SIRT1 modulation of the acetylation status, cytosolic localization, and activity of LKB1 - Possible role in AMP-activated protein kinase activation
SIRT1 modulation of the acetylation status, cytosolic localization, and activity of LKB1 - Possible role in AMP-activated protein kinase activation
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DOI：
10.1074/jbc.m805711200
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发表时间：
2008-10-10
影响因子：
4.8
通讯作者：
Ido, Yasuo
中科院分区：
文献类型：
--
作者：
Lan, Fan;Cacicedo, Jose M.;Ido, Yasuo
SIRT1，一种组蛋白/蛋白质去乙酰化酶，和amp活化蛋白激酶（AMPK）是负责长寿和能量稳态的关键酶。我们研究了这些分子之间是否存在涉及主要AMPK激酶LKB1的机制连接。初步研究表明，LKB1在培养的（HEK293T）细胞、小鼠白色脂肪组织和大鼠肝脏中发生乙酰化。在293T细胞中，SIRT1过表达降低了LKB1的赖氨酸乙酰化，同时增加了LKB1的活性、细胞质/核比以及与LKB1激活剂STRAD的关联。相比之下，在研究中，SIRT1的短发夹RNA对这些参数有相反的影响。质谱分析证实LKB1的乙酰化发生在多个但特异的赖氨酸残基上；然而，只有赖氨酸48突变为精氨酸，模拟去乙酰化，复制了激活SIRT1的所有效果。SIRT1也影响LKB1的下游靶标。因此，它的过表达增加了AMPK和乙酰辅酶a羧化酶的磷酸化，相反，RNA干扰介导的SIRT1敲低降低了AMPK和另一个LKB1靶点MARK1的磷酸化。与培养细胞的结果一致，与饥饿的大鼠相比，饥饿48小时的大鼠肝脏中LKB1赖氨酸乙酰化总量减少了60%，这与LKB1和AMPK活性的适度但显著的增加有关。这些结果表明，LKB1去乙酰化受SIRT1调控，这反过来影响其细胞内定位、与STRAD的关联、激酶活性和激活AMPK的能力。
SIRT1, a histone/protein deacetylase, and AMP-activated protein kinase (AMPK) are key enzymes responsible for longevity and energy homeostasis. We examined whether a mechanistic connection exists between these molecules that involves the major AMPK kinase LKB1. Initial studies demonstrated that LKB1 is acetylated in cultured (HEK293T) cells, mouse white adipose tissue, and rat liver. In the 293T cells, SIRT1 overexpression diminished lysine acetylation of LKB1 and concurrently increased its activity, cytoplasmic/nuclear ratio, and association with the LKB1 activator STRAD. In contrast, short hairpin RNA for SIRT1, where studied, had opposite effects on these parameters. Mass spectrometric analysis established that acetylation of LKB1 occurs on multiple, but specific, lysine residues; however, only mutation of lysine 48 to arginine, which mimics deacetylation, reproduced all of the effects of activated SIRT1. SIRT1 also affected downstream targets of LKB1. Thus its overexpression increased AMPK and acetyl-CoA carboxylase phosphorylation, and conversely, RNA interference-mediated SIRT1 knockdown reduced AMPK phosphorylation and that of another LKB1 target MARK1. Consistent with the results in cultured cells, total LKB1 lysine acetylation was decreased by 60% in the liver of 48-h starved rats compared with starved-refed rats, and this was associated with modest but significant increases in both LKB1 and AMPK activities. These results suggest that LKB1 deacetylation is regulated by SIRT1 and that this in turn influences its intracellular localization, association with STRAD, kinase activity, and ability to activate AMPK.