REGULATION OF APOPROTEIN E BIOSYNTHESIS IN HEPATOTYCTES & ASSOC W/LIPOPROTEIN

在这个项目中，载脂蛋白E的三个方面的可用性将是 研究：载脂蛋白E与脂蛋白相关的决定因素， 受刺激载脂蛋白E分泌的转录后调节 外源性脂蛋白与载脂蛋白的转录调控 肝细胞中的E产生。 载脂蛋白E与甘油三酯相关- 富含脂蛋白（VLDL和乳糜微粒残留物）和较大的HDL 粒子 决定这些关联的脱辅基蛋白序列将 使用结构域特异性诱变和肝细胞中的表达进行研究 和在异质系统（杆状病毒）中。 突变型脱辅基蛋白E 与新生和成熟VLDL和HDL的关联将被检查。 HDL和 LDL刺激类固醇生成细胞中载脂蛋白E产生4-5倍， 而不影响载脂蛋白E基因的转录。 这一机制 将在类固醇生成细胞系中研究刺激。 的结构域 将描述这种作用所需的脱辅基蛋白E。 最后，研究了肝细胞胆固醇负荷和修饰 细胞内固醇平衡对脱辅基蛋白E基因转录的影响 将详细探讨。 两种激动剂-孕酮和25 将研究羟基胆固醇。 将努力确定 载脂蛋白E基因的顺式作用序列及其反式作用因子 负责这项规定。

In this project, the three aspects of apoprotein E availability will be studied: the determinants of apoprotein E association with lipoprotein, the post-transcriptional regulation of apoprotein E secretion as stimulated by exogenous lipoproteins and the transcriptional regulation of apoprotein E production in hepatocytes. Apoprotein E associates with triglyceride- rich lipoproteins (VLDL and chylomicron remnants) and with larger HDL particles. The apoprotein sequences that determine these associations will be studied using domain specific mutagenesis and expression in hepatocytes and in heterogeneous systems (baculovirus). Mutant apoprotein E association with nascent and mature VLDL and HDL will be examined. HDL and LDL stimulates apoprotein E production 4-5 fold in steroidogenic cells, without effecting apoprotein E gene transcription. Mechanisms of this stimulation will be studied in a steroidogenic cell line. The domains of apoprotein E required for this effect will be delineated. Finally, the effects of cholesterol loading of hepatocytes and of modifying intracellular sterol balance on the transcription of the apoprotein E gene will be explored in detail. Two agonists -progesterone and 25 hydroxycholesterol will be studied. Efforts will be made to define the cis-acting sequences of apoprotein E gene and the trans-acting factors responsible for this regulation.