title: MRP4 knockdown enhances migration, suppresses apoptosis, and produces aggregated morphology in human retinal vascular endothelial cells.
abstract: 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.
authors.affiliation: Department of Surgery Related, Division of Ophthalmology, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan.
authors.forename: Mizuki
authors.initials: M
authors.lastname: Tagami
authors.forename: Sentaro
authors.initials: S
authors.lastname: Kusuhara
authors.forename: Hisanori
authors.initials: H
authors.lastname: Imai
authors.forename: Akiyoshi
authors.initials: A
authors.lastname: Uemura
authors.forename: Shigeru
authors.initials: S
authors.lastname: Honda
authors.forename: Yasutomo
authors.initials: Y
authors.lastname: Tsukahara
authors.forename: Akira
authors.initials: A
authors.lastname: Negi
mesh_terms: D017209:Apoptosis / Q000235:genetics*; D002465:Cell Movement / Q000235:genetics; D049109:Cell Proliferation; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000378:metabolism / Q000473:pathology*; D055785:Gene Knockdown Techniques; D006801:Humans; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics / Q000502:physiology*; D018919:Neovascularization, Physiologic / Q000235:genetics*; D012160:Retina / Q000166:cytology / Q000502:physiology*; D015861:Retinal Neovascularization / Q000235:genetics* / Q000473:pathology; D012171:Retinal Vessels / Q000378:metabolism / Q000473:pathology*
chemical_list: D027425:ATP-Binding Cassette, Sub-Family C Proteins; C073492:ABCC4 protein, human