Abnormal collagen fibrils in tendons of biglycan/fibromodulin-deficient mice lead to gait impairment, ectopic ossification, and osteoarthritis.
Small leucine-rich proteoglycans (SLRPs) regulate extracellular matrix organization, a process essential in development, tissue repair, and metastasis. In vivo interactions of biglycan and fibromodulin, two SLRPs highly expressed in tendons and bones, were investigated by generating biglycan/fibromodulin double-deficient mice. Here we show that collagen fibrils in tendons from mice deficient in biglycan and/or fibromodulin are structurally and mechanically altered resulting in unstable joints. As a result, the mice develop successively and progressively 1) gait impairment, 2) ectopic tendon ossification, and 3) severe premature osteoarthritis. Forced use of the joints increases ectopic ossification and osteoarthritis in the double-deficient mice, further indicating that structurally weak tendons cause the phenotype. The study shows that mutations in SLRPs may predispose to osteoarthritis and offers a valuable and unique animal model for spontaneous osteoarthritis characterized by early onset and a rapid progression of the disease.
Ameye
Laurent
L
Craniofacial and Skeletal Diseases Branch, NIDCR, National Institutes of Health, Bethesda, Maryland, USA. Laurent.Ameye@rdls.nestle.com
Aria
Dean
D
Jepsen
Karl
K
Oldberg
Ake
A
Xu
Tianshun
T
Young
Marian F
MF
D000818:Animals; D058578:Biglycan; D001696:Biomechanical Phenomena; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology; D005080:Exercise Test; D016326:Extracellular Matrix Proteins; D024022:Fibrillar Collagens / Q000648:ultrastructure*; D000071235:Fibromodulin; D007596:Joints; D007700:Kinetics; D007794:Lameness, Animal / Q000209:etiology* / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D008954:Models, Biological; D009999:Ossification, Heterotopic / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology; D010003:Osteoarthritis / Q000209:etiology* / Q000473:pathology; D011509:Proteoglycans / Q000235:genetics* / Q000502:physiology; D011859:Radiography; D013710:Tendons / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000648:ultrastructure
C546885:Bgn protein, mouse; D058578:Biglycan; D002352:Carrier Proteins; D016326:Extracellular Matrix Proteins; D024022:Fibrillar Collagens; C000604332:Fmod protein, mouse; D011509:Proteoglycans; D000071235:Fibromodulin