RXR-Heterodimeric Receptors in the GI Tract

描述(申请人提供)：流行病学研究表明 膳食脂肪营养素的数量和含量影响糖尿病的发生。 结肠癌。过氧化体增殖物激活受体(PPAR)是 维甲酸-x-受体(RXR)异二聚体家族成员 转录调节因子，并激活基因转录以响应 脂肪酸及其代谢物。PPAR-伽马和PPAR-增量(测试版)在 并与结肠癌的发病机制有关。PPAR必须 与RXRs进行异源二聚，以便与DNA反应元件结合。RXRS绑定 9-顺式维甲酸，是一种维生素A代谢物，最近被 显示还与二十二碳六烯酸结合。RXR也形成同源二聚体，并且 为许多其他核受体指定合作伙伴，这些核受体 肠上皮细胞。因此，PPAR参与混合组装 与RXR相互作用的受体。我们建议检验这个假设 RXR-PPAR异源二聚体在调节脂质营养中的重要作用 肠道细胞中的信号。我们建议直接测量RXR、PPAR和 在培养的肠道细胞中RXR-PPAR异二聚体水平，或 分离小鼠结肠上皮细胞。我们计划测量功能 在体外改变RXR-PPAR异二聚体形成的后果 Caco-2细胞，来自原发的人类结肠癌和 通过使用转基因小鼠模型进行活体实验。我们将搜索躯体 与人类相关的RXR-α基因突变和剪接变异体 结肠癌。了解RXR-PPAR的结构基础 异源二聚我们将在PPAR-伽马中映射最小的肽结构域， 可以破坏RXR-PPAR相互作用。我们建议研究内异二聚作用 RXR与最小多肽相互作用的核磁共振研究 技巧。

DESCRIPTION (provided by applicant): Epidemiological studies indicate that the amount and content of dietary lipid nutrients influence the development of colon cancer. The peroxisomal proliferator activated receptors (PPARs) are members of the retinoid-x-receptor (RXR) heterodimeric family of transcriptional regulators, and activate gene transcription in response to fatty acids and their metabolites. PPAR-gamma and PPAR-delta (beta) are in the colon and have been implicated in the pathogenesis of colon cancer. PPARs must heterodimerize with RXRs in order to bind to DNA response elements. RXRs bind 9-cis-retinoic acids, which is a vitamin A metabolite, and has recently been shown to also bind docosahexaenoic acid. RXRs also form homodimers and are obligate partners for a number of other nuclear receptors that are in intestinal epithelial cells. Thus the PPARs participate in mixed assembly of receptors that interact with RXR. We propose to test the hypothesis that RXR-PPAR heterodimers play an important role in mediating lipid nutrient signals in intestinal cells. We propose to directly measure RXR, PPAR, and RXR-PPAR heterodimer levels in intestinal cells that are grown in culture, or epithelial cells isolated from mouse colons. We plan to measure the functional consequences of altering RXR-PPAR heterodimer formation in vitro by using Caco-2 cells, which are derived from a primary human colon carcinoma and in vivo by using genetically engineered mouse models. We will search for somatic mutations and splicing variants in RXR-alpha that are associated with human colon cancers. To understand the structural basis for RXR-PPAR heterodimerization we will map the minimal peptide domain in PPAR-gamma that can disrupt RXR-PPAR interactions. We propose to study intraheterodimerization interactions between RXR and the minimal peptide by nuclear magnetic resonance techniques.