IGF-1 signaling pathway in HIV-1 in CNS disease

项目2：HIV-1CMS疾病中的IGF-1信号通路。 相当数量的艾滋病毒患者会出现认知障碍和痴呆症。据信，细胞 而白质中HIV-1感染细胞释放的病毒因子，尤其是TNFa，是起作用的 对于艾滋病大脑中出现的神经元损伤。因此，我们证明了长期暴露于 分化为TNFoc的神经元在没有神经元的情况下导致神经元突起回缩 细胞凋亡。HIV-1感染也会损害神经保护途径，包括胰岛素样生长 因子1(IGF-1)信号系统。因此，在早期的研究中，我们证明了IGF-1可以保护 来自TNFa的神经元引起神经元突起的收缩。我们已经证明了TNFa会触发 IRS-1(PS-IRS-1)在分化神经元膜筏上的丝氨酸磷酸化，而pSIRS-1- 1干扰整合素介导的细胞反应，细胞反应直接参与维持 神经元突起和神经元突起。 这些观察结果使我们假设，在艾滋病毒脑炎中，神经元突起的变性是 由TNFa诱导的PS-IRS-1与神经元整合素之间的相互作用导致脱离 以及神经元突起的回缩。TNFoc的这一有害行为被胰岛素样生长因子-L介导的 IRS-1的酪氨酸磷酸化(Py-IRS-1)，支持神经元突起和 促进组织重塑和神经元生长。我们已经通过实验证明了这一假设。 描述了三个具体的目标。在目标1中，我们将分析神经元突起的密度。 HIV脑炎(HIVE)受TNFoc积累的影响不同。在目标2中，我们将评估 TnFcc对IRS-1亚细胞定位和磷酸化状态的影响；并将进行分子分析 IGF-IR基因敲除后原代培养神经元中IRS-1、(31-整合素)与ADAMS的相互作用 胚胎和年龄匹配的非转基因窝产仔。最后，在目标3中，我们将检查 胰岛素样生长因子-I刺激对肿瘤坏死因子-α介导的视神经牵拉后神经元再生和组织重塑的影响 来自IGF-IR基因敲除胚胎和年龄匹配的分化神经球培养中的神经元突起 非转基因窝产仔。该项目的结果将识别和表征新的分子 事件，影响蜂巢范例中神经元突起的稳定性，可能还影响其他神经学 以TNFcc积聚为特征的疾病。理解IGF-1之间的交叉相互作用 而TNFa信号通路将有助于开发基于胰岛素样生长因子-L的新的治疗方法 神经性疾病，其中神经元突起的收缩/退化是常见的事件。

Project #2. IGF-1 signaling pathway in HIV-1 CMS disorders. A significant number of HIV patients develop cognitive disorders and dementia. It is believed that cellular and viral factors released by the HIV-1 infected cells in the white matter, most notably TNFa , are responsible for neuronal injury seen in AIDS brains. Accordingly, we demonstrated that prolonged exposure of differentiated neurons to TNFoc leads to the retraction of neuronal processes in the absence of neuronal apoptosis. HIV-1 infection can also compromise neuroprotective pathways including the insulin-like growth factor 1 (IGF-1) signaling system. Accordingly, in earlier studies we demonstrated that IGF-1 protects neurons from TNFa-induced retraction of neuronal processes. We have demonstrated that TNFa triggers serine phosphorylation of IRS-1 (pS-IRS-1) at the membrane rafts of differentiated neurons, and that pSIRS- 1 interferes with integrin-mediated cellular responses, which are directly involved in the maintenance of neuronal processes and neuronal outgrowth. These observations led us to hypothesize that in HIV encephalitis degeneration of neuronal processes is caused by TNFa-induced interaction between pS-IRS-1 and neuronal integrins, which leads to detachment and retraction of neuronal processes. This detrimental action of TNFoc is counteracted by IGF-l-mediated tyrosine phosphorylation of IRS-1 (pY-IRS-1), which supports the binding of neuronal processes and facilitates tissue remodeling and neuronal outgrowth. We have addressed this hypothesis by experiments described in three Specific Aims. In Aim#1. we will analyze density of neuronal processes in the regions of HIV encephalitis (HIVE) differentially affected by the accumulation of TNFoc. In Aim#2. we will evaluate effects of TNFcc on subcellular localization and phosphorylation status of IRS-1; and will analyze molecular interactions between IRS-1, (31-integrin and ADAMs in primary neuronal cultures from the IGF-IR knockout embryos and from age-matching non-transgenic littermates. Finally, in Aim#3. we will examine effects of IGF-I stimulation on neuronal regeneration and tissue remodeling after TNFa -mediated retraction of neuronal processes in differentiated neurosphere cultures from the IGF-IR knockout embryos and from agematching non-transgenic littermates. The outcome of this project will identify and characterize new molecular events, which affect stability of neuronal processes in the paradigm of HIVE, and possibly other neurological disorders characterized by the accumulation of TNFcc. Understanding the cross interaction between IGF-1 and TNFa signaling pathways will help to develop new IGF-l-based therapeutic approaches against neurological disorders in which retraction/degeneration of neuronal processes is a common event.