Hormonal mechanisms of gene regulation

脂联素是一种由脂肪组织分泌的激素，有助于保持肝脏、骨骼肌、胰腺和血管的健康。当一个人变得肥胖时，他们的脂肪细胞不再产生那么多的脂联素。因此，有人认为肥胖的负面影响是由于缺乏脂联素造成的。脂联素的关键功能之一是帮助控制血糖（葡萄糖）水平。这意味着脂联素与胰岛素一起控制肝脏产生葡萄糖。肥胖者体内脂联素的减少可能是胰岛素水平必须增加以控制血糖水平的原因。我们已经研究胰岛素如何控制血糖超过25年，但没有人研究脂联素如何帮助。我们想看看这个问题，因为我们的一些工作表明脂联素激活一种叫做FoxO 6的关键蛋白质，它也被胰岛素激活。有趣的是，两者都是FoxO 6。我们希望确定脂联素和胰岛素如何通过FoxO 6协调肝脏的葡萄糖生产。 基于我们的研究结果，我们提出了以下假设：胰岛素和脂联素联合作用导致肝脏FoxO 6磷酸化的减少是由于14-3-3支架蛋白结合减少，从而阻断FoxO 6对特定基因的作用。 该假说认为，脂联素和胰岛素通过改变另一种称为14-3-3的蛋白质与FoxO 6结合的能力，共同干扰FoxO 6的激活。由此产生的FoxO 6失活导致参与肝脏产生葡萄糖的某些基因的表达减少。 为了解决这一假设，我们建议完成三个独立的目标，每个目标都为我们提供有关胰岛素和脂联素如何影响FoxO 6的信息。目的1将确定存在于细胞中的将信号从胰岛素和脂联素受体发送到FoxO 6的因子。目的2将使用针对FoxO 6的这种修饰形式的特异性抗体来检测FoxO 6的磷酸化状态（这与其活化有关），以响应胰岛素和脂联素。我们将包括在这个分析中的不同形式的脂联素，已知存在于血液中。它们是全长的，代表脂肪细胞分泌的脂联素的形式，以及球状形式，脂联素的较短版本，由能够去除一小部分蛋白质的酶在血液中产生。目的3将研究14-3-3与FoxO 6的结合是否受胰岛素和脂联素的影响。这些实验将提供胰岛素和脂联素在调节肝脏葡萄糖产生中直接相互作用的第一个机制证据。总的来说，正在提出的项目将描绘串扰的关键点，并增加我们对有效肝功能至关重要的细胞过程的理解。

Adiponectin is a hormone secreted by fat tissue that helps keep the liver, skeletal muscle, pancreas and blood vessels healthy. When a person becomes obese, their fat cells no longer make as much adiponectin. Because of this, it has been suggested that the negative effects of obesity are caused by a lack of adiponectin. One of the key functions of adiponectin is to help control blood sugar (glucose) levels. This means that adiponectin works with insulin in controlling glucose production by the liver. Less adiponectin in obesity may be the reason insulin levels have to increase to keep glucose levels in check. We have been studying how insulin works to control glucose for over 25 years, but no one has looked at how adiponectin helps. We want to look at this question because some of our work showed adiponectin activates a key protein called FoxO6, which is also activated by insulin. Interestingly, both together inactivate FoxO6. We wish to determine how adiponectin and insulin work to coordinate glucose production by the liver via FoxO6. Based on our results, we propose the following hypothesis: the reduction in hepatic FoxO6 phosphorylation that occurs as a result of the combined actions of insulin and adiponectin is due to a decrease in the binding of the 14-3-3 scaffold protein, which blocks the action of FoxO6 on specific genes. What is being suggested in the hypothesis is that adiponectin and insulin together interfere with the activation of FoxO6 by changing the ability of another protein called 14-3-3 to bind to FoxO6. The resulting inactivation of FoxO6 leads to a decrease in the expression of certain genes involved in the production of glucose by the liver. To address the hypothesis, we propose completing three separate objectives, each providing us with information regarding how insulin and adiponectin affect FoxO6. Objective 1 will identify the factors present in the cell that send signals from the insulin and adiponectin receptors to FoxO6. Objective 2 will examine the phosphorylation state of FoxO6 (which relates to its activation) using specific antibodies to this modified form of FoxO6 in response to insulin and adiponectin. We will include in this analysis the different forms of adiponectin that are known to be present in the blood. These are the full-length, which represents the form of adiponectin that is secreted by fat cells, and the globular form, a shorter version of adiponectin that is produced in the blood by an enzyme capable of removing a small piece of the protein. Objective 3 will investigate if 14-3-3 binding to FoxO6 is affected by insulin and adiponectin. These experiments will provide the first mechanistic evidence of a direct interaction between insulin and adiponectin in the regulation of glucose production by the liver. Overall, the project being proposed will delineate the key points of cross-talk and add to our understanding of the cellular processes that are critical for efficient liver function.