Vranka J A, Johnson E, Zhu X, Shepardson A, Alexander J P, Bradley J M, Wirtz M K, Weleber R G, Klein M L, Acott T S
Department of Ophthalmology, Casey Eye Institute, Oregon Health Sciences University, Portland 97201, USA.
Curr Eye Res. 1997 Feb;16(2):102-10. doi: 10.1076/ceyr.16.2.102.5086.
Extracellular matrix homeostasis is dependent in part upon a family of matrix metalloproteinases and their specific inhibitors, the tissue inhibitors of metalloproteinases (TIMPs). Recently, gene defects in TIMP-3 have been identified in the affected individuals of several families with Sorsby's fundus dystrophy (SFD). Very little information is available regarding TIMP-3 function or even its existence in the retina or choroid.
We used reverse transcription-polymerase chain reaction and Northern analysis to evaluate the expression of TIMP mRNA and Western immunoblots to evaluate TIMP protein produced by select cells of the human retina and choroid. We also used these methods and immunohistochemistry to localize the TIMPs in the retina and choroid.
TIMP-3 transcripts are found in cultured human retinal pigment epithelium (RPE), choroidal microcapillary endothelium and pericytes. RPE cells also express and secrete TIMP-3 protein, which is localized to the extracellular matrix and is not found in culture medium; TIMP-1 and -2 are found almost exclusively in the medium. Immunohistochemistry of human retina/choroid sections shows pronounced TIMP-3 immunostaining in Bruch's membrane, particularly near the surface of the RPE and endothelial cells, presumably in their basement membranes, with minimal staining in other portions of the retina. Immunostaining for TIMP-1 is absent and for TIMP-2 is much less prevalent, but detectable in Bruch's membrane.
TIMP-1, -2 and -3 exhibit distinctive expression patterns in the retina and choroid. This distribution and expression pattern partially explains why TIMP-3 mutations result in SFD, rather than other retinal pathologies, such as those associated with proliferative diabetic retinopathy.
细胞外基质稳态部分依赖于基质金属蛋白酶家族及其特异性抑制剂——金属蛋白酶组织抑制剂（TIMPs）。最近，在几个患有索斯比眼底营养不良（SFD）的家族的患病个体中发现了TIMP - 3基因缺陷。关于TIMP - 3在视网膜或脉络膜中的功能甚至其存在情况，目前所知甚少。
我们使用逆转录 - 聚合酶链反应和Northern分析来评估TIMP mRNA的表达，并使用Western免疫印迹法评估人视网膜和脉络膜特定细胞产生的TIMP蛋白。我们还使用这些方法和免疫组织化学来定位视网膜和脉络膜中的TIMPs。
在培养的人视网膜色素上皮（RPE）、脉络膜微血管内皮细胞和周细胞中发现了TIMP - 3转录本。RPE细胞也表达并分泌TIMP - 3蛋白，该蛋白定位于细胞外基质，在培养基中未发现；TIMP - 1和 - 2几乎只存在于培养基中。人视网膜/脉络膜切片的免疫组织化学显示，在布鲁赫膜中TIMP - 3免疫染色明显，特别是在RPE和内皮细胞表面附近，可能在它们的基底膜中，而在视网膜的其他部分染色极少。TIMP - 1免疫染色缺失，TIMP - 2免疫染色较少见，但在布鲁赫膜中可检测到。
TIMP - 1、 - 2和 - 3在视网膜和脉络膜中表现出独特的表达模式。这种分布和表达模式部分解释了为什么TIMP - 3突变会导致SFD，而不是其他视网膜病变，如与增殖性糖尿病视网膜病变相关的病变。
