Sirt1 Activates Piezo1 to Drive Bone Formation and Fracture Repair in Mice
A newly identified Sirt1–Piezo1 molecular axis accelerates bone healing; resveratrol in a targeted yeast capsule delivery system shows strong preclinical promise.
Summary
Researchers at Southern University of Science and Technology identified a novel molecular axis in which the longevity-associated deacetylase Sirt1 directly binds, deacetylates, and activates the mechanosensitive ion channel Piezo1 in chondrocytes, boosting calcium influx and promoting bone formation. Using chondrocyte-specific Piezo1 knockout mice, fracture models, and distraction osteogenesis models, the team showed that Piezo1 is upregulated in cartilage callus during healing, and its deletion severely impairs repair. Sirt1 activators SRT2104 and resveratrol both enhanced Piezo1 activity and accelerated fracture healing. A novel yeast microcapsule oral formulation of resveratrol selectively targeted inflammatory fracture sites, improving bioavailability and therapeutic efficacy, pointing toward a clinically translatable strategy for bone repair.
Detailed Summary
Bone fractures remain a major clinical burden, particularly in aging populations where impaired healing is common. Mechanical signals are critical drivers of bone repair, and the mechanosensitive ion channel Piezo1 has emerged as a key mediator of osteogenesis. However, the molecular regulators controlling Piezo1 activity in bone cells were largely unknown. This study identifies Sirt1—a NAD+-dependent deacetylase strongly linked to longevity and metabolic health—as a potent upstream activator of Piezo1 in chondrocytes.
The researchers first established that Piezo1 is dynamically upregulated in cartilage callus during fracture healing using immunofluorescence staining of mouse femoral fracture and distraction osteogenesis (DO) models at 1, 2, and 4 weeks post-surgery. Single-cell RNA sequencing reanalysis of published datasets (GSE150291 and GSE154247) confirmed that Piezo1 expression is highly enriched in chondrocyte lineages and is significantly elevated at post-fracture day 14, coinciding with upregulation of endochondral ossification genes including Osx, Col1a1, Alp, and Vegfa.
Using chondrocyte-specific Piezo1 knockout mice (Col2a1-Cre; Piezo1-flox), the team demonstrated that Piezo1 deletion severely impaired endochondral ossification, mechanically induced osteogenesis, and fracture healing. Conversely, pharmacological activation of Piezo1 with Yoda1 accelerated these processes. Mechanistically, Sirt1 overexpression or activation with SRT2104 dose-dependently increased Piezo1 protein levels. Co-immunoprecipitation and deacetylation assays showed that Sirt1 physically binds Piezo1, deacetylates it, and enhances its channel activity and calcium influx in chondrocytes. Critically, Piezo1 deletion in chondrocytes abolished the bone-repair-promoting effects of SRT2104, confirming that Piezo1 is the essential downstream effector of Sirt1 in this context.
Resveratrol (RSV), a natural Sirt1 activator found in red wine and various plants, also potently activated Piezo1 and enhanced bone repair in vivo. To overcome RSV's poor oral bioavailability, the team developed a yeast microcapsule (YC)-based oral delivery system (YC-RSV). Yeast cell wall-derived microcapsules are biocompatible, macrophage-targeting, and capable of loading small molecules. YC-RSV was shown to selectively accumulate at inflammatory fracture sites via macrophage chemotaxis, significantly improving drug delivery efficiency and therapeutic outcomes compared to free RSV.
These findings establish a previously unrecognized Sirt1–Piezo1 signaling axis that couples cellular energy/NAD+ sensing with mechanotransduction to regulate bone homeostasis and repair. The development of a targeted oral RSV formulation adds translational relevance, suggesting that Sirt1 activators—already under clinical investigation for aging-related conditions—could be repurposed or optimized for bone fracture indications.
Key Findings
- Piezo1 is markedly upregulated in cartilage callus during fracture healing and distraction osteogenesis in mice.
- Chondrocyte-specific Piezo1 deletion severely impairs endochondral ossification and delays fracture repair.
- Sirt1 physically binds and deacetylates Piezo1, increasing its channel activity and calcium influx in chondrocytes.
- The Sirt1 activator SRT2104 accelerates bone repair via Piezo1; this effect is abolished by chondrocyte Piezo1 deletion.
- A yeast microcapsule oral formulation of resveratrol selectively targets fracture sites and enhances bone healing in vivo.
Methodology
The study used chondrocyte-specific Piezo1 knockout mice, femoral fracture and distraction osteogenesis mouse models, single-cell RNA sequencing reanalysis, co-immunoprecipitation, calcium imaging, and a novel yeast microcapsule drug delivery system. Both genetic loss-of-function and pharmacological gain-of-function approaches were employed to establish causality.
Study Limitations
All experiments were conducted in mice, and translation to human fracture biology requires validation. The study does not fully characterize which specific lysine residues on Piezo1 are deacetylated by Sirt1, limiting mechanistic precision. Long-term safety and efficacy of the YC-RSV formulation in aged or osteoporotic models was not assessed.
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