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Inhibition of excessive mitochondrial fission protects the cardiomyocyte against palmitate‐induced lipotoxicity
Author(s) -
Li SinJin,
Chen ChingYi
Publication year - 2018
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2018.32.1_supplement.543.3
Subject(s) - mitochondrial fission , fis1 , lipotoxicity , mfn2 , dnm1l , mitochondrial fusion , mitophagy , microbiology and biotechnology , pink1 , mitochondrion , gene knockdown , biology , apoptosis , endocrinology , biochemistry , mitochondrial dna , insulin , insulin resistance , autophagy , gene
Mitochondria play the major role in maintaining the optimal cardiac function. Recently, mitochondrial dynamics have been connected with cardiovascular diseases. Cardiac oxidative stress and imbalanced mitochondrial dynamics (decreased fusion and excessive fission) are involved in lipotoxicity‐induced cardiomyopathy. Our aim was to investigate the role of mitochondrial dynamic in H9c2 cells under lipotoxicity. Treatment of H9c2 cells (cardiomyoblast) with 200 μM palmitate resulted in decreased cell viability and decreased ATP production. Palmitate treatment for 3 h elevated protein expression of the dynamin‐related protein‐1 (DRP1, a mitochondrial fission protein) and PTEN‐induced putative kinase 1 (PINK1, marker of mitophagy), but 24 h incubation with palmitate reduced expression of mitochondrial fusion‐ (mitofusin‐2, Mfn2), fission‐ (DRP1 and fission 1 protein, Fis1) and mitophagy‐ related proteins. To correct the mitochondrial imbalance on the initiation of lipotoxicity, we inhibited Drp1 to evaluate whether this action restores mitochondrial function. Knockdown of DRP1 resulted in decreased apoptosis in cells after palmitate treatment for 24 h. To further determine the functional effects of knockdown of DRP1 on palmitate stress in a short‐term or long‐term period (plamitate treatment for 1 h or 24 h), we measured cellular respiration using Seahorse analyzer. Treatment of H9c2 with plamitate for 1 h reduced the oxygen consumption rate and extracellular acidification rate during basal respiration, whereas inhibition of DRP1 maintained the mitochondrial functions. This result indicated that the energetic function was shifted to quiescence in palmitate‐treated cells whereas knockdown of DRP1 cell did not have this effect. Palmitate treatment resulted in a remarkable reduction ATP production while knockdown of DRP1 restored their reductions. Non‐mitochondrial oxygen consumption (e.g. ROS generation) was upregulated with palmitate treatment, but DPR1 suppression decreased ROS generation. However, there was lower basal respiration, ATP production and FCCP‐stimulated maximal respiration in both groups following 24 h‐palmitate treatment which indicated that DRP1 knockdown could not restore mitochondrial oxidative function. In conclusion, palmitate disrupted mitochondrial dynamic and induced cell death, whereas inhibition of mitochondrial fission (DRP1) at the onset of lipotoxicity maintained the mitochondrial function and cell survival; however, it did not restore mitochondrial function after prolonged palmitate stress, demonstrating its limitations. Support or Funding Information MOST‐104‐2313‐B‐002‐038‐MY3 This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .