title: Increased cell and matrix accumulation during atherogenesis in mice with vessel wall-specific deletion of discoidin domain receptor 1.
abstract: BACKGROUND
  Discoidin domain receptor (DDR)1 is a collagen receptor expressed on both smooth muscle cells (SMCs) and macrophages, where it plays important roles regulating cell and matrix accumulation during atherogenesis. Systemic deletion of DDR1 resulted in attenuated plaque growth but accelerated matrix accumulation in LDLR-deficient mice. Deletion of DDR1 solely on bone marrow-derived cells resulted in decreased macrophage accumulation and plaque growth but no change in matrix accumulation.
  
  
  OBJECTIVE
  These findings led us to hypothesize that accelerated matrix accumulation was attributable to the increased synthetic ability of Ddr1(-/-) resident vascular wall SMCs.
  
  
  RESULTS
  We used bone marrow transplantation to generate chimeric mice and investigate the role of SMC DDR1 during atherogenesis. Mice with deficiency of DDR1 in vessel wall-derived cells (Ddr1(+/+-->-/-)) or control mice (Ddr1(+/+-->+/+)) were fed an atherogenic diet for 12 weeks. We observed a 3.8-fold increase in the size of aortic sinus plaques in Ddr1(+/+-->-/-) compared to Ddr1(+/+-->+/+) mice. This was attributed to pronounced accumulation of collagen, elastin, proteoglycans, and fibronectin and resulted in a thickened fibrous cap. The enhanced matrix accumulation decreased the proportion of plaque area occupied by cells but was associated with a shift in the cellular composition of the lesions toward increased numbers of vessel wall-derived SMCs compared to bone marrow-derived macrophages. In vitro studies confirmed that Ddr1(-/-) SMCs expressed more matrix, proliferated more, and migrated farther than Ddr1(+/+) SMCs.
  
  
  CONCLUSIONS
  DDR1 expression on resident vessel wall SMCs limits proliferation, migration and matrix accumulation during atherogenesis.
authors.affiliation: Department of Laboratory Medicine and Pathobiology, University of Toronto, Medical Sciences Building, Room 6213, 1 King's College Circle, Toronto, ON M5S 1A8, Canada.
authors.forename: Christopher
authors.initials: C
authors.lastname: Franco
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: Ahmad
authors.forename: Guangpei
authors.initials: G
authors.lastname: Hou
authors.forename: Eric
authors.initials: E
authors.lastname: Wong
authors.forename: Michelle P
authors.initials: MP
authors.lastname: Bendeck
mesh_terms: D000818:Animals; D001018:Aortic Diseases / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D050197:Atherosclerosis / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D016026:Bone Marrow Transplantation; D002465:Cell Movement; D049109:Cell Proliferation; D003094:Collagen / Q000378:metabolism; D000070819:Discoidin Domain Receptor 1; D004195:Disease Models, Animal; D004549:Elastin / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005353:Fibronectins / Q000378:metabolism; D005355:Fibrosis; D008264:Macrophages / Q000378:metabolism; D008297:Male; D020782:Matrix Metalloproteinases / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000201:enzymology* / Q000473:pathology; D032389:Myocytes, Smooth Muscle / Q000201:enzymology* / Q000473:pathology; D011509:Proteoglycans / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000172:deficiency* / Q000235:genetics; D013997:Time Factors; D018183:Transplantation Chimera; D015854:Up-Regulation
chemical_list: D016326:Extracellular Matrix Proteins; D005353:Fibronectins; D011509:Proteoglycans; D012333:RNA, Messenger; D003094:Collagen; D004549:Elastin; C083249:Ddr1 protein, mouse; D000070819:Discoidin Domain Receptor 1; D020794:Receptor Protein-Tyrosine Kinases; D020928:Mitogen-Activated Protein Kinases; D020782:Matrix Metalloproteinases