Institute of Metabolic Science Metabolic Research Laboratories and the Department of Clinical Biochemistry, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0QQ, United Kingdom.
J Biol Chem. 2011 Oct 7;286(40):34998-5006. doi: 10.1074/jbc.M111.278853. Epub 2011 Jul 12.
Perilipin (PLIN1) is a constitutive adipocyte lipid droplet coat protein. N-terminal amphipathic helices and central hydrophobic stretches are thought to anchor it on the lipid droplet, where it appears to function as a scaffold protein regulating lipase activity. We recently identified two different C-terminal PLIN1 frame shift mutations (Leu-404fs and Val-398fs) in patients with a novel subtype of partial lipodystrophy, hypertriglyceridemia, severe insulin resistance, and type 2 diabetes (Gandotra, S., Le Dour, C., Bottomley, W., Cervera, P., Giral, P., Reznik, Y., Charpentier, G., Auclair, M., Delépine, M., Barroso, I., Semple, R. K., Lathrop, M., Lascols, O., Capeau, J., O'Rahilly, S., Magré, J., Savage, D. B., and Vigouroux, C. (2011) N. Engl. J. Med. 364, 740-748.) When overexpressed in preadipocytes, both mutants fail to inhibit basal lipolysis. Here we used bimolecular fluorescence complementation assays to show that the mutants fail to bind ABHD5, permitting its constitutive coactivation of ATGL, resulting in increased basal lipolysis. siRNA-mediated knockdown of either ABHD5 or ATGL expression in the stably transfected cells expressing mutant PLIN1 reduced basal lipolysis. These insights from naturally occurring human variants suggest that the C terminus sequesters ABHD5 and thus inhibits basal ATGL activity. The data also suggest that pharmacological inhibition of ATGL could have therapeutic potential in patients with this rare but metabolically serious disorder.
perilipin (PLIN1) 是一种组成型脂肪细胞脂滴外壳蛋白。其 N 端两亲性螺旋和中心疏水性延伸部分被认为将其锚定在脂滴上，在那里它似乎作为调节脂肪酶活性的支架蛋白发挥作用。我们最近在患有新型部分脂肪营养不良、高三酰甘油血症、严重胰岛素抵抗和 2 型糖尿病的患者中发现了两种不同的 C 端 PLIN1 移码突变（Leu-404fs 和 Val-398fs）（Gandotra，S.，Le Dour，C.，Bottomley，W.，Cervera，P.，Giral，P.，Reznik，Y.，Charpentier，G.，Auclair，M.，Delépine，M.，Barroso，I.，Semple，R. K.，Lathrop，M.，Lascols，O.，Capeau，J.，O'Rahilly，S.，Magré，J.，Savage，D. B.，和 Vigouroux，C.（2011）N. Engl. J. Med. 364, 740-748.）。当在人前脂肪细胞中过表达时，两种突变体均不能抑制基础脂肪分解。在这里，我们使用双分子荧光互补测定法显示，突变体不能与 ABHD5 结合，从而允许其对 ATGL 的组成型共激活，导致基础脂肪分解增加。在稳定转染表达突变型 PLIN1 的细胞中，siRNA 介导的 ABHD5 或 ATGL 表达的敲低降低了基础脂肪分解。这些来自天然存在的人类变异体的见解表明，C 端将 ABHD5 隔离，从而抑制基础 ATGL 活性。这些数据还表明，在患有这种罕见但代谢严重疾病的患者中，ATGL 的药理学抑制可能具有治疗潜力。
