Sirtuin 6 ameliorates arthritis through modulating cyclic AMP-responsive element binding protein/CCN1/cyclooxygenase 2 pathway in osteoblasts.

Abstract

INTRODUCTION:

CCN1 is an immediate-early gene product pivotal for arthritis progression. We have previously shown that sirtuin 6 (SIRT6) inhibited hypoxia-induced CCN1 expression in osteoblasts. Herein we examined the contribution of cyclic AMP-responsive element binding protein (CREB)/CRE to this suppressive action and the influence of CCN1 on cyclooxygenase (COX) 2 synthesis.

MATERIALS AND METHODS:

MC3T3-E1 murine osteoblasts were cultured under normoxia (21% oxygen) or hypoxia (2% oxygen). Expressions of CCN1, phospho-CREB (Ser133), COX2 and relevant kinases were assessed by Western blot. SIRT6 was overexpressed in cultured osteoblasts and arthritic joints by a lentiviral-based technique. Activities of CCN1 gene promoter constructs were examined by luciferase reporter assay. Interaction between CREB and CCN1 promoter was assessed by chromatin immunoprecipitation (ChIP). Collagen-induced arthritis (CIA) was established in 20 rats to evaluate the effects of SIRT6 therapy on osteoblastic expressions of phospho-CREB, CCN1 and COX2.

RESULTS:

SIRT6 suppressed hypoxia-enhanced CCN1 expression and CREB phosphorylation. Attenuation of calcium/calmodulin-dependent protein kinase II (CaMKII) may be responsible for SIRT6-induced CREB inhibition. CRE at - 286 bp upstream of the ATG start codon was essential for CCN1 expression under hypoxia and SIRT6 reduced hypoxia-stimulated CREB/CRE interaction. Forced expression of CREB rescued SIRT6-suppressed CCN1 synthesis. CCN1 induced COX2 expression in osteoblasts. In rat CIA, the therapeutic effect of SIRT6 was accompanied by decreases in osteoblastic expressions of phospho-CREB, CCN1 and COX2.

CONCLUSION:

Our study indicated that the benefits of SIRT6 to inflammatory arthritis and bone resorption are at least partially derived from its modulation of CREB/CCN1/COX2 pathway in osteoblasts.

• Authors: Sze-Kwan Lin, Han-Wei Wang, Chia-Tung Shun, Cheng-Ning Yang, Chi-Yuan Hong, Eddie Hsiang-Hua Lai, Shih-Jung Cheng, Mu-Hsiung Chen, Hsiang Yang, Hung-Ying Lin, Fang-Yu Wu, Sang-Heng Kok
• Journal: Journal of bone and mineral metabolism (J Bone Miner Metab) Vol. 41 Issue 6 Pg. 772-784 (Nov 2023) ISSN: 1435-5604 [Electronic] Japan
• PMID: 37898986 (Publication Type: Journal Article)
• Copyright: © 2023. The Japanese Society Bone and Mineral Research.

Chemical References

• Cyclooxygenase 2
• Cyclic AMP Response Element-Binding Protein
• Oxygen
• Sirtuins
• Cyclic AMP

Topics

• Rats
• Mice
• Animals
• Cyclooxygenase 2 (genetics, metabolism, pharmacology)
• Osteoblasts (metabolism)
• Cyclic AMP Response Element-Binding Protein (metabolism, pharmacology)
• Hypoxia
• Arthritis, Experimental (genetics, metabolism)
• Phosphorylation
• Oxygen (metabolism, pharmacology)
• Sirtuins (metabolism, pharmacology)
• Cyclic AMP (metabolism, pharmacology)