Hemoglobin expression and regulation in glaucoma: insights into retinal ganglion cell oxygenation.
Hemoglobin expression and regulation in glaucoma: insights into retinal ganglion cell oxygenation.
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DOI：
10.1167/iovs.09-4014
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发表时间：
2010-02
影响因子：
4.4
通讯作者：
G. Tezel;Xiangjun Yang;C. Luo;Jian Cai;Angela D Kain;D. Powell;M. Kuehn;W. Pierce
中科院分区：
文献类型：
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作者：
G. Tezel;Xiangjun Yang;C. Luo;Jian Cai;Angela D Kain;D. Powell;M. Kuehn;W. Pierce
目的研究血红蛋白（Hb）在正常组织和肿瘤组织中的表达、细胞分布和调节。方法采用蛋白质组学方法对高眼压大鼠眼、正常大鼠眼和正常人青光眼眼的血红蛋白表达进行分析。通过定量（q）RT-PCR、Western印迹分析、免疫组织化学和培养物中新Hb合成的分析来验证蛋白质组学结果。在大鼠RGCs和大胶质细胞的原代培养物中以及将胶质细胞条件培养基转移到RGCs后，还研究了Hb表达的低血糖调节。红细胞生成素（EPO）信号传导在Hb诱导和细胞存活中的作用通过应用重组（r）EPO处理和通过使用低氧培养物的可溶性EPO受体处理进行EPO中和实验来确定。结果：在体内研究结果显示，血红蛋白在视网膜和视神经乳头大胶质细胞和RGCs的表达，表明约2倍的上调，在高眼压大鼠眼和青光眼的人供体眼相对于对照眼。体外研究结果共同支持缺氧通过缺氧诱导的EPO信号以自分泌方式促进神经胶质细胞Hb表达。被动转移实验的基础上，缺氧诱导的生产胶质细胞EPO也被发现上调血红蛋白的表达在RGCs的旁分泌方式，从而增加这些神经元的缺氧生存。结论本研究结果为通过调节大胶质细胞和RGCs中Hb的表达来研究内层视网膜和视神经乳头的组织氧转运提供了新的见解。Hb表达的上调似乎是促进细胞氧合的内在保护机制，并且还可以提供自由基清除。
PURPOSE To determine expression, cellular distribution, and regulation of hemoglobin (Hb) in normal and glaucomatous tissues. METHODS Proteomic analysis of Hb expression was conducted on protein samples from ocular hypertensive and control rat eyes and human donor eyes with or without glaucoma. Proteomic findings were validated by quantitative (q)RT-PCR, Western blot analysis, immunohistochemistry, and the analysis of new Hb synthesis in culture. Hypoxic regulation of Hb expression was also studied in primary cultures of rat RGCs and macroglia and after transfer of the glia-conditioned medium to RGCs. The role of erythropoietin (EPO) signaling in Hb induction and cell survival was determined by applying recombinant (r)EPO treatment and performing EPO neutralization experiments by using soluble EPO receptor treatment of hypoxic cultures. RESULTS In vivo findings revealed Hb expression in the retina and optic nerve head macroglia and RGCs, suggesting an approximately two-fold upregulation in ocular hypertensive rat eyes and glaucomatous human donor eyes relative to the control eyes. In vitro findings collectively supported that hypoxia boosts glial Hb expression through hypoxia-inducible EPO signaling in an autocrine manner. Based on passive transfer experiments, hypoxia-induced production of glial EPO was also found to upregulate Hb expression in RGCs in a paracrine manner, thereby increasing the hypoxic survival of these neurons. CONCLUSIONS Findings of this study provide new insights into tissue oxygen transport in the inner retina and optic nerve head through the regulated expression of Hb in macroglia and RGCs. Upregulation of Hb expression appears to be an intrinsic protective mechanism to facilitate cellular oxygenation and may also provide free radical scavenging.