Genetic and pharmacological inhibition of Rho-associated kinase II enhances adipogenesis
Genetic and pharmacological inhibition of Rho-associated kinase II enhances adipogenesis
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DOI：
10.1074/jbc.m705972200
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发表时间：
2007-10-05
影响因子：
4.8
通讯作者：
Nakao, Kazuwa
中科院分区：
文献类型：
--
作者：
Noguchi, Michio;Hosoda, Kiminori;Nakao, Kazuwa
Rho相关激酶（ROCK）调节肌动蛋白细胞骨架的重组。在脂肪形成过程中，丝状肌动蛋白的结构从长应力纤维转化为皮质肌动蛋白，表明ROCK参与脂肪形成。已经鉴定了两种ROCK亚型：ROCK-I和ROCK-II。然而，ROCK的药理学抑制剂不能区分两种ROCK亚型。在本研究中，我们使用遗传学和药理学方法研究了ROCK在脂肪形成和肌动蛋白细胞骨架中的作用。Y-27632抑制两种ROCK亚型的活性，通过上调3 T3-L1细胞中的成脂转录因子来增强脂肪形成。此外，Y-27632恢复了溶血磷脂酸对脂肪形成的抑制作用，溶血磷脂酸可激活Rho。关于肌动蛋白细胞骨架，Y-27632破坏了3 T3-L1前脂肪细胞中的应力纤维。接下来，我们分析了分别来自ROCK-I和ROCK-II敲除小鼠的小鼠胚胎成纤维细胞（MEFs）的脂肪形成。与野生型MEFs相比，ROCK-II（-/-）MEFs的成脂能力明显增强，而ROCK-I（-/-）MEFs的成脂能力则无明显差异。与药理学方法相反，与野生型MEFs相比，ROCK-II（-/-）MEFs的肌动蛋白细胞骨架没有明显的改变。在3 T3-L1细胞中，通过RNA干扰敲低ROCK-II增强了成脂转录因子的表达，而ROCK-I则没有。此外，Y-27632抑制IRS-1丝氨酸磷酸化并增强3 T3-L1前脂肪细胞中Akt磷酸化。同样，与野生型MEFs相比，ROCK-II（-/-）MEFs中Akt磷酸化增强。总之，抑制ROCK-II，而不是ROCK-I，增强脂肪形成伴随着脂肪形成转录因子的上调。胰岛素信号的增强可能有助于脂肪生成的增强。
Rho-associated kinase (ROCK) regulates reorganization of actin cytoskeleton. During adipogenesis, the structure of filamentous actin is converted from long stress fibers to cortical actin, suggesting that the ROCK is involved in adipogenesis. Two ROCK isoforms have been identified: ROCK-I and ROCK-II. However, pharmacological inhibitors of ROCK cannot distinguish two ROCK isoforms. In the present study, we examined the role of ROCK in adipogenesis and actin cytoskeleton using genetic and pharmacological approaches. Y-27632, which inhibits the activity of both ROCK isoforms, enhanced adipogenesis through the up-regulation of adipogenic transcription factors in 3T3-L1 cells. Furthermore, Y-27632 restored inhibition of adipogenesis by lysophosphatidic acid, which activates Rho. Regarding actin cytoskeleton, Y-27632 disrupted stress fibers in 3T3-L1 preadipocytes. Next, we analyzed adipogenesis of mouse embryonic fibroblasts (MEFs) derived from ROCK-I and ROCK-II knock-out mice, respectively. Adipogenesis of ROCK-II (-/-) MEFs was markedly enhanced compared with wild-type MEFs while that of ROCK-I (-/-) MEFs was not. In contrast to pharmacological approaches, no obvious alteration was found in actin cytoskeleton of ROCK-II(-/-) MEFs compared with wild-type MEFs. In 3T3-L1 cells, knockdown of ROCK-II by RNA interference enhanced the expression of adipogenic transcription factors while that of ROCK-I did not. Moreover, Y-27632 inhibited IRS-1 serine phosphorylation and enhanced Akt phosphorylation in 3T3-L1 preadipocytes. Similarly, Akt phosphorylation in ROCK-II (-/-) MEFs was augmented compared with wild-type MEFs. In conclusion, inhibition of ROCK-II, not ROCK-I, enhances adipogenesis accompanied by the up-regulation of adipogenic transcription factors. Augmentation of insulin signaling may contribute to the enhancement of adipogenesis.