RNAi screens reveal novel metabolic regulators: RIP140, MAP4k4 and the lipid droplet associated fat specific protein (FSP) 27
RNAi screens reveal novel metabolic regulators: RIP140, MAP4k4 and the lipid droplet associated fat specific protein (FSP) 27
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DOI：
10.1111/j.1748-1716.2007.01786.x
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发表时间：
2008-01-01
影响因子：
6.3
通讯作者：
Czech, M. P.
中科院分区：
文献类型：
--
作者：
Puri, V.;Virbasius, J. V.;Czech, M. P.
脂肪组织通过控制循环脂质水平和产生可以调节肌肉和肝脏等组织中脂肪酸代谢的分子来调节全身代谢和胰岛素敏感性。我们已经开发了RNA干扰（RNAi）筛选，以确定培养的脂肪细胞中调节胰岛素信号传导和关键代谢途径的基因。这些基于短干扰RNA（siRNA）的筛选鉴定了转录辅阻遏物受体相互作用蛋白140（RIP 140）（J Clin Invest 116：125，2006）和促分裂原活化蛋白激酶（MAP 4k 4）（Proc Natl Acad Sci USA 103：2087，2006）作为胰岛素响应性己糖摄取和氧化代谢的负调节剂。基因表达谱分析显示，RIP 140缺失上调葡萄糖摄取、糖酵解、三羧酸循环、脂肪酸氧化、线粒体生物合成和氧化磷酸化途径中的基因簇的表达。RIP 140基因敲除小鼠在高脂饮食下抵抗体重增加，并显示出增强的葡萄糖耐量。脂肪细胞中的MAP 4k 4缺失增加了许多RIP 140敏感基因，增加了脂肪形成并介导了肿瘤坏死因子-α（TNF-α）的一些作用。值得注意的是，在我们的RNAi筛选中的另一个命中是脂肪特异性蛋白27（FSP 27），Cidea的高度表达的同种型。我们发现FSP 27出乎意料地与脂滴特异性结合并调节脂肪储存。我们的结论是，RIP 140，MAP 4k 4和新的脂滴蛋白FSP 27是脂肪组织代谢的强大调节剂，是控制代谢性疾病的潜在治疗靶点。这些新蛋白的发现验证了RNAi筛选发现2型糖尿病和肥胖症新治疗方法的能力。
Adipose tissue modulates whole body metabolism and insulin sensitivity by controlling circulating lipid levels and producing molecules that can regulate fatty acid metabolism in such tissues as muscle and liver. We have developed RNA interference (RNAi) screens to identify genes in cultured adipocytes that regulate insulin signalling and key metabolic pathways. These short interfering RNA (siRNA)-based screens identified the transcriptional corepressor receptor interacting protein 140 (RIP140) (J Clin Invest 116: 125, 2006) and the mitogen-activated protein kinase (MAP4k4) (Proc Natl Acad Sci USA 103: 2087, 2006) as negative regulators of insulin-responsive hexose uptake and oxidative metabolism. Gene expression profiling revealed that RIP140 depletion upregulates the expression of clusters of genes in the pathways of glucose uptake, glycolysis, tricarboxylic acid cycle, fatty acid oxidation, mitochondrial biogenesis and oxidative phosphorylation. RIP140-null mice resist weight gain on a high-fat diet and display enhanced glucose tolerance. MAP4k4 depletion in adipocytes increases many of the RIP140-sensitive genes, increases adipogenesis and mediates some actions of tumour necrosis factor-alpha (TNF-alpha). Remarkably, another hit in our RNAi screens was fat specific protein 27 (FSP27), a highly expressed isoform of Cidea. We discovered that FSP27 unexpectedly associates specifically with lipid droplets and regulates fat storage. We conclude that RIP140, MAP4k4 and the novel lipid droplet protein FSP27 are powerful regulators of adipose tissue metabolism and are potential therapeutic targets for controlling metabolic disease. The discovery of these novel proteins validates the power of RNAi screening for discovery of new therapeutic approaches to type 2 diabetes and obesity.