Antiadipogenic Influence of HIV Protease Inhibitors

HIV 蛋白酶抑制剂的抗脂肪形成作用

• 批准号: 6700257
• 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 2006-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6700257
• 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 + 患者脂肪营养不良综合征 (LDS) 的分子基础。 LDS的特征是皮下脂肪组织脂肪萎缩并伴有内脏脂肪组织肥大。 LDS 患者经常表现出胰岛素抵抗和高甘油三酯血症的迹象。 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导致内脏肥胖代偿性增加有关。 内脏脂肪增多会促进胰岛素抵抗，增加非酯化脂肪酸流向肝脏的流量，并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（促进甘油三酯的损失、脂肪细胞特异性蛋白表达的损失以及可能通过细胞凋亡机制降低活力）。 因此，PI可能通过损害脂肪细胞活力和/或通过抑制脂肪生成来防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 PI 通过阻止脂肪形成转录因子 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 PI 抑制的分子标记。 待研究的潜在 PI 依赖性效应可能会阻断 C/EBPα 和/或 PPARgamma 的表达，包括：1) 抑制 C/EBPα 和 PPARgamma 基因表达的 C/EBPbeta/δ 依赖性转录激活，2) 无法去抑制 C/EBP 未分化蛋白 (CUP)/AP-2α 和 Sp1 依赖性抑制 C/EBPα 基因表达和 3) 未能失活抗脂肪形成 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 的拮抗作用的影响。 人类原代脂肪细胞将从皮下和内脏库中分离出来，并检查 PI 诱导的差异效应。 待研究的潜在 PI 依赖性机制包括：1) TNFα 信号转导途径中下游信号成分的激活和 2) GLUT4 葡萄糖转运蛋白功能的抑制。 小鼠体内前脂肪细胞植入技术将用于测试所提出的 PI 作用分子机制。 拟议研究的长期目标是促进缺乏脂肪萎缩潜力的抗艾滋病毒疗法的设计。