SIRT3: A Potential Target of Different Types of Osteoporosis.

Osteoporosis (OP) is a common age-related disease. OP is mainly a decrease in bone density and mass caused by the destruction of bone microstructure, which leads to an increase in bone fragility. SIRT3 is a mitochondrial deacetylase that plays critical roles in mitochondrial homeostasis, metabolic regulation, gene transcription, stress response, and gene stability. Studies have shown that the higher expression levels of SIRT3 are associated with decreased levels of oxidative stress in the body and may play important roles in the prevention of age-related diseases. SIRTs can enhance the osteogenic potential and osteoblastic activity of bone marrow mesenchymal stromal cells not only by enhancing PGC-1α, FOXO3, SOD2, and oxidative phosphorylation, but also by anti-aging and reducing mitochondrial autophagy. SIRT3 is able to upregulate antioxidant enzymes to exert an inhibitory effect on osteoclasts, however, it has been shown that the inflammatory cascade response can in turn increase SIRT3 and inhibit osteoclast differentiation through the AMPK-PGC-1β pathway. SIRT3 plays an important role in different types of osteoporosis by affecting osteoblasts, osteoclasts, and bone marrow mesenchymal cells. In this review, we discuss the classification and physiological functions of SIRTs, the effects of SIRT3 on OCs osteoblasts, and BMSCs, and the roles and mechanisms of SIRT3 in different types of OP, such as diabetic OP, glucocorticoid-induced OP, postmenopausal OP, and senile OP.