Changes of the unique odontogenic properties of rat apical bud cells under the developing apical complex microenvironment / 国际口腔科学杂志·英文版

<p><b>AIM</b>To characterize the odontogenic capability of apical bud and phenotypical change of apical bud cells (ABCs) in different microenvironment.</p><p><b>METHODOLOGY</b>Incisor apical bud tissues from neonatal SD rat were dissected and transplanted into the renal capsules to determine their odontogenic capability. Meanwhile ABCs were cultured and purified by repeated differential trypsinization. Then ABCs were cultured with conditioned medium from developing apical complex cells (DAC-CM). Immunocytochemistry, reverse transcriptase polymerase chain reaction (RT-PCR) and scanning electron microscope (SEM) were performed to compare the biological change ofABC treated with or without DAC-CM.</p><p><b>RESULTS</b>First we confirmed the ability of apical bud to form crown-like structure ectopically. Equally important, by using the developing apical complex (DAC) conditioned medium, we found the microenvironment created by root could abrogate the "crown" features of ABCs and promote their proliferation and differentiation.</p><p><b>CONCLUSION</b>ABCs possess odontogenic capability to form crown-like tissues and this property can be affected by root-produced microenvironment.</p>

Effects and molecular mechanism of nicotine on odontoblasts / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To observe the effects of nicotine on the proliferation of odontoblasts and explore the possible mechanism.</p><p><b>METHODS</b>Odontoblasts MDPC-23 were cultured, inoculated and divided into two groups randomly. With no stimuli added for the control group, the experimental group was stimulated by 100 microg/mL nicotine. After 8 hours, 10 micromol/L BrdU was added to label cells at S stage in cell cycle. 24 hours later, odontoblasts were fixed and immunofluorescence staining was performed with specific mouse BrdU antibody. After counterstaining with propidium iodide, BrdU positive cells were arbitrarily scored microscopically by an independent estimation conducted three times, and the corresponding total cell number in the same vision were counted in both groups. BrdU positive cell rates were calculated and compared statistically. At the same time, odontoblasts MDPC-23 were cultured and stimulated by 100 microg/mL nicotine, the dynamic Ca2+ concentration inside the cytoplasm were detected immediately by a confocal laser scanning microscope.</p><p><b>RESULTS</b>The ratio of S stage cells in the experimental group was 36.3% significantly lower than that (48.2%) in the control group. After the addition of 100 microg/mL nicotine, the Ca2+ concentration inside the cytoplasm rose rapidly, sustained at a high level for a short time and then relapsed gradually.</p><p><b>CONCLUSION</b>Nicotine had inhibitory effects on the proliferation of odontoblasts MDPC-23, which might be related to the increased Ca2+ concentration in the cytoplasm.</p>

Expression feature and bioinformatic analysis of molar root patterning gene 1 / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To examine the expression of molar root patterning gene 1 (Mrp1) and predict the Mrp1 structure by bioinformatics analysis.</p><p><b>METHODS</b>A pair of Mrp1-specific PCR primers were designed, and RT-PCR method was used to study the mRNA's expression pattern in rat molar root and other organs. Gene positioning and other protein sequence prediction were carried out by chromosome analysis and other bioinformatics analysis.</p><p><b>RESULTS</b>Mrp1 was expressed not only in the molar but also in the developing pancreas, liver, lung and kidney tissues. Mrp1 was located in the 18q12.3 chromosome of the rats and the Mrp1 amino acids sequence had about 37% homology with a known protein Uroplakin IIIb (p35) which was an urothelial differentiation membrane molecular marker. A trans-membrane structure, 5 PKC phosphorylation sites and 4 CKII phosphorylation sites in Mrp1 were found.</p><p><b>CONCLUSIONS</b>Mrp1 has a broad expression in different developing organs, and it may have a important function in the rat tooth root development.</p>

Expression, subcellular localization and nuclear translocation of transcription factor up stream stimulatory factor-1 in odontoblasts / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To examine the expression and subcellular localization of transcription factor USF1 in odontoblasts and investigate whether nuclear translocation occurs under stimuli.</p><p><b>METHODS</b>Odontoblasts MDPC-23 were cultured on coverslips and divided into 2 groups. Group 1 received no stimuli, and group 2 was stimulated by nicotine with various concentrations respectively for 1h. Then the mountings of odontoblasts were prepared and immunocytochemical staining was performed with specific USF1 antibody via SABC method. Hela cells were used as positive control.</p><p><b>RESULTS</b>The staining was positive in the cytoplasm of odontoblasts in group 1, but in the nuclei of Hela cells and in 100 mg/L nicotine-stimulated odontoblasts in group 2.</p><p><b>CONCLUSIONS</b>There exists USF1 protein in odontoblasts, which locates in the cytoplasm and could translocate into nuclei under the stimulation of nicotine.</p>

Regulation of osteopontin expression in odontoblasts by upstream stimulatory factor 1 / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the regulation effects of upstream stimulatory factor 1 (USF1) on osteopontin expression in odontoblasts.</p><p><b>METHODS</b>Odontoblast MDPC-23 was cultured and stably transfected with PCMV-USF1 or A-USF plasmids. Total RNA was extracted and osteopontin expression examined by semi-quantitative RT-PCR. Gray value of osteopontin was measured and statistic analysis performed.</p><p><b>RESULTS</b>Clones of stable PCMV-USF1 and A-USF plasmids transfection were obtained. Compared with the control, osteopontin was upregulated in PCMV-USF1 transfection group, and downregulated in A-USF transfection group.</p><p><b>CONCLUSIONS</b>Upstream stimulatory factor 1 could regulate the osteopontin expression in odontoblasts, which could be blocked partly by A-USF.</p>