Lamin A in Adipocyte Differentation and Survival

描述(由申请人提供)：编码核纤层蛋白A和C的LMNA基因突变已被证明导致Dunnigan型部分脂营养不良，这是一种常染色体显性遗传病，以局部脂肪丢失和胰岛素抵抗为特征。这一发现牵涉到核膜的中间细丝蛋白层蛋白A和C，这是参与控制体内脂肪分布的新途径的一部分。我们的假设是，板层蛋白A和C的主要作用突变干扰了这一调节脂肪细胞分化或生存的途径。这一探索性研究项目的目的是确定Dunnigan型部分性脂营养不良患者的突变层蛋白A是否在体外和体外阻止脂肪细胞分化或降低脂肪细胞的存活。 在特定的目标1中，我们将研究在Dunnigan型部分脂营养不良患者中发现的表达野生型lamin A错义突变的3T3-L1前脂肪细胞系。我们将检查这些细胞，并确定突变层蛋白A是否阻止它们在体外分化为脂肪细胞或降低它们的存活率。在特定的目标2中，我们将创建在AP2脂肪细胞活性启动子的控制下表达野生型和突变型lamin A的转基因小鼠系。在转基因小鼠中，脂肪细胞的分布将在年轻和年长时进行评估，因为在人类中，Dunnigan型部分脂营养不良症的脂肪丢失发生在青春期开始之后。探索性项目中的工作将证明或反驳核层粘连蛋白A在脂肪细胞发育或生存中发挥作用的假设。这一假说的证实将对确定治疗人类肥胖和糖尿病的新细胞靶点具有重要意义。

DESCRIPTION (provided by applicant): Mutations in the LMNA gene that encodes nuclear lamins A and C have been shown to cause Dunnigan-type partial lipodystrophy, an autosomal dominant inherited disease characterized by regional fat loss and insulin resistance. This finding implicates lamins A and C, intermediate filament proteins of the nuclear envelope, as part of a novel pathway involved in the control of body fat distribution. Our hypothesis is that dominantly acting mutations in lamins A and C interfere with this pathway that regulates fat cell differentiation or survival. The goal of this exploratory research project is to determine if mutant lamin A from patients with Dunnigan-type partial lipodystrophy blocks adipocyte differentiation or decreases adipocyte survival in vitro and in vitro. In Specific Aim 1, we will study 3T3-L1 pre-adipocyte cell lines that express wild-type lamin A with missense mutations found in patients with Dunnigan-type partial lipodystrophy. We will examine these cells and determine if the mutant lamin A blocks their in vitro differentiation into adipocytes or decreases their survival. In Specific Aim 2, we will create transgenic mouse lines that express wild-type and mutant lamin A under control of an Ap2 adipocyte-active promoter. Adipocyte cell distribution will be assessed in the transgenic mice, both at young and older ages as, in humans, fat loss in Dunnigan-type partial lipodystrophy occurs after the onset of puberty. The work in the exploratory project will prove or disprove the hypothesis that nuclear lamin A functions in fat cell development or survival. Confirmation of this hypothesis will have implications for the identification of new cellular targets to treat human obesity and diabetes mellitus.