Regulation of AMP-Activated Protein Kinase by LKB1 and CaMKK in Adipocytes
Regulation of AMP-Activated Protein Kinase by LKB1 and CaMKK in Adipocytes
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DOI：
10.1002/jcb.23053
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发表时间：
2011-05-01
影响因子：
4
通讯作者：
Goransson, Olga
中科院分区：
文献类型：
--
作者：
Gormand, Amelie;Henriksson, Emma;Goransson, Olga
AMP 激活蛋白激酶 (AMPK) 是一种丝氨酸/苏氨酸激酶，可调节细胞和全身能量稳态。在脂肪组织中，AMPK 的激活已被证明是对各种细胞外刺激的反应。然而，在脂肪细胞中激活 AMPK 的上游激酶仍然难以捉摸。先前的研究已确定 LKB1 是肌肉、肝脏和其他组织中的主要 AMPK 激酶。在某些细胞类型中，Ca2+/钙调蛋白依赖性蛋白激酶激酶β (CaMKK beta) 已被证明可以响应细胞内 Ca2+ 水平的增加而激活 AMPK。我们的目的是研究 LKB1 和/或 CaMKK 是否在脂肪细胞中充当 AMPK 激酶。我们使用来自小鼠的脂肪组织和分离的脂肪细胞，其中LKB1的表达降低至野生型（LKB1亚效型小鼠）的10-20%。我们发现，LKB1 低等态小鼠的脂肪细胞的基础 AMPK 活性降低了 40%，并且在 AMPK 激活剂苯乙双胍存在的情况下，AMPK 活性降低。我们还证明，用细胞内 [Ca2+] 升高剂刺激 3T3L1 脂肪细胞会导致 AMPK 途径的激活。抑制剂 STO-609 或 siRNA 对 CaMKK 同工型（特别是 CaMKKb）的抑制可阻断 Ca2+-，但不能阻断苯乙双胍、AICAR-或毛喉素诱导的 AMPK 激活，表明 CaMKK 响应 Ca2+ 激活 AMPK。总的来说，我们表明，在未刺激的脂肪细胞中和苯乙双胍存在的情况下，LKB1 是维持正常 AMPK 信号传导所必需的。此外，我们证明了Ca2+/CaMKK信号通路的存在也可以调节脂肪细胞中AMPK的活性。 J.细胞。生物化学。 112: 1364-1375, 2011。(C) 2011 Wiley-Liss, Inc.
AMP-activated protein kinase (AMPK) is a serine/threonine kinase that regulates cellular and whole body energy homeostasis. In adipose tissue, activation of AMPK has been demonstrated in response to a variety of extracellular stimuli. However, the upstream kinase that activates AMPK in adipocytes remains elusive. Previous studies have identified LKB1 as a major AMPK kinase in muscle, liver, and other tissues. In certain cell types, Ca2+/calmodulin-dependent protein kinase kinase beta (CaMKK beta) has been shown to activate AMPK in response to increases of intracellular Ca2+ levels. Our aim was to investigate if LKB1 and/or CaMKK function as AMPK kinases in adipocytes. We used adipose tissue and isolated adipocytes from mice in which the expression of LKB1 was reduced to 10-20% of that of wild-type (LKB1 hypomorphic mice). We show that adipocytes from LKB1 hypomorphic mice display a 40% decrease in basal AMPK activity and a decrease of AMPK activity in the presence of the AMPK activator phenformin. We also demonstrate that stimulation of 3T3L1 adipocytes with intracellular [Ca2+]-raising agents results in an activation of the AMPK pathway. The inhibition of CaMKK isoforms, particularly CaMKKb, by the inhibitor STO-609 or by siRNAs, blocked Ca2+-, but not phenformin-, AICAR-, or forskolin-induced activation of AMPK, indicating that CaMKK activated AMPK in response to Ca2+. Collectively, we show that LKB1 is required to maintain normal AMPK-signaling in non-stimulated adipocytes and in the presence of phenformin. In addition, we demonstrate the existence of a Ca2+/CaMKK signaling pathway that can also regulate the activity of AMPK in adipocytes. J. Cell. Biochem. 112: 1364-1375, 2011. (C) 2011 Wiley-Liss, Inc.