Species‐specific roles of cellular communication network proteins in cartilage development: A comparative study using in vitro chondrogenic models

Cellular communication network (CCN) proteins are key matricellular regulators of cartilage development, yet their species‐specific roles and network‐level context remain unclear. This study integrated bulk RNA sequencing from chicken and mouse embryonic limb bud micromass cultures and human mesenchymal stem cell chondrogenesis with co‐expression, protein–protein interaction, and ortholog analyses to construct CCN‐centered regulatory networks across models. CCN1 and CCN2 emerged as dominant, conserved hubs enriched in collagen‐containing extracellular matrix, cartilage development, and growth factor signaling modules, whereas CCN3–CCN6 showed lower context‐dependent expression and connectivity. Functional and ortholog analyses revealed moderate pathway conservation, with high conservation of IGF, EGFR, and HIF‐1 signaling, but reduced overlap in hypoxia and mechanosensing/Hippo categories, indicating species‐specific tuning of environmental sensing. A focused ortholog screen identified multifunctional conserved hubs, including COL2A1 , TGFBR1 , SMAD3 , RUNX2 , HIF1A , IGF1 , SPP1 , and CD44 . Single‐cell RNA‐seq meta‐analysis of human iPSC‐derived chondrogenesis and embryonic limb datasets showed CCN1/2 expression and homologous network activity peaking in mesenchymal and early chondrocyte populations, consistent with model‐dependent persistence into hypertrophic and ossification stages in vivo. Overall, this work defines a conserved CCN1/2‐centered axis integrating extracellular matrix formation with growth factor and mechanical cues, providing a framework for model selection and CCN‐targeted cartilage regeneration strategies.