Department of Surgery Related, Division of Ophthalmology, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan.
Biochem Biophys Res Commun. 2010 Oct 1;400(4):593-8. doi: 10.1016/j.bbrc.2010.08.109. Epub 2010 Sep 6.
The multidrug resistance protein (MRP) MRP4/ABCC4 is an ATP-binding cassette transporter that actively effluxes endogenous and xenobiotic substrates out of cells. In the rodent retina, Mrp4 mRNA and protein are exclusively expressed in vascular endothelial cells, but the angiogenic properties of Mrp4 are poorly understood so far. This study aims to explore the angiogenic properties of MRP4 in human retinal microvascular endothelial cells (HRECs) utilizing the RNA interference (RNAi) technique. MRP4 expression was decreased at the mRNA and protein levels after stimulation with exogenous vascular endothelial growth factor in a dose-dependent manner. RNAi-mediated MRP4 knockdown in HRECs do not affect cell proliferation but enhances cell migration. Moreover, cell apoptosis induced by serum starvation was less prominent in MRP4 siRNA-treated HRECs as compared to control siRNA-treated HRECs. In a Matrigel-based tube-formation assay, although MRP4 knockdown did not lead to a significant change in the total tube length, MRP4 siRNA-treated HRECs assembled and aggregated into a massive tube-like structure, which was not observed in control siRNA-treated HRECs. These results suggest that MRP4 is uniquely involved in retinal angiogenesis.
多药耐药相关蛋白（MRP）MRP4/ABCC4 是一种三磷酸腺苷结合盒转运蛋白，可将内源性和外源性底物主动从细胞内排出。在啮齿动物视网膜中，Mrp4mRNA 和蛋白仅在血管内皮细胞中表达，但迄今为止，Mrp4 的血管生成特性仍知之甚少。本研究旨在利用 RNA 干扰（RNAi）技术探讨 MRP4 在人视网膜微血管内皮细胞（HRECs）中的血管生成特性。外源性血管内皮生长因子刺激后，MRP4 的表达在 mRNA 和蛋白水平上均呈剂量依赖性下降。MRP4 敲低对 HRECs 的细胞增殖没有影响，但增强了细胞迁移。此外，与对照 siRNA 处理的 HRECs 相比，血清饥饿诱导的细胞凋亡在 MRP4 siRNA 处理的 HRECs 中不那么明显。在基于 Matrigel 的管形成测定中，尽管 MRP4 敲低并未导致总管长度发生显著变化，但 MRP4 siRNA 处理的 HRECs 组装并聚集形成大量管状结构，而在对照 siRNA 处理的 HRECs 中未观察到这种结构。这些结果表明，MRP4 独特地参与了视网膜血管生成。
