Comparative transcriptomics of fibrocartilage stem cells and knee chondrogenic progenitors identifies a DKK3-PI3K/AKT regulatory axis

Objective This study aimed to compare fibrocartilage stem cells (FCSCs) and knee chondrogenic progenitor cells (CPCs) through RNA sequencing to identify key mechanisms regulating FCSCs function, and to explore the role of Dickkopf-3 (DKK3) in maintaining FCSCs chondrogenic potential in association with the PI3K/AKT pathway. Design: FCSCs were isolated from temporomandibular joint (TMJ) condylar cartilage and CPCs from knee articular cartilage of 6-week-old male Sprague-Dawley (SD) rats. RNA sequencing analyzed transcriptional differences. DKK3 knockdown in FCSCs was performed using short hairpin RNA (shRNA), followed by chondrogenic differentiation assays. PI3K/AKT pathway activation was assessed via Western blot, immunofluorescence, and rescue experiments with the PI3K/AKT activator Recilisib. Results DKK3 expression was higher in FCSCs than CPCs (p < .05). DKK3 knockdown reduced chondrogenic markers (Sox9, Col2a1, Aggrecan) and PI3K/AKT activity (p < .05), while recombinant DKK3 rescued the IL-1β-induced impairment of FCSCs chondrogenesis (p < .05). Recilisib restored PI3K/AKT signaling and chondrogenic capacity in DKK3-deficient FCSCs (p < .05). Transcriptomics revealed FCSCs’ unique enrichment in extracellular matrix (ECM) remodeling and PI3K/AKT pathways compared to CPCs. Conclusions Our results suggested that DKK3 appears to maintain FCSCs’ chondrogenic potential via the PI3K/AKT pathway activation, highlighting a tissue-specific regulatory mechanism critical for TMJ cartilage homeostasis.