungrana, Hao Wang, Mohammad Kasim Fatmi, Di Ren, Meredith Krause-Hauch, Ji Li.

Sirtuin1 (SIRT1) is involved in regulating substrate metabolism in the cardiovascular system. Metabolic homeostasis plays a critical role in hypertrophic heart failure. We hypothesize that cardiac SIRT1 can modulate substrate metabolism during pressure overload-induced heart failure. The inducible cardiomyocyte Sirt1 knockout (icSirt1-/-) and its wild type littermates (Sirt1f/f) C57BL/6J mice were subjected to transverse aortic constriction (TAC) surgery to induce pressure overload. The pressure overload induces upregulation of cardiac SIRT1 in Sirt1f/f but not icSirt1-/- mice. The cardiac contractile dysfunctions caused by TAC-induced pressure overload occurred in Sirt1f/f but not in icSirt1-/- mice. Intriguingly, Sirt1f/f heart showed a drastic reduction in systolic contractility and electric signals during post-TAC surgery, whereas icSirt1-/- heart demonstrated significant resistance to pathological stress by TAC-induced pressure overload as evidenced by no significant changes in systolic contractile functions and electric properties. The targeted proteomics showed that the pressure overload triggered downregulation of the SIRT1-associated IDH2 (isocitrate dehydrogenase 2) that resulted in increased oxidative stress in mitochondria. Moreover, metabolic alterations were observed in Sirt1f/f but not in icSirt1-/- heart in response to TAC-induced pressure overload. Thus, SIRT1 interferes with metabolic homeostasis through mitochondrial IDH2 during pressure overload. Inhibition of SIRT1 activity benefits cardiac functions under pressure overload-related pathological conditions.

Keywords: Mitochondria; Pressure overload; SIRT1; Substrate metabolism

DOI: https://doi.org/10.1016/j.bbrc.2022.11.014

Biochim Biophys Acta Gen Subj. 2022 Nov 18. pii: S0304-4165(22)00196-9. [Epub ahead of print] 130278

Polyunsaturated ω3 fatty acids prevent the cardiac hypertrophy in hypertensive rats.

M R Zavala, M L Longarzo, R F Vázquez, O Vélez Rueda, S M Maté, M C Villa-Abrille.

It has been demonstrated that supplementation with the two main omega 3 polyunsaturated fatty acids (ω3 FAs), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA), leads to modifications in the cardiac physiology. ω3 FAs can affect the membrane's lipid composition, as well as proteins' location and/or function. The Na+/H+ exchanger (NHE1) is an integral membrane protein involved in the maintenance of intracellular pH and its hyperactivity has been associated with the development of various cardiovascular diseases such as cardiac hypertrophy. Our aim was to determine the effect of ω3 FAs on systolic blood pressure (SBP), lipid profiles, NHE1 activity, and cardiac function in spontaneously hypertensive rats (SHR) using Wistar rats (W) as normotensive control. After weaning, the rats received orally ω3 FAs (200 mg/kg body mass/day/ 4 months). We measured SBP, lipid profiles, and different echocardiography parameters, which were used to calculate cardiac hypertrophy index, systolic function, and ventricular geometry. The rats were sacrificed, and ventricular cardiomyocytes were obtained to measure NHE1 activity. While the treatment with ω3 FAs did not affect the SBP, lipid analysis of plasma revealed a significant decrease in omega-6/omega-3 ratio, correlated with a significant reduction in left ventricular mass index in SHR. The NHE1 activity was significantly higher in SHR compared with W. While in W the NHE1 activity was similar in both groups, a significant decrease in NHE1 activity was detected in SHRs supplemented with ω3 FAs, reaching values comparable with W. Altogether, these findings revealed that diet supplementation with ω3 FAs since early age prevents the development of cardiac hypertrophy in SHR, perhaps by decreasing NHE1 activity, without altering hemodynamic overload.

Keywords: Cardiac hypertrophy; DHA; EPA; NHE1; Omega 3 polyunsaturated fatty acids; SHR

DOI: https://doi.org/10.1016/j.bbagen.2022.130278