gp130/STAT3 signaling is required for homeostatic proliferation and anabolism in postnatal growth plate and articular chondrocytes

Liu et al. demonstrate the role of gp130/STAT3 signalling in the development and homeostasis of chondrocytes in the growth plate and articular cartilage. The authors report that tamoxifen-induced deletion of STAT3 or gp130 in chondrocytes after birth results in defective chondrocyte proliferation, growth plate fusion and stunting, and signs of progressive dysfunction of the articular cartilage, with female mice more strongly affected than males. Growth of long bones and vertebrae is maintained postnatally by a long-lasting pool of progenitor cells. Little is known about the molecular mechanisms that regulate the output and maintenance of the cells that give rise to mature cartilage. Here we demonstrate that postnatal chondrocyte-specific deletion of a transcription factor Stat3 results in severely reduced proliferation coupled with increased hypertrophy, growth plate fusion, stunting and signs of progressive dysfunction of the articular cartilage. This effect is dimorphic, with females more strongly affected than males. Chondrocyte-specific deletion of the IL-6 family cytokine receptor gp130, which activates Stat3, phenocopied Stat3-deletion; deletion of Lifr, one of many co-receptors that signals through gp130, resulted in a milder phenotype. These data define a molecular circuit that regulates chondrogenic cell maintenance and output and reveals a pivotal positive function of IL-6 family cytokines in the skeletal system with direct implications for skeletal development and regeneration.

Automated summary

The study demonstrates the significance of gp130/STAT3 signaling in the development and homeostasis of chondrocytes in the growth plate and articular cartilage. The findings suggest that the deletion of STAT3 or gp130 in chondrocytes can lead to defective chondrocyte proliferation, growth plate fusion, and dysfunction of the articular cartilage. The study also highlights the positive role of IL-6 family cytokines in the skeletal system.