EZH2 Impairs Human Dental Pulp Cell Mineralization via the Wnt/β-Catenin Pathway

Abstract

The enhancer of zeste homolog 2 (EZH2) is a catalytic subunit of PRC2 (polycomb repressor complex 2). It mediates gene silencing via methyltransferase activity and is involved in the determination of cell lineage. However, the function of EZH2 and the underlying mechanisms by which it affects the differentiation of human dental pulp cell (hDPC) have remained underexplored. In this research, we found that EZH2 expression decreased during the mineralization of hDPCs, with attenuated H3K27me3 (trimethylation on lysine 27 in histone H3). Overexpression of EZH2 impaired the odontogenic differentiation of hDPCs, while EZH2 without methyltransferase activity mutation (mutation of suppressed variegation of 3 to 9, enhancer of zeste and trithorax domain, EZH2ΔSET) did not display this phenotype. In addition, siRNA knockdown studies showed that EZH2 negatively modulated hDPC differentiation in vitro and inhibited mineralized nodule formation in transplanted β-tricalcium phosphate / hDPC composites. To further investigate the underlying mechanisms, we explored the Wnt/β-catenin signaling pathway in view of the fact that previous research had documented the essential role that it plays during hDPC mineralization, as well as its links to EZH2 in other cells. We demonstrated for the first time that EZH2 depletion activated the Wnt/β-catenin signaling pathway and enhanced the accumulation of β-catenin in hDPCs. Chromatin immunoprecipitation analysis suggested that these effects are attributable to the level of the EZH2-regulated H3K27me3 on the β-catenin promoter. We conclude that EZH2 plays a negative role during the odontogenic differentiation of hDPCs. Suppression of EZH2 could promote hDPC mineralization by epigenetically regulating the expression of β-catenin and activating the Wnt canonical signaling pathway.

Analysis of hard tissue regeneration and Wnt signalling in dental pulp tissues after direct pulp capping with different materials

“…β‐catenin expression was up‐regulated during the odontoblastic differentiation of DPSCs (Han et al ). Activating Wnt/β‐catenin signalling either by WNT7B or by depleting the enhancer of zeste homolog 2 (EZH2) similarly promoted DPSC differentiation (Li et al , Lv et al ). In contrast, β‐catenin knockdown inhibited DPSC odontoblastic differentiation (Han et al ).…”

Epigenetic Regulation of Dental Pulp Stem Cell Fate

“…When β -tricalcium phosphate/DPSCs transfected with siEZH2 are transplanted under the skin of nude mice, the formation of mineralized tissue is improved. Further, the results of a CHIP assay suggested that EZH2 downregulates the expression of β -catenin by increasing the levels of H3K27me3 on the promoter region of β-catenin , eventually suppressing the Wnt/ β -catenin signaling pathway that is critical for odontogenic differentiation [ 110 ]. EZH2 is also related to the proliferation, osteogenic differentiation, and inflammatory response of DPSCs.…”

circAKT3 positively regulates osteogenic differentiation of human dental pulp stromal cells via miR-206/CX43 axis

“…We performed in vivo bone formation analysis using subcutaneous transplantation as described previously [21]. In brief, we soaked beta-tricalcium phosphate (β-TCP) blocks (5 mm × 5 mm × 2 mm) in OM for 30 min at 37°C.…”