title: Neuropilins 1 and 2 mediate neointimal hyperplasia and re-endothelialization following arterial injury.
abstract: OBJECTIVE
  Neuropilins 1 and 2 (NRP1 and NRP2) play crucial roles in endothelial cell migration contributing to angiogenesis and vascular development. Both NRPs are also expressed by cultured vascular smooth muscle cells (VSMCs) and are implicated in VSMC migration stimulated by PDGF-BB, but it is unknown whether NRPs are relevant for VSMC function in vivo. We investigated the role of NRPs in the rat carotid balloon injury model, in which endothelial denudation and arterial stretch induce neointimal hyperplasia involving VSMC migration and proliferation.
  
  
  RESULTS
  NRP1 and NRP2 mRNAs and proteins increased significantly following arterial injury, and immunofluorescent staining revealed neointimal NRP expression. Down-regulation of NRP1 and NRP2 using shRNA significantly reduced neointimal hyperplasia following injury. Furthermore, inhibition of NRP1 by adenovirally overexpressing a loss-of-function NRP1 mutant lacking the cytoplasmic domain (ΔC) reduced neointimal hyperplasia, whereas wild-type (WT) NRP1 had no effect. NRP-targeted shRNAs impaired, while overexpression of NRP1 WT and NRP1 ΔC enhanced, arterial re-endothelialization 14 days after injury. Knockdown of either NRP1 or NRP2 inhibited PDGF-BB-induced rat VSMC migration, whereas knockdown of NRP2, but not NRP1, reduced proliferation of cultured rat VSMC and neointimal VSMC in vivo. NRP knockdown also reduced the phosphorylation of PDGFα and PDGFβ receptors in rat VSMC, which mediate VSMC migration and proliferation.
  
  
  CONCLUSIONS
  NRP1 and NRP2 play important roles in the regulation of neointimal hyperplasia in vivo by modulating VSMC migration (via NRP1 and NRP2) and proliferation (via NRP2), independently of the role of NRPs in re-endothelialization.
authors.affiliation: Division of Medicine, Centre for Cardiovascular Biology and Medicine, University College London, 5 University Street, London WC1E 6JF, UK i.zachary@ucl.ac.uk c.pellet-many@ucl.ac.uk.
authors.forename: Caroline
authors.initials: C
authors.lastname: Pellet-Many
authors.affiliation: Division of Medicine, Centre for Cardiovascular Biology and Medicine, University College London, 5 University Street, London WC1E 6JF, UK.
authors.forename: Vedanta
authors.initials: V
authors.lastname: Mehta
authors.affiliation: Division of Medicine, Centre for Cardiovascular Biology and Medicine, University College London, 5 University Street, London WC1E 6JF, UK.
authors.forename: Laura
authors.initials: L
authors.lastname: Fields
authors.affiliation: Division of Medicine, Centre for Cardiovascular Biology and Medicine, University College London, 5 University Street, London WC1E 6JF, UK.
authors.forename: Marwa
authors.initials: M
authors.lastname: Mahmoud
authors.affiliation: Division of Medicine, Centre for Cardiovascular Biology and Medicine, University College London, 5 University Street, London WC1E 6JF, UK.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Lowe
authors.affiliation: Division of Medicine, Centre for Cardiovascular Biology and Medicine, University College London, 5 University Street, London WC1E 6JF, UK.
authors.forename: Ian
authors.initials: I
authors.lastname: Evans
authors.affiliation: Division of Medicine, Centre for Cardiovascular Biology and Medicine, University College London, 5 University Street, London WC1E 6JF, UK.
authors.forename: Jorge
authors.initials: J
authors.lastname: Ruivo
authors.affiliation: Division of Medicine, Centre for Cardiovascular Biology and Medicine, University College London, 5 University Street, London WC1E 6JF, UK i.zachary@ucl.ac.uk c.pellet-many@ucl.ac.uk.
authors.forename: Ian
authors.initials: I
authors.lastname: Zachary
mesh_terms: D000800:Angioplasty, Balloon / Q000009:adverse effects; D000818:Animals; D020212:Carotid Artery Injuries / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D002465:Cell Movement; D049109:Cell Proliferation; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000473:pathology / Q000502:physiology; D006965:Hyperplasia; D008297:Male; D032389:Myocytes, Smooth Muscle / Q000378:metabolism; D058426:Neointima / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D039942:Neuropilin-1 / Q000378:metabolism*; D039943:Neuropilin-2 / Q000378:metabolism*; D010982:Platelet-Derived Growth Factor / Q000378:metabolism; D017207:Rats, Sprague-Dawley; D015854:Up-Regulation
chemical_list: D039943:Neuropilin-2; D010982:Platelet-Derived Growth Factor; D039942:Neuropilin-1
keywords: Endothelial cells; Neointimal hyperplasia; Neuropilins; Re-endothelialization; Smooth muscle cells