Antiobesity Mechanism of CLA Isomer in Human Adipocytes

描述(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，肥胖是美国最普遍的营养相关疾病。本应用的目的是确定共轭亚油酸(CLA)、脂肪酸(FA)S在牛肉、乳制品和膳食补充剂中发现的降低某些动物和人类脂肪细胞甘油三酯(TG)含量的异构体特定机制。这一提议的中心假设是反式-10，顺式-12共轭亚油酸激活脂质信号，从而抑制过氧化体增殖物激活受体(PPAR)？活性，从而减少葡萄糖和脂肪酸的摄取，以合成甘油三酯。这一假说是基于我们的发现，即反式-10，顺式-12CLA，而不是顺式-9，反式-11CLA，直接增加饱和脂肪酸与单不饱和脂肪酸的比例，并激活促炎信号，从而抑制PPAR？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(MEK/ERK)和核因子-kappaB(NF？B)信号转导。这项研究的基本原理是，一旦我们了解了反式-10，顺-12共轭亚油酸是如何降低人类脂肪细胞的甘油三酯含量，并确定了潜在的代谢后果，它作为一种有效和安全的饮食补充剂用于控制肥胖的效果就可以得到有效的评估。为了实现这些目标，将在人类(前)脂肪细胞的原代培养中检测以下特定目标：目标1.确定CLA调节PPAR的机制？在脂肪细胞中；目的2.确定前脂肪细胞和脂肪细胞中的NF？B和MEK/ERK信号在介导共轭亚油酸抑制PPAR？中的作用；以及目标3.确定共轭亚油酸或其代谢产物如何影响诱导脱脂的信号。在目标1中，我们将检测共轭亚油酸对PPAR？转录和稳定性的影响。靶基因，PPAR？磷酸化，配体诱导的PPRE报告的激活，以及PPAR？、共激活子、共抑制子和基础转录因子对内源性PPAR的募集？靶基因。在……里面 目的#2，我们将研究针对NF？B和MEK/ERK的化学抑制剂和siRNAs对我们的候选细胞因子和PPAR？靶基因以及对葡萄糖和脂肪酸的吸收和代谢。在目标#3中，我们将研究共轭亚油酸对脂类和已知激活NFKB和/或MEK/ERK并导致脱脂的细胞信号合成的异构体特异性影响。关联性。拟议的研究具有重要意义，因为它们有望导致深入了解共轭亚油酸异构体的作用机制，并促进开发新的安全饮食减肥策略。因此，与肥胖相关的健康问题和经济成本有望减少。

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.