Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, 351 Taché Avenue, Winnipeg, Manitoba, Canada R2H 2A6 Department of Physiology, University of Manitoba, Winnipeg, Manitoba, Canada.
Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, 351 Taché Avenue, Winnipeg, Manitoba, Canada R2H 2A6.
Cardiovasc Res. 2014 Jul 1;103(1):72-80. doi: 10.1093/cvr/cvu066. Epub 2014 Mar 20.
Fibroblast growth factor 2 (FGF-2) protects the heart from ischaemia- and reperfusion-induced cell death by a mechanism linked to protein kinase C (PKC)ε-mediated connexin 43 (Cx43) phosphorylation. Cx43 localizes predominantly to gap junctions, but has also been detected at subsarcolemmal (SSM), but not interfibrillar (IFM), mitochondria, where it is considered important for cardioprotection. We have now examined the effect of FGF-2 administration to the heart on resistance to calcium-induced permeability transition (mPTP) of isolated SSM vs. IFM suspensions, in relation to mitochondrial PKCε/Cx43 levels, phosphorylation, and the presence of peptide Gap27, a Cx43 channel blocker.
FGF-2 perfusion increased resistance to calcium-induced mPTP in SSM and IFM suspensions by 2.9- and 1.7-fold, respectively, compared with their counterparts from vehicle-perfused hearts, assessed spectrophotometrically as cyclosporine A-inhibitable swelling. The salutary effect of FGF-2 was lost in SSM, but not in IFM, in the presence of Gap27. FGF-2 perfusion increased relative levels of PKCε, phospho(p) PKCε, and Tom-20 translocase in SSM and IFM, and of Cx43 in SSM. Phospho-serine (pS) 262- and pS368-Cx43 showed a 30- and 8-fold increase, respectively, in SSM from FGF-2-treated, compared with untreated, hearts. Stimulation of control SSM with phorbol 12-myristate 13-acetate (PMA), a PKC activator, increased both calcium tolerance and mitochondrial Cx43 phosphorylation at S262 and S368. The PMA-induced phosphorylation of mitochondrial Cx43 was prevented by εV1-2, a PKCε-inhibiting peptide.
SSM are more responsive than IFM to FGF-2-triggered protection from calcium-induced mPTP, by a mitochondrial Cx43 channel-mediated pathway, associated with mitochondrial Cx43 phosphorylation at PKCε target sites.
成纤维细胞生长因子 2（FGF-2）通过与蛋白激酶 C（PKC）ε介导的连接蛋白 43（Cx43）磷酸化相关的机制，保护心脏免受缺血再灌注引起的细胞死亡。Cx43 主要定位于缝隙连接，但也在亚肌小节（SSM）而非肌纤维间（IFM）线粒体中检测到，在那里它被认为对心脏保护很重要。我们现在研究了 FGF-2 给药对分离的 SSM 与 IFM 悬浮液中钙诱导的通透性转换（mPTP）的抗性的影响，与线粒体 PKCε/Cx43 水平、磷酸化以及肽 Gap27（Cx43 通道阻滞剂）的存在有关。
与对照心脏相比，FGF-2 灌注使 SSM 和 IFM 悬浮液中钙诱导的 mPTP 的抗性分别增加了 2.9 倍和 1.7 倍，通过环孢菌素 A 抑制性肿胀来评估分光光度法。在 SSM 中，Gap27 的存在使 FGF-2 的有益作用丧失，但在 IFM 中则没有。FGF-2 灌注增加了 SSM 和 IFM 中的 PKCε、磷酸化 pPKCε 和 Tom-20 转位酶的相对水平，以及 SSM 中的 Cx43。与未经处理的心脏相比，FGF-2 处理的 SSM 中 Cx43 的磷酸化丝氨酸（pS）262 和 pS368 分别增加了 30 倍和 8 倍。用佛波醇 12-肉豆蔻酸 13-醋酸盐（PMA）刺激对照 SSM（PKC 激活剂）可增加钙耐受性和线粒体 Cx43 在 S262 和 S368 处的磷酸化。PKCε 抑制肽 εV1-2 可阻止 PMA 诱导的线粒体 Cx43 磷酸化。
与 IFM 相比，SSM 对 FGF-2 触发的钙诱导 mPTP 的保护作用更敏感，通过与 PKCε 靶位的线粒体 Cx43 通道相关的途径，与线粒体 Cx43 在 PKCε 靶位的磷酸化有关。
