Nagineni Chandrasekharam N, Samuel William, Nagineni Sahrudaya, Pardhasaradhi Komanduri, Wiggert Barbara, Detrick Barbara, Hooks John J
National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
J Cell Physiol. 2003 Dec;197(3):453-62. doi: 10.1002/jcp.10378.
Vascular endothelial growth factor (VEGF) is a major agent in choroidal and retinal neovascularization, events associated with age-related macular degeneration (AMD) and diabetic retinopathy. Retinal pigment epithelium (RPE), strategically located between retina and choroid, plays a critical role in retinal disorders. We have examined the effects of various growth factors on the expression and secretion of VEGF by human retinal pigment epithelial cell cultures (HRPE). RT-PCR analyses revealed the presence of three isoforms of mRNA corresponding to VEGF 121, 165, and 189 that were up regulated by TGF-beta1. TGF-beta1, beta2, and beta3 were the potent inducers of VEGF secretion by HRPE cells whereas bFGF, PDGF, TGF-alpha, and GM-CSF had no effects. TGF-beta receptor type II antibody significantly reversed induction of VEGF secretion by TGF-beta. In contrast activin, inhibin and BMP, members of TGF-beta super family, had no effects on VEGF expression in HRPE. VEGF mRNA levels and protein secretion induced by TGF-beta were significantly inhibited by SB203580 and U0126, inhibitors of MAP kinases, but not by staurosporine and PDTC, protein kinase C and NF-kappaB pathway inhibitors, respectively. TGF-beta also induced VEGF expression by fibroblasts derived from human choroid of eye. TGF-beta induction of VEGF secretion by RPE and choroid cells may play a significant role in choroidal neovascularization (CNV) in AMD. Since the secretion of VEGF by HRPE is regulated by MAP kinase pathways, MAP kinase inhibitors may have potential use as therapeutic agents for CNV in AMD.
血管内皮生长因子（VEGF）是脉络膜和视网膜新生血管形成中的主要因子，这些新生血管形成事件与年龄相关性黄斑变性（AMD）和糖尿病性视网膜病变相关。视网膜色素上皮（RPE）位于视网膜和脉络膜之间，在视网膜疾病中起关键作用。我们已经研究了各种生长因子对人视网膜色素上皮细胞培养物（HRPE）中VEGF表达和分泌的影响。逆转录聚合酶链反应（RT-PCR）分析显示存在与VEGF 121、165和189相对应的三种mRNA亚型，它们被转化生长因子-β1（TGF-β1）上调。TGF-β1、β2和β3是HRPE细胞分泌VEGF的有效诱导剂，而碱性成纤维细胞生长因子（bFGF）、血小板衍生生长因子（PDGF）、转化生长因子-α（TGF-α）和粒细胞-巨噬细胞集落刺激因子（GM-CSF）则无作用。II型TGF-β受体抗体可显著逆转TGF-β对VEGF分泌的诱导作用。相比之下，TGF-β超家族成员激活素、抑制素和骨形态发生蛋白（BMP）对HRPE中VEGF表达无作用。TGF-β诱导的VEGF mRNA水平和蛋白分泌被丝裂原活化蛋白激酶（MAP激酶）抑制剂SB203580和U0126显著抑制，但分别不受蛋白激酶C和核因子-κB途径抑制剂星形孢菌素和吡咯烷二硫代氨基甲酸盐（PDTC）的抑制。TGF-β还可诱导源自人眼脉络膜的成纤维细胞表达VEGF。TGF-β诱导RPE和脉络膜细胞分泌VEGF可能在AMD的脉络膜新生血管形成（CNV）中起重要作用。由于HRPE分泌VEGF受MAP激酶途径调控，MAP激酶抑制剂可能有潜力用作AMD中CNV的治疗药物。
