Goto Noriko, Fujimoto Katsumi, Fujii Sakiko, Ida-Yonemochi Hiroko, Ohshima Hayato, Kawamoto Takeshi, Noshiro Mitsuhide, Shukunami Chisa, Kozai Katsuyuki, Kato Yukio
Department of Pediatric Dentistry, Institute of Biomedical & Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan.
Department of Dental and Medical Biochemistry, Institute of Biomedical & Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan; Department of Molecular Biology and Biochemistry, Institute of Biomedical & Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan.
Stem Cells Int. 2016;2016:8035759. doi: 10.1155/2016/8035759. Epub 2016 Aug 28.
Msh homeobox 1 (MSX1) encodes a transcription factor implicated in embryonic development of limbs and craniofacial tissues including bone and teeth. Although MSX1 regulates osteoblast differentiation in the cranial bone of young animal, little is known about the contribution of MSX1 to the osteogenic potential of human cells. In the present study, we investigate the role of MSX1 in osteogenic differentiation of human dental pulp stem cells isolated from deciduous teeth. When these cells were exposed to osteogenesis-induction medium, runt-related transcription factor-2 (RUNX2), bone morphogenetic protein-2 (BMP2), alkaline phosphatase (ALPL), and osteocalcin (OCN) mRNA levels, as well as alkaline phosphatase activity, increased on days 4-12, and thereafter the matrix was calcified on day 14. However, knockdown of MSX1 with small interfering RNA abolished the induction of the osteoblast-related gene expression, alkaline phosphatase activity, and calcification. Interestingly, DNA microarray and PCR analyses revealed that MSX1 knockdown induced the sterol regulatory element-binding protein 2 (SREBP2) transcriptional factor and its downstream target genes in the cholesterol synthesis pathway. Inhibition of cholesterol synthesis enhances osteoblast differentiation of various mesenchymal cells. Thus, MSX1 may downregulate the cholesterol synthesis-related genes to ensure osteoblast differentiation of human dental pulp stem cells.
Msh 同源框 1（MSX1）编码一种转录因子，参与包括骨骼和牙齿在内的四肢及颅面部组织的胚胎发育。尽管 MSX1 在幼龄动物颅骨中调节成骨细胞分化，但关于 MSX1 对人类细胞成骨潜能的作用却知之甚少。在本研究中，我们调查了 MSX1 在从乳牙分离的人牙髓干细胞成骨分化中的作用。当这些细胞暴露于成骨诱导培养基时， runt 相关转录因子 2（RUNX2）、骨形态发生蛋白 2（BMP2）、碱性磷酸酶（ALPL）和骨钙素（OCN）的 mRNA 水平以及碱性磷酸酶活性在第 4 - 12 天增加，此后在第 14 天基质发生钙化。然而，用小干扰 RNA 敲低 MSX1 消除了成骨细胞相关基因表达、碱性磷酸酶活性和钙化的诱导。有趣的是，DNA 微阵列和 PCR 分析显示，MSX1 敲低诱导了胆固醇合成途径中的固醇调节元件结合蛋白 2（SREBP2）转录因子及其下游靶基因。抑制胆固醇合成可增强各种间充质细胞的成骨细胞分化。因此，MSX1 可能下调胆固醇合成相关基因，以确保人牙髓干细胞的成骨细胞分化。
