Ogawa Asa, Sakatsume Minoru, Wang Xingzhi, Sakamaki Yunichi, Tsubata Yutaka, Alchi Bassam, Kuroda Takeshi, Kawachi Hiroshi, Narita Ichiei, Shimizu Fujio, Gejyo Fumitake
Division of Clinical Nephrology and Rheumatology, Institute of Nephrology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
Nephron Exp Nephrol. 2007;106(3):e77-87. doi: 10.1159/000103020. Epub 2007 May 22.
BACKGROUND/AIMS: Our previous comprehensive analysis of the genes expressed in kidneys with anti-glomerular basement membrane (GBM) nephritis using DNA microarrays showed that SM22alpha was one of the highly expressed genes. SM22alpha is a 22-kDa cytoskeletal protein that is exclusively expressed in smooth muscle cells. We investigated the localization of SM22alpha at mRNA and protein levels, and its pathological significance in anti-GBM nephritis kidneys.
Northern blot analysis, in situ hybridization, immunohistochemistry and double immunofluorescence studies were performed. The specific antibody (Ab) against SM22alpha was obtained by immunization of rabbits with recombinant rat SM22alpha protein.
SM22alpha mRNA expression was upregulated in kidneys and inducibly expressed in the parietal and visceral glomerular epithelial cells in anti-GBM nephritis kidneys. Immunohistochemistry with anti-SM22alpha Ab showed that SM22alpha protein was localized in the same series of cells. Double immunofluorescence with anti-SM22alpha and anti-glomerular cell markers demonstrated that SM22alpha might be expressed in epithelial cells of injured glomeruli. In visceral epithelial cells, SM22alpha might be expressed in cells in which podocyte specific markers, podocalyxin and nephrin were lost.
The injured glomerular epithelial cells in anti-GBM nephritis might undergo structural and functional alterations, including the expression of a smooth muscle marker, SM22alpha.
背景/目的：我们之前利用DNA微阵列对患有抗肾小球基底膜（GBM）肾炎的肾脏中表达的基因进行的综合分析表明，SM22α是高表达基因之一。SM22α是一种22 kDa的细胞骨架蛋白，仅在平滑肌细胞中表达。我们研究了SM22α在mRNA和蛋白水平的定位及其在抗GBM肾炎肾脏中的病理意义。
进行了Northern印迹分析、原位杂交、免疫组织化学和双重免疫荧光研究。通过用重组大鼠SM22α蛋白免疫兔子获得了抗SM22α的特异性抗体（Ab）。
在抗GBM肾炎肾脏中，SM22α mRNA表达在肾脏中上调，并在壁层和脏层肾小球上皮细胞中诱导表达。用抗SM22α抗体进行免疫组织化学显示，SM22α蛋白定位于同一系列细胞中。用抗SM22α和抗肾小球细胞标志物进行双重免疫荧光显示，SM22α可能在受损肾小球的上皮细胞中表达。在内脏上皮细胞中，SM22α可能在足细胞特异性标志物足突融合蛋白和nephrin缺失的细胞中表达。
抗GBM肾炎中受损的肾小球上皮细胞可能发生结构和功能改变，包括平滑肌标志物SM22α的表达。
