Zenkel Matthias, Kruse Friedrich E, Jünemann Anselm G, Naumann Gottfried O H, Schlötzer-Schrehardt Ursula
Department of Ophthalmology, University of Erlangen-Nürnberg, Erlangen, Germany.
Invest Ophthalmol Vis Sci. 2006 May;47(5):1982-90. doi: 10.1167/iovs.05-1580.
To determine the role of the extracellular chaperone clusterin in the pathophysiology of pseudoexfoliation (PEX) syndrome/glaucoma, which is characterized by the stable deposition of abnormal extracellular fibrillar material in anterior segment tissues.
Real-time PCR, in situ hybridization, and immunohistochemistry were applied to analyze the mRNA and protein expression of clusterin in PEX eyes of patients without and with glaucoma and to compare them with eyes of patients with primary open-angle glaucoma and angle-closure glaucoma and with normal control eyes. Aqueous levels of clusterin were determined by Western blot analysis. Real-time PCR and Western blot analysis were used to study the effect of TGF-beta1, which is significantly increased in the aqueous humor of PEX eyes, on clusterin expression by nonpigmented ciliary epithelial cells in vitro.
Clusterin mRNA was ubiquitously expressed in most ocular cells and tissues, particularly in the epithelium of ciliary processes, whereas the protein was mostly located to extracellular structures, such as ocular basement membranes and stromal fibers. Real-time PCR and in situ hybridization displayed significant downregulation of clusterin mRNA in all anterior segment tissues of PEX eyes, irrespective of the presence or type of glaucoma, compared with normal and glaucomatous control eyes, whereas posterior segment tissues did not show any differential expression. A generally decreased immunoreactivity, but a prominent binding of clusterin to all PEX deposits, could be observed in ocular tissues of PEX eyes. Clusterin levels in aqueous humor were significantly reduced in eyes of patients with PEX syndrome compared with normal and glaucomatous control eyes. The expression of clusterin mRNA and protein in nonpigmented ciliary epithelial cells was significantly downregulated by TGF-beta1 in vitro.
Considering the known role of clusterin as a highly efficient extracellular chaperone, its deficiency in the anterior segment of PEX eyes may promote the stress-induced aggregation and stable deposition of the pathologic extracellular matrix product characteristic of PEX syndrome.
确定细胞外伴侣蛋白簇集素在假性剥脱（PEX）综合征/青光眼病理生理学中的作用，该综合征的特征是在前节组织中异常细胞外纤维状物质的稳定沉积。
应用实时聚合酶链反应（PCR）、原位杂交和免疫组织化学分析无青光眼和有青光眼的PEX患者眼中簇集素的mRNA和蛋白表达，并将其与原发性开角型青光眼、闭角型青光眼患者的眼睛以及正常对照眼进行比较。通过蛋白质印迹分析测定房水中簇集素的水平。利用实时PCR和蛋白质印迹分析研究在PEX患者房水中显著升高的转化生长因子β1（TGF-β1）对体外非色素睫状上皮细胞中簇集素表达的影响。
簇集素mRNA在大多数眼细胞和组织中普遍表达，尤其是在睫状突上皮中，而该蛋白主要定位于细胞外结构，如眼基底膜和基质纤维。与正常和青光眼对照眼相比，实时PCR和原位杂交显示，无论是否存在青光眼及其类型如何，PEX患者所有前节组织中簇集素mRNA均显著下调，而后节组织未显示任何差异表达。在PEX患者的眼组织中可观察到免疫反应性普遍降低，但簇集素与所有PEX沉积物有显著结合。与正常和青光眼对照眼相比，PEX综合征患者眼中房水中簇集素水平显著降低。体外实验中，TGF-β1可显著下调非色素睫状上皮细胞中簇集素mRNA和蛋白的表达。
鉴于簇集素作为一种高效细胞外伴侣蛋白的已知作用，其在PEX患者眼前节的缺乏可能会促进应激诱导的病理性细胞外基质产物的聚集和稳定沉积，这是PEX综合征的特征。
