Hypoxia and Potassium Channel Activity in T Lymphocytes

描述(由申请人提供)：在生理(如高海拔)和病理(如心肺疾病和癌症)两种情况下都可能遇到氧气供应减少(缺氧)。虽然缺氧通常与几种人类疾病的不良结局有关，但参与疾病进展的不同类型的细胞对氧气供应变化的基本机制仍然知之甚少。免疫细胞参与多种疾病状态，其功能影响病理的缓解或改善。各种体外研究表明，低氧可抑制宿主免疫细胞的功能。虽然低氧抑制T细胞活性的机制还不是很清楚，但低氧对其他类型细胞的下游影响已经被广泛研究。因此，我们知道K通道活性的抑制是缺氧后发生的早期事件之一，最终导致细胞功能的改变。Kv1.3基因编码的K通道在T淋巴细胞中表达，控制膜电位和细胞活性。初步数据表明，人T淋巴细胞中的天然Kv1.3通道和重组Kv1.3通道在低氧条件下受到抑制。抑制这些通道可以抑制T细胞的激活。事实上，进一步的初步证据表明，低氧抑制T淋巴细胞的钙动员和增殖。因此，我们推测低氧对T细胞功能的影响部分是通过抑制Kv1.3通道的能力来实现的。本研究旨在研究低氧对T细胞Kv1.3通道活性的影响，并确定其低氧抑制的功能意义。还将进行实验，以确定介导T细胞Kv1.3通道氧敏感性的信号通路。将综合使用电生理学、免疫学和分子生物学技术。这些研究结果将为低氧下免疫反应的分子基础提供新的见解，并将进一步加深我们对低氧介导的T细胞功能变化的离子机制的理解。

DESCRIPTION (provided by applicant): A decrease in oxygen availability (hypoxia) can be encountered both in physiological (e.g. high altitude) and pathological conditions (e.g. cardio-pulmonary diseases and cancer). Although hypoxia is usually associated with a poor outcome in several human disorders, the basic mechanisms by which the different cell types involved in the progression of the disease respond to the change in O2 availability are still poorly understood. Immune cells participate in many disease states and their functionality affects the remission or amelioration of the pathology. Various in vitro studies have indicated that hypoxia can inhibit the function of the host immune cells. While the mechanisms whereby hypoxia inhibits T cell activity are not well understood, the downstream effects of hypoxia on other cell types have been extensively studied. Thus we know that inhibition of K channel activity is one of the early events that occur following hypoxia and which eventually leads to changes in cellular function. K channels encoded by the Kv1.3 gene are expressed in T lymphocytes and control membrane potential and cell activity. Preliminary data indicate that native (in human T lymphocytes) and recombinant Kv1.3 channels are inhibited by hypoxia. Inhibition of these channels has been shown to inhibit T cell activation. Indeed, further preliminary evidence indicates that hypoxia inhibits Ca 2+ mobilization and proliferation in T lymphocytes. Therefore we hypothesize that the effect of hypoxia on T cell function is in part mediated by the ability of hypoxia to inhibit Kv1.3 channels. The proposed research aims to study the effect of hypoxia on Kv1.3 channel activity in T cells and to determine the functional implications of their hypoxic-inhibition. Experiments will be also performed to identify the signaling pathways mediating the oxygen sensitivity of Kv1.3 channels in T cells. A combination of electrophysiological, immunological and molecular biological techniques will be used. Findings from the proposed studies will provide new insights into the molecular basis of the immune response in hypoxia and will further our understanding of the ionic mechanisms of hypoxia-mediated changes in T cell function.