期刊
JOURNAL OF BIOLOGICAL CHEMISTRY
卷 294, 期 42, 页码 15282-15292出版社
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.RA119.009477
关键词
calcium; cardiomyocyte; mitochondria; mitochondrial permeability transition (MPT); ryanodine receptor; sarcoplasmic reticulum (SR); anoxia?reoxygenation; caffeine; cardiac infarction; ryanodine
资金
- Institut National de la Sante et de la Recherche Medicale (INSERM, U1060, Lyon, France)
Calcium homeostasis is essential for cell survival and is precisely controlled by several cellular actors such as the sarco/endoplasmic reticulum and mitochondria. Upon stress induction, Ca2+ released from sarco/endoplasmic reticulum stores and from extracellular Ca2+ pools accumulates in the cytosol and in the mitochondria. This induces Ca2+ overload and ultimately the opening of the mitochondrial permeability transition pore (mPTP), promoting cell death. Currently, it is unclear whether intracellular Ca2+ stores are sufficient to promote the mPTP opening. Ca2+ retention capacity (CRC) corresponds to the maximal Ca2+ uptake by the mitochondria before mPTP opening. In this study, using permeabilized cardiomyocytes isolated from adult mice, we modified the standard CRC assay by specifically inducing reticular Ca2+ release to investigate the respective contributions of reticular Ca2+ and extracellular Ca2+ to mPTP opening in normoxic conditions or after anoxia?reoxygenation. Our experiments revealed that Ca2+ released from the sarco/endoplasmic reticulum is not sufficient to trigger mPTP opening and corresponds to ?50% of the total Ca2+ levels required to open the mPTP. We also studied mPTP opening after anoxia?reoxygenation in the presence or absence of extracellular Ca2+. In both conditions, Ca2+ leakage from internal stores could not trigger mPTP opening by itself but significantly decreased the CRC. Our findings highlight how a modified CRC assay enables the investigation of the role of reticular and extracellular Ca2+ pools in the regulation of the mPTP. We propose that this method may be useful for screening molecules of interest implicated in mPTP regulation.
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