Department of Oral Implantation, Affiliated Haikou Hospital, Xiangya Medical School, Central South University, Hainan Provincial Stomatology Center, Haikou, Hainan 570208, P.R. China.
Mol Med Rep. 2018 Jul;18(1):993-1000. doi: 10.3892/mmr.2018.9052. Epub 2018 May 23.
Nacre (mother of pearl) is a bioactive material capable of facilitating osteoblast proliferation and differentiation; however, further investigation into the mechanism underlying the effects of nacre on the stimulation of bone differentiation is required. The present study aimed to elucidate the effects of water‑soluble nano‑pearl powder (WSNNP) on osteoblast differentiation and to examine the underlying mechanisms. A MTT assay revealed that WSNNP (10, 25 and 50 µg/ml) may stimulate the viability of preosteoblastic MC3T3‑E1 cells and 50 µg/ml WSNNP exhibited the maximum stimulatory effect. Furthermore, WSNNP significantly enhanced the protein expression levels of differentiation markers, including collagen I, runt‑related transcription factor 2 (RUNX2), secreted phosphoprotein1 (SPP1) and alkaline phosphatase (ALP) in a dose‑dependent manner, which indicated that WSNNP may promote osteoblast differentiation. Subsequently, whether autophagy serves a role in WSNNP‑mediated differentiation of osteoblasts was investigated via western blotting and immunofluorescence. The results of the present study demonstrated that WSNNP treatment significantly evoked the expression of autophagy markers, including microtubule‑associated light chain 3 (LC3)II/I, Beclin1 and autophagy‑related 7 (ATG7), whereas the autophagy inhibitor 3‑methyladenine significantly inhibited WSNNP‑induced osteoblast differentiation. Furthermore, the role of WSNNP on the potential signaling pathways that activate autophagy was investigated. The present study reported that WSNNP may significantly upregulate the mitogen‑activated protein kinase kinase (MEK)/extracellular signal‑regulated kinase (ERK) signaling pathway. Treatment with the MEK inhibitor U0126 significantly inhibited the protein expression levels of WSNNP‑induced differentiation markers, including collagen I, RUNX2, SPP1 and ALP, and autophagy markers, including LC3II/I, Beclin1 and ATG7. Therefore, the findings of the present study suggested that WSNNP may contribute to osteoblast differentiation by enhancing autophagy via the MEK/ERK signaling pathway, thus suggesting a novel direction for optimizing the biological materials in bone implants.
珍珠母（珍珠层）是一种具有生物活性的物质，能够促进成骨细胞的增殖和分化;然而，需要进一步研究珍珠母刺激骨分化的作用机制。本研究旨在阐明水溶纳米珍珠粉（WSNNP）对成骨细胞分化的影响，并探讨其潜在机制。MTT 检测结果表明，WSNNP（10、25 和 50μg/ml）可能刺激前成骨细胞 MC3T3-E1 细胞的活力，且 50μg/ml WSNNP 表现出最大的刺激作用。此外，WSNNP 可显著增强分化标志物，包括胶原 I、 runt 相关转录因子 2（RUNX2）、分泌型磷蛋白 1（SPP1）和碱性磷酸酶（ALP）的蛋白表达水平，呈剂量依赖性，表明 WSNNP 可能促进成骨细胞分化。随后，通过 Western blot 和免疫荧光法研究了自噬是否在 WSNNP 介导的成骨细胞分化中发挥作用。本研究结果表明，WSNNP 处理可显著诱导自噬标志物，包括微管相关轻链 3（LC3）II/I、Beclin1 和自噬相关基因 7（ATG7）的表达，而自噬抑制剂 3-甲基腺嘌呤（3-MA）可显著抑制 WSNNP 诱导的成骨细胞分化。此外，还研究了 WSNNP 对激活自噬的潜在信号通路的作用。本研究报道，WSNNP 可能显著上调丝裂原活化蛋白激酶激酶（MEK）/细胞外信号调节激酶（ERK）信号通路。用 MEK 抑制剂 U0126 处理可显著抑制 WSNNP 诱导的分化标志物，包括胶原 I、RUNX2、SPP1 和 ALP，以及自噬标志物，包括 LC3II/I、Beclin1 和 ATG7 的蛋白表达水平。因此，本研究结果表明，WSNNP 可能通过 MEK/ERK 信号通路增强自噬促进成骨细胞分化，从而为优化骨植入物中的生物材料提供了新的方向。
