Department of Maxillofacial Tissue Regeneration, School of Dentistry and Institute of Oral Biology, School of Dentistry, Kyung Hee University, Seoul, Republic of Korea.
PLoS One. 2013 Apr 17;8(4):e61960. doi: 10.1371/journal.pone.0061960. Print 2013.
We recently reported that overexpression of thymosin beta-4 (Tβ4) in transgenic mice promotes abnormal hair growth and tooth development, but the role of Tβ4 in dental pulp regeneration was not completely understood. The aim of this study was to investigate the role of Tβ4 on odontoblastic differentiation and the underlying mechanism regulating pulp regeneration in human dental pulp cells (HDPCs). Our results demonstrate that mRNA and protein expression of Tβ4 is upregulated during odontogenic differentiation in HDPCs. Transfection with Tβ4 siRNA decreases OM-induced odontoblastic differentiation by decreasing alkaline phosphatase (ALP) activity, mRNA expression of differentiation markers, and calcium nodule formation. In contrast, Tβ4 activation with a Tβ4 peptide promotes these processes by enhancing the phosphorylation of p38, JNK, and ERK mitogen-activated protein kinases (MAPKs), bone morphogenetic protein (BMP) 2, BMP4, phosphorylation of Smad1/5/8 and Smad2/3, and expression of transcriptional factors such as Runx2 and Osterix, which were blocked by the BMP inhibitor noggin. The expression of integrin receptors α1, α2, α3, and β1 and downstream signaling molecules including phosphorylated focal adhesion kinase (p-FAK), p-paxillin, and integrin-linked kinase (ILK) were increased by Tβ4 peptide in HDPCs. ILK siRNA blocked Tβ4-induced odontoblastic differentiation and activation of the BMP and MAPK transcription factor pathways in HDPCs. In conclusion, this study demonstrates for the first time that Tβ4 plays a key role in odontoblastic differentiation of HDPCs and activation of Tβ4 could provide a novel mechanism for regenerative endodontics.
我们最近报道过，在转基因小鼠中过表达胸腺素β-4（Tβ4）可促进异常的毛发生长和牙齿发育，但 Tβ4 在牙髓再生中的作用尚不完全清楚。本研究旨在探讨 Tβ4 在人牙髓细胞（HDPCs）牙源性分化和调节牙髓再生的潜在机制中的作用。我们的结果表明，Tβ4 的 mRNA 和蛋白表达在 HDPCs 的牙源性分化过程中上调。Tβ4 siRNA 的转染通过降低碱性磷酸酶（ALP）活性、分化标志物的 mRNA 表达和钙结节形成，减少 OM 诱导的牙本质分化。相比之下，Tβ4 肽的激活通过增强 p38、JNK 和 ERK 丝裂原活化蛋白激酶（MAPKs）、骨形态发生蛋白（BMP）2、BMP4、Smad1/5/8 和 Smad2/3 的磷酸化以及转录因子如 Runx2 和 Osterix 的表达，促进这些过程，这些过程被 BMP 抑制剂 noggin 阻断。Tβ4 肽在 HDPCs 中增加整合素受体α1、α2、α3 和β1 的表达以及下游信号分子，包括磷酸化粘着斑激酶（p-FAK）、p-桩蛋白和整合素连接激酶（ILK）。ILK siRNA 阻断了 Tβ4 诱导的 HDPCs 牙本质分化和 BMP 和 MAPK 转录因子通路的激活。总之，本研究首次证明 Tβ4 在 HDPCs 的牙本质分化和 Tβ4 的激活中起着关键作用，为再生牙髓学提供了一种新的机制。
