Sirtuin 3 is required for osteogenic differentiation through maintenance of PGC-1ɑ-SOD2-mediated regulation of mitochondrial function

Abstract

Osteogenic differentiation is crucial for the maintenance of bone homeostasis. Sirtuin 3 (SIRT3), a member of sirtuins family, functions as a critical deacetylase that regulates many key proteins. In the current study, we aimed to clarify the role of SIRT3 in osteogenic differentiation and the possible mechanisms, using mouse pre-osteoblastic MC3T3-E1 cells. Expression of SIRT3 was substantially increased in differentiated MC3T3-E1 cells. Knock down of SIRT3 significantly decreased alkaline phosphatase (ALP) staining, and mRNA expression of runt-related transcription factor 2 (Runx2) and collagen type I ɑ 1 (Col1ɑ1), and osteocalcin in differentiated MC3T3-E1 cells. Overexpression of wild type but not mutant SIRT3 could reverse SIRT3 knockdown-resulted decrease of ALP staining. Complex I, II, III, IV, and V activities, oxygen consumption and mitochondrial membrane potential were significantly decreased by SIRT3 knockdown. Moreover, SIRT3 knockdown reduced mitochondrial density, increased mitochondrial size and decreased the expression of NRF1 and TFAM. Knock down of SIRT3 decreased mRNA and protein expression of SOD2 and increased ROS level. Overexpression of SOD2 significantly suppressed SIRT3 knockdown-induced decrease of mitochondrial function and osteogenic differentiation. SIRT3 knockdown resulted in a significant decrease of PGC-1ɑ protein expression but not mRNA expression. Overexpression of wild type but not mutant SIRT3 could reverse SIRT3 knockdown-resulted decrease of PGC-1ɑ protein expression. Moreover, we detected a direct interaction between SIRT3 and PGC-1ɑ and SIRT3 knockdown reduced SIRT3 and PGC-1ɑ interaction, resulting in a reduction of PGC-1ɑ protein stability and PGC-1ɑ-binding in the promoters of SOD2. Overexpression of PGC-1ɑ blocked SIRT3 knockdown-induced decrease of SOD2 expression, increase of ROS level, and decrease of mitochondrial function and biogenesis, leading to improvement of osteogenesis. Overall, the data provide a better understanding of the role of SIRT3 in osteogenic differentiation.

Impact of natural curcumin on the progression of experimental periodontitis in diabetic rats

“…In agreement with our findings, a recent in vitro study revealed that SIRT was significantly increased after the therapy with CURC under hyperglycemic conditions . Interestingly, Ding et al, using mouse pre‐osteoblastic MC3T3‐E1 cells, showed that SIRT is required for osteogenic differentiation, supporting the relevant biological role of this marker in conditions involving bone tissue breakdown, as revealed in the present study.…”

Isocitrate dehydrogenase 2 protects mice from high-fat diet-induced metabolic stress by limiting oxidative damage to the mitochondria from brown adipose tissue

“…In addition, the expression of Errα was significantly decreased in the IDH2KO HFD mice, and because ERRα is a major DNAbinding partner for PGC-1α, its reduction would lead to an even further decrease in the expression of key mitochondrial genes. These genes include Sirt3 and Sod2, which are both activated by the concerted action of ERRα and PGC-1α [24][25][26] . In fact, prior studies have suggested that Sirt3 is important for limiting oxidative damage 27 through regulating IDH2 deacetylation 28,29 .…”

Functional and therapeutic potential of mitochondrial SIRT3 deacetylase in disease conditions

“…This further improved oxygen consumption rate and the NAD + /NADH ratio through compensatory mechanism which increased mitochondrial mass and bioenergetics acting via PGC1α-SIRT3-UCP2 axis [21]. The relationship between SIRT3 and PGC1α has already been well discussed in previous studies [22][23][24].…”