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Interleukin-1beta up-regulation of Smad7 via NF-kappaB activation in human chondrocytes.
Arthritis Rheum. 2008 Jan; 58(1):221-6.AR

Abstract

OBJECTIVE

We have previously shown that interleukin-1beta (IL-1beta) impairs transforming growth factor beta (TGFbeta) signaling through TGFbeta receptor type II (TGFbetaRII) down-regulation and Smad7 up-regulation. This mechanism could account for the reduced responsiveness of osteoarthritic chondrocytes to TGFbeta and the cartilage breakdown linked to this disease. The aim of this study was to investigate the molecular mechanism underlying the IL-1beta-induced stimulation of Smad7 in human articular chondrocytes.

METHODS

Human articular chondrocytes were treated with IL-1beta in the presence of TGFbeta1, pyrrolidine dithiocarbamate (a repressor of the NF-kappaB pathway), or cycloheximide. Then, steady-state messenger RNA and protein levels were estimated by real-time reverse transcription-polymerase chain reaction and immunocytology. In addition, transient transfections of p65 expression vector or p65-targeted short hairpin RNA were performed to define the effect of NF-kappaB on Smad7 expression.

RESULTS

TGFbetaRII overexpression restored the TGFbeta response of human articular chondrocytes. However, this effect was transient, implying that a secondary mechanism was responsible for the alteration of the TGFbeta response with long-term exposure to IL-1beta. Moreover, IL-1beta caused a late induction of the inhibitory Smad7. This effect was direct, since it did not require de novo synthesis. In addition, we established, by experiments with gain/loss of function, that the up-regulation of Smad7 by IL-1beta is mediated through the NF-kappaB pathway, especially the p65 subunit.

CONCLUSION

These findings clarify the regulatory process of IL-1beta on Smad7 expression. Understanding the molecular basis of IL-1beta induction of Smad7 and the reduction of chondrocyte responsiveness to TGFbeta provides new insights into the molecular mechanisms of osteoarthritis and may facilitate the identification of novel approaches for its treatment.

Authors+Show Affiliations

University of Caen Lower Normandy, Faculty of Medicine, Caen, France.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

18163503

Citation

Baugé, C, et al. "Interleukin-1beta Up-regulation of Smad7 Via NF-kappaB Activation in Human Chondrocytes." Arthritis and Rheumatism, vol. 58, no. 1, 2008, pp. 221-6.
Baugé C, Attia J, Leclercq S, et al. Interleukin-1beta up-regulation of Smad7 via NF-kappaB activation in human chondrocytes. Arthritis Rheum. 2008;58(1):221-6.
Baugé, C., Attia, J., Leclercq, S., Pujol, J. P., Galéra, P., & Boumédiene, K. (2008). Interleukin-1beta up-regulation of Smad7 via NF-kappaB activation in human chondrocytes. Arthritis and Rheumatism, 58(1), 221-6. https://doi.org/10.1002/art.23154
Baugé C, et al. Interleukin-1beta Up-regulation of Smad7 Via NF-kappaB Activation in Human Chondrocytes. Arthritis Rheum. 2008;58(1):221-6. PubMed PMID: 18163503.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Interleukin-1beta up-regulation of Smad7 via NF-kappaB activation in human chondrocytes. AU - Baugé,C, AU - Attia,J, AU - Leclercq,S, AU - Pujol,J-P, AU - Galéra,P, AU - Boumédiene,K, PY - 2008/1/1/pubmed PY - 2008/3/11/medline PY - 2008/1/1/entrez SP - 221 EP - 6 JF - Arthritis and rheumatism JO - Arthritis Rheum. VL - 58 IS - 1 N2 - OBJECTIVE: We have previously shown that interleukin-1beta (IL-1beta) impairs transforming growth factor beta (TGFbeta) signaling through TGFbeta receptor type II (TGFbetaRII) down-regulation and Smad7 up-regulation. This mechanism could account for the reduced responsiveness of osteoarthritic chondrocytes to TGFbeta and the cartilage breakdown linked to this disease. The aim of this study was to investigate the molecular mechanism underlying the IL-1beta-induced stimulation of Smad7 in human articular chondrocytes. METHODS: Human articular chondrocytes were treated with IL-1beta in the presence of TGFbeta1, pyrrolidine dithiocarbamate (a repressor of the NF-kappaB pathway), or cycloheximide. Then, steady-state messenger RNA and protein levels were estimated by real-time reverse transcription-polymerase chain reaction and immunocytology. In addition, transient transfections of p65 expression vector or p65-targeted short hairpin RNA were performed to define the effect of NF-kappaB on Smad7 expression. RESULTS: TGFbetaRII overexpression restored the TGFbeta response of human articular chondrocytes. However, this effect was transient, implying that a secondary mechanism was responsible for the alteration of the TGFbeta response with long-term exposure to IL-1beta. Moreover, IL-1beta caused a late induction of the inhibitory Smad7. This effect was direct, since it did not require de novo synthesis. In addition, we established, by experiments with gain/loss of function, that the up-regulation of Smad7 by IL-1beta is mediated through the NF-kappaB pathway, especially the p65 subunit. CONCLUSION: These findings clarify the regulatory process of IL-1beta on Smad7 expression. Understanding the molecular basis of IL-1beta induction of Smad7 and the reduction of chondrocyte responsiveness to TGFbeta provides new insights into the molecular mechanisms of osteoarthritis and may facilitate the identification of novel approaches for its treatment. SN - 0004-3591 UR - https://www.unboundmedicine.com/medline/citation/18163503/Interleukin_1beta_up_regulation_of_Smad7_via_NF_kappaB_activation_in_human_chondrocytes_ L2 - https://doi.org/10.1002/art.23154 DB - PRIME DP - Unbound Medicine ER -