PIEZO1-Primary Cilia Axis Mediates Compressive Stress-Induced Growth Plate Degeneration and Ossification in Adolescent Idiopathic Scoliosis.

Abstract

Adolescent idiopathic scoliosis (AIS) is linked to mechanical stress-induced growth plate dysfunction. PIEZO1 (mechanosensitive ion channel) mediates chondrocyte apoptosis via calcium, and primary cilia (mechanosensory organelles) regulate cartilage matrix synthesis, but their interplay in stress-induced growth plate degeneration/ossification remains unclear; this study explored the PIEZO1-primary cilia axis's role. Conditional IFT88 knockout (IFT88-cKO) mice were generated via <i>Col2a1</i>-<i>CreERT</i> and <i>Ift88</i> ^{<i>flox /</i>} ^<i>flox</i> crosses (tamoxifen-induced). 8-week-old C57BL/6J mice were divided into control, wild-type caudal compression (CC, 10 kPa), and IFT88-CKO CC groups (samples at 8 weeks, MRI at 4 weeks). Primary growth plate chondrocytes from 5-day-old C57BL/6J mice were cultured, stressed (self-developed device, 100 kPa), or treated with Yoda1 (PIEZO1 agonist)/chloral hydrate (cilia disruptor)/siRNA (PIEZO1/IFT88 knockdown). Detection included Western blot, RT-qPCR, immunofluorescence, immunohistochemistry, ARS/ALP/ABS/HE/Safranine O staining, and transcriptome sequencing. PIEZO1 co-localized with primary cilia (ac-α-Tubulin labeled) in chondrocytes; chloral hydrate reduced cil-ia-positive cells (97.2% → 16.6%, <i>p</i> < 0.001). Stress upregulated PIEZO1, decreased COL2A1 (cartilage marker), increased RUNX2 (osteogenic marker), and enhanced ALP/ARS staining. Transcriptome identified 11,534 differ-entially expressed genes (e.g., upregulated PIEZO1/IFT88, downregulated ACAN). SiPIEZO1 reduced IFT88 (non-stress), while siIFT88 feedback-upregulated PIEZO1 (stress). Yoda1 induced cartilage degeneration, which was reversed by siIFT88/chloral hydrate. In vivo, CC increased disc degeneration score (2 → 12), while IFT88-cKO reduced it to 8 and attenuated COL2A1 downregulation/RUNX2 upregulation. The PIEZO1-primary cilia axis mediates stress-induced growth plate degeneration/ossification: stress upregulates PIEZO1, which relies on primary cilia to promote chondrocyte apoptosis and abnormal ossification; cilia disruption alleviates these effects. This provides insights into AIS pathogenesis and identifies PIEZO1/primary cilia as therapeutic targets.