Regulation of embryonic endochondral ossification by Smurf2.
Smurf2 is an E3 ubiquitin ligase that targets TGF-beta receptor activated Smad2 and Smad3 for the proteasome in primary articular chondrocytes, thus stimulating their hypertrophic differentiation. Comparatively, how Smurf2 functions in growth plate chondrocytes in a developing long bone is an open question. In this study, we measured the mRNA levels of endogenous Smurf2 and type X collagen in chick growth plate at different embryonic stages to monitor the correlation between the level of Smurf2 expression and chondrocyte maturational stage. We found that high levels of Smurf2 were associated with the differentiative and proliferative stages, while Smurf2 levels were thereafter decreased as the chondrocytes matured toward hypertrophy. In addition, we injected Smurf2-RCAS into chick wing buds at HH stage 20-23 and examined how the ectopic overexpression of Smurf2 in condensing chondrogenic mesenchyme affects the subsequent process of chondrocyte maturation and ossification during embryonic development. Histological analysis showed that overexpression of Smurf2 in a developing wing bud accelerated chondrocyte maturation and endochondral ossification, which may result from a decrease in TGF-beta signaling in the infected chondrocytes with Smurf2-RCAS.
Wu
Qiuqian
Q
Department of Orthopaedics, Center for Musculoskeletal Research, University of Rochester Medical Center, 601 Elmwood Avenue, Box 665, Rochester, New York 14642, USA. qiuqian_wu@urmc.rochester.edu
Wang
Meina
M
Zuscik
Michael J
MJ
Chen
Di
D
O'Keefe
Regis J
RJ
Rosier
Randy N
RN
D000818:Animals; D002356:Cartilage / Q000196:embryology*; D002454:Cell Differentiation / Q000502:physiology; D049109:Cell Proliferation; D002642:Chick Embryo; D019902:Chondrocytes / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D010012:Osteogenesis / Q000502:physiology*; D014158:Transcription, Genetic; D016212:Transforming Growth Factor beta / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D014921:Wings, Animal / Q000196:embryology
D016212:Transforming Growth Factor beta; C471641:SMURF2 protein, human; D044767:Ubiquitin-Protein Ligases