Transforming Growth Factor-Beta and Sonic Hedgehog Signaling in Palatal Epithelium Regulate Tenascin-C Expression in Palatal Mesenchyme During Soft Palate Development
Transforming Growth Factor-Beta and Sonic Hedgehog Signaling in Palatal Epithelium Regulate Tenascin-C Expression in Palatal Mesenchyme During Soft Palate Development
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DOI：
10.3389/fphys.2020.00532
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发表时间：
2020-06-04
影响因子：
4
通讯作者：
Sakai, Takayoshi
中科院分区：
文献类型：
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作者：
Ohki, Shirabe;Oka, Kyoko;Sakai, Takayoshi
在腭发生过程中，腭架首先在舌的两侧垂直生长，然后改变其生长方向为水平。细胞外基质（ECM）在腭架形态的这些动态变化中起着重要作用。腱生蛋白-C（tenascin-C，TNC）是一种细胞外基质糖蛋白，在腭架后部有独特的表达，但其表达调控机制尚不清楚。由于转化生长因子-β 3（TGF-β 3）和音刺猬（SHH）信号是已知的腭发育中发挥重要作用，我们调查是否TGF-β 3和SHH参与的TNC表达的调节在发育腭。TGF-β 3增加TNC mRNA和蛋白质在原代小鼠胚胎腭间充质细胞（MEPM）的表达，从腭间充质解剖在胚胎13.5-14.0天。有趣的是，免疫组化实验显示，TNC表达在腭上皮细胞中缺乏TGF-β II型受体并表现出软腭裂的K14-cre; Tgfbr 2（fl/fl）小鼠中减少，而TNC表达在腭间充质细胞中缺乏TGF-β II型受体并表现出完全腭裂的Wnt 1-cre; Tgfbr 2（fl/fl）小鼠中保持。SHH还可增加MEPM细胞TNC mRNA和蛋白的表达。然而，尽管TGF-β 3上调了O 9 -1细胞（颅神经嵴细胞系）中TNC mRNA和蛋白的表达，但SHH没有。此外，TGF-β抑制O 9 -1细胞中成骨细胞分化标志物（osterix和碱性磷酸酶）的表达，并诱导成纤维细胞标志物（纤连蛋白和骨膜蛋白）的表达，而SHH不影响O 9 -1细胞中成骨细胞和成纤维细胞标志物的表达。然而，免疫组织化学实验表明，TNC表达减少在后腭上皮SHH信号缺乏的Shh（-/+）; MFCS 4（+/-）小鼠的后腭架。两者合计，我们的研究结果支持的建议，TGF-β和SHH信号在腭上皮协调TNC的表达在腭后间充质通过旁分泌机制。这一信号级联反应可能在腭发育的后期颅神经嵴细胞分化为成纤维细胞样细胞时起作用。TGF-β和SHH信号对ECM相关蛋白的时空调节不仅有助于组织的构建，而且有助于沿腭架前后轴沿着的细胞分化或决定。
During palatogenesis, the palatal shelves first grow vertically on either side of the tongue before changing their direction of growth to horizontal. The extracellular matrix (ECM) plays an important role in these dynamic changes in palatal shelf morphology. Tenascin-C (TNC) is an ECM glycoprotein that shows unique expression in the posterior part of the palatal shelf, but little is known about the regulation of TNC expression. Since transforming growth factor-beta-3 (TGF-beta 3) and sonic hedgehog (SHH) signaling are known to play important roles in palatogenesis, we investigated whether TGF-beta 3 and SHH are involved in the regulation of TNC expression in the developing palate. TGF-beta 3 increased the expression of TNC mRNA and protein in primary mouse embryonic palatal mesenchymal cells (MEPM) obtained from palatal mesenchyme dissected at embryonic day 13.5-14.0. Interestingly, immunohistochemistry experiments revealed that TNC expression was diminished inK14-cre;Tgfbr2(fl/fl)mice that lack the TGF-beta type II receptor in palatal epithelial cells and exhibit cleft soft palate, whereas TNC expression was maintained inWnt1-cre;Tgfbr2(fl/fl)mice that lack the TGF-beta type II receptor in palatal mesenchymal cells and exhibit a complete cleft palate. SHH also increased the expression of TNC mRNA and protein in MEPM cells. However, although TGF-beta 3 up-regulated TNC mRNA and protein expression in O9-1 cells (a cranial neural crest cell line), SHH did not. Furthermore, TGF-beta inhibited the expression of osteoblastic differentiation markers (osterix and alkaline phosphatase) and induced the expression of fibroblastic markers (fibronectin and periostin) in O9-1 cells, whereas SHH did not affect the expression of osteoblastic and fibroblastic markers in O9-1 cells. However, immunohistochemistry experiments showed that TNC expression was diminished in the posterior palatal shelves ofShh(-/+);MFCS4(+/-)mice, which have deficient SHH signaling in the posterior palatal epithelium. Taken together, our findings support the proposal that TGF-beta and SHH signaling in palatal epithelium co-ordinate the expression of TNC in the posterior palatal mesenchyme through a paracrine mechanism. This signal cascade may work in the later stage of palatogenesis when cranial neural crest cells have differentiated into fibroblast-like cells. The spatiotemporal regulation of ECM-related proteins by TGF-beta and SHH signaling may contribute not only to tissue construction but also to cell differentiation or determination along the anterior-posterior axis of the palatal shelves.