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[Effect of acylation stimulating protein on the perilipin and adipophilin expression during 3T3-L1 preadipocyte differentiation.] [Ariticle in Chinese]

WU Jing, LU Hui-Ling^*, HU Xiu-Fen, LIANG Xiao-Yan, LIN Han-Hua, WANG Hong-Wei, FAN Xiao-Wei

Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China

Abstract

Perilipin and adipophilin, two significant lipid droplet (LD)-specific proteins, participate in storing fat or ectopic lipid deposition and fat mobilization in many types of mammalian cells. Acylation stimulating protein (ASP) is a novel adipocyte-derived hormone known for a major determinant for triglyceride synthesis (TGS) and lipid metabolism. The present study was aimed to investigate: (1) whether ASP, rather than insulin, is a powerful potentiator which could physiologically and directly influence TGS during 3T3-L1 preadipocyte differentiation; (2) whether ASP exposure at indicated time points during 3T3-L1 preadipocyte differentiation could influence the gene/protein expression of adipophilin and perilipin. 3T3-L1 preadipocytes were differentiated by traditional hormone cocktail and divided into control, ASP and insulin groups according to the treatment of ASP (1 μmol/L) or insulin (100 nmol/L). ASP-stimulated and insulin-stimulated TGS rate at indicated time points (0 d, 3 d, 6 d, 9 d) were assayed by measuring the incorporation of [3H]-oleic acid into TG, and the corresponding glucose transport was assayed by [3H]-2-DG uptake. The effects of ASP or insulin on gene/protein expression of adipophilin and perilipin at indicated time points were evaluated by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) and Western blot. The results obtained were as follows: (1) on the 3rd and 6th day of differentiation, ASP dramatically enhanced TGS rate compared with control group (P<0.05, P<0.01); There was no significant difference in TGS rate between insulin group and control group; (2) on the 6th and 9th day of differentiation, both ASP and insulin promoted glucose uptake (P<0.05, P<0.01), and the promoting effect in ASP group was greater than that in insulin group; (3) ASP elevated adipophilin gene and protein expression at the very early stage of differentiation (P<0.05, P<0.001) and had no significant effect from the 4th day of differentiation. Perilipin gene and protein expression increased throughout preadipocyte differentiation and its expression was up-regulated following ASP stimulation from the 3rd day of differentiation (P<0.05, P<0.001) to the end of differentiation (P<0.05); (4) Insulin did not affect gene and protein variation pattern of adipophilin and perilipin. Taken together, this study provides evidence that ASP-evoked changes in gene and protein expression of adipophilin and perilipin correlate with ASPstimulated TGS acceleration, and adipophilin and perilipin are involved in the molecular mechanism of ASP-induced adipogenesis and LD formation.

Key words: acylation stimulating protein; lipid droplets associated proteins; lipid metabolism; adipocyte

Received: 2008-07-24　　Accepted: 2008-10-28

Corresponding author: 卢慧玲　　E-mail: huilinglu@yahoo.cn

Citing This Article：

WU Jing, LU Hui-Ling, HU Xiu-Fen, LIANG Xiao-Yan, LIN Han-Hua, WANG Hong-Wei, FAN Xiao-Wei. [Effect of acylation stimulating protein on the perilipin and adipophilin expression during 3T3-L1 preadipocyte differentiation.] [Ariticle in Chinese] . Acta Physiol Sin 2009; 61 (1): 56-64 (in Chinese with English abstract).