Adiponectin signaling and regulation

产品描述（申请人提供）：脂联素/Acrp 30是最近发现的脂肪组织来源的激素，具有抗糖尿病和胰岛素增敏功能。脂联素信号如何从其受体转导并在细胞中调节目前尚不清楚。为了鉴定脂联素受体下游的相互作用分子，我们使用脂联素受体1（AdipoR 1）的细胞内部分作为诱饵筛选酵母双杂交cDNA文库。该筛选导致鉴定APPL-1作为AdipoR 1相关蛋白，APPL-1是一种含有磷酸酪氨酸结合PTB）结构域、普列克底物同源（PH）结构域和亮氨酸拉链基序的衔接蛋白。APPL-1在体外和哺乳动物细胞中与AdipoR 1相互作用。重要的是，APPL-1的过表达刺激AMP活化蛋白激酶（AMPK）和p38丝裂原活化蛋白激酶（MAPK）的磷酸化，这两种蛋白激酶都已被证明介导脂联素刺激的脂肪酸氧化和葡萄糖摄取。这些新的发现表明，AdipoR 1和APPL-1之间的相互作用，迄今为止唯一确定的细胞内信号分子结合脂联素受体，可能是脂联素结合及其下游事件之间缺失的环节。为了验证这一假设，我们将：1）确定调节APPL-1和AdipoR 1相互作用的分子机制; 2）表征APPL-1刺激p38 MAPK磷酸化的生化机制以及APPL-1在脂联素刺激的p38 MAPK激活和下游功能中的功能作用; 3）阐明APPL-1刺激AMPK磷酸化的生化机制，并表征APPL-1在脂联素刺激的AMPK活化和下游功能中的功能作用。这些研究的结果不仅有助于我们了解脂联素信号通路及其调控，而且还将为临床重要疾病（如肥胖和2型糖尿病）的新药理学干预措施的设计提供有价值的信息。

DESCRIPTION (provided by applicant): Adiponectin/Acrp30 is a recently identified adipose tissue-derived hormone with anti-diabetic and insulin sensitizing functions. How the adiponectin signal is transduced from its receptor and regulated in cells is currently unknown. To identify interacting molecules downstream of the adiponectin receptor, we screened a yeast two-hybrid cDNA library using the intracellular portion of the adiponectin receptor 1 (AdipoR1) as bait. This screening led to the identification of APPL-1, an Adaptor protein containing a Phosphotyrosine binding PTB) domain, a Pleckstrin homology (PH) domain, and a Leucine zipper motif, as an AdipoR1-associated protein. APPL-1 interacted with AdipoR1 in vitro and in mammalian cells. Importantly, overexpression of APPL-1 stimulated phosphorylation of AMP activated protein kinase (AMPK) and p38 mitogen activated protein kinase (MAPK), both of which have been shown to mediate adiponectin-stimulated fatty acid oxidation and glucose uptake. These novel findings suggest that the interaction between AdipoR1 and APPL-1, the only intracellular signaling molecule identified so far that binds to the adiponectin receptor, may be the missing link between adiponectin binding and its downstream events. To test this hypothesis, we will: 1) Define the molecular mechanisms that regulate the interaction between APPL-1 and AdipoR1; 2) Characterize the biochemical mechanism by which APPL-1 stimulates p38 MAPK phosphorylation and the functional role of APPL-1 in adiponectin-stimulated p38 MAPK activation and downstream function; 3) Elucidate the biochemical mechanism by which APPL-1 stimulates AMPK phosphorylation and characterize the functional role of APPL-1 in adiponectin-stimulated AMPK activation and downstream function. Results from these studies will not only shed light on our understanding of the adiponectin signaling pathway and its regulation, but will also provide valuable information on the design of new pharmacological interventions for clinically important diseases such as obesity and Type 2 Diabetes.