title: Downregulation of Syndecan-1 induce glomerular endothelial cell dysfunction through modulating internalization of VEGFR-2.
abstract: Ischemic acute kidney injury (AKI) remains to have high morbidity and mortality rates. The mechanism of glomerular endothelial cells (GEnC) dysfunction in the development of ischemic AKI is still unclear. Syndecan-1, one kind of heparan sulfate proteoglycan (HSPG), is extensively studied in tumor for its effects in promoting angiogenesis. In this study, we found that, Syndecan-1 was reduced in GEnC both in vivo and in vitro after hypoxia treatment. Besides, down-regulation of Syndecan-1 could lead to dysfunction and apoptosis of GEnC, as indicated by increased cell permeability, decreased cell viability and inhibited tube formation. VEGF-VEGFR-2 signaling is essential in maintaining biology of GEnC, and activation of its downstream effectors, ERK1/2, AKT, and Rac1, were inhibited in GEnC transfected with Syndecan-1 siRNA compared with control siRNA. Moreover, membrane VEGFR-2 expression was reduced significantly in GEnC transfected with Syndecan-1 siRNA. Clathrin-mediated endocytosis of VEGFR-2 is essential in the activation of VEGF-VEGFR-2 signaling. Our further study demonstrated that down-regulation of Syndecan-1 in GEnC inhibit VEGF-VEGFR-2 signaling by recruiting VEGFR-2 to the Caveolin-dependent endocytosis route, there by sequestering it from Clathrin-mediated endocytosis. Moreover, as shown by immunofluorescence and immunoprecipitation analysis, VEGFR-2 co-localizes and interacts with Syndecan-1, indicating Syndecan-1 may act as a co-receptor of VEGFR-2, thus to mediate internalization of VEGFR-2. We speculated that down-regulation of Syndecan-1 could inhibit VEGF-VEGFR-2 signaling through regulating internalization of VEGFR-2, thus leading to dysfunction and apoptosis of GEnC. This indicates a potential target for the therapy of ischemic AKI.
authors.affiliation: Department of Nephrology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, 100 HaiNing Road, Shanghai 200080, People's Republic of China.
authors.forename: Zhou
authors.initials: Z
authors.lastname: Jing
authors.affiliation: Department of Nephrology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, 100 HaiNing Road, Shanghai 200080, People's Republic of China. Electronic address: ywj4169@163.com.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Wei-Jie
authors.affiliation: Department of Nephrology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, 100 HaiNing Road, Shanghai 200080, People's Republic of China.
authors.forename: Zhu-Ge
authors.initials: ZG
authors.lastname: Yi-Feng
authors.affiliation: Department of Nephrology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, 100 HaiNing Road, Shanghai 200080, People's Republic of China.
authors.forename: Hao
authors.initials: H
authors.lastname: Jing
mesh_terms: D000818:Animals; D017209:Apoptosis; D002462:Cell Membrane / Q000378:metabolism; D004195:Disease Models, Animal; D015536:Down-Regulation; D004705:Endocytosis; D042783:Endothelial Cells / Q000378:metabolism* / Q000473:pathology*; D000860:Hypoxia / Q000150:complications / Q000378:metabolism / Q000473:pathology; D007511:Ischemia / Q000150:complications / Q000378:metabolism / Q000473:pathology; D007678:Kidney Glomerulus / Q000098:blood supply / Q000473:pathology*; D008297:Male; D051379:Mice; D011485:Protein Binding; D034741:RNA, Small Interfering / Q000378:metabolism; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D053668:Syndecan-1 / Q000378:metabolism*; D014162:Transfection; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism*
chemical_list: D034741:RNA, Small Interfering; D053668:Syndecan-1; D042461:Vascular Endothelial Growth Factor A; D040301:Vascular Endothelial Growth Factor Receptor-2
keywords: Glomerular endothelial cell; Injury; Syndecan-1; VEGFR-2