过氧化物酶体增殖物激活受体γ2及其靶基因在胎儿生长受限子鼠内脏脂肪中的表达

Expression of peroxisome proliferator activated receptor gamma 2 and its target genes in visceral fat tissueof growth restricted offspring in rats

目的研究胎儿生长受限（fetalgrowthrestriction，FGR）子鼠内脏脂肪组织中转录因子过氧化物酶体增殖物激活受体72（peroxisomeproliferatoractivatedreceptorgamma2，PPAR72）及其靶基因——脂肪分化相关蛋白（adiposed｜fferentiationrelatedprotein，ADFP）、磷酸烯醇式丙酮酸羧激酶1（phosphoen01pyruvatecarboxykinase1，PCKl）的表达变化，探讨其在成年肥胖和代谢综合征发生中的作用机制。方法采用孕期低蛋白饮食法建立大鼠FGR模型。以雄性子鼠为研究对象，采用实时荧光定量逆转录=聚合酶链反应（reversetranscription—polymerasechainreaction，PCR）和蛋白印迹实验检测3周龄和8周龄子鼠肾周脂肪组织中的PPAR72基因及其靶基因ADFP、PCKl的mRNA和蛋白表达，与同龄正常对照组子鼠进行比较。数据采用独立样本t检验及Spearman直线相关分析。结果3周龄和8周龄FGR组子鼠肾周脂肪组织中PPAR72tuRNA的转录水平明显高于同龄对照组子鼠（3周龄：2．43±0．38与1．03±0．11，t=2．74，P〈0．05；8周龄：2．17±0．34与1．07±0．14，￡=2．49，P〈0．05），蛋白含量也明显增高（3周龄：1．07±0．17与0．41±0．06，t=3．01，P％O．05；8周龄：1．29--4-0．20与0．68士0．09，t=2．62，P〈0．05），分别是对照组的（261±31）％和（190_--4_24）％。3周龄和8周龄FGR组子鼠。肾周脂肪组织中PPAR72调控的靶基因ADFPmRNA（3周龄：1．87±0．29与1．02±0．12，t=2．20；8周龄：1．64±0．31与1．06-4-0．14，t=3．47）和PCKlmRNA含量（3周龄：2．03±0．26与0．98±0．08，t=2．97；8周龄：l_79±0．28与1．03±0．11，t=3．24）和蛋白表达水平（ADFP蛋白表达3周龄：0．43±0．06与0．14±0．03，t=3．01；8周龄：0．71±0．09与0．38±0．05，t=3．06；PCKl蛋白表达3周龄：0．82±0．10与0．39±0．05，t=2．65；8周龄：0．85-4-0．11与0．67±0．07，t=2．86）也均高于对照组（P均〈0．05），且2个靶基因的表达水平与PPAR72表达均成正相关（mRNA表达水平：r=0．907和0．826，P均〈0．01；蛋白表达水平：r=0．763和0．805，P均〈0．05）。结论宫内发育的“程序化”影响使FGR子代内脏脂肪组织中PPAR72表达增加，进而引起靶基因ADFP和PCKl的表达增加，引起脂肪细胞积聚，这可能是成年肥胖和代谢综合征发生的机制之一。

Objective To investigate the expression of transcription factor peroxisome proliferator activated receptor gamma 2 （PPAR2） and its target genes--adipose differentiation-related protein （ADFP） and phosphoenolpyruvate carboxykinasel （PCK1） in visceral fat of growth restricted rat offspring, in order to explore their effects on the incidence of obesity and metabolism syndrome. Methods Fetal growth restriction （FGR） rat model was established by maternal low-protein diet and only male offsprings were studied. The mRNA expressions of PPAR2, ADFP and PCK1 in perirenalfat tissues were measured at 3 week （W3） and 8 week （W8）-old rats by real time quantitative reverse transcription-polymerase chain reaction （real-time-RT-PCR）. PPAR）2, ADFP and PCK1 protein levels in the perrenal fat tissues were determined by Western blot. Statistical analysis was performed with t-test and Spearman linear correlation analysis. Results The PPAR2 mRNA level in perrenal fat tissue of FGR rats at W3 and W8 were significantly elevated than that of the controls （W3：2.43 0.38 vs 1.034-O. 11,t=2.74,PO. O5;W8：2.170.34 vs 1.074-O. 14,t=2.49,PO. 05）, and PPAR/2 protein content was also increased （W3：l. 070.17 vs 0.41±0.06,t=3.01,P0.05;W8： 1.29±0.20 vs0.68--0.09,t=2.62,P0.05）, which equal to （261±31） and （19024） % of control, respectively. Increased mRNA and protein levels of the target genes ADFP and PCK1 in perrenal fat tissue were also found in the FGR rats at W3 and W8 compared with the same aged control rats （ADFP mRNA at W3..1. 874-0.29 vs 1.02=0. 12,t=2.20;ADFP mRNA at W8：1.64 0.31 vs 1.064-0.14,t=3.47; PCK1 mRNA at W3：2.030.26 vs 0.980.08,t=2.97;PCK1 mRNA at W8：l. 79±0.28 vs 1. 034-0.11,t=3.24; ADFP protein at W3 ： 0. 43 = 0. 06 vs 0. 14= 0. 03 , t= 3. 01; ADFP protein at W8：0.71=0.09 vs 0.38＋0.05,t=3.06;PCK1 protein at W3： 0.820. 10 vs 0. 394-0.05,t=2.65;PCK1 protein at WS： 0.85＋0.11 vs 0. 674-0.07,t=2.86; all P%0.05）. The protein and mRNA expressions of ADFP and PCK1 were positively correlated with expression the levels ofPPAR72 （mRNA：r 0.907 and 0.826,both P%0.01;protein：r=0.763 and 0. 805,both P0.05）. Conclusions Intrauterine programming＂ increases the expression of PPAR2 in perrenal adipose tissue of FGR individuals, which might contribute to the increased expressions of its target genes ADFP and PCK1, thereby causes the accumulation of adipose cells and subsequently promotes obesity and metabolism syndrome in adulthood.