Loss of MCT1, MCT3, and MCT4 expression in the retinal pigment epithelium and neural retina of the 5A11/basigin-null mouse
Loss of MCT1, MCT3, and MCT4 expression in the retinal pigment epithelium and neural retina of the 5A11/basigin-null mouse
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DOI：
10.1167/iovs.02-0552
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发表时间：
2003-03-01
影响因子：
4.4
通讯作者：
Linser, PJ
中科院分区：
文献类型：
--
作者：
Philp, NJ;Ochrietor, JD;Linser, PJ
目的.神经视网膜表达多种单羧酸转运蛋白（MCT），这些转运蛋白可能在外视网膜的代谢中发挥关键作用。最近，据报道，MCTI和-4靶向质膜需要与5A 11/basigin（CD 147）结合。在本研究中，研究了5A 11/basigin null小鼠（Bsg（-/-））中视网膜电图振幅降低可能与MCT表达改变有关的假设。采用同种型特异性抗体，通过免疫荧光显微镜分析Bsg（-/-）小鼠中MCT的表达和亚细胞分布。蛋白质表达用Western blot分析，mRNA表达用RT-PCR检测。Bsg（-/-）小鼠组织切片的免疫荧光标记显示MCT抗体标记显著减少。在RPE的顶膜和神经视网膜中有MCT 1标记的损失。在RPE野生型小鼠的基底外侧膜中表达的MCT 3在Bsg（-/-）小鼠的顶膜和基底外侧膜中均以极低水平表达。Bsg（-/-）小鼠RPE和视网膜中葡萄糖转运蛋白（GLUT）-1的表达或分布没有变化。从野生型和Bsg（-/-）眼睛制备的洗涤剂可溶性裂解物的Western印迹分析证实，Bsg（-/-）小鼠中MCTI、MCT 3和MCT 4蛋白水平严重降低。RT-PCR分析野生型和Bsg（-/-）小鼠的mRNA水平表明，MCTI转录本在Bsg（-/-）小鼠中以正常水平表达。在Bsg（-/-）小鼠中，RPE中MCT 1和-3蛋白的积累严重减少，同时神经视网膜中MCT 1和-4也减少，这支持了5A 11/basigin在将这些转运蛋白靶向质膜中的作用。MCTI和-4在Muller细胞和感光细胞表面上的表达减少可能损害外视网膜中的能量代谢，导致感光细胞功能异常和变性。
PURPOSE. The neural retina expresses multiple monocarboxylate transporters (MCTs) that are likely to play a key role in the metabolism of the outer retina. Recently, it was reported that targeting of MCTI and -4 to the plasma membrane requires association with 5A11/basigin (CD147). In the present study, the hypothesis that reduced amplitudes in the electroretinograms in the 5A11/basigin null mouse (Bsg(-/-)) may be linked to altered expression of MCTs was studied.METHODS. The expression and subcellular distribution of MCTs in Bsg(-/-) mice was analyzed by immunofluorescence microscopy with isoform-specific antibodies. Protein expression was analyzed by Western blot analysis, and mRNA expression was examined with RT-PCR.RESULTS. Immunofluorescence labeling of tissue sections from the Bsg(-/-) mice revealed a dramatic reduction in labeling with MCT antibodies. There was a loss of MCT1 labeling in the apical membrane of the RPE and in the neural retina. MCT3, which is expressed in the basolateral membrane of the RPE wild-type mouse, was expressed at very low levels in both the apical and basolateral membranes of the Bsg(-/-) mouse. There was no change in expression or distribution of the glucose transporter (GLUT)-1 in the RPE and retina of the Bsg(-/-) mouse. Western blot analysis of detergent-soluble lysates prepared from wild-type and Bsg(-/-) eyes confirmed that the levels of MCTI, MCT3, and MCT4 protein were severely reduced in Bsg(-/-) mice. RT-PCR analyses of mRNA levels from wild-type and Bsg(-/-) mice demonstrated that the MCTI transcript was expressed at normal levels in Bsg(-/-) mice.CONCLUSIONS. In Bsg(-/-) mice, there is a severe reduction in accumulation of the MCT1 and -3 proteins in the RPE and a concomitant reduction in MCT1 and -4 in the neural retina supporting a role for 5A11/basigin in the targeting of these transporters to the plasma membrane. Decreased expression of MCTI and -4 on the surfaces of Muller and photoreceptor cells may compromise energy metabolism in the outer retina, leading to abnormal photoreceptor cell function and degeneration.