Department of Oral Biology, College of Stomatology, Dalian Medical University, Dalian, Liaoning 116044, China; Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, TX 75246, USA.
Department of Oral Biology, College of Stomatology, Dalian Medical University, Dalian, Liaoning 116044, China.
Exp Cell Res. 2018 Feb 15;363(2):188-195. doi: 10.1016/j.yexcr.2018.01.004. Epub 2018 Jan 11.
FAM20C mutations compromise the mineralization of skeleton and tooth in both human and mouse. Putatively, the mineralization disorder is attributed to the elevated fibroblast growth factor 23 (FGF23), which reduced the serum phosphorus by suppressing the reabsorption of phosphorus in kidney. Besides the regulation on systemic phosphorus homeostasis, FAM20C was also implicated to regulate cell behaviors and gene expression through a cell-autonomous manner. To identify the primary effects of Fam20c on dental mesenchymal cells, mouse Fam20c-deficient dental mesenchymal cells were generated by removing the floxed alleles from the immortalized mouse Fam20c dental mesenchymal cells with Cre-expressing lentivirus. The removal of Fam20c exerted no impact on cell morphology, but suppressed the proliferation and mobility of the dental mesenchymal cells. Fam20c deficiency also significantly reduced the expression of Osterix, Runx2, type I Collagen a 1 (Col1a1), Alkaline phosphatase (Alpl) and the members of the small integrin-binding ligand, N-linked glycoprotein (SIBLING) family, but increased Fgf23 expression. Consistently, the in vitro mineralization of Fam20c-deficient dental mesenchymal cells was severely disabled. However, supplements of the non-collagenous proteins from wild type rat dentin failed to rescue the compromised mineralization, suggesting that the roles of FAM20C in tooth mineralization are more than phosphorylating local matrices and regulating systemic phosphorus metabolism. Moreover, the down-regulated BMP signaling pathways in the Fam20c deficient dental mesenchymal cells revealed that the kinase activity of FAM20C might be required to maintain BMP signaling. In summary, our study discloses that Fam20c indeed regulates cell behaviors and cell signaling pathway in a cell-autonomous manner.
FAM20C 突变会损害人类和小鼠骨骼和牙齿的矿化。推测这种矿化障碍是由于成纤维细胞生长因子 23（FGF23）的升高引起的，它通过抑制肾脏对磷的重吸收来降低血清磷。除了对全身磷稳态的调节外，FAM20C 还通过细胞自主方式被牵连到调节细胞行为和基因表达。为了确定 Fam20c 对牙间质细胞的主要影响，通过用表达 Cre 的慢病毒去除永生化的 Fam20c 牙间质细胞中的 floxed 等位基因，生成了 Fam20c 缺失的小鼠牙间质细胞。 Fam20c 的缺失对细胞形态没有影响，但抑制了牙间质细胞的增殖和迁移。 Fam20c 缺失还显著降低了 Osterix、Runx2、I 型胶原 a1（Col1a1）、碱性磷酸酶（Alpl）和小整合素结合配体，N-连接糖蛋白（SIBLING）家族成员的表达，但增加了 Fgf23 的表达。一致地，fam20c 缺失的牙间质细胞的体外矿化严重受损。然而，野生型大鼠牙本质中非胶原蛋白的补充未能挽救受损的矿化，这表明 FAM20C 在牙齿矿化中的作用不仅仅是磷酸化局部基质和调节全身磷代谢。此外，fam20c 缺失的牙间质细胞中下调的 BMP 信号通路表明 FAM20C 的激酶活性可能是维持 BMP 信号所必需的。总之，我们的研究揭示了 Fam20c 确实以细胞自主的方式调节细胞行为和细胞信号通路。
