Role of cell cycle protein in HIV encephalitis

描述（由申请人提供）：包括趋化因子、细胞因子、神经营养因子（NTF）、活性氧和病毒蛋白。大多数这些因素刺激细胞周期调节机制的变化，这决定了非神经元系统的细胞结果。这使我们提出细胞周期蛋白在HIVE患者的神经元中表现出改变的活性，这种活性决定了神经元在响应细胞外环境中巨噬细胞分泌因子的冲击时的存活。我们观察到在HIVE和SIVE中，pRb通过磷酸化（ppRb）失活增加，细胞质E2F1增加。使用体外培养，NTF和趋化因子刺激ppRb和细胞质E2F1增加，但过氧化氢没有。由于E2F1分布和pRb磷酸化的变化发生在响应神经营养/生存信号的细胞中，而不发生在响应氧化应激的细胞中，我们提出ppRb和细胞质E2F1增加的疾病神经元是“存活”神经元。这导致我们假设E2F1和ppRb决定神经元的活力依赖于它们的亚细胞分布和相互作用伙伴，这是由细胞外环境中普遍的信号提示决定的。我们提出了以下目的：1)确定细胞质E2F1是否对hiv相关毒素提供神经保护；2)确定MDMx在神经保护因子与神经毒性因子反应神经元中调节细胞存活和E2F1亚细胞定位中的作用；3)确定pRb在营养因子反应中的翻译后修饰是否发生在不同氨基酸上，而在毒性因子反应中修饰的残基则不同。这些研究将阐明细胞周期蛋白在HIVE和其他具有炎症成分的神经退行性疾病中决定神经元存活的作用。

DESCRIPTION (provided by applicant): including chemokines, cytokines, neurotrophic factors (NTF), reactive oxygen species, and viral proteins. Most of these factors stimulate changes in cell cycle regulatory machinery which determines cellular outcomes in non-neuronal systems. This has led us to propose that cell cycle proteins exhibit altered activity in neurons of patients with HIVE and this activity determines neuronal survival in response to the onslaught of macrophage secreted factors present in the extracellular milieu. We have observed increased inactivation of pRb by phosphorylation (ppRb) and increased cytoplasmic E2F1 in HIVE and SIVE. Using in vitro cultures, NTF and chemokines stimulate increased ppRb and cytoplasmic E2F1, but hydrogen peroxide does not. Because the changes in E2F1 distribution and pRb phosphorylation occur in cells responding to neurotrophic/survival signals, but not in cells responding to oxidative stress, we propose that neurons in the disease with increased ppRb and cytoplasmic E2F1 are "surviving" neurons. This has led us to hypothesize that E2F1 and ppRb determine neuronal viability dependent on their subcellular distribution and interaction partners which is determined by the prevailing signaling cues in the extracellular milieu. The following aims are proposed: 1) To determine whether cytoplasmic E2F1 provides neuroprotection from HIVE-associated toxins, 2) To determine the role of MDMx in regulating cell survival and E2F1 subcellular localization in neurons responding to neuroprotective versus neurotoxic factors, and 3) To determine if post-translational modification of pRb in response to trophic factors occurs on different amino acids as compared to those residues modified in response to toxic factors. These studies will elucidate the role of cell cycle proteins in determining neuronal survival in HIVE and other neurodegenerative diseases with inflammatory components.