Txnip regulates glycolysis and tricarboxylic acid cycle balance to maintain bone homeostasis

Bone remodeling and energy metabolism are closely linked in mammals. Maintaining a balanced glycolysis and tricarboxylic acid (TCA) cycle ratio is essential for bone remodeling. Therefore, it was of great interest to reveal key regulators in bone remodeling under different glucose metabolic states. We created genetic knockout mice for Thioredoxin-interacting protein ( Txnip ) in bone marrow-derived macrophages (BMMs) and mesenchymal stromal cells (BMSCs), followed by bone histomorphometry and histological analysis. Metabolic regulation mechanisms were investigated using Seahorse and 13 C-Glucose tracer metabolic flux experiments. KAN0438757-specific 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (pfkfb3) inhibitor was selected for rescue experiments. Txnip knockout led to increased anaerobic glycolysis and disrupted the TCA cycle, thereby inhibiting osteoclast formation. Knockout of Txnip , which enhanced that enhanced glycolysis also damaged osteoblast differentiation due to impaired TCA cycle. Elevated Txnip levels were observed in aged human bone marrow derived mesenchymal stem cells (BMSCs) and mice BMSCs. Txnip upregulation blocked glucose influx and impaired subsequent glycolysis and TCA cycle, resulting in impaired bone formation. Reduced osteoblast differentiation is correlated with delayed fracture healing during BMSCs-enrichment therapy in aged patients. Txnip is essential for balanced glycolysis and TCA cycle. Either extremely low or extremely high expression of Txnip will disrupt this balance and thus impair bone homeostasis. Elevated Txnip levels in senescent human BMSCs correlate with delayed fracture healing during aging. The Txnip inhibition for rebuilding balanced glycolysis and the TCA cycle has great clinical translation potential in autologous BMSCs-enrichment therapy in aged patients.