Osteopontin stimulates apoptosis in adult cardiac myocytes via the involvement of CD44 receptors, mitochondrial death pathway, and endoplasmic reticulum stress
Osteopontin stimulates apoptosis in adult cardiac myocytes via the involvement of CD44 receptors, mitochondrial death pathway, and endoplasmic reticulum stress
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DOI：
10.1152/ajpheart.00954.2013
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发表时间：
2014-04-01
影响因子：
4.8
通讯作者：
Singh, Krishna
中科院分区：
文献类型：
--
作者：
Dalal, Suman;Zha, Qinqin;Singh, Krishna
骨桥蛋白（OPN）表达增加与心肌细胞凋亡增加和心肌功能障碍有关。本研究的目的是鉴定OPN的受体，并探讨OPN诱导心肌细胞凋亡的机制。将成年大鼠心室肌细胞（ARVM）和以肌细胞特异性方式表达OPN的转基因小鼠用于体外和体内研究。用纯化的OPN（20 nM）蛋白或腺病毒介导的OPN表达治疗诱导ARVM细胞凋亡。OPN与CD 44受体共免疫沉淀，而不与β（1）或β（3）整合素共免疫沉淀。邻位连接试验证实了OPN与CD 44受体的相互作用。中和抗CD 44抗体抑制OPN刺激的细胞凋亡。OPN激活JNK，增加Bax的表达和细胞色素c的水平，表明线粒体死亡途径的参与。OPN增加内质网（ER）应激，表现为Gadd 153表达增加和caspase-12活化。使用SP 600125抑制JNK或使用salubrinal或半胱天冬酶-12抑制剂抑制ER应激显著减少OPN刺激的细胞凋亡。成年小鼠心肌中骨桥蛋白的表达与左心室功能下降和心肌细胞凋亡增加相关在心脏中，OPN表达增加JNKs和caspase-12活性，以及Bax和Gadd 153的表达。因此，OPN通过CD 44受体起作用，通过线粒体死亡途径和ER应激诱导肌细胞凋亡。
Increased osteopontin (OPN) expression associates with increased myocyte apoptosis and myocardial dysfunction. The objective of this study was to identify the receptor for OPN and get insight into the mechanism by which OPN induces cardiac myocyte apoptosis. Adult rat ventricular myocytes (ARVMs) and transgenic mice expressing OPN in a myocyte-specific manner were used for in vitro and in vivo studies. Treatment with purified OPN (20 nM) protein or adenoviral-mediated OPN expression induced apoptosis in ARVMs. OPN co-immunoprecipitated with CD44 receptors, not with beta(1) or beta(3) integrins. Proximity ligation assay confirmed interaction of OPN with CD44 receptors. Neutralizing anti-CD44 antibodies inhibited OPN-stimulated apoptosis. OPN activated JNKs and increased expression of Bax and levels of cytosolic cytochrome c, suggesting involvement of mitochondrial death pathway. OPN increased endoplasmic reticulum (ER) stress, as evidenced by increased expression of Gadd153 and activation of caspase-12. Inhibition of JNKs using SP600125 or ER stress using salubrinal or caspase-12 inhibitor significantly reduced OPN-stimulated apoptosis. Expression of OPN in adult mouse heart in myocyte-specific manner associated with decreased left ventricular function and increased myocyte apoptosis. In the heart, OPN expression increased JNKs and caspase-12 activities, and expression of Bax and Gadd153. Thus, OPN, acting via CD44 receptors, induces apoptosis in myocytes via the involvement of mitochondrial death pathway and ER stress.