title: Post-conditioning protects cardiomyocytes from apoptosis via PKC(epsilon)-interacting with calcium-sensing receptors to inhibit endo(sarco)plasmic reticulum-mitochondria crosstalk.
abstract: The intracellular Ca(2+) concentration ([Ca(2+)](i)) is increased during cardiac ischemia/reperfusion injury (IRI), leading to endo(sarco)plasmic reticulum (ER) stress. Persistent ER stress, such as with the accumulation of [Ca(2+)](i), results in apoptosis. Ischemic post-conditioning (PC) can protect cardiomyocytes from IRI by reducing the [Ca(2+)](i) via protein kinase C (PKC). The calcium-sensing receptor (CaR), a G protein-coupled receptor, causes the production of inositol phosphate (IP(3)) to increase the release of intracellular Ca(2+) from the ER. This process can be negatively regulated by PKC through the phosphorylation of Thr-888 of the CaR. This study tested the hypothesis that PC prevents cardiomyocyte apoptosis by reducing the [Ca(2+)](i) through an interaction of PKC with CaR to alleviate [Ca(2+)](ER) depletion and [Ca(2+)](m) elevation by the ER-mitochondrial associated membrane (MAM). Cardiomyocytes were post-conditioned after 3 h of ischemia by three cycles of 5 min of reperfusion and 5 min of re-ischemia before 6 h of reperfusion. During PC, PKC(epsilon) translocated to the cell membrane and interacted with CaR. While PC led to a significant decrease in [Ca(2+)](i), the [Ca(2+)](ER) was not reduced and [Ca(2+)](m) was not increased in the PC and GdCl(3)-PC groups. Furthermore, there was no evident psi(m) collapse during PC compared with ischemia/reperfusion (I/R) or PKC inhibitor groups, as evaluated by laser confocal scanning microscopy. The apoptotic rates detected by TUNEL and Hoechst33342 were lower in PC and GdCl(3)-PC groups than those in I/R and PKC inhibitor groups. Apoptotic proteins, including m-calpain, BAP31, and caspase-12, were significantly increased in the I/R and PKC inhibitor groups. These results suggested that PKC(epsilon) interacting with CaR protected post-conditioned cardiomyocytes from programmed cell death by inhibiting disruption of the mitochondria by the ER as well as preventing calcium-induced signaling of the apoptotic pathway.
authors.affiliation: Department of Pathophysiology, Harbin Medical University, Harbin 150086, China.
authors.forename: Shiyun
authors.initials: S
authors.lastname: Dong
authors.forename: Zongyan
authors.initials: Z
authors.lastname: Teng
authors.forename: Fang-Hao
authors.initials: FH
authors.lastname: Lu
authors.forename: Ya-Jun
authors.initials: YJ
authors.lastname: Zhao
authors.forename: Hulun
authors.initials: H
authors.lastname: Li
authors.forename: Huan
authors.initials: H
authors.lastname: Ren
authors.forename: He
authors.initials: H
authors.lastname: Chen
authors.forename: Zhen-Wei
authors.initials: ZW
authors.lastname: Pan
authors.forename: Yan-Jie
authors.initials: YJ
authors.lastname: Lv
authors.forename: Bao-Feng
authors.initials: BF
authors.lastname: Yang
authors.forename: Ye
authors.initials: Y
authors.lastname: Tian
authors.forename: Chang-Qing
authors.initials: CQ
authors.lastname: Xu
authors.forename: Wei-Hua
authors.initials: WH
authors.lastname: Zhang
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D057775:Ischemic Postconditioning; D032383:Myocytes, Cardiac / Q000166:cytology*; D051744:Protein Kinase C-epsilon / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D020239:Receptor Cross-Talk; D044169:Receptors, Calcium-Sensing / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D044169:Receptors, Calcium-Sensing; D051744:Protein Kinase C-epsilon
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