LGR5 Modulates Differentiated Phenotypes of Chondrocytes Through PI3K/AKT Signaling Pathway.

Abstract

Tissue engineering is increasingly viewed as a promising avenue for functional cartilage reconstruction. However, chondrocyte dedifferentiation during in vitro culture remains an obstacle for clinical translation of tissue engineered cartilage. Re-differentiated induction have been employed to induce dedifferentiated chondrocytes back to their original phenotype. Regrettably, these strategies have been proven to be only moderately effective. To explore underlying mechanism, RNA transcriptome sequencing was conducted on primary chondrocytes (P0), dedifferentiated chondrocytes (P5), and redifferentiated chondrocytes (redifferentiation-induction of P5, P5.R). Based on multiple bioinformatics analysis, LGR5 was identified as a target gene. Subsequently, stable cell lines with LGR5 knocking-down and overexpression were established using P0 chondrocytes. The phenotypic changes in P1 and P5 chondrocytes with either LGR5 knockdown or overexpression were assessed to ascertain the potential influence of LGR5 dysregulation on chondrocyte phenotypes. Regulatory mechanism was then investigated using bioinformatic analysis, protein-protein docking, immunofluorescence co-localization and immunoprecipitation. The current study found that dysregulation of LGR5 can significantly impact the dedifferentiated phenotypes of chondrocytes (P5). Upregulation of LGR5 appears to activate the PI3K/AKT signal via increasing the phosphorylation levels of AKT (p-AKT1). Moreover, the increase of p-AKT1 may stabilize β-catenin and enhance the intensity of Wnt/β-catenin signal, and help to restore the dedifferentated phenotype of chondrocytes. LGR5 can modulate the phenotypes of chondrocytes in P5 passage through PI3K/AKT signaling pathway.