Mottillo Emilio P, Shen Xiang Jun, Granneman James G
Center for Integrative Metabolic and Endocrine Research, Department of Psychiatry and Behavioral Neuroscience, Wayne State University School of Medicine, Detroit, MI 48201, USA.
Am J Physiol Endocrinol Metab. 2007 Nov;293(5):E1188-97. doi: 10.1152/ajpendo.00051.2007. Epub 2007 Aug 21.
Free fatty acids (FFA) are important extracellular and intracellular signaling molecules and are thought to be involved in beta-adrenergic-induced remodeling of adipose tissue, which involves a transient inflammatory response followed by mitochondrial biogenesis and increased oxidative capacity. This work examined the role of hormone-sensitive lipase (HSL), a key enzyme of acylglycerol metabolism, in white adipose tissue (WAT) remodeling using genetic inactivation or pharmacological inhibition. Acute treatment with the beta(3)-adrenergic agonist CL-316,243 (CL) induced expression of inflammatory markers and caused extravasation of myeloid cells in WAT of wild-type (WT) mice. HSL-knockout (KO) mice had elevated inflammatory gene expression in the absence of stimulation, and acute injection of CL did not further recruit myeloid cells, nor did it further elevate inflammatory gene expression. Acute pharmacological inhibition of HSL with BAY 59-9435 (BAY) had no effect on inflammatory gene expression in WAT or in cultured 3T3-L1 adipocytes. However, BAY prevented induction of inflammatory cytokines by beta-adrenergic stimulation in WAT in vivo and in cultured 3T3-L1 adipocytes. Chronic CL treatment stimulated mitochondrial biogenesis, expanded oxidative capacity, and increased lipid droplet fragmentation in WT mice, and these effects were significantly impaired in HSL-KO mice. In contrast to HSL-KO mice, mice with defective signaling of Toll-like receptor 4, a putative FFA receptor, showed normal beta-adrenergic-induced remodeling of adipose tissue. Overall, results reveal the importance of HSL activity in WAT metabolic plasticity and inflammation.
游离脂肪酸(FFA)是重要的细胞外和细胞内信号分子,被认为参与β-肾上腺素能诱导的脂肪组织重塑,这一过程涉及短暂的炎症反应,随后是线粒体生物发生和氧化能力增强。这项研究利用基因失活或药物抑制,研究了酰基甘油代谢的关键酶——激素敏感性脂肪酶(HSL)在白色脂肪组织(WAT)重塑中的作用。用β3-肾上腺素能激动剂CL-316,243(CL)进行急性处理,可诱导野生型(WT)小鼠WAT中炎症标志物的表达,并导致髓样细胞外渗。HSL基因敲除(KO)小鼠在未受刺激时炎症基因表达升高,急性注射CL既不会进一步募集髓样细胞,也不会进一步提高炎症基因表达。用BAY 59-9435(BAY)对HSL进行急性药物抑制,对WAT或培养的3T3-L1脂肪细胞中的炎症基因表达没有影响。然而,BAY可防止体内WAT和培养的3T3-L1脂肪细胞中β-肾上腺素能刺激诱导的炎症细胞因子产生。慢性CL处理可刺激WT小鼠的线粒体生物发生、扩大氧化能力并增加脂滴碎片化,而这些作用在HSL-KO小鼠中显著受损。与HSL-KO小鼠不同,Toll样受体4(一种假定的FFA受体)信号传导缺陷的小鼠表现出正常的β-肾上腺素能诱导的脂肪组织重塑。总体而言,研究结果揭示了HSL活性在WAT代谢可塑性和炎症中的重要性。