title: Thrombospondin-1 activation of signal-regulatory protein-α stimulates reactive oxygen species production and promotes renal ischemia reperfusion injury.
abstract: Ischemia reperfusion injury (IRI) causes tissue and organ injury, in part, through alterations in tissue blood flow and the production of reactive oxygen species. The cell surface receptor signal-regulatory protein-α (SIRP-α) is expressed on inflammatory cells and suppresses phagocytosis, but the function of SIRP-α in IRI has not been determined. We reported previously that the matricellular protein thrombospondin-1 is upregulated in IRI. Here, we report a novel interaction between thrombospondin-1 and SIRP-α on nonphagocytic cells. In cell-free experiments, thrombospondin-1 bound SIRP-α. In vascular smooth muscle cells and renal tubular epithelial cells, treatment with thrombospondin-1 led to phosphorylation of SIRP-α and downstream activation of Src homology domain 2-containing phosphatase-1. Thrombospondin-1 also stimulated phosphorylation of p47(phox) (an organizer subunit for nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 1/2) and increased production of superoxide, both of which were abrogated by knockdown or antibody blockade of SIRP-α. In rodent aortic rings, treatment with thrombospondin-1 increased the production of superoxide and inhibited nitric oxide-mediated vasodilation in a SIRP-α-dependent manner. Renal IRI upregulated the thrombospondin-1-SIRP-α signaling axis and was associated with increased superoxide production and cell death. A SIRP-α antibody that blocks thrombospondin-1 activation of SIRP-α mitigated the effects of renal IRI, increasing blood flow, suppressing production of reactive oxygen species, and preserving cellular architecture. A role for CD47 in SIRP-α activation in these pathways is also described. Overall, these results suggest that thrombospondin-1 binding to SIRP-α on nonphagocytic cells activates NADPH oxidase, limits vasodilation, and promotes renal IRI.
authors: Vascular Medicine Institute.
authors: Mingyi
authors: M
authors: Yao
authors: Vascular Medicine Institute, Starzl Transplantation Institute.
authors: Natasha M
authors: NM
authors: Rogers
authors: Vascular Medicine Institute, Department of Pharmacology and Chemical Biology.
authors: Gábor
authors: G
authors: Csányi
authors: Vascular Medicine Institute, Department of Pharmacology and Chemical Biology.
authors: Andres I
authors: AI
authors: Rodriguez
authors: Center for Biologic Imaging, and.
authors: Mark A
authors: MA
authors: Ross
authors: Center for Biologic Imaging, and.
authors: Claudette
authors: C
authors: St Croix
authors: Vascular Medicine Institute.
authors: Heather
authors: H
authors: Knupp
authors: Vascular Medicine Institute.
authors: Enrico M
authors: EM
authors: Novelli
authors: Starzl Transplantation Institute.
authors: Angus W
authors: AW
authors: Thomson
authors: Vascular Medicine Institute, Department of Pharmacology and Chemical Biology.
authors: Patrick J
authors: PJ
authors: Pagano
authors: Vascular Medicine Institute, Starzl Transplantation Institute, Department of Pharmacology and Chemical Biology, Division of Pulmonary, Allergy and Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania jsi5@pitt.edu.
authors: Jeffrey S
authors: JS
authors: Isenberg
mesh_terms: D000818:Animals; D000943:Antigens, Differentiation / Q000378:metabolism*; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000378:metabolism*; D051928:CD47 Antigen / Q000378:metabolism; D002478:Cells, Cultured; D006801:Humans; D007674:Kidney Diseases / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D010766:Phosphorylation / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D011971:Receptors, Immunologic / Q000378:metabolism*; D015427:Reperfusion Injury / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D019700:Thrombospondin 1 / Q000378:metabolism*
chemical_list: D000943:Antigens, Differentiation; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D051928:CD47 Antigen; C497894:CD47 protein, human; C584934:CD47 protein, rat; C497895:Cd47 protein, mouse; D020030:Nitric Oxide Donors; C501922:Sirpa protein, mouse; D017382:Reactive Oxygen Species; D011971:Receptors, Immunologic; C501920:SIRPA protein, human; C481348:SPZ1 protein, human; C501924:Sirpa protein, rat; D019700:Thrombospondin 1; C582391:Thbs1 protein, rat; C585483:Thbs1 protein, mouse; D009599:Nitroprusside