Department of Pediatric Dentistry, School of Dental Medicine, Tsurumi University, 2-1-3 Tsurumi, Tsurumi-ku, Yokohama 230-8501, Japan.
Department of Biochemistry and Molecular Biology, School of Dental Medicine, Tsurumi University, 2-1-3 Tsurumi, Tsurumi-ku, Yokohama 230-8501, Japan.
Arch Oral Biol. 2022 Nov;143:105540. doi: 10.1016/j.archoralbio.2022.105540. Epub 2022 Sep 6.
During enamel formation, transforming growth factor-beta (TGF-β) isoforms exhibit different activities for gene expression, apoptosis, and endocytosis. This study aimed to investigate the differential response of TGF-β isoforms to epithelial-mesenchymal transition (EMT) in enamel epithelial cells.
Using a mouse enamel epithelial cell line (mHAT9d) cultured in the presence of each TGF-β isoform, (1) the morphological changes in EMT were explored, (2) EMT-related genes were analyzed by next-generation sequencing (NGS), (3) TGF-β pathway for EMT was identified by inhibition experiments, and (4) the expression of the TGF-β receptor gene in response to the binding affinity of the TGF-β isoform were analyzed.
EMT was observed in mHAT9d cultured in the presence of TGF-β1 and β3 but not TGF-β2. The expression of both epithelial and mesenchymal marker genes was observed in mHAT9d exhibiting EMT. NGS analysis suggested extracellular signal-regulated kinase (ERK) and Rho pathways as TGF-β signaling pathways associated with EMT. However, EMT in mHAT9d cultured in the presence of TGF-β1 or β3 occurred even in presence of an ERK1/2 inhibitor and was suppressed by Rho-kinase inhibitor. The expression of co-receptors for TGF-β signaling in mHAT9d cells reduced following stimulation with each TGF-β isoform. In contrast, endoglin levels increased following TGF-β1 or β3 stimulation, but no change was noted in response to TGF-β2.
We propose that in TGF-β-stimulated enamel epithelial cells, EMT mainly occurred via the Rho signaling pathway, and the differences in response across TGF-β isoforms were due to their endoglin-mediated binding affinity for the TGF-β receptor.
在釉质形成过程中，转化生长因子-β（TGF-β）同工型表现出不同的基因表达、细胞凋亡和内吞作用活性。本研究旨在探讨 TGF-β同工型对釉质上皮细胞上皮-间充质转化（EMT）的不同反应。
使用在存在每种 TGF-β同工型的情况下培养的小鼠釉质上皮细胞系（mHAT9d），（1）探索 EMT 中的形态变化，（2）通过下一代测序（NGS）分析 EMT 相关基因，（3）通过抑制实验鉴定 EMT 的 TGF-β途径，以及（4）分析 TGF-β 受体基因对 TGF-β同工型结合亲和力的反应。
在存在 TGF-β1 和 β3 的情况下培养的 mHAT9d 中观察到 EMT，而在存在 TGF-β2 的情况下则没有观察到。在表现出 EMT 的 mHAT9d 中观察到上皮和间充质标记基因的表达。NGS 分析表明细胞外信号调节激酶（ERK）和 Rho 途径是与 EMT 相关的 TGF-β信号通路。然而，即使在存在 ERK1/2 抑制剂的情况下，在存在 TGF-β1 或 β3 的情况下培养的 mHAT9d 中也会发生 EMT，并且 Rho 激酶抑制剂可抑制 EMT。mHAT9d 细胞中 TGF-β 信号转导的共受体表达在受到每种 TGF-β 同工型刺激后减少。相比之下，TGF-β1 或 β3 刺激后内格林水平增加，但对 TGF-β2 没有变化。
我们提出，在 TGF-β 刺激的釉质上皮细胞中，EMT 主要通过 Rho 信号通路发生，而对 TGF-β 同工型的反应差异是由于其与 TGF-β 受体的内格林介导的结合亲和力。
