Growth Hormone Signaling to the Nucleus

描述(申请人提供)：生长激素(GH)对生长和新陈代谢产生深刻的生理影响，并与胰岛素抵抗和可能的癌症有关。对生长激素的许多反应取决于它调节基因转录的能力。我们假设GH调控的转录是通过多组分核蛋白复合体在靶基因上的有序组装来介导的，并且GH诱导的关键蛋白的修饰可以引导它们进入和离开复合体。我们的方法是利用染色质免疫沉淀(CHIP)和Re-Chip来确定GH调节的复合体的组成，并确定模型基因c-fos上的组装动力学。同时，我们还将研究GH对转录因子C/EBPp的翻译后修饰，这是GH刺激c-fos转录所必需的。复杂组装的顺序将与C/EBPp翻译后修饰的时机和组合有关，包括磷酸化、乙酰化和SUMO化。当生长激素对复合体的调节被确定后，我们将验证它们在体内生长激素调节基因表达中的功能重要性。相关性：生长激素用于治疗生长激素缺乏症的矮小。生长激素的合成代谢特性正被用于治疗，以改善艾滋病毒患者的伤口愈合和扭转其消瘦。然而，GH也是糖尿病的诱因，降低了对胰岛素的敏感性。最近，生长激素-胰岛素样生长因子轴被认为与癌症有关，这扩大了我们理解生长激素作用基础的需要。这项拟议的研究将提供生长激素如何通过调节基因来改变细胞功能的基本信息。有了这些信息，我们可以确定新的分子靶点，以开发对生长激素敏感的条件更有效的治疗方法，并避免糖尿病和癌症等条件下的生长激素相关并发症。

DESCRIPTION (provided by applicant): Growth hormone (GH) exerts profound physiological effects on growth and metabolism, and is implicated in insulin resistance and possibly cancer. Many responses to GH depend on its ability to regulate gene transcription. We hypothesize that GH-regulated transcription is mediated by the ordered assembly of multicomponent nucleoprotein complexes on target genes and that GH-induced modifications of critical proteins can direct them into and out of the complexes. Our approach is to dissect the assembly of the multicomponent complexes in response to GH using chromatin immunoprecipitation (ChIP) and re-ChIP to define GH-regulated components of complexes and determine the dynamics of assembly on the model gene c-fos. In parallel, we will also examine post-translational modifications induced by GH on the transcription factor C/EBPp, which is essential for GH-stimulated transcription of c-fos. The sequence of complex assembly will be related to the timing and combinations of post-translational modifications of C/EBPp including phosphorylation, acetylation and sumoylation. When regulation of complexes by GH is determined, we will validate their functional importance for GH-regulated gene expression in vivo. Relevance: GH is used for treatment of short stature in GH deficiency. The anabolic properties of GH are being used therapeutically to improve wound healing and to reverse wasting in HIV patients. However, GH is also diabetogenic and reduces sensitivity to insulin. Recently, the GH-IGF axis has been implicated in cancer, broadening our need to understand the basis of GH action. The proposed studies will provide fundamental information about how GH alters cell function by regulating genes. With this information, we can identify new molecular targets to develop more effective therapies for conditions responsive to GH and to avoid GH-related complications in conditions such as diabetes and cancer.