Constitutively active signal transducer and activator of transcription 5 can replace the requirement for growth hormone in adipogenesis of 3T3-F442A preadipocytes
Constitutively active signal transducer and activator of transcription 5 can replace the requirement for growth hormone in adipogenesis of 3T3-F442A preadipocytes
复制标题
DOI：
10.1210/me.2003-0139
复制
发表时间：
2003-12-01
影响因子：
--
通讯作者：
Waters, MJ
中科院分区：
文献类型：
--
作者：
Shang, CA;Waters, MJ
尽管它是 GH 作用的最佳体外模型，但 GH 用于诱导小鼠 3T3-F442A 前脂肪细胞分化的机制仍不清楚。在这里，我们研究了三种转录调节因子在脂肪形成中的作用。这些调节因子要么响应 GH [Stra13，信号转导器和转录激活因子 (Stat) 3] 被快速诱导，要么对 GH 信号转导至关重要 (Stat5)。使用 3T3-F442A 前脂肪细胞的逆转录病毒转染来增加 Stra13、Stat3 和 Stat5a 的表达。通过定量 RT-PCR 测定，仅 Stat5a 转染增加了响应 GH 的脂肪生成标志物过氧化物酶体增殖物激活受体 γ、CCAAT 增强子结合蛋白 (C/EBP)α 和脂肪蛋白 2/脂肪酸结合蛋白的表达。用组成型活性的 Stat3 和 Stat5a 转染表明，组成型活性的 Stat5a 而不是 Stat3 能够替代脂肪形成的 GH 需求。具有持续活性的 Stat5a（而非 Stat3）能够增加脂滴的形成和 α-甘油磷酸脱氢酶的表达，使其达到成熟脂肪细胞中的水平。持续活跃的 Stat5a 还能够将 C/EBPα 转录物的表达增加到与 GH 相似的水平，并在较小程度上增加 C/EBPβ、过氧化物酶体增殖物激活受体 γ 和脂肪蛋白 2/脂肪酸结合蛋白转录物的表达。在 GH 的脂肪分解作用表现之前，年轻 GH 受体缺失小鼠的附睾脂肪库大小显着减少，支持了 GH 在小鼠脂肪生成中的体内作用。我们得出的结论是，Stat5 是 GH 诱导和潜在的催乳素诱导的小鼠脂肪生成的关键因素。
Although it is the best characterized in vitro model of GH action, the mechanisms used by GH to induce differentiation of murine 3T3-F442A preadipocytes remain unclear. Here we have examined the role of three transcriptional regulators in adipogenesis. These regulators are either rapidly induced in response to GH [Stra13, signal transducer and activator of transcription (Stat) 3] or of central importance to GH signaling (Stat5). Retroviral transfection of 3T3-F442A preadipocytes was used to increase expression of Stra13, Stat3, and Stat5a. Only Stat5a transfection increased the expression of adipogenic markers peroxisome proliferator-activated receptor gamma, CCAAT enhancer binding protein (C/EBP)alpha, and adipose protein 2/fatty acid-binding protein in response to GH, as determined by quantitative RT-PCR. Transfection with constitutively active Stat3 and Stat5a revealed that constitutively active Stat5a but not Stat3 was able to replace the GH requirement for adipogenesis. Constitutively active Stat5a but not Stat3 was able to increase the formation of lipid droplets and expression of alpha-glycerol phosphate dehydrogenase toward levels seen in mature adipocytes. Constitutively active Stat5a was also able to increase the expression of transcripts for C/EBPalpha to similar levels as GH, and of C/EBPbeta, peroxisome proliferator-activated receptor gamma, and adipose protein 2/fatty acid-binding protein transcripts to a lesser extent. An in vivo role for GH in murine adipogenesis is supported by significantly decreased epididymal fat depot size in young GH receptor-deleted mice, before manifestation of the lipolytic actions of GH. We conclude that Stat5 is a critical factor in GH-induced, and potentially prolactin-induced, murine adipogenesis.