Cyclic AMP regulates extracellular matrix gene expression and metabolism in cultured primary rat chondrocytes.
In osteo- and rheumatoid arthritis, the synovial fluid surrounding chondrocytes contains increased levels of prostaglandin E(2) (PGE(2)), an agent known to elevate intracellular cyclic AMP (cAMP). However, the effect of PGE(2)/cAMP on mRNA expression in chondrocytes is largely unknown. In this report, we assess the effect of the cell-permeable cAMP analog adenosine 8-(4-chloro-phenylthio)-3',5'-cyclic monophosphate (CPT-cAMP) and PGE(2) on mRNA expression in primary neonatal rat chondrocytes. CPT-cAMP decreased type II collagen, link protein, parathyroid hormone/parathyroid hormone-related peptide receptor and alkaline phosphatase, increased glyceraldehyde-3-phosphate dehydrogenase mRNA and lactate efflux, but did not alter type X collagen or aggrecan mRNA. The effect of CPT-cAMP on type II collagen and link protein mRNAs and chondrocyte metabolism were attenuated by the transcriptional inhibitor actinomycin D, indicating that the ability of CPT-cAMP to suppress mRNA expression was not due to alterations in mRNA stability, but were instead likely due to transcriptional mechanisms. CPT-cAMP-treatment induced GSK3 beta phosphorylation and beta-catenin-mediated transcriptional activity. Pharmacological inhibition of GSK3 beta paralleled the effects of CPT-cAMP on type II collagen, link protein and chondrocyte metabolism, suggesting that the effect of CPT-cAMP on chondrocytes may be GSK3 beta/beta-catenin-dependent. The effects of CPT-cAMP on beta-catenin-mediated transcription, cell metabolism and mRNA expression were mimicked by the cAMP-elevating agent PGE(2), providing a physiologically relevant context for our studies. Collectively, these results suggest that agents that elevate cAMP signaling may impair chondrocyte function in conditions such as arthritis.
Rockel
Jason S
JS
Canadian Institutes of Health Research Group in Skeletal Development and Remodeling, Department of Anatomy and Cell Biology, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Ontario, Canada. jsrockel@uwo.ca
Grol
Matthew
M
Bernier
Suzanne M
SM
Leask
Andrew
A
D000818:Animals; D001168:Arthritis / Q000235:genetics / Q000378:metabolism; D002356:Cartilage / Q000166:cytology / Q000502:physiology; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000378:metabolism*; D024043:Collagen Type II / Q000235:genetics / Q000378:metabolism; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000378:metabolism*; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000378:metabolism; D015232:Dinoprostone / Q000378:metabolism; D005109:Extracellular Matrix / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D038362:Glycogen Synthase Kinase 3 / Q000235:genetics / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015290:Second Messenger Systems / Q000502:physiology; D013582:Synovial Fluid / Q000737:chemistry / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D024043:Collagen Type II; D017362:Cyclic AMP Response Element-Binding Protein; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D000242:Cyclic AMP; D000071679:Glycogen Synthase Kinase 3 beta; D038362:Glycogen Synthase Kinase 3; D015232:Dinoprostone