CCDC134 regulates the osteogenic differentiation of human dental pulp stem cells

To study the regulatory effect of coiled-coil domain containing 134 (CCDC134) on the osteogenic differentiation of human dental pulp stem cells (hDPSCs).

HDPSCs were isolated and cultured from dental pulp tissue and transfected with NC-CCDC134, shCCDC134 and CCDC134 lentiviruses. They were divided into the control group, negative control group, CCDC134 downregulation (shCCDC134) group and CCDC134 overexpression (CCDC134) group. Surface markers of hDPSCs (Stro-1, CD105, CD34, CD45) were detected by flow cytometry; colony formation was analyzed by toluidine blue staining; ALP expression was estimated by ALP staining; mineralized nodule formation was evaluated by alizarin red staining; lipid droplet formation was examined by oil red staining; and gene and protein expression of CCDC134, Runt-related transcription factor 2 (RUNX2), osteocalcin (OCN), bone morphogenetic protein-2 (BMP-2), and mothers against decapentaplegic homolog 1 (SMAD1) was detected by qPCR and western blot, respectively. Further, a BMP-2 activator (BMP-2) and inhibitor (Dorsomorphin) were used to down-regulate and up-regulate CCDC134, respectively (shCCDC134, shCCDC134+BMP-2, CCDC134, CCDC134+Dorsomorphin), in hDPSCs. The hDPSC aggregates were subcutaneously transplanted into nude mice for 2 months, and new bone formation was detected by H&E staining. The BMP-2/SMAD1 signaling in each group was detected by qPCR.

hDPSCs showed high expression of mesenchymal markers and low expression of hematopoietic markers. Compared with the control group, the expression of CCDC134 was increased in the osteogenic-induced hDPSCs (P < 0.05). Compared with the negative control group, the expression of CCDC134 was decreased in the shCCDC134 group, whereas it was increased in the CCDC134 group (P < 0.05). The mineralized nodules, osteogenic genes and proteins in the shCCDC134 group were decreased (P < 0.05), while they were increased in the CCDC134 group (P < 0.05). The expression of BMP-2/SMAD1 signaling decreased in the shCCDC134 group, while it increased in the CCDC134 group (P < 0.05). Compared to the shCCDC134 group, osteogenic genes and proteins increased in the shCCDC134+BMP-2 group, and subcutaneous new bone formation increased in nude mice (P < 0.05). The indexes of the CCDC134+Dorsomorphin group decreased compared with the CCDC134 group (P < 0.05).

CCDC134 promotes the osteogenic differentiation of hDPSCs by regulating the BMP-2/SMAD1 signaling pathway.