TY - JOUR
T1 - Induction of an osteoarthritis-like phenotype and degradation of phosphorylated Smad3 by Smurf2 in transgenic mice
AU - Wu, Qiuqian
AU - Kim, Kyung Ok
AU - Sampson, Erik R.
AU - Chen, Di
AU - Awad, Hani
AU - O'Brien, Todd
AU - Puzas, J. Edward
AU - Drissi, Hicham
AU - Schwarz, Edward M.
AU - O'Keefe, Regis J.
AU - Zuscik, Michael J.
AU - Rosier, Randy N.
PY - 2008/10
Y1 - 2008/10
N2 - Objective. To determine whether Smurf2, an E3 ubiquitin ligase known to inhibit transforming growth factor β (TGFβ) signaling, is expressed in human osteoarthritic (OA) cartilage and can initiate OA in mice. Methods. Human OA cartilage was obtained from patients undergoing knee arthroplasty. Samples were graded histologically using the Mankin scale and were examined immunohistochemically for Smurf2 expression. A transgene driven by the collagen 2α1 promoter was used to overexpress Smurf2 in mice. Smurf2 overexpression in mouse sternal chondrocytes was confirmed by reverse transcription-polymerase chain reaction and Western blotting. Changes in articular cartilage area, chondrocyte number, and chondrocyte diameter were assessed histomorphometrically using OsteoMeasure software. Alterations in type X collagen and matrix metalloproteinase 13 (MMP-13) in articular chondrocytes were examined by in situ hybridization and immunohistochemistry, respectively. Joint bone phenotypes were evaluated by microfocal computed tomography. The effects of Smurf2 overexpression on TGFβ signaling were examined using a luciferase-based reporter and immunoprecipitation/Western blotting. Results. Human OA cartilage strongly expressed Smurf2 as compared with nonarthritic human cartilage. By 8 months of age, Smurf2-transgenic mice exhibited decreased articular cartilage area, fibrillation, clefting, eburnation, subchondral sclerosis, and osteophytes. Increased expression of type X collagen and MMP-13 were also detected in articular cartilage from transgenic mice. Transgenic sternal chondrocytes showed reduced TGFβ signaling as well as decreased expression and increased ubiquitination of pSmad3. Conclusion. Smurf2 is up-regulated during OA in humans, and Smurf2-transgenic mice spontaneously develop an OA-like phenotype that correlates with decreased TGFβ signaling and increased pSmad3 degradation. Overall, these results suggest a role of Smurf2 in the pathogenesis of OA.
AB - Objective. To determine whether Smurf2, an E3 ubiquitin ligase known to inhibit transforming growth factor β (TGFβ) signaling, is expressed in human osteoarthritic (OA) cartilage and can initiate OA in mice. Methods. Human OA cartilage was obtained from patients undergoing knee arthroplasty. Samples were graded histologically using the Mankin scale and were examined immunohistochemically for Smurf2 expression. A transgene driven by the collagen 2α1 promoter was used to overexpress Smurf2 in mice. Smurf2 overexpression in mouse sternal chondrocytes was confirmed by reverse transcription-polymerase chain reaction and Western blotting. Changes in articular cartilage area, chondrocyte number, and chondrocyte diameter were assessed histomorphometrically using OsteoMeasure software. Alterations in type X collagen and matrix metalloproteinase 13 (MMP-13) in articular chondrocytes were examined by in situ hybridization and immunohistochemistry, respectively. Joint bone phenotypes were evaluated by microfocal computed tomography. The effects of Smurf2 overexpression on TGFβ signaling were examined using a luciferase-based reporter and immunoprecipitation/Western blotting. Results. Human OA cartilage strongly expressed Smurf2 as compared with nonarthritic human cartilage. By 8 months of age, Smurf2-transgenic mice exhibited decreased articular cartilage area, fibrillation, clefting, eburnation, subchondral sclerosis, and osteophytes. Increased expression of type X collagen and MMP-13 were also detected in articular cartilage from transgenic mice. Transgenic sternal chondrocytes showed reduced TGFβ signaling as well as decreased expression and increased ubiquitination of pSmad3. Conclusion. Smurf2 is up-regulated during OA in humans, and Smurf2-transgenic mice spontaneously develop an OA-like phenotype that correlates with decreased TGFβ signaling and increased pSmad3 degradation. Overall, these results suggest a role of Smurf2 in the pathogenesis of OA.
UR - http://www.scopus.com/inward/record.url?scp=54949147630&partnerID=8YFLogxK
U2 - 10.1002/art.23946
DO - 10.1002/art.23946
M3 - Article
C2 - 18821706
AN - SCOPUS:54949147630
SN - 0004-3591
VL - 58
SP - 3132
EP - 3144
JO - Arthritis and Rheumatism
JF - Arthritis and Rheumatism
IS - 10
ER -