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，这是美国最流行的营养相关疾病。本申请的目的是鉴定在牛肉、乳制品和膳食补充剂中发现的共轭亚油酸（CLA）、脂肪酸（FA）通过其降低某些动物和人类的肥胖的异构体特异性机制，降低人类脂肪细胞的甘油三酯（TG）含量。这个建议的中心假设是，反式-10，顺式-12共轭亚油酸激活脂质传播的信号，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。这一假设是基于我们的研究结果表明，反式-10，顺式-12共轭亚油酸，而不是顺式-9，反式-11共轭亚油酸，直接增加饱和脂肪酸的比例，单不饱和脂肪酸，并激活促炎信号，抑制过氧化物酶体增殖物激活受体？活动CLA的这些作用依赖于丝裂原活化蛋白激酶/细胞外信号调节激酶激酶（MEK/ERK）和核因子κ B（NF？B）信令。这项研究的基本原理是，一旦我们了解了反式-10，顺式-12共轭亚油酸如何降低人类脂肪细胞的甘油三酯含量，并确定潜在的代谢后果，它作为控制肥胖的膳食补充剂的有效性和安全性就可以得到有效的评估。为了实现这些目标，将在人（前）脂肪细胞的原代培养物中检查以下特定目标：目标#1。确定CLA调节PPAR的机制？在脂肪细胞中;目标#2。确定NF的作用？前脂肪细胞和脂肪细胞中B和MEK/ERK信号通路介导CLA抑制PPAR？目标#3确定CLA或其代谢产物如何影响诱导脱脂的信号。在目标#1，我们将研究CLA的转录和稳定性的PPAR？靶基因，过氧化物酶体增殖物激活受体？磷酸化、配体诱导的PPRE报告基因活化和PPAR？募集，共激活因子，共抑制因子和基础转录因子内源性过氧化物酶体增殖物激活受体？靶基因在 目标#2，我们将研究化学抑制剂和siRNA靶向NF？B和MEK/ERK对我们的候选细胞因子和PPAR？靶基因以及葡萄糖和FA摄取和代谢。在目标#3中，我们将检查CLA对脂质合成和已知激活NF κ B和/或MEK/ERK并引起去脂的细胞信号的异构体特异性作用。本案无关拟议的研究是重要的，因为它们有望导致深入了解CLA异构体的作用机制，并促进开发新的和安全的减肥饮食策略。因此，预计与肥胖有关的健康问题和财务费用将减少。

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.