Protein kinase C-epsilon activation induces mitochondrial dysfunction and fragmentation in renal proximal tubules.
Protein kinase C-epsilon activation induces mitochondrial dysfunction and fragmentation in renal proximal tubules.
复制标题
DOI：
10.1152/ajprenal.00364.2010
复制
发表时间：
2011-02
期刊：
影响因子：
--
通讯作者：
G. Nowak;Diana Bakajsova;A. Samarel
中科院分区：
文献类型：
--
作者：
G. Nowak;Diana Bakajsova;A. Samarel
PKC-ε活化介导对心肌缺血再灌注损伤的保护作用。线粒体是PKC-ε这些保护机制的亚细胞靶点。此前，我们已经证明PKC-ε的激活参与了氧化损伤的肾小管上皮细胞的线粒体功能障碍(RPTC；Nowak G，Bakajsova D，Clifton GL am J Physiol Renal Physiol286：F307-F316,2004)。本研究的目的是探讨PKC-ε激活在线粒体功能障碍中的作用，并确定PKC-ε在肾癌中的作用靶点。用腺病毒技术在原代培养的肾小管上皮细胞中高表达了pKC-ε的活性突变体和非活性突变体。活化的PKC-ε水平升高伴随着PKC-ε易位到线粒体。持续的PKC-ε激活导致第三态呼吸、电子传递速率、三磷酸腺苷生成量、三磷酸腺苷含量以及复合体I和IV以及F(0)F(1)-ATPase活性下降。此外，PKC-ε的激活增加了线粒体膜电位和氧化剂的产生，并导致线粒体碎裂和RPTC死亡。在线粒体碎裂之前，动力蛋白相关蛋白在线粒体中积累。抗氧化剂可阻断PKC-ε诱导的氧化剂生成的增加，但不能阻止线粒体碎裂和细胞死亡。失活的PKC-ε突变体对线粒体的功能、形态、氧化剂的产生和RPTC的活性没有影响。我们认为，活性的PKC-ε靶向于RPTC中的络合物I和IV以及F(0)F(1)-ATPase。蛋白激酶C-ε激活介导线粒体功能障碍、超极化和碎裂。它还诱导氧化剂的产生和细胞死亡，但氧化应激不是RPTC死亡的机制。这些结果表明，与PKC-ε激活对心肌细胞的保护作用相比，持续的PKC-ε激活不利于心肌细胞线粒体的功能和活性。
PKC-ε activation mediates protection from ischemia-reperfusion injury in the myocardium. Mitochondria are a subcellular target of these protective mechanisms of PKC-ε. Previously, we have shown that PKC-ε activation is involved in mitochondrial dysfunction in oxidant-injured renal proximal tubular cells (RPTC; Nowak G, Bakajsova D, Clifton GL Am J Physiol Renal Physiol 286: F307-F316, 2004). The goal of this study was to examine the role of PKC-ε activation in mitochondrial dysfunction and to identify mitochondrial targets of PKC-ε in RPTC. The constitutively active and inactive mutants of PKC-ε were overexpressed in primary cultures of RPTC using the adenoviral technique. Increases in active PKC-ε levels were accompanied by PKC-ε translocation to mitochondria. Sustained PKC-ε activation resulted in decreases in state 3 respiration, electron transport rate, ATP production, ATP content, and activities of complexes I and IV and F(0)F(1)-ATPase. Furthermore, PKC-ε activation increased mitochondrial membrane potential and oxidant production and induced mitochondrial fragmentation and RPTC death. Accumulation of the dynamin-related protein in mitochondria preceded mitochondrial fragmentation. Antioxidants blocked PKC-ε-induced increases in the oxidant production but did not prevent mitochondrial fragmentation and cell death. The inactive PKC-ε mutant had no effect on mitochondrial functions, morphology, oxidant production, and RPTC viability. We conclude that active PKC-ε targets complexes I and IV and F(0)F(1)-ATPase in RPTC. PKC-ε activation mediates mitochondrial dysfunction, hyperpolarization, and fragmentation. It also induces oxidant generation and cell death, but oxidative stress is not the mechanism of RPTC death. These results show that in contrast to protective effects of PKC-ε activation in cardiomyocytes, sustained PKC-ε activation is detrimental to mitochondrial function and viability in RPTC.