Cyclic AMP regulates extracellular matrix gene expression and metabolism in cultured primary rat chondrocytes

Matrix Biol. 2009 Jul;28(6):354-64. doi: 10.1016/j.matbio.2009.05.005. Epub 2009 Jun 6.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Arthritis / genetics
  • Arthritis / metabolism
  • Cartilage / cytology
  • Cartilage / physiology
  • Cells, Cultured
  • Chondrocytes / cytology
  • Chondrocytes / metabolism*
  • Collagen Type II / genetics
  • Collagen Type II / metabolism
  • Cyclic AMP / analogs & derivatives
  • Cyclic AMP / metabolism*
  • Cyclic AMP Response Element-Binding Protein / genetics
  • Cyclic AMP Response Element-Binding Protein / metabolism
  • Dinoprostone / metabolism
  • Extracellular Matrix* / genetics
  • Extracellular Matrix* / metabolism
  • Gene Expression Regulation*
  • Glycogen Synthase Kinase 3 / genetics
  • Glycogen Synthase Kinase 3 / metabolism
  • Glycogen Synthase Kinase 3 beta
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Second Messenger Systems / physiology
  • Synovial Fluid / chemistry
  • Synovial Fluid / metabolism
  • Tumor Necrosis Factor-alpha / metabolism

Substances

  • Collagen Type II
  • Cyclic AMP Response Element-Binding Protein
  • RNA, Messenger
  • Tumor Necrosis Factor-alpha
  • Cyclic AMP
  • Glycogen Synthase Kinase 3 beta
  • Glycogen Synthase Kinase 3
  • Dinoprostone