整合素αvβ5在培养的人视网膜色素上皮细胞吞噬作用过程中参与光感受器视杆细胞外段的结合。

Integrin alphavbeta5 participates in the binding of photoreceptor rod outer segments during phagocytosis by cultured human retinal pigment epithelium.

作者信息

Lin H, Clegg D O

机构信息

Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara 93106, USA.

出版信息

Invest Ophthalmol Vis Sci. 1998 Aug;39(9):1703-12.

PMID:9699560

Abstract

PURPOSE

To examine the expression of integrin vitronectin receptors (integrins alphavbeta3 and alphavbeta5) in native human fetal retinal pigment epithelium (RPE) and cultured hunman fetal RPE and to examine the role of RPE VnRs in the phagocytosis of photoreceptor rod outer segments (ROS).

METHODS

Monoclonal antibodies against human integrin subunit alphav and heterodimers alphavbeta3 (LM609) and alphavbeta5 (P1F6) were used to label freshly isolated human fetal RPE explant and cultured human fetal RPE and to immunoprecipitate membrane proteins from cultured human RPE. Effects of antibodies and peptides that inhibit integrin vitronectin receptors on phagocytosis of ROS by RPE were determined using cultured human fetal RPE and fluorescein-labeled bovine outer segments.

RESULTS

Antibodies against integrin subunit alphav and against alphavbeta5 (P1F6) labeled the RPE apical membrane in both native tissue and cultured RPE, while anti-alphavbeta3 antibody (LM609) labeled less than 1% of cultured RPE and did not label native RPE. Antibodies against alphav and alphavbeta5 P1F6 also immunoprecipitated 2 protein bands corresponding to integrin subunits alphav and beta5 from a membrane extract of cultured human RPE. The peptide Gly-Arg-Gly-Asp-Ser-Pro (GRGDSP, 1 mM) inhibited the total ROS uptake (externally bound and ingested) by 48% (P < 0.001) and ingestion of ROS by 37% (P < 0.001). Antibody PIF6 (50 microg/ml) inhibited the total ROS uptake and the ingestion of ROS by 63% (P < 0.001) and 43% (P < 0.01), respectively.

CONCLUSIONS

The integrin alphavbeta5 vitronectin receptor is expressed on the apical membrane of human RPE and participates in the binding of photoreceptor ROS during phagocytosis by cultured human RPE.

摘要

目的

检测整合素玻连蛋白受体（整合素αvβ3和αvβ5）在人胎儿视网膜色素上皮（RPE）原代组织及培养的人胎儿RPE中的表达，并研究RPE玻连蛋白受体在光感受器视杆细胞外节（ROS）吞噬过程中的作用。

方法

使用抗人整合素亚基αv的单克隆抗体以及异二聚体αvβ3（LM609）和αvβ5（P1F6）标记新鲜分离的人胎儿RPE外植体及培养的人胎儿RPE，并从培养的人RPE中免疫沉淀膜蛋白。使用培养的人胎儿RPE和荧光素标记的牛外节，测定抑制整合素玻连蛋白受体的抗体和肽对RPE吞噬ROS的影响。

结果

抗整合素亚基αv抗体和抗αvβ5（P1F6）抗体在原代组织和培养的RPE中均标记RPE顶端膜，而抗αvβ3抗体（LM609）标记的培养RPE少于1%，且未标记原代RPE。抗αv和αvβ5 P1F6抗体还从培养的人RPE膜提取物中免疫沉淀出与整合素亚基αv和β5相对应的2条蛋白带。肽甘氨酸-精氨酸-甘氨酸-天冬氨酸-丝氨酸-脯氨酸（GRGDSP，1 mM）使ROS的总摄取量（外部结合和摄取）降低48%（P<0.001），ROS摄取量降低37%（P<0.001）。抗体PIF6（50μg/ml）使ROS的总摄取量和摄取量分别降低63%（P<0.001）和43%（P<0.01）。