Elucidation of IL-1/TGF-beta interactions in mouse chondrocyte cell line by genome-wide gene expression.
OBJECTIVE
To elucidate the antagonism between interleukin-1 (IL-1) and transforming growth factor-beta (TGF-beta) at the gene expression level, as IL-1 and TGF-beta are postulated to be critical mediators of cartilage degeneration/protection in rheumatic diseases.


METHODS
The H4 chondrocyte cell line was validated by comparing metalloproteinase expression profile with intact murine cartilage by reverse transcription polymerase chain reaction. Genome-wide gene expression in the H4 cells in response to IL-1 and TGF-beta, alone and in combination, was analyzed by using oligonucleotide arrays negotiating approximately 12,000 genes.


RESULTS
The response of cartilage and the H4 cell line to IL-1 and TGF-beta was comparable. Oligonucleotide array analysis demonstrated a mutual but asymmetrical antagonism as the dominant mode of interaction between IL-1 and TGF-beta. Cluster analysis revealed a remarkable selectivity in the mode of action exerted by TGF-beta on IL-1 regulated genes: antagonistic on pro-inflammatory genes whereas additive on growth regulators such as vascular endothelial growth factor (VEGF) and connective tissue growth factor (CTGF). While the former cluster underlined the protective effect of TGF-beta, the latter underscored the adverse effect of TGF-beta. We further identified potentially novel classes of target genes under control of TGF-beta such as ras family, histones, proteasome components, and ubiquitin family, highlighting the importance of such genes in TGF signaling besides the well-characterized SMAD pathway.


CONCLUSIONS
We identified a cluster of genes as potential targets mediating the adverse effect of TGF-beta such as fibrosis. Transcriptional regulation of ras GTPase and ubiquitin/proteasome pathways is likely to be a novel mechanism mediating the effect of TGF-beta and its interaction with IL-1. These down-stream genes and pathways can be targets in future therapy.
Takahashi
N
N
Department of Rheumatology Research and Advanced Therapeutics, UMC Nijmegen/NCMLS, Nijmegen, The Netherlands. n.takahashi@reuma.umcn.nl
Rieneck
K
K
van der Kraan
P M
PM
van Beuningen
H M
HM
Vitters
E L
EL
Bendtzen
K
K
van den Berg
W B
WB
D000818:Animals; D002358:Cartilage, Articular / Q000378:metabolism; D002460:Cell Line; D019902:Chondrocytes / Q000378:metabolism*; D016000:Cluster Analysis; D055513:Connective Tissue Growth Factor; D015870:Gene Expression / Q000235:genetics*; D017874:Immediate-Early Proteins / Q000235:genetics / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D007375:Interleukin-1 / Q000235:genetics / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D015398:Signal Transduction / Q000235:genetics; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism*; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism
C526318:CCN2 protein, mouse; D017874:Immediate-Early Proteins; D036341:Intercellular Signaling Peptides and Proteins; D007375:Interleukin-1; D016212:Transforming Growth Factor beta; D042461:Vascular Endothelial Growth Factor A; D055513:Connective Tissue Growth Factor