Antiadipogenic Influence of HIV Protease Inhibitors

HIV 蛋白酶抑制剂的抗脂肪形成作用

• 批准号: 6848325
• 负责人: M DANIEL LANE
• 金额: $ 26.81万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-02-01 至 2007-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6848325
• 关键词: HIV infections; adipocytes; apoptosis; biological signal transduction; cell differentiation; clinical research; drug screening /evaluation; enhancer binding protein; gene expression; glucose transporter; human immunodeficiency virus 1; human subject; human therapy evaluation; hypertriglyceridemia; insulin sensitivity /resistance; laboratory mouse; lipodystrophy; lipolysis; microorganism disease chemotherapy; molecular pathology; peroxisome proliferator activated receptor; protease inhibitor; protein structure function; receptor expression; syndrome; tissue /cell culture; transcription factor

The primary objective of the proposed studies is to elucidate the molecular basis of the lipodystrophy syndrome (LDS) in HIV+ patients treated with HIV protease inhibitors (PIs). LDS is characterized by lipoatrophy of subcutaneous adipose tissue with accompanying hypertrophy of visceral adipose tissue. Patients with LDS often show signs of insulin resistance and hypertriglyceridemia. Our central hypothesis is that the lipoatrophy is related to a selective atrophic effect of PIs on the subcutaneous adipocyte leading to a compensatory increase in visceral adiposity. The increased visceral adiposity promotes insulin resistance, increased flux of non-esterified fatty acid to the liver and increased very low density lipoprotein- triglyceride production and secretion. Our preliminary results using model preadipocyte cell lines (3T3-L1 and -F442A) demonstrate that several PIs inhibit preadipocyte differentiation and/or antagonize the adipocyte phenotype (promote loss of triglyceride, loss of adipocyte-specific protein expression and decreased viability perhaps via an apoptotic mechanism). Thus, PIs may promote subcutaneous lipoatrophy in patients with LDS by compromising adipocyte viability and/or preventing replacement of lost adipocytes by inhibiting adipogenesis. We hypothesize that PIs block adipogenesis by preventing expression of the adipogenic transcription factors CCAAT/enhancer-binding protein (C/EBP) alpha and peroxisome proliferator-activated receptor (PPAR) gamma as these are the earliest observable molecular markers to be repressed by PIs. Potential PI-dependent effects to be investigated and that may block expression of C/EBPalpha and/or PPARgamma include: 1) Inhibition of C/EBPbeta/delta-dependent transcriptional activation of C/EBPalpha and PPARgamma gene expression, 2) Failure to derepress C/EBP undifferentiated protein (CUP)/AP-2alpha- and Sp1-dependent repression of C/EBPalpha gene expression and 3) Failure to inactivate antiadipogenic Wnt signaling pathways. We hypothesize that subcutaneous adipocytes are more susceptible than visceral adipocytes to the antagonistic effects of PIs. Human primary adipocytes will be isolated from subcutaneous and visceral depots and examined for differential PI-induced effects. Potential PI- dependent mechanisms to be investigated include: 1) Activation of downstream signaling components in the TNFalpha signal transduction pathway and 2) Inhibition of GLUT4 glucose transporter function. An in vivo preadipocyte implantation technique in mice will be used to test proposed molecular mechanisms of PI action. The long term objective of the proposed research is to facilitate the design of anti-HIV therapeutics that lack lipoatrophic potential.

拟议研究的主要目的是阐明接受HIV蛋白酶抑制剂（pi）治疗的HIV+患者脂质营养不良综合征（LDS）的分子基础。LDS的特征是皮下脂肪组织的脂肪萎缩，并伴有内脏脂肪组织的肥大。LDS患者通常表现为胰岛素抵抗和高甘油三酯血症。我们的中心假设是，脂肪萎缩与pi对皮下脂肪细胞的选择性萎缩作用有关，导致内脏脂肪代偿性增加。内脏脂肪的增加促进胰岛素抵抗，增加非酯化脂肪酸到肝脏的通量，增加极低密度脂蛋白-甘油三酯的产生和分泌。我们使用模型前脂肪细胞系（3T3-L1和-F442A）的初步结果表明，几种pi抑制前脂肪细胞分化和/或拮抗脂肪细胞表型（可能通过凋亡机制促进甘油三酯的丢失，脂肪细胞特异性蛋白表达的丢失和活力的降低）。因此，PIs可能通过抑制脂肪生成而降低脂肪细胞活力和/或阻止丢失的脂肪细胞的替代，从而促进LDS患者的皮下脂肪萎缩。我们假设PIs通过阻止脂肪生成转录因子CCAAT/增强子结合蛋白(C/EBP) α和过氧化物酶体增殖物激活受体(PPAR) γ的表达来阻止脂肪生成，因为这些是最早可观察到的被PIs抑制的分子标记。可能阻断C/EBPalpha和/或PPARgamma表达的pi依赖性潜在影响包括：1)抑制C/EBPbeta/ δ依赖性C/EBPalpha和PPARgamma基因表达的转录激活，2)未能抑制C/EBP未分化蛋白(CUP)/AP-2alpha-和sp1依赖性C/EBPalpha基因表达的抑制，3)未能灭活抗脂肪Wnt信号通路。我们假设皮下脂肪细胞比内脏脂肪细胞更容易受到pi的拮抗作用。人类原代脂肪细胞将从皮下和内脏储存中分离出来，并检查pi诱导的差异效应。潜在的PI依赖机制包括：1)激活TNFalpha信号转导通路中的下游信号成分；2)抑制GLUT4葡萄糖转运蛋白功能。在小鼠体内的前脂肪细胞植入技术将用于测试所提出的PI作用的分子机制。拟议研究的长期目标是促进设计缺乏脂肪萎缩潜力的抗hiv疗法。