Ookuma Yukiko F, Kiyoshima Tamotsu, Kobayashi Ieyoshi, Nagata Kengo, Wada Hiroko, Fujiwara Hiroaki, Yamaza Haruyoshi, Nonaka Kazuaki, Sakai Hidetaka
Laboratory of Oral Pathology, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Fukuoka 812-8582, Japan.
Histochem Cell Biol. 2013 Feb;139(2):355-70. doi: 10.1007/s00418-012-1033-1. Epub 2012 Oct 6.
Thymosin beta-4 (Tβ4) is known to be ubiquitously involved in the actin monomer sequestering on the cytoskeleton. Our previous study showed specific temporal and special in situ expression pattern of Tβ4 mRNA in dental epithelial and mesenchymal cells in the developing tooth germ of the mouse lower first molar. In this study, we examined the functional implications of Tβ4 in the developmental course of the mouse lower first molar. An inhibition assay using Tβ4 antisense sulfur-substituted oligodeoxynucleotide (AS S-ODN) in cultured embryonic day 11.0 (E11.0) mandibles showed a significant growth inhibition of the tooth germ. However, no growth arrest of the cultured E15.0 tooth germ was observed by using Tβ4 AS S-ODN. The Tβ4 knockdown led to significantly decreased expression levels of type II/III runt-related transcription factor 2 (Runx2) and nucleolin (Ncl) in the cultured E11.0 mandibles. Since our previous studies proved that the inhibition of type II/III Runx2 and Ncl translations resulted in the developmental arrest of the tooth germ in the cultured E11.0 mandible, Tβ4 appears to play roles in tooth germ development via the regulation of the type II/III Runx2 and Ncl expressions. Tβ4 knockdown also resulted in decreased secretion of matrix metalloproteinase (Mmp)-2, a reduced cell motility activity and upregulation of E-cadherin in dental epithelial mDE6 cells. These results suggest that Tβ4 plays multiple functional roles in odontogenic epithelial cells in the early stages of tooth germ development by regulating the expression of odontogenesis-related genes.
已知胸腺素β-4（Tβ4）广泛参与肌动蛋白单体在细胞骨架上的隔离。我们之前的研究显示，Tβ4 mRNA在小鼠下颌第一磨牙发育中的牙胚的牙上皮和间充质细胞中具有特定的时空原位表达模式。在本研究中，我们检测了Tβ4在小鼠下颌第一磨牙发育过程中的功能意义。在培养的胚胎第11.0天（E11.0）下颌骨中使用Tβ4反义硫代寡脱氧核苷酸（AS S-ODN）进行抑制试验，结果显示牙胚有显著的生长抑制。然而，使用Tβ4 AS S-ODN未观察到培养的E15.0牙胚生长停滞。Tβ4基因敲低导致培养的E11.0下颌骨中II/III型 runt相关转录因子2（Runx2）和核仁素（Ncl）的表达水平显著降低。由于我们之前的研究证明，抑制II/III型Runx2和Ncl的翻译会导致培养的E11.0下颌骨中牙胚发育停滞，Tβ4似乎通过调节II/III型Runx2和Ncl的表达在牙胚发育中发挥作用。Tβ4基因敲低还导致基质金属蛋白酶（Mmp）-2分泌减少、细胞运动活性降低以及牙上皮mDE6细胞中E-钙黏蛋白上调。这些结果表明，Tβ4通过调节牙发生相关基因的表达，在牙胚发育早期的成牙上皮细胞中发挥多种功能作用。
