Marian Moazez J, Mukhopadhyay Partha, Borchman Douglas, Paterson Christopher A
Department of Biochemistry and Molecular Biology, University of Louisville, Louisville, Ky, USA.
Ophthalmic Res. 2008;40(2):86-93. doi: 10.1159/000113886. Epub 2008 Jan 25.
The plasma membrane calcium ATPase (PMCA) pump is the major mechanism by which calcium is removed from the lens. The aim of this study was to determine if mRNA and proteins levels of PMCA isoforms changed with age or lens opacity. mRNA was quantified using a quantitative real-time reverse transcription polymerase chain reaction assay (RT-PCR). PMCA protein levels were quantified using Western blot analysis. No PMCA mRNA or proteins were detected in human lens fiber cells. The mRNA and protein levels of PMCA1, 3 and 4 in the epithelium of cataractous lenses were similar to those of epithelium from age-matched clear lenses and were also the same in younger lenses. PMCA2 mRNA and protein levels were 1.6-2.5 times higher, respectively, in cataractous lenses compared to age-matched clear lenses. Elevated PMCA2 expression in cataractous lenses might be a compensatory mechanism to overcome higher intracellular calcium levels in cataract.
质膜钙ATP酶（PMCA）泵是晶状体清除钙的主要机制。本研究的目的是确定PMCA亚型的mRNA和蛋白质水平是否随年龄或晶状体混浊而变化。使用定量实时逆转录聚合酶链反应测定法（RT-PCR）对mRNA进行定量。使用蛋白质印迹分析对PMCA蛋白水平进行定量。在人晶状体纤维细胞中未检测到PMCA mRNA或蛋白质。白内障晶状体上皮中PMCA1、3和4的mRNA和蛋白质水平与年龄匹配的透明晶状体上皮相似，在较年轻的晶状体中也是如此。与年龄匹配的透明晶状体相比，白内障晶状体中PMCA2的mRNA和蛋白质水平分别高出1.6 - 2.5倍。白内障晶状体中PMCA2表达升高可能是一种补偿机制，以克服白内障中较高的细胞内钙水平。
