Age-related expression patterns of Bag-1 and Bcl-2 in growth plate and articular chondrocytes.
Aging cartilage displays increased chondrocyte apoptosis and decreased responsiveness of chondrocytes to growth factors. The molecular mechanisms responsible for these changes have not been identified. Bag-1 is a Bcl-2-binding protein that promotes cell survival, interacts with a diverse group of cellular proteins, and may integrate multiple pathways involved in controlling cell survival, growth, and phenotype. Bcl-2 is important for maintaining chondrocyte phenotype and delaying terminal differentiation and apoptosis of chondrocytes. Comparatively little is known about the role of Bag-1 in cartilage. Here we show that both growth plate and articular chondrocytes in the mouse express the Bag-1 protein. In the growth plate, Bag-1 expression is prominent in the late proliferative and prehypertrophic chondrocytes, displaying a pattern similar to what has been reported for Bcl-2. Further, the expression of both Bcl-2 and Bag-1 declines with age in the articular cartilage. Growth assays demonstrate that knocking down Bag-1 expression causes a decrease in growth rate. These results suggest that Bag-1 is involved in the regulation of chondrocyte phenotype and cartilage aging.
Department of Anatomy, Northeastern Ohio Universities College of Medicine, Rootstown, OH 44272, USA. wehj@neoucom.edu
Mary D
MD
Kinkel
Rieko
R
Yagi
Denise
D
McBurney
Ashleigh
A
Nugent
Walter E
WE
Horton
D000375:Aging / Q000378:metabolism*; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002358:Cartilage, Articular / Q000166:cytology / Q000378:metabolism*; D002455:Cell Division / Q000502:physiology; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000378:metabolism*; D004268:DNA-Binding Proteins; D005786:Gene Expression Regulation; D006132:Growth Plate / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D014018:Tissue Distribution; D014157:Transcription Factors
C091732:BCL2-associated athanogene 1 protein; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D014157:Transcription Factors