Auto-acetylation stabilizes p300 in cardiac myocytes during acute oxidative stress, promoting STAT3 accumulation and cell survival
Auto-acetylation stabilizes p300 in cardiac myocytes during acute oxidative stress, promoting STAT3 accumulation and cell survival
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DOI：
10.1007/s10549-012-2069-6
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发表时间：
2012-08-01
影响因子：
3.8
通讯作者：
Bishopric, Nanette H.
中科院分区：
文献类型：
--
作者：
Jain, Sumit;Wei, Jianqin;Bishopric, Nanette H.
核乙酰转移酶p300在血流动力学应激过程中在心脏中被快速而稳定地诱导，但这种诱导的机制尚不清楚。为了确定氧化应激在p300诱导中的作用，我们将新生大鼠心肌细胞暴露于阿霉素（DOX，1 μ M）或其载体，并监测p300蛋白含量和稳定性24小时。p300水平在1小时内大幅上升，并保持升高至少24小时，而p300转录水平下降。在放线菌酮的存在下，在控制细胞中的p300的估计半衰期约为4.5小时，典型的立即早期反应蛋白。DOX处理使p300 t（1/2）延长至> 24 h，表明p300水平的急剧升高可归因于蛋白质的快速稳定。p300稳定化完全是由于乙酰化p300种类的增加，对蛋白酶体降解的抗性大大增强。p300的半衰期依赖于其乙酰转移酶活性，在p300抑制剂姜黄素和漆树酸的存在下下降，并随着组蛋白脱乙酰酶（HDAC）抑制而增加。同时，乙酰-STAT 3、磷酸-STAT 3-（Tyr 705）和-（Ser 727）增加，以及STAT 3半衰期的延长。siRNA介导的p300基因敲除消除了所有这些作用，并强烈增强了DOX介导的心肌细胞凋亡。我们的结论是，DOX诱导急性放大p300水平通过自动乙酰化和稳定。反过来，升高的p300通过STAT 3的乙酰化、活化和稳定化提供了心肌细胞中对抗急性氧化应激的关键防御。我们的研究结果表明，HDAC抑制剂可能通过促进p300的自动乙酰化来降低急性蒽环类药物介导的心脏毒性。
The nuclear acetyltransferase p300 is rapidly and stably induced in the heart during hemodynamic stress, but the mechanism of this induction is unknown. To determine the role of oxidative stress in p300 induction, we exposed neonatal rat cardiac myocytes to doxorubicin (DOX, 1 mu M) or its vehicle, and monitored p300 protein content and stability for 24 h. Levels of p300 rose substantially within 1 h and remained elevated for at least 24 h, while p300 transcript levels declined. In the presence of cycloheximide, the estimated half-life of p300 in control cells was approximately 4.5 h, typical of an immediate-early response protein. DOX treatment prolonged p300 t(1/2) to > 24 h, indicating that the sharp rise in p300 levels was attributable to rapid protein stabilization. p300 stabilization was entirely due to an increase in acetylated p300 species with greatly enhanced resistance to proteasomal degradation. The half-life of p300 was dependent on its acetyltransferase activity, falling in the presence of p300 inhibitors curcumin and anacardic acid, and increasing with histone deacetylase (HDAC) inhibition. At the same time, acetyl-STAT3, phospho-STAT3-(Tyr 705) and -(Ser 727) increased, together with a prolongation of STAT3 half-life. SiRNA-mediated p300 knockdown abrogated all of these effects, and strongly enhanced DOX-mediated myocyte apoptosis. We conclude that DOX induces an acute amplification of p300 levels through auto-acetylation and stabilization. In turn, elevated p300 provides a key defense against acute oxidative stress in cardiac myocytes by acetylation, activation, and stabilization of STAT3. Our results suggest that HDAC inhibitors could potentially reduce acute anthracycline-mediated cardiotoxicity by promoting p300 auto-acetylation.