MyD88, IRAK1 and TRAF6 knockdown in human chondrocytes inhibits interleukin-1-induced matrix metalloproteinase-13 gene expression and promoter activity by impairing MAP kinase activation

Cell Signal. 2007 Dec;19(12):2549-57. doi: 10.1016/j.cellsig.2007.08.013. Epub 2007 Aug 25.

Abstract

Interleukin-1 (IL-1) is the major prototypic proinflammatory cytokine that stimulates degradation of cartilage in arthritis by inducing prominent collagen II-degrading matrix metalloproteinase-13 (MMP-13). Nothing is known about the involvement of adaptor proteins, MyD88, IRAK1 and TRAF6 in MMP-13 regulation. Here we investigated for the first time the role of these proteins in IL-1-regulated MMP-13 expression in chondrocytes. MyD88 homodimerization inhibitory peptide diminished the expression of MMP-13 gene, promoter activity, phosphorylation of mitogen-activated protein kinases (MAPKs), c-Jun and activating protein 1 (AP-1) activity. Knockdown of MyD88, IRAK1 and TRAF6 by RNA interference (RNAi) drastically down-regulated the expression of IL-1-induced MMP-13 mRNA and protein levels and MMP-13 promoter-driven luciferase activity. Non-specific control siRNA had no effect. Mechanisms of MMP-13 inhibition involved reduced phosphorylation of ERK, p38, JNK and c-Jun as well as AP-1 transcription factor binding activity. The genetic evidence presented here demonstrates that MyD88, IRAK1 and TRAF6 proteins are crucial early mediators for the IL-1-induced MMP-13 regulation through MAPK pathways and AP-1 activity. These proteins could constitute important therapeutic targets for arthritis-associated cartilage loss by MMP-13.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cells, Cultured
  • Chondrocytes / drug effects
  • Chondrocytes / enzymology
  • Chondrocytes / metabolism*
  • Dimerization
  • Enzyme Activation
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • Gene Expression Regulation, Enzymologic
  • Humans
  • Interleukin-1 Receptor-Associated Kinases / genetics
  • Interleukin-1 Receptor-Associated Kinases / metabolism*
  • Interleukin-1beta / metabolism*
  • JNK Mitogen-Activated Protein Kinases / metabolism
  • MAP Kinase Signaling System
  • Matrix Metalloproteinase 13 / genetics
  • Matrix Metalloproteinase 13 / metabolism*
  • Mitogen-Activated Protein Kinases / metabolism*
  • Myeloid Differentiation Factor 88 / antagonists & inhibitors
  • Myeloid Differentiation Factor 88 / genetics
  • Myeloid Differentiation Factor 88 / metabolism*
  • Peptides / pharmacology
  • Phosphorylation
  • Promoter Regions, Genetic* / drug effects
  • Proto-Oncogene Proteins c-jun / metabolism
  • RNA Interference*
  • RNA, Small Interfering / metabolism
  • TNF Receptor-Associated Factor 6 / genetics
  • TNF Receptor-Associated Factor 6 / metabolism*
  • Transcription Factor AP-1 / metabolism
  • Transfection
  • p38 Mitogen-Activated Protein Kinases / metabolism

Substances

  • Interleukin-1beta
  • MYD88 protein, human
  • Myeloid Differentiation Factor 88
  • Peptides
  • Proto-Oncogene Proteins c-jun
  • RNA, Small Interfering
  • TNF Receptor-Associated Factor 6
  • Transcription Factor AP-1
  • IRAK1 protein, human
  • Interleukin-1 Receptor-Associated Kinases
  • Extracellular Signal-Regulated MAP Kinases
  • JNK Mitogen-Activated Protein Kinases
  • Mitogen-Activated Protein Kinases
  • p38 Mitogen-Activated Protein Kinases
  • Matrix Metalloproteinase 13