title: Protein Phosphotyrosine Phosphatase 1B (PTP1B) in Calpain-dependent Feedback Regulation of Vascular Endothelial Growth Factor Receptor (VEGFR2) in Endothelial Cells: IMPLICATIONS IN VEGF-DEPENDENT ANGIOGENESIS AND DIABETIC WOUND HEALING.
abstract: The VEGF/VEGFR2/Akt/eNOS/NO pathway is essential to VEGF-induced angiogenesis. We have previously discovered a novel role of calpain in mediating VEGF-induced PI3K/AMPK/Akt/eNOS activation through Ezrin. Here, we sought to identify possible feedback regulation of VEGFR2 by calpain via its substrate protein phosphotyrosine phosphatase 1B (PTP1B), and the relevance of this pathway to VEGF-induced angiogenesis, especially in diabetic wound healing. Overexpression of PTP1B inhibited VEGF-induced VEGFR2 and Akt phosphorylation in bovine aortic endothelial cells, while PTP1B siRNA increased both, implicating negative regulation of VEGFR2 by PTP1B. Calpain inhibitor ALLN induced VEGFR2 activation, which can be completely blocked by PTP1B overexpression. Calpain activation induced by overexpression or Ca/A23187 resulted in PTP1B cleavage, which can be blocked by ALLN. Moreover, calpain activation inhibited VEGF-induced VEGFR2 phosphorylation, which can be restored by PTP1B siRNA. These data implicate calpain/PTP1B negative feedback regulation of VEGFR2, in addition to the primary signaling pathway of VEGF/VEGFR2/calpain/PI3K/AMPK/Akt/eNOS. We next examined a potential role of PTP1B in VEGF-induced angiogenesis. Endothelial cells transfected with PTP1B siRNA showed faster wound closure in response to VEGF. Aortic discs isolated from PTP1B siRNA-transfected mice also had augmented endothelial outgrowth. Importantly, PTP1B inhibition and/or calpain overexpression significantly accelerated wound healing in STZ-induced diabetic mice. In conclusion, our data for the first time demonstrate a calpain/PTP1B/VEGFR2 negative feedback loop in the regulation of VEGF-induced angiogenesis. Modulation of local PTP1B and/or calpain activities may prove beneficial in the treatment of impaired wound healing in diabetes.
authors.affiliation: From the Divisions of Molecular Medicine and Cardiology, Departments of Anesthesiology and Medicine, Cardiovascular Research Laboratories, David Geffen School of Medicine at University of California Los Angeles (UCLA), California 90095.
authors.forename: Yixuan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: From the Divisions of Molecular Medicine and Cardiology, Departments of Anesthesiology and Medicine, Cardiovascular Research Laboratories, David Geffen School of Medicine at University of California Los Angeles (UCLA), California 90095.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Li
authors.affiliation: From the Divisions of Molecular Medicine and Cardiology, Departments of Anesthesiology and Medicine, Cardiovascular Research Laboratories, David Geffen School of Medicine at University of California Los Angeles (UCLA), California 90095.
authors.forename: Ji Youn
authors.initials: JY
authors.lastname: Youn
authors.affiliation: From the Divisions of Molecular Medicine and Cardiology, Departments of Anesthesiology and Medicine, Cardiovascular Research Laboratories, David Geffen School of Medicine at University of California Los Angeles (UCLA), California 90095 hcai@mednet.ucla.edu.
authors.forename: Hua
authors.initials: H
authors.lastname: Cai
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D000818:Animals; D002154:Calpain / Q000235:genetics / Q000378:metabolism*; D002417:Cattle; D003921:Diabetes Mellitus, Experimental / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D042783:Endothelial Cells / Q000473:pathology; D057809:HEK293 Cells; D006801:Humans; D008297:Male; D051379:Mice; D018919:Neovascularization, Physiologic; D052250:Nitric Oxide Synthase Type III / Q000235:genetics / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics / Q000378:metabolism*; D014945:Wound Healing
chemical_list: C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; D019869:Phosphatidylinositol 3-Kinases; C000588866:KDR protein, human; C000592875:Kdr protein, mouse; D040301:Vascular Endothelial Growth Factor Receptor-2; D055372:AMP-Activated Protein Kinases; C516607:PTPN1 protein, human; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; C516609:Ptpn1 protein, mouse; D002154:Calpain
keywords: Akt PKB; PTP1B; VEGFR2; angiogenesis; calpain; diabetes; vascular endothelial growth factor (VEGF); wound healing