Perilipiin and Lipolysis

描述（由申请方提供）：脂肪细胞脂解通过增加循环游离脂肪酸（FFA）水平而显著促进肥胖相关疾病的发病机制。FFA促进胰岛素抵抗和2型糖尿病。我实验室的长期目标是阐明脂解调节的分子机制。拟定的研究将研究周磷脂A（Peri A）的结构/功能关系，Peri A是一种脂滴相关磷蛋白，可调节激素敏感脂肪酶（HSL）和非HSL脂肪酶介导的脂解作用。Peri A作为基础脂解的抑制剂（在没有激素刺激的情况下）和作为蛋白激酶A（PKA）刺激的脂解的有效增强剂（在激素刺激的存在下）双重起作用。尽管其具有重要的调节作用，但Peri A调节脂肪酶作用的主要序列和机制尚未确定。 我们的初步研究表明，Perilipin通过多个调节结构域调节脂解，这些结构域表现出令人惊讶的脂肪酶特异性。所提出的研究将1）鉴定通过HSL和非HSL脂肪酶调节基础和PKA刺激的脂解的Peri A的最小结构域，2）确定PKA磷酸化位点在通过HSL和非HSL脂肪酶的PKA刺激的脂解中的相对作用，和3）确定改变的Peri A表达的体内作用，使用Peri A转基因小鼠和Peri缺失小鼠的Peri A截短和Peri A PKA位点突变体。 我们的脂肪细胞和全身研究将测量基础脂解、对β-肾上腺素能药物的脂解反应和对胰岛素的抗脂解反应。这些研究将提供Peri A表达水平、调节结构域和磷酸化位点如何调节基础和刺激脂解的体内概念验证测试。这些数据将用于预防和治疗糖尿病、高脂血症和其他肥胖相关疾病。

DESCRIPTION (provided by applicant): Adipocyte lipolysis contributes significantly to the pathogenesis of obesity-associated diseases by increasing levels of circulating free fatty acids (FFA). FFA promote insulin resistance and type 2 diabetes. My laboratory's long-term goal is to elucidate molecular mechanisms of lipolysis regulation. The proposed studies will investigate structure / function relationships of Perilipin A (Peri A), a lipid droplet- associated phosphoprotein that regulates lipolysis mediated by hormone sensitive lipase (HSL) and non-HSL lipase(s). Peri A acts dually as a suppressor of basal lipolysis (in the absence of hormonal stimulation) and as a potent enhancer of protein kinase A (PKA)-stimulated lipolysis (in the presence of hormonal stimulation). Despite its important regulatory role, the primary sequences and the mechanism(s) by which Peri A regulates lipase actions have not been determined. Our preliminary studies indicate that Perilipin regulates lipolysis via multiple regulatory domains, which exhibit surprising lipase specificity. The proposed studies will 1) identify the minimal domains of Peri A that modulate basal and PKA-stimulated lipolysis by HSL and non-HSL lipase(s), 2) determine the relative role of PKA phosphorylation sites in PKA- stimulated lipolysis by HSL and non-HSL lipase, and 3) define the in vivo effects of altered Peri A expression, Peri A truncations and Peri A PKA site mutants using Peri A transgenic and Peri null mice. Our adipocyte and systemic studies will measure basal lipolysis, lipolytic response to beta-adrenergic agents, and antilipolytic response to insulin. These studies will provide in vivo proof of concept tests of how Peri A expression levels, regulatory domains, and phosphorylation sites regulate basal and stimulated lipolysis. These data will be directed to the prevention and treatment of diabetes, hyperlipidemia and other obesity - associated disorders.