Characterization of Fam20C expression in odontogenesis and osteogenesis using transgenic mice / 国际口腔科学杂志·英文版

Our previous studies have demonstrated that Fam20C promotes differentiation and mineralization of odontoblasts, ameloblasts, osteoblasts and osteocytes during tooth and bone development. Ablation of the Fam20C gene inhibits bone and tooth growth by increasing fibroblast growth factor 23 in serum and causing hypophosphatemia in conditional knockout mice. However, control and regulation of the expression of Fam20C are still unknown. In this study, we generated a transgenic reporter model which expresses green fluorescence protein (GFP) driven by the Fam20C promoter. Recombineering was used to insert a 16 kb fragment of the mouse Fam20C gene (containing the 15 kb promoter and 1.1 kb of exon 1) into a pBluescript SK vector with the topaz variant of GFP and a bovine growth hormone polyadenylation sequence. GFP expression was subsequently evaluated by histomorphometry on cryosections from E14 to adult mice. Fluorescence was evident in the bone and teeth as early as E17.5. The GFP signal was maintained stably in odontoblasts and osteoblasts until 4 weeks after birth. The expression of GFP was significantly reduced in teeth, alveolar bone and muscle by 8 weeks of age. We also observed colocalization of the GFP signal with the Fam20C antibody in postnatal 1- and 7-day-old animals. Successful generation of Fam20C-GFP transgenic mice will provide a unique model for studying Fam20C gene expression and the biological function of this gene during odontogenesis and osteogenesis.

A single nucleotide polymorphism in the matrix metalloproteinase 2 promoter is closely associated with high risk of nasopharyngeal carcinoma in Cantonese from southern China / 癌症

Matrix metalloproteinase 2 (MMP2) has been shown to play an important role in several steps of cancer development. The -1306C/T polymorphism of the MMP2 gene displays a strikingly lower promoter activity than the T allele, and the CC genotype in the MMP2 promoter has been reported to associate with the development of several cancers. To assess the contribution of the MMP2 -1306C/T polymorphism to the risk of nasopharyngeal carcinoma (NPC), we conducted a case-control study and analyzed MMP2 genotypes in 370 patients with NPC and 390 frequency-matched controls using real-time PCR-based TaqMan allele analysis. We found that subjects with the CC genotype had an increased risk (OR = 1.55, 95% CI = 1.05-2.27) of developing NPC compared to those with the CT or TT genotypes. Furthermore, we found that the risk of NPC was markedly increased in subjects who were smokers (OR = 15.04, 95% CI = 6.65-33.99), heavy smokers who smoked ≥ 20 pack-years (OR = 18.66, 95% CI = 7.67-45.38), or young (<60 years) at diagnosis (OR = 1.52, 95% CI = 1.01-2.29). Our results provide molecular epidemiological evidence that the MMP2 -1306C/T promoter polymorphism is associated with NPC risk, and this association is especially noteworthy in heavy smokers.

Immortalized human odontoblast-like cell line expressed dentin extracellular matrix in vitro / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To determine whether dentin matrix proteins were expressed by the human odontoblast-like cell line hTERT-hOd-1 in vitro.</p><p><b>METHODS</b>Collagen type I, bone sialoprotein (BSP), dentin matrix protein 1 (DMP1) and the marker for odontoblast, dentin sialophosphoprotein (DSPP) and dentin sialoprotein (DSP) were detected in these cells by immunohistochemistry, RT-PCR and in situ hybridization. During being cultured in mineralizing medium for 5 weeks, the secretion of OC and activity of ALP were measured once a week.</p><p><b>RESULTS</b>DSPP, DMP1, BSP and collagen type I were expressed in hTERT-hOd-1 either at mRNA or protein level. Under the induction of mineralizing medium, the cells showed higher activity of ALP and increased secretion of OC.</p><p><b>CONCLUSION</b>hTERT-hOd-1 expressed dentin extracellular matrix in vitro, which means the cell line has the potential of mineralization.</p>