Noncanonical Wnt5a signaling regulates tendon stem/progenitor cells senescence

The structural and functional properties of tendon decline with age, and these changes contribute to tendon disorder. Tendon stem/progenitor cells (TSPCs) play a vital role in tendon repair, regeneration and homeostasis maintaining. Although studies have demonstrated that tendon aging is closely associated with the altered TSPCs function on senescence, the cellular and molecular mechanisms of TSPCs senescence remain largely unknown. This study was designed to investigate the role of Wnt5a in TSPCs senescence.

TSPCs were isolated from 2-month-old and 20-month-old male C57BL/6 mice. The expression of Wnt5a was determined by RNA sequencing, qRT-PCR and western blotting. TSPCs were then treated with Wnt5a shRNA or recombinant Wnt5a or AG490 or IFN-γ or Ror2-siRNA. Western blotting, β-gal staining, qRT-PCR, immunofluorescence staining and cell cycle analysis were used for confirming the role of Wnt5a in TSPCs senescence.

We found a canonical to noncanonical Wnt signaling shift due to enhanced expression of Wnt5a in aged TSPCs. Functionally, we demonstrated that inhibition of Wnt5a attenuated TSPCs senescence, age-related cell polarity and the senescence-associated secretory phenotype (SASP) expression in aged TSPCs. Mechanistically, the JAK-STAT signaling pathway was activated in aged TSPCs, while Wnt5a knockdown inhibited the JAK-STAT signaling pathway, suggesting that Wnt5a modulates TSPCs senescence via JAK-STAT signaling pathway. Moreover, knockdown of Ror2 inhibited Wnt5a-induced activation of the JAK-STAT signaling pathway, which indicates that Wnt5a potentiates JAK-STAT signaling pathway through Ror2, and Ror2 acts as the functional receptor of Wnt5a in TSPCs senescence.

Our results demonstrate a critical role of noncanonical Wnt5a signaling in TSPCs senescence, and Wnt5a could be an attractive therapeutic target for antagonizing tendon aging.