MOLECULAR BASIS OF ADIPOGENESIS

描述：(改编自申请人的摘要)在拟议的研究中， 申请者的目标将是识别和表征哺乳动物的基因 参与调节脂肪细胞分化的早期阶段。 目前，还没有形态或分子标记来鉴定 哺乳动物中的脂肪细胞前体。分子开关允许 这些细胞的成脂编程还不是很清楚。因此， 申请者将重点研究与可比性相关的分子。 在果蝇，果蝇黑腹果蝇中的过程，并测试 这些基因的同源基因在哺乳动物系统中扮演着类似的角色。水果 苍蝇携带着一种名为脂肪体的结构，这种结构似乎具有 哺乳动物脂肪组织和肝脏的同源物。早期的研究表明 识别出在前体细胞形成中起关键作用的基因 果蝇的脂肪身体。其中一个这样的基因是果蝇蛇(SRP)基因。 蛇是一个有趣的基因，因为它是GATA家族的成员，并且 已被证明是果蝇发育的重要因素 脂肪体和造血系统。蛇也是内皮细胞所必需的 肠道的发育、分化和形态发生。申请人 假设GATA家族蛇的哺乳动物同源物(S) 转录因子，也在哺乳动物的脂肪组织中表达并发挥作用 在脂肪生成中扮演着重要的角色。申请者的初步实验已经 证明了GATA转录家族中至少有两个成员 GATA-2和GATA-3因子在成人脂肪组织中高表达 老鼠。有趣的是，GATA-3的表达仅限于白色而不是棕色 脂肪组织。此外，在分离的成熟细胞中未检测到表达。 脂肪细胞提示GATA-3在脂肪中表达的主要来源 组织是脂肪细胞的前体。这些因素有力地支持了这一点。 在培养的3T3-F442a和3T3-L1前脂肪细胞中也有表达，但它们的 在分化过程中，表达在很早的时候就减少了。在表达时 从结构上讲，它们会阻止脂肪细胞的分化。 具体目的是(A)描述GATA的表达和生物学特性 脂肪细胞中的因子，b)研究GATA因子调节的机制 关注潜在的串扰对脂肪细胞分化的影响 成脂转录因子，以及c)产生功能转基因的收益 在小鼠体内检测GATA对成脂生物学的影响。通过这条线路 在调查过程中，申请人希望获得关于 这是一个涉及脂肪生成的关键生物学过程。

DESCRIPTION: (Adapted from the applicant's abstract) In the proposed studies, the applicant's goal will be to identify and characterize mammalian genes involved in the regulation of early stages of adipocyte differentiation. Currently, there are no morphological or molecular markers to identify adipocyte precursors in mammals. The molecular switches that permit the adipogenic programming of these cells are not well understood. Therefore, the applicant will focus on molecules that have been implicated in comparable processes in the fruit fly, Drosophila Melanogaster, and test whether homologues of these genes play similar roles in mammalian systems. The fruit fly carries a structure called fat body that appears to be the functional homologue of mammalian adipose tissue and liver. Earlier studies have identified genes that play a crucial role in the formation of precursor cells of the Drosophila fat body. One such gene is the Drosophila serpent (srp) gene. Serpent is an interesting gene since it is a member of the GATA family and has been demonstrated to be an essential factor for the development of Drosophila fat body and the hemapoietic system. Serpent is also required for endodermal development and differentiation and morphogenesis of the gut. The applicant hypothesizes that the mammalian homologue(s) of serpent, GATA family of transcription factors, is also expressed in mammalian adipose tissue and plays an important role in adipogenesis. The applicant's preliminary experiments have demonstrated that at least two members of the GATA family of transcription factors, GATA-2 and GATA-3, are expressed highly in the adipose tissue of adult mice. Interestingly, GATA-3 expression is restricted to white and not brown adipose tissue. Furthermore, expression was not detected in isolated mature adipocytes suggesting that the primary source of GATA-3 expression in adipose tissue is adipocyte precursors. In strong support of this, these factors are also expressed in cultured 3T3-F442A and 3T3-L1 preadipocytes but their expression is diminished very early during differentiation. When expressed constitutively, they block the differentiation of adipocytes. Specific aims are to (a) characterize the expression and biology of GATA factors in adipocytes, b) study the mechanisms by which GATA factors regulate differentiation of adipocytes by focusing on potential crosstalk with adipogenic transcription factors, and c) generate gain of function transgenic mice to test the biology of GATA on adipogenesis in vivo. Through this line of investigation, the applicant hopes to obtain novel and important information on a key biological process involving adipogenesis.