Antiobesity Mechanism of CLA Isomer in Human Adipocytes

描述（由申请人提供）：项目摘要。该项目的长期目标是开发新的饮食策略来控制人类肥胖，这是美国最普遍的营养相关疾病。本申请的目的是确定异构体特异性机制，通过该机制，牛肉、乳制品和膳食补充剂中发现的共轭亚油酸 (CLA)、脂肪酸 (FA) 可以减少某些动物和人类的肥胖，并降低人类脂肪细胞的甘油三酯 (TG) 含量。该提议的中心假设是反式 10、顺式 12 CLA 激活脂质信号，抑制过氧化物酶体增殖物激活受体 (PPAR)-?活性，从而减少用于 TG 合成的葡萄糖和 FA 的摄取。这一假设基于我们的研究结果，证明反式 10、顺式 12 CLA，而不是顺式 9、反式 11 CLA，直接增加饱和 FA 与单不饱和 FA 的比例，并激活抑制 PPAR 的促炎信号？活动。 CLA 的这些作用依赖于丝裂原激活蛋白激酶/细胞外信号调节激酶激酶 (MEK/ERK) 和核因子 kappa B (NF?B) 信号传导。这项研究的基本原理是，一旦我们了解反式 10、顺式 12 CLA 如何降低人类脂肪细胞的 TG 含量并确定潜在的代谢后果，就可以有效评估其作为控制肥胖的膳食补充剂的有效性和安全性。为了实现这些目标，将在人类（前）脂肪细胞的原代培养物中检查以下具体目标：目标＃1。确定 CLA 调节 PPAR 的机制？在脂肪细胞中；目标#2。确定前脂肪细胞和脂肪细胞中 NFκB 和 MEK/ERK 信号在介导 CLA 抑制 PPAR? 中的作用；和目标#3。确定 CLA 或其代谢物如何影响诱导脱脂的信号。在目标 #1 中，我们将检查 CLA 对 PPAR 转录和稳定性的影响？靶基因，PPAR？磷酸化、配体诱导的 PPRE 报告基因激活，以及将 PPAR?、共激活因子、共抑制因子和基础转录因子募集至内源性 PPAR?目标基因。在 目标 #2，我们将研究针对 NF?B 和 MEK/ERK 的化学抑制剂和 siRNA 对候选细胞因子和 PPAR 诱导的影响？目标基因以及葡萄糖和 FA 的摄取和代谢。在目标 #3 中，我们将检查 CLA 对脂质合成和已知可激活 NFKB 和/或 MEK/ERK 并导致脱脂的细胞信号的异构体特异性影响。关联。拟议的研究意义重大，因为它们有望深入了解 CLA 异构体的作用机制，并促进新型、安全的减肥饮食策略的发展。因此，与肥胖相关的健康问题和财务成本预计会减少。

DESCRIPTION (provided by applicant): Project Summary. The long-term goal of this project is to develop novel dietary strategies for the control of human obesity, the most prevalent nutrition-related disease in America. The objective of this application is to identify isomer-specific mechanisms by which conjugated linoleic acid (CLA), fatty acid (FA)s found in beef, dairy foods, and dietary supplements that decrease adiposity in certain animals and humans, reduces the triglyceride (TG) content of human adipocytes. The central hypothesis for this proposal is that trans-10, cis-12 CLA activates lipid-borne signals that suppress peroxisome proliferator activated receptor (PPAR)-? activity, thereby reducing the uptake of glucose and FAs for TG synthesis. This hypothesis is based on our findings demonstrating that trans-10, cis-12 CLA, but not cis-9, trans-11 CLA, directly increases the ratio of saturated FAs to monounsaturated FAs, and activates proinflammatory signals that suppress PPAR? activity. These actions of CLA are dependent on mitogen-activated protein kinase / extracellular signal-regulated kinase kinase (MEK/ERK) and nuclear factor kappa B (NF?B) signaling. The rationale for this research is that once we understand how trans-10, cis-12 CLA reduces the TG content of human adipocytes and identify potential metabolic consequences, it's effective and safe use as a dietary supplement for controlling obesity can be evaluated effectively. To accomplish these objectives, the following specific aims will be examined in primary cultures of human (pre) adipocytes: Aim #1. Identify the mechanism by which CLA regulates PPAR? in adipocytes; Aim #2. Determine the role of NF?B and MEK/ERK signaling in preadipocytes and adipocytes in mediating CLA's suppression of PPAR?; and Aim #3. Determine how CLA or its metabolites impact on signals that induce delipidation. In Aim #1, we will examine CLA's effects on the transcription and stability of PPAR? target genes, PPAR? phosphorylation, ligand-induced activation of a PPRE reporter, and recruitment of PPAR?, co-activators, co-repressors, and basal transcription factors to endogenous PPAR? target genes. In Aim #2, we will investigate the impact of chemical inhibitors and siRNAs targeting NF?B and MEK/ERK on the induction of our candidate cytokines and PPAR? target genes and on glucose and FA uptake and metabolism. In Aim #3, we will examine CLA's isomer-specific effects on the synthesis of lipids and cell signals known to activate NFKB and/or MEK/ERK and cause delipidation. Relevance. The proposed studies are significant because they are expected to lead to an in-depth understanding of the mechanism of action of CLA isomers and to promote the development of novel and safe dietary strategies for weight loss. As a consequence, reductions in health problems and financial costs related to obesity would be expected.