Akt activation improves oxidative phosphorylation in renal proximal tubular cells following nephrotoxicant injury.
Akt activation improves oxidative phosphorylation in renal proximal tubular cells following nephrotoxicant injury.
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DOI：
10.1152/ajprenal.00463.2007
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发表时间：
2008-02
期刊：
影响因子：
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通讯作者：
Zabeena P. Shaik;E. Kim Fifer;G. Nowak
中科院分区：
文献类型：
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作者：
Zabeena P. Shaik;E. Kim Fifer;G. Nowak
以前，我们发现蛋白激酶B（Akt）激活增加了细胞内ATP水平，并减少了肾毒性物质S-（1，2-二氯乙烯基）-L-半胱氨酸（DCVC）损伤的肾近端小管细胞（RPTC）的坏死（Shaik ZP，Fifer EK，Nowak G. Am J Physiol Renal Physiol 292：F292-F303，2007）。本研究探讨了Akt在改善DCVC损伤的RPTC中线粒体功能的作用。我们的数据显示了一个新的观察，磷酸化（活性）Akt是本地化的线粒体未受伤的RPTC，无论是在线粒体和线粒体外膜。肾毒性药物损伤的RPTC中，线粒体活性Akt水平降低，这种降低与线粒体功能障碍有关。DCVC降低基础、非偶联和状态3呼吸; ATP产生;复合物I、II和III的活性;线粒体膜电位（DeltaPsi（m））;和F（0）F（1）-ATP酶活性。在DCVC损伤的RPTC中表达组成型活性Akt增加了线粒体中磷酸化Akt的水平，减少了基础和解偶联呼吸的减少，增加了复合物I偶联状态3呼吸和ATP的产生，增强了复合物I、复合物III和F（0）F（1）的活性。-ATP酶，并改善DeltaPsi（m）。相比之下，通过表达显性失活（失活）Akt或使用20 μ M LY 294002来抑制Akt活化加剧了电子传递速率、状态3呼吸、ATP产生、Δ Psi（m）以及复合物I、复合物III和F（0）F（1）-ATP酶活性的降低。总之，我们的数据表明，Akt活化通过以下方式促进毒物损伤的RPTC中的线粒体呼吸和ATP产生：1）改善呼吸链的完整性并维持复合物I和复合物III的活性，2）减少DeltaPsi（m）的降低，以及3）恢复F（0）F（1）-ATP酶活性。
Previously, we showed that protein kinase B (Akt) activation increases intracellular ATP levels and decreases necrosis in renal proximal tubular cells (RPTC) injured by the nephrotoxicant S-(1, 2-dichlorovinyl)-l-cysteine (DCVC) (Shaik ZP, Fifer EK, Nowak G. Am J Physiol Renal Physiol 292: F292-F303, 2007). This study examined the role of Akt in improving mitochondrial function in DCVC-injured RPTC. Our data show a novel observation that phosphorylated (active) Akt is localized in mitochondria of noninjured RPTC, both in mitoplasts and the mitochondrial outer membrane. Mitochondrial levels of active Akt decreased in nephrotoxicant-injured RPTC, and this decrease was associated with mitochondrial dysfunction. DCVC decreased basal, uncoupled, and state 3 respirations; ATP production; activities of complexes I, II, and III; the mitochondrial membrane potential (DeltaPsi(m)); and F(0)F(1)-ATPase activity. Expressing constitutively active Akt in DCVC-injured RPTC increased the levels of phosphorylated Akt in mitochondria, reduced the decreases in basal and uncoupled respirations, increased complex I-coupled state 3 respiration and ATP production, enhanced activities of complex I, complex III, and F(0)F(1)-ATPase, and improved DeltaPsi(m). In contrast, inhibiting Akt activation by expressing dominant negative (inactive) Akt or using 20 microM LY294002 exacerbated decreases in electron transport rate, state 3 respiration, ATP production, DeltaPsi(m), and activities of complex I, complex III, and F(0)F(1)-ATPase. In conclusion, our data show that Akt activation promotes mitochondrial respiration and ATP production in toxicant-injured RPTC by 1) improving integrity of the respiratory chain and maintaining activities of complex I and complex III, 2) reducing decreases in DeltaPsi(m), and 3) restoring F(0)F(1)-ATPase activity.