Wnt/β-catenin signaling regulates the proliferation and differentiation of mesenchymal progenitor cells through the p53 pathway.

Fuyou Wang,Xiaojun Duan,Liu Yang,Lin Guo,Gang Dai,Guangxing Chen,Ying Zhang,Hongxing Chang,Rajeev Samant,Xu Peng

doi:10.1371/journal.pone.0097283

Abstract

ObjectiveMesenchymal progenitor cells (MPCs) are found in articular cartilage from normal controls and patients with osteoarthritis (OA). Nevertheless, the molecular mechanisms of the proliferation and differentiation of these cells remain unclear. In this study, we aimed to determine the involvement of Wnt/β-catenin signaling in regulating the proliferation and differentiation of MPCs.MethodsMPCs were isolated from the articular cartilage of normal and OA patients. Cells were sorted by immunomagnetic cell separation. Cell proliferation capacity was evaluated using the MTT assay. Toluidine blue staining and immunostaining with anti-collagen II or anti-aggrecan antibodies were used to determine the chondrogenic differentiation capabilities of MPCs. The mRNA and protein expression of target genes were examined by quantitative real-time polymerase chain reaction and Western blotting, respectively. Knock-down of p53 expression was achieved with RNA interference.ResultsMost cells isolated from the normal and OA patients were CD105+ and CD166+ positive (Normal subjects: CD105+/CD166+, 94.6%±1.1%; OA: CD105+/CD166+, 93.5%±1.1%). MPCs derived from OA subjects exhibited decreased differentiation capabilities and enhanced Wnt/β-catenin activity. Inhibition of Wnt/β-catenin signaling promoted proliferation and differentiation, whereas activation of this pathway by treatment with rWnt3a protein decreased the proliferation and differentiation of normal MPCs. Additionally, Wnt/β-catenin signaling positively regulated p53 expression, and silencing of p53 increased proliferation and differentiation of MPCs.ConclusionsWnt/β-catenin regulated the proliferation and differentiation of MPCs through the p53 pathway.

Highlights

Mesenchymal progenitor cells (MPCs), known as mesenchymal stem cells, have been found in various human tissues, including human adult bone marrow [1]
The frequency of MPCs is increased in OA cartilage [8], suggesting that these progenitor cells may be involved in the pathogenesis of arthritis
Activation of b-catenin in articular chondrocytes in adult mice led to the development of an OA-like phenotype [9], and b-catenin levels are increased in human OA samples [9]

Summary

Introduction

Mesenchymal progenitor cells (MPCs), known as mesenchymal stem cells, have been found in various human tissues, including human adult bone marrow [1]. These cells are thought to be involved in mesenchymal tissue maintenance and repair and may have great therapeutic potential due to their ability to selfrenew and differentiate into multiple tissue types [2,3]. The frequency of MPCs is increased in OA cartilage [8], suggesting that these progenitor cells may be involved in the pathogenesis of arthritis. Activation of b-catenin in articular chondrocytes in adult mice led to the development of an OA-like phenotype [9], and b-catenin levels are increased in human OA samples [9]

Methods

Results

Conclusion