Hypoxia and Potassium Channel Activity in T Lymphocytes

描述（由申请人提供）：在生理（例如高海拔）和病理条件（例如心肺疾病和癌症）中都会遇到氧可用性降低（缺氧）。尽管缺氧通常与几种人类疾病的不良结局相关，但参与疾病进展的不同细胞类型对O2可用性变化的反应的基本机制仍然知之甚少。免疫细胞参与许多疾病状态，其功能影响病理的缓解或改善。各种体外研究表明，缺氧可抑制宿主免疫细胞的功能。虽然缺氧抑制T细胞活性的机制还不清楚，但缺氧对其他细胞类型的下游影响已被广泛研究。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，并最终导致细胞功能的变化。由Kv1.3基因编码的K通道在T淋巴细胞中表达，并控制膜电位和细胞活性。初步数据表明，天然（在人T淋巴细胞）和重组Kv1.3通道被缺氧抑制。这些通道的抑制已显示抑制T细胞活化。事实上，进一步的初步证据表明，缺氧抑制了T淋巴细胞中Ca2+的动员和增殖.因此，我们假设缺氧对T细胞功能的影响部分是由缺氧抑制Kv1.3通道的能力介导的。该研究旨在研究缺氧对T细胞Kv1.3通道活性的影响，并确定其缺氧抑制的功能意义。还将进行实验以鉴定介导T细胞中Kv1.3通道的氧敏感性的信号通路。将使用电生理学、免疫学和分子生物学技术的组合。从拟议的研究结果将提供新的见解缺氧的免疫反应的分子基础，并将进一步了解缺氧介导的T细胞功能的变化的离子机制。

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.