Cui Chen, Chen Shihong, Qiao Jingting, Qing Li, Wang Lingshu, He Tianyi, Wang Chuan, Liu Fuqiang, Gong Lei, Chen Li, Hou Xinguo
Department of Endocrinology, Qilu Hospital of Shandong University, Jinan 250012, China.
Department of Endocrinology, The Second Hospital of Shandong University, Jinan, 250033, China.
Biochem Biophys Res Commun. 2018 Apr 6;498(3):445-452. doi: 10.1016/j.bbrc.2018.02.199. Epub 2018 Feb 28.
Mitochondria play an important role in cellular metabolism and are closely related with metabolic stress. Recently, several studies have shown that mitophagy mediated by PTEN-induced putative kinase 1 (PINK1) and Parkin may play a critical role in clearing the damaged mitochondria and maintaining the overall balance of intracellular mitochondria in quality and quantity. A previous study showed that PINK1 and Parkin were overexpressed in adipose tissue in obese subjects. However, it is still unclear whether a direct relationship exists between obesity and mitophagy. In this study, we created a high-fat-diet (HFD)-induced obese mouse model and examined the expression of PINK1 and Parkin in adipose tissue using western blot and real-time quantitative PCR. After we confirmed that there is an interesting difference between regular-chow-fed mice and HFD-induced obese mice in the expression of PINK1 and Parkin in vivo, we further tested the expression of PINK1 and Parkin in 3T3-L1 preadipocytes in vitro by treating cells with palmitic acid (PA) to induce metabolic stress. To better understand the role of PINK1 and Parkin in metabolic stress, 3T3-L1 preadipocytes were transfected with small interfering RNA (siRNA) of PINK1 and Parkin followed by PA treatment. Our results showed that under lower concentrations of PA, PINK1 and Parkin can be activated and play a protective role in resisting the harmful effects of PA, including protecting the mitochondrial function and resisting cellular death, while under higher concentrations of PA, the expression of PINK1 and Parkin can be inhibited. These results suggest that PINK1-Parkin can protect mitochondrial function against metabolic stress induced by obesity or PA to a certain degree.
线粒体在细胞代谢中发挥着重要作用，且与代谢应激密切相关。最近，多项研究表明，由磷酸酶及张力蛋白同源物诱导假定激酶1（PINK1）和帕金蛋白介导的线粒体自噬，在清除受损线粒体以及维持细胞内线粒体在质量和数量上的整体平衡方面可能起着关键作用。先前的一项研究表明，肥胖受试者的脂肪组织中PINK1和帕金蛋白表达上调。然而，肥胖与线粒体自噬之间是否存在直接关系仍不清楚。在本研究中，我们建立了高脂饮食（HFD）诱导的肥胖小鼠模型，并使用蛋白质免疫印迹法和实时定量聚合酶链反应检测脂肪组织中PINK1和帕金蛋白的表达。在确认正常饮食喂养的小鼠和HFD诱导的肥胖小鼠体内PINK1和帕金蛋白的表达存在显著差异后，我们进一步在体外通过用棕榈酸（PA）处理3T3-L1前脂肪细胞以诱导代谢应激，来检测PINK1和帕金蛋白的表达。为了更好地理解PINK1和帕金蛋白在代谢应激中的作用，我们用PINK1和帕金蛋白的小干扰RNA（siRNA）转染3T3-L1前脂肪细胞，随后进行PA处理。我们的结果表明，在较低浓度的PA作用下，PINK1和帕金蛋白可以被激活，并在抵抗PA的有害影响方面发挥保护作用，包括保护线粒体功能和抵抗细胞死亡，而在较高浓度的PA作用下，PINK1和帕金蛋白的表达会受到抑制。这些结果表明，PINK1-帕金蛋白可以在一定程度上保护线粒体功能免受肥胖或PA诱导的代谢应激影响。
