PHLPP-1 negatively regulates Akt activity and survival in the heart.
PHLPP-1 negatively regulates Akt activity and survival in the heart.
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DOI：
10.1161/circresaha.109.215020
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发表时间：
2010-08-20
影响因子：
20.1
通讯作者：
Brown JH
中科院分区：
文献类型：
--
作者：
Miyamoto S;Purcell NH;Smith JM;Gao T;Whittaker R;Huang K;Castillo R;Glembotski CC;Sussman MA;Newton AC;Brown JH
最近发现的PHLPP-1（PH结构域富含亮氨酸重复蛋白磷酸酶-1）选择性地使Akt在Ser 473处去磷酸化并终止癌细胞中的Akt信号传导。PHLPP-1在心脏中的调节作用尚未被考虑。为了验证阻断/抑制PHLPP-1可能构成增强Akt信号并提供心脏保护的新方法的假设。PHLPP-1在新生大鼠心室肌细胞（NRVM）和成年小鼠心室肌细胞（AMVM）中表达。在白血病抑制因子（LIF）刺激的NRVMs中，通过小干扰RNA敲低PHLPP-1显著增强Akt（p-Akt）在Ser 473的磷酸化，但不增强Thr 308的磷酸化。增加的磷酸化伴随着更大的Akt催化活性。PHLPP-1敲低增强LIF介导的针对阿霉素的心脏保护，并且还保护心肌细胞免受H2 O2的侵害。Akt对线粒体的直接作用与心脏保护有关，线粒体/细胞质分级显示PHLPP-1在线粒体中显著富集。证明了PHLPP-1敲低增强LIF介导的线粒体p-Akt增加和伴随的线粒体己糖激酶-II增加的能力。我们产生了PHLPP-1敲除（KO）小鼠，并证明了从KO小鼠分离的AMVM在Ser 473处对激动剂的反应中显示出增强的p-Akt。当离体灌注心脏进行缺血/再灌注，p-Akt在全心脏匀浆和线粒体馏分显着增加。此外，在PHLPP-1 KO心脏中，由缺血/再灌注引起的p-Akt的增加被增强，并且伴随地，梗死面积显著减小。这些结果暗示PHLPP-1作为心脏中Akt活性和细胞存活的内源性负调节剂。
The recently discovered PHLPP-1 (PH domain leucine-rich repeat protein phosphatase-1) selectively dephosphorylates Akt at Ser473 and terminates Akt signaling in cancer cells. The regulatory role of PHLPP-1 in the heart has not been considered. To test the hypothesis that blockade/inhibition of PHLPP-1 could constitute a novel way to enhance Akt signals and provide cardioprotection. PHLPP-1 is expressed in neonatal rat ventricular myocytes (NRVMs) and in adult mouse ventricular myocytes (AMVMs). PHLPP-1 knockdown by small interfering RNA significantly enhances phosphorylation of Akt (p-Akt) at Ser473, but not at Thr308, in NRVMs stimulated with leukemia inhibitory factor (LIF). The increased phosphorylation is accompanied by greater Akt catalytic activity. PHLPP-1 knockdown enhances LIF-mediated cardioprotection against doxorubicin and also protects cardiomyocytes against H2O2. Direct Akt effects at mitochondria have been implicated in cardioprotection and mitochondria/cytosol fractionation revealed a significant enrichment of PHLPP-1 at mitochondria. The ability of PHLPP-1 knockdown to potentiate LIF-mediated increases in p-Akt at mitochondria and an accompanying increase in mitochondrial hexokinase-II was demonstrated. We generated PHLPP-1 knockout (KO) mice and demonstrate that AMVMs isolated from KO mice show potentiated p-Akt at Ser473 in response to agonists. When isolated perfused hearts are subjected to ischemia/reperfusion, p-Akt in whole-heart homogenates and in the mitochondrial fraction is significantly increased. Additionally in PHLPP-1 KO hearts, the increase in p-Akt elicited by ischemia/reperfusion is potentiated and, concomitantly, infarct size is significantly reduced. These results implicate PHLPP-1 as an endogenous negative regulator of Akt activity and cell survival in the heart.