Department of Pharmacology, Faculty of Medicine, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki, Osaka 569-8686, Japan.
Int J Mol Sci. 2017 Oct 25;18(11):2232. doi: 10.3390/ijms18112232.
The E3 ubiquitin ligase, von Hippel-Lindau (VHL), regulates protein expression by polyubiquitination. Although the protein VHL (pVHL) was reported to be involved in the heart function, the underlying mechanism is unclear. Here, we show that pVHL was upregulated in hearts from two types of genetically dilated cardiomyopathy (DCM) mice models. In comparison with the wild-type mouse, both DCM mice models showed a significant reduction in the expression of phospholamban (PLN), a potent inhibitor of sarco(endo)plasmic reticulum Ca-ATPase, and enhanced interaction between pVHL and PLN. To clarify whether pVHL is involved in PLN degradation in failing hearts, we used carbonylcyanide -chlorophenylhydrazone (CCCP), a mitochondrial membrane potential (MMP)-lowering reagent, to mimic the heart failure condition in PLN-expressing HEK293 cells and found that CCCP treatment resulted in PLN degradation and increased interaction between PLN and pVHL. However, these effects were reversed with the addition of -acetyl-l-cysteine. Furthermore, the co-transfection of and PLN in HEK293 cells decreased PLN expression under oxidative stress, whereas knockdown of increased PLN expression both under normal and oxidative stress conditions. Together, we propose that oxidative stress upregulates pVHL expression to induce PLN degradation in failing hearts.
E3 泛素连接酶，von Hippel-Lindau（VHL），通过多泛素化调节蛋白质表达。尽管已经报道了蛋白 VHL（pVHL）参与心脏功能，但潜在的机制尚不清楚。在这里，我们表明在两种遗传性扩张型心肌病（DCM）小鼠模型的心脏中上调了 pVHL。与野生型小鼠相比，两种 DCM 小鼠模型均显示出肌浆网 Ca2+-ATP 酶（PLN）的表达显著降低，这是一种强大的肌浆网 Ca2+-ATP 酶抑制剂，并且 pVHL 与 PLN 之间的相互作用增强。为了阐明 pVHL 是否参与衰竭心脏中的 PLN 降解，我们使用羰基氰化物-氯苯腙（CCCP），一种降低线粒体膜电位（MMP）的试剂，模拟表达 PLN 的 HEK293 细胞中的心力衰竭条件，发现 CCCP 处理导致 PLN 降解和 PLN 与 pVHL 之间的相互作用增加。然而，加入 -乙酰-l-半胱氨酸可逆转这些作用。此外，在 HEK293 细胞中共转染和 PLN 可在氧化应激下降低 PLN 表达，而 敲低则在正常和氧化应激条件下均增加 PLN 表达。综上所述，我们提出氧化应激上调 pVHL 表达，从而诱导衰竭心脏中的 PLN 降解。
