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The Role of Mitophagy in Doxorubicin‐Induced Cardiomyocyte Death
Author(s) -
Weiner Ashley,
Kaminaris Amanda,
Kobayashi Satoru,
Gerdes Martin,
Liang Qiangrong
Publication year - 2016
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.30.1_supplement.1015.2
Subject(s) - mitophagy , parkin , pink1 , microbiology and biotechnology , mitochondrion , autophagy , programmed cell death , ubiquitin ligase , biology , chemistry , ubiquitin , apoptosis , biochemistry , medicine , parkinson's disease , gene , disease
Doxorubicin (DOX), one of the most commonly used antineoplastic agents, is effective against many cancers, but limited by its toxicities on non‐cancerous cells, especially cardiomyocytes. Although some strategies have been attempted, development of a specific therapy targeting DOX‐induced heart failure has not yet been created, largely because the mechanism remains poorly understood. DOX sets off a cellular cascade leading to mitochondrial disruption, with cell death being the ultimate event. Since mitochondrial density is up to 35% in cardiomyocytes, DOX‐induced mitochondrial malfunction can cause a serious shortage of energy supply. In this study, we investigated whether DOX treatment results in excessive elimination of mitochondria through the autophagy‐lysosome pathway known as mitophagy, and if this leads to an increase in cardiomyocyte death. Mitochondrial morphology and the levels of mitophagy in DOX‐treated H9c2 cardiac myoblasts were examined with adenovirus‐encoded mtRosella, a mitochondrial‐targeted pH sensitive dual fluorescent fusion protein. Confocal imaging analyses show that DOX enhanced mitochondrial fragmentation and increased mitophagy. To determine the underlying mechanism that mediated DOX‐induced mitophagy, we examined the expression levels of several proteins that regulate mitophagy. The serine/threonine protein kinase PINK1 and the E3 ubiquitin ligase Parkin comprise a well‐established pathway involved in the activation of mitophagy. The protein levels and mitochondrial translocation of Parkin and PINK1were all increased at 2 hours after DOX treatment, but only the effects on PINK1 were sustained at 24 hours. Parkin levels were actually reduced at this time point. These results suggest that the PINK1/Parkin pathway may contribute to DOX‐induced mitophagy and cell death. Indeed, overexpression of Parkin via adenovirus‐mediated gene transfer accelerated DOX‐induced mitochondrial morphology changes and induced mitophagy, which was associated with exaggerated cell death as indicated by propidium iodide (PI)‐uptake and cellular levels of cleaved caspase‐3 and cleaved Poly ADP ribose polymerase. Conversely, Parkin knockdown by siRNA inhibited DOX‐induced mitophagy and reduced apoptotic marker levels and PI‐uptake. These results suggest that DOX‐induced mitochondrial fission and mitophagy are detrimental to cardiac cells. Strategies that limit mitochondrial degradation through PINK1/Parkin mediated mitophagy may help reduce DOX cardiotoxicity. Support or Funding Information This study is supported by the following NIH grant: 1R15HL120027‐01A1