title: Calreticulin Regulates Neointima Formation and Collagen Deposition following Carotid Artery Ligation.
abstract: OBJECTIVE
  The endoplasmic reticulum (ER) stress protein, calreticulin (CRT), is required for the production of TGF-β-stimulated extracellular matrix (ECM) by fibroblasts. Since TGF-β regulates vascular fibroproliferative responses and collagen deposition, we investigated the effects of CRT knockdown on vascular smooth-muscle cell (VSMC) fibroproliferative responses and collagen deposition.
  
  
  METHODS
  Using a carotid artery ligation model of vascular injury, Cre-recombinase-IRES-GFP plasmid was delivered with microbubbles (MB) to CRT-floxed mice using ultrasound (US) to specifically reduce CRT expression in the carotid artery.
  
  
  RESULTS
  In vitro, Cre-recombinase-mediated CRT knockdown in isolated, floxed VSMCs decreased the CRT transcript and protein, and attenuated the induction of collagen I protein in response to TGF-β. TGF-β stimulation of collagen I was partly blocked by the NFAT inhibitor 11R-VIVIT. Following carotid artery ligation, CRT staining was upregulated with enhanced expression in the neointima 14-21 days after injury. Furthermore, Cre-recombinase-IRES-GFP plasmid delivered by targeted US reduced CRT expression in the neointima of CRT-floxed mice and led to a significant reduction in neointima formation and collagen deposition. The neointimal cell number was also reduced in mice, with a local, tissue-specific knockdown of CRT.
  
  
  CONCLUSIONS
  This work establishes a novel role for CRT in mediating VSMC responses to injury through the regulation of collagen deposition and neointima formation.
authors.affiliation: Department of Pathology, University of Alabama at Birmingham, Birmingham, Ala., USA.
authors.forename: Kurt A
authors.initials: KA
authors.lastname: Zimmerman
authors.forename: Dongqi
authors.initials: D
authors.lastname: Xing
authors.forename: Manuel A
authors.initials: MA
authors.lastname: Pallero
authors.forename: Ailing
authors.initials: A
authors.lastname: Lu
authors.forename: Masahito
authors.initials: M
authors.lastname: Ikawa
authors.forename: Leland
authors.initials: L
authors.lastname: Black
authors.forename: Kenneth L
authors.initials: KL
authors.lastname: Hoyt
authors.forename: Janusz H
authors.initials: JH
authors.lastname: Kabarowski
authors.forename: Marek
authors.initials: M
authors.lastname: Michalak
authors.forename: Joanne E
authors.initials: JE
authors.lastname: Murphy-Ullrich
mesh_terms: D000818:Animals; D064032:Calbindin 2 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D002339:Carotid Arteries / Q000378:metabolism / Q000473:pathology; D020212:Carotid Artery Injuries / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D049109:Cell Proliferation; D002478:Cells, Cultured; D024042:Collagen Type I / Q000235:genetics / Q000378:metabolism*; D000090602:Collagen Type I, alpha 1 Chain; D004195:Disease Models, Animal; D008026:Ligation; D018345:Mice, Knockout; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology / Q000601:surgery; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D058426:Neointima; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D015854:Up-Regulation
chemical_list: C576511:Calb2 protein, mouse; D064032:Calbindin 2; D024042:Collagen Type I; D000090602:Collagen Type I, alpha 1 Chain; D016212:Transforming Growth Factor beta