Development in immunochemical control of regulatory enzymes and receptors concerned in the lipid metabolism and the application for low-fat meat production

本研究旨在确定参与脂肪积累的酶和受体，并通过免疫化学方法进行控制，以减少家畜的肥胖，从而生产“低脂肉类”。脂肪组织脂蛋白脂酶(LPL)杂交瘤细胞株可获得24个与鸡LPL特异结合的阳性克隆，其中3个克隆能有效降低脂肪组织中LPL活性。连续滴注LPL抗体(CLP-16)14天的雏鸡，脂肪垫重量显著低于对照组，但体重略有下降。这些发现表明，持续给予抗LPL单抗是改变LPL活性从而控制肉鸡肥胖度的有效手段。脂肪组织脂蛋白受体(LR8)用LRP、LRP380和LR8的抗血清进行免疫印迹分析表明，LR8存在于鸡脂肪组织中，与鸡的肥胖有关。然而，给予LR8抗体并不改变鸡脂肪细胞对VLDL的摄取。肝脂蛋白受体(HLR)：通过对鸡肝脏cDNA文库的筛选，未能鉴定到新的鸡脂蛋白受体基因克隆。然而，在鸡肝细胞膜的配基印迹分析中发现了新的低密度脂蛋白结合蛋白(100和130 kDa)。新的低密度脂蛋白结合蛋白具有与哺乳动物低密度脂蛋白受体家族不同的非结合钙离子和受体相关蛋白(RAP)的特征。血浆胆固醇酯转运蛋白(CETP)产蛋前鸡血浆中CETP活性较高，而蛋鸡血浆中未检测到CETP活性。这些结果表明，鸡CETP在胆固醇代谢中起着重要作用。我们一直在尝试用人CETP探针获得鸡CETP的cDNA克隆，但目前还没有得到鸡CETP的cDNA序列。

The present study was conducted to identify enzymes and receptors involved in fat accumulation and to control by immunochemical methods to reduce obesity domestic animals and consequently produce "Low fat meat".1. Adipose tissue lipoprotein lipase (LPL)We could have obtained 24 positive clones of hybridoma to bind specifically with chicken LPL and 3 clones out of 24 were effective to reduce LPL activity in adipose tissues. In chickens received continuous infusion of LPL antibody (CLP-16) for 14 days, adipose fat pad weight was significantly lower than the control chickens whereas the body weight decreased to a small extent. These findings suggest that persistent administration of anti-LPL monoclonal antibody is effective mean to modify LPL activity and consequently manipulate fatness in broiler chickens.2. Adipose tissue lipoprotein receptor (LR)It was shown following western blot analysis using antiserum of various LRs (LRP, LRP380, and LR8) that LR8 was present in chicken adipose tissues and concerned in the chicken adiposity. However, administration of LR8 antibody did not modify VLDL uptake to chicken adipocytes.3. Hepatic lipoprotein receptor (HLR)It was not able to identify the new cDNA clone of chicken HLR though the screening of chicken liver cDNA library. However, new LDL binding proteins (100 and 130kDa) were detected in the ligand blot analysis in chicken liver membrane. The new LDL binding proteins were characterized by no-binding Ca ion and receptor associated protein (RAP), which were different from LDL receptor family obtained in mammals.4. Plasma cholesteryl ester transfer protein (CETP)The CETP activity in chicken plasma was high before laying eggs whereas that in laying hens was not detectable. These results suggested that chicken CETP play an important role to the cholesterol metabolism. We have been trying to obtain chicken CETP cDNA clone using human CETP probe, while at present chicken CETP cDNA sequence is still not available.