Smads蛋白在成牙本质细胞系MDPC-23中的表达及功能

目的研究Smads蛋白在成牙本质细胞系MDPC-23作为转化生长因子(TGF)β信号分子的作用。方法常规条件下培养MDPC-23细胞,在TGF-β1刺激培养1h后,观察细胞内Smad分子的定位变化。将Smads真核表达载体分别与报告基因载体p3TP-Lux瞬时共转染至MDPC-23,在TGF-β1刺激培养24h后,裂解细胞,用双荧光素酶报告基因检测系统检测细胞裂解液中的荧光素酶活性。结果MDPC-23细胞表达Smad2和Smad3蛋白分子,主要定位于细胞质,在TGF-β1刺激1h后,Smad2和Smad3从胞质向胞核转位聚集。TGF-β1可诱导p3TP-Lux基础启动子活性,约增加13倍。过表达野生型Smad3蛋白可促进TGF-β1对p3TP-Lux启动子活性的诱导,但是过表达Smad3突变体抑制TGF-β1对p3TP-Lux启动子活性的诱导。和Smad3作用相比,过表达Smad2野生型或突变型蛋白对TGF-β1诱导p3TP-Lux启动子活性无明显影响。结论在成牙本质细胞系MDPC-23内,Smad信号途径存在并参与介导TGF-β1诱导的转录调控。     

Smad分子在骨形成蛋白2调控成牙本质细胞Ⅰ型胶原基因表达中的作用

目的　研究Smad蛋白在骨形成蛋白 2 (bonemorphogeneticprotein 2 ,BMP 2 )调控小鼠成牙本质细胞系MDPC 2 3内Ⅰ型胶原α2链 [collagenα2 (Ⅰ ) ,COL1A2 ]表达中的作用。方法　细胞免疫组化观察MDPC 2 3细胞内BMP 2细胞内信号分子Smad1、Smad5和Smad6的表达。瞬时转染和报告基因检测观察Smad1、Smad5和Smad6在BMP 2调控COL1A2基因转录中的作用。结果　MDPC 2 3细胞表达Smad1、Smad5和Smad6。BMP 2能诱导含COL1A2基因启动子的荧光素酶报告基因活性。Smad1或Smad5过表达增强BMP 2诱导的COLIA2基因启动子活性 ,而Smad6过表达抑制BMP 2诱导的COL1A2基因启动子活性。过表达Smad1或Smad5突变型载体可以阻断BMP 2的诱导能力。结论　在MDPC 2 3细胞内 ,Smad信号途径存在并发挥功能 ,参与调控BMP 2对COL1A2基因的转录。Smad信号途径可能在BMP 2调控成牙本质细胞分化和牙本质形成过程中发挥重要作用     

Dentin-specific proteins in MDPC-23 cell line

Only four established odontoblast-like cell lines have been reported in the literature (1–6). Of the four, only two synthesize dentin-specific proteins. These studies report that the cell line MO6-G3 synthesizes phosphophoryn (DPP), dentin sialoprotein (DSP) and dentin matrix protein-1 (DMP-1), while MDPC-23 synthesizes DSP, but not DMP-1. The objective of the present study was to determine whether polyclonal antibodies to rat DSP and DPP would label odontoblasts on microscopic sections of day-19 fetal mouse incisor odontoblasts as well as cultured cells of the MDPC-23 cell line. The spontaneously immortalized MDPC-23 cell line was derived from fetal mouse molar papillae, made continuous by the 3T6 method and cloned by dilution. These cultures have been passaged 77 times after cloning, form multilayered nodules, and have high alkaline phosphatase activity. The data show positive reactivity in odontoblasts in 19-d mouse fetal incisors as well as in cultures of MDPC-23 cells by fluorescence and confocal microscopy. In addition, these cultures were characterized by phase microscopy and scanning and transmission electron microscopy. These findings suggest that MDPC-23 cells are of the odontoblast lineage.     

Expression of TGF-beta1, Smad7 and cell apoptosis in epithelium of oral lichen planus

OBJECTIVE: To examine the expression of TGF-beta1, Smad7 and cell apoptosis in oral lichen planus (OLP) and to evaluate the possible pathogenesis of oral lichen planus. METHODS: Immunohistochemical technique was used to study the expression of TGF-beta1 and Smad7 in the epithelia cells of 17 OLP cases and 7 normal oral mucosa (NOM). TUNEL was used for detecting the cell apoptosis in 17 OLP cases and 7 NOM. RESULTS: TGF-beta1 was moderately positive in the epithelia cells of OLP. All the epithelia cells in OLP showed strong cytoplasmic staining. The expression of TGF-beta1 and Smad7 were significantly increased in OLP compared with that in NOM (P < 0.05). Cell apoptotic index (AI) was remarkably increased in epithelia cells in OLP cases, and the cell apoptosis was localized in basal and suprabasal epithelial layers. There was a positive correlation between TGF-beta1 expression and cell apoptosis in the epithelia of OLP (r = 0.69, P <0.05). CONCLUSIONS: High expression of TGF-beta1 and Smad7 in the epithelia of OLP suggests that TGF-beta1-Smad7 signal pathway was disturbed in oral lichen planus. The imbalance of TGF-beta1-Smad7 pathway may contribute to the mechanisms of cell apoptosis of epithelial cells in OLP.     

ClC chloride channels in tooth germ and odontoblast-like MDPC-23 cells

OBJECTIVE: To detect expression of ClC chloride channel mRNA in tooth germ and odontoblasts, and explore the affect of chloride channel function on cell proliferation and cell cycle. DESIGN: We extracted total RNA of tooth germ from newborn C57BL mice and mouse odontoblast-like cells (MDPC-23), then detected mRNA expression of chloride channel genes Clcn1-7 with RT-PCR. We used chloride channel blocker 5-nitro-2-(3- phenylpropylamino)benzoic acid (NPPB) to interfere with chloride channel function of MDPC-23 cells. Cell proliferation rate and cell cycle were detected with MTT assay and flow cytometry, respectively. Student's t-test was used to determine statistical significance between control and treatment groups. RESULTS: The mRNA of Clcn1-7 chloride channel genes was expressed in tooth germ of newborn mice. Clcn3, Clcn5 and Clcn7 mRNAs were expressed in MDPC-23 cells. NPPB slowed down the proliferation rate of MDPC-23 cells from day 2 to day 4 (P<0.01), and also changed the proportion of cell cycle phase. Comparing to the control, the proportion of G2/M phase cells reduced from 3.93+/-2.62% to 0.54+/-0.25% (P<0.05). The ratio of G1/G2 increased from 1.86+/-0.01 to 1.95+/-0.02 (P<0.05). CONCLUSIONS: There is abundant chloride channel gene expression in tooth germ. Some of these chloride channels may regulate tooth development through effects on cell proliferation and cell cycle signal pathway.     

Temporal Induction of Secretory Leukocyte Protease Inhibitor (SLPI) in Odontoblasts by Lipopolysaccharide and Wound Infection

IntroductionThe secretory leukocyte protease inhibitor (SLPI) is a bacterial lipopolysaccharide (LPS)-induced product of macrophages that antagonizes the LPS-induced activation of a number of proinflammatory signaling factors. From our previous experiments, it was found that SLPI was expressed slightly in odontoblast-like cells (MDPC-23). Therefore, these experiments were designed to determine the function of SLPI in MDPC-23 and odontoblasts during the inflammatory response caused by infections and wounds.MethodsMDPC-23 cells were exposed to 100 ng/mL Escherichia coli LPS, and artificial wounds were induced in the right first molar of the maxillary of rats. In addition, a morphological change in the MDPC-23 cells was observed after LPS treatment. MDPC-23 cells were transfected transiently with the nuclear factor kappa-B (NF-κB) promoter binding vector.ResultsThe level of SLPI expression increased strongly 30 minutes after the LPS treatment. Scanning electron microscopy revealed many extensions of the cytoplasmic processes after LPS stimulation. SLPI was expressed along the dentinal tubules and odontoblasts layer in rat teeth after an artificial wound. SLPI also inhibited the LPS-induced activation of NF-κB in MDPC-23.ConclusionsWe report for the first time that SLPI is expressed temporally in infected odontoblasts and may participate in the anti-inflammatory response through NF-κB signaling in odontoblast-like cells.     

尼古丁抑制成牙本质细胞增殖及作用机制的研究

目的观察尼古丁对成牙本质细胞增殖的抑制作用,并检测其对成牙本质细胞中Ca2+浓度的影响,以探讨尼古丁抑制成牙本质细胞的分子机制。方法体外培养成牙本质细胞系MDPC- 23细胞, 按每毫升2×104个接种,随机分为实验组和对照组,对照组不加任何刺激,实验组施加质量浓度为100 μg/mL尼古丁,并于8 h后加入浓度为10 μmol/L BrdU进行细胞周期标记,刺激24 h后固定细胞,行免疫荧光抗BrdU染色,碘化丙锭（PI）复染胞核,荧光显微镜下计数细胞总数与BrdU阳性细胞数,计算S期阳性细胞率并进行统计学分析。培养成牙本质细胞于特制培养皿中,施加质量浓度为100 μg/mL尼古丁刺激,激光共聚焦显微镜下检测成牙本质细胞中Ca2+浓度的动态变化。结果实验组、对照组S期阳性细胞率分别为36.3%、48.2%,实验组显著低于对照组。尼古丁刺激后,成牙本质细胞中Ca2+浓度迅速升高,在较高水平维持一段时间后缓慢下降。结论尼古丁可抑制成牙本质细胞增殖,这种作用同尼古丁升高成牙本质细胞中Ca2+浓度有关。     

Effect of antisense oligonucleotide against mouse dentine matrix protein 1 on mineralization ability and calcium ions metabolism in odontoblast-like cell line MDPC-23

AIM: To study the mineralization ability and the dynamic changes of intracellular and extracellular concentrations of calcium ions in the odontoblast-like cell line MDPC-23 affected by antisense oligonucleotide (AS-ODN) against mouse dentine matrix protein 1 (DMP1). METHODOLOGY: The expression of DMP1 in MDPC-23 cells was detected by an immunohistochemical method and its blocking outcome by the Western blot method. The alkaline phosphatase (ALP) activity, size and number of mineralized nodules, and the intracellular free ([Ca2+]if), total ([Ca2+]it) and the extracellular ([Ca2+]e) calcium ion concentrations in MDPC-23 cells in the experimental group affected with AS-ODN were compared with those in the control group (paired-samples t-test). RESULTS: Dentine matrix protein 1 was stably expressed in a stable way in MDPC-23 cells; the expression was only just detectable at 12 h and became negative after 24 h affected by AS-ODN. Compared with the control groups, ALP activity of MDPC-23 cells in the AS-ODN group was decreased (P < 0.05), and both the number and size of mineralized nodules were smaller than those in the control group. [Ca2+]if in the AS-ODN group increased and then decreased after 24 h. [Ca2+]it dropped substantially to the lowest point at 24 h (P < 0.01). [Ca2+]e increased before treatment for 24 h and then dropped, however, it was still higher than that of the control group. CONCLUSIONS: Antisense oligonucleotide against DMP1 could decrease mineralization ability and affect the intracellular and extracellular concentrations of calcium ions in MDPC-23 cells. This would indicate that DMP1 regulates the metabolism and transportation of calcium ions in odontoblasts, and thus boosts dentine mineralization.     

细胞内信号转导分子——Smad7在人牙胚发育中的表达和意义

目的　探讨Smad7在TGF-β调节牙胚发育过程中的作用。方法　采用免疫组化ABC法观察Smad7在人牙胚发育各个时期的表达分布及其变化情况。结果　人牙胚发育各个时期均表达Smad7,但各期分布模式有所不同。Smad7在不同发育时期牙胚中的分布与TGF-β及其特异的信号转导分子Smad2、3有相似之处。结论　Smad7 可能在TGF-β调节成釉细胞和成牙本质细胞分化的信号转导通路中起一定的作用。     

TLR4 mediates LPS-induced VEGF expression in odontoblasts

Lipopolysaccharide (LPS) from gram-negative bacteria cell walls such as Prevotella intermedia and Escherichia coli induce vascular endothelial growth factor (VEGF) expression in odontoblasts, but not in undifferentiated dental pulp cells. CD14 and TLR4 are responsible for LPS signaling in macrophages, but their expression levels and function in dental pulp cells are unknown. We showed here that murine odontoblast-like cells (MDPC-23) express CD14 and TLR4 by immunohistochemistry and flow cytometry. In contrast, undifferentiated dental pulp cells (OD-21) presented low or no expression of these two receptors. MDPC-23 cells showed CD14 and TLR4 up-regulation upon exposure to LPS, as determined by real time PCR. Dominant negative murine TLR4 (DN-mTLR4) transfected MDPC-23 cells did not show upregulated VEGF expression in response to LPS stimulation. These results demonstrate that odontoblast-like cells express CD14 and TLR4, and that LPS-induced VEGF expression is mediated, at least in part, by TLR4 signaling.     

神经生长因子受体介导的黑色素瘤抗原编码基因同源蛋白对牙髓细胞增殖的影响

目的探索神经生长因子受体介导的黑色素瘤抗原编码基因同源蛋白(NRAGE)对人牙髓细胞(h DPCs)和小鼠成牙本质细胞(MDPC-23)细胞增殖的影响。方法重组慢病毒转染细胞稳定敲除h DPCs和MDPC-23的NRAGE表达,体外组织块法原代培养h DPCs和MDPC-23,进而检测NRAGE对h DPCs和MDPC-23的增殖影响。采用CCK-8法分析NRAGE对h DPCs和MDPC-2细胞增殖的影响,流式细胞术分析NRAGE对h DPCs和MDPC-23的细胞周期分布和细胞凋亡影响。免疫荧光法检测NRAGE和NF-κB的表达和定位,分析NF-κB蛋白表达水平,并用IKK抑制剂处理细胞后,分析细胞周期和细胞凋亡。结果重组慢病毒转染后NRAGE的mRNA和蛋白水平下降显着。NRAGE敲减后抑制了h DPCs和MDPC-23的增殖活性和凋亡。NRAGE敲减后显示h DPCs的G0G1期滞留显著,而对MDPC-23没有影响。同时,NRAGE敲减后激活NF-κB信号通路。IKK抑制剂可以抑制NRAGE敲除后对h DPCs和MDPC-23的细胞凋亡的抑制作用。结论 NRAGE敲减后抑制牙髓细胞的增殖活性。NRAGE通过NF-κB信号通路调控h DPCs的细胞周期和凋亡。     

核心结合因子α1对牙本质涎磷蛋白基因转录调控的影响

目的观察核心结合因子α1(corebindingfactorα1,cbfα1)对牙本质涎磷蛋白(dentinsialophosphoprotein,DSPP)基因启动活性的影响。方法选择小鼠成牙本质细胞样细胞MDPC-23为实验细胞,DSPP基因上游2.6kb片段(-2475bp～ 53bp)为启动子。通过采用瞬时转染、报告基因等方法,用SPSS10.0统计软件包对结果进行统计学分析,观察在MDPC-23中,cbfα1对DSPP基因启动子启动活性的影响。结果在MDPC-23细胞中,pGL3-Enhancer-2.6K pcDNA3-cbfα1共转染组荧光素酶的表达量显著小于pGL3-Enhancer-2.6K pcDNA3共转染组(P<0.01)。结论cbfα1对DSPP基因上游-2475bp～ 53bp区域的启动活性有抑制作用。     

The roles of Smad 2/3 in transforming growth factor-beta 1 signaling in human dental pulp cells]

OBJECTIVE: To explore the roles of Smad 2/3 in transforming growth factor-beta(1) (TGF-beta(1)) signaling by human dental pulp cells. METHODS: Laser scanning confocal microscope was used to observe translocation of Smad 2/3 from plasma into nucleus in cultured dental pulp cells at early stage of TGF-beta(1) treatment, and changes of Smad 2/3 protein expression at later stage were evaluated by Western blot analyses. RESULTS: The expression of Smad 2/3 (fluorescence intensity) kept decreasing in cytoplasm but increasing in nucleus within 2 h after TGF-beta(1) treatment, forming a trend that Smad 2/3 translocated into nucleus from cytoplasma. The total amount of Smad 2 protein remained unchanged before and after TGF-beta(1) treatment, but the expression level of Smad 3 decreased markedly after 24 h treatment and kept dropping by 48 h. CONCLUSIONS: The results suggest that the Smad 2/3 may be the downstream signal transducers of TGF-beta(1) in human dental pulp cells and Smad 2/3 may mediate TGF-beta(1) signaling by translocation early in TGF-beta(1) treatment, while down-regulation of Smad 3 expression by TGF-beta(1) at later stage is involved in negative modulation of TGF-beta(1) signaling.     

牙本质基质蛋白1基因反义核酸对MDPC-23细胞内、外钙离子浓度的影响

目的观察牙本质基质蛋白1(DMP1)基因反义寡核苷酸作用下成牙本质细胞系MDPC-23细胞内、外钙离子浓度的动态变化,揭示牙本质矿化机制。方法以稳定表达DMP1的MDPC-23细胞为靶细胞,10μmol/L反义DMP1(AS-ODN)为阻断剂,用Western blot法检测不同时间细胞DMP1的表达情况,并观察不同作用时间内MDPC-23细胞内游离钙离子[(Ca2+)if]、总钙离子[(Ca2+)it]和细胞外钙离子[(Ca2+)e]的动态变化。结果Western blot法检测DMP1蛋白在MDPC-23细胞的表达在AS-ODN加入后12 h时减弱,24 h后完全阻断。与正常组和正义核酸组(S-ODN)相比较(平均荧光值为87.46±39.60),AS-ODN组(Ca2+)if先升高(平均荧光值12 h处为104.10±27.06;24 h处为98.46±19.92),AS-ODN作用24 h后,(Ca2+)if又降低(平均荧光值36 h处为77.54±14.95;48 h处为68.43±22.11);(Ca2+)it明显降低,于24 h处至最低值(0.142±0.233)mmol/L(P<0.01);(Ca2+)e呈上升趋势,且与对照组差异无显著性(P>0.05)。结论反义DMP1能够影响MDPC-23细胞内(Ca2+)if和(Ca2+)it浓度,提示DMP1参与调节成牙本质细胞的钙离子代谢和转运过程,可能在牙本质矿化过程中发挥作用。     

Toxicity of chlorhexidine on odontoblast-like cells

Chlorhexidine gluconate (CHX) is recommended for a number of clinical procedures and it has been pointed out as a potential cavity cleanser to be applied before adhesive restoration of dental cavities. Objective: As CHX may diffuse through the dentinal tubules to reach a monolayer of odontoblasts that underlies the dentin substrate, this study evaluated the cytotoxic effects of different concentrations of CHX on cultured odontoblast-like cells (MDPC23). Material and Methods: Cells were cultured and exposed to CHX solutions at concentrations of 0.06%, 0.12%, 0.2%, 1% and 2%. Pure culture medium (α-MEM) and 3% hydrogen peroxide were used as negative and positive control, respectively. After exposing the cultured cells to the controls and CHX solutions for 60 s, 2 h or 60 s with a 24h recovery period, cell metabolism (MTT assay) and total protein concentration were evaluated. Cell morphology was assessed under scanning electron microscopy. CHX had a dose-dependent toxic effect on the MDPC-23 cells. Results: Statistically significant difference was observed when the cells were exposed to CHX in all periods (p<0.05). Significant difference was also determined for all CHX concentrations (p<0.05). The 60-s exposure time was the least cytotoxic (p<0.05), while exposure to CHX for 60 s with a 24-h recovery period was the most toxic to the cells (p<0.05). Conclusion: Regardless of the exposure time, all CHX concentrations had a high direct cytotoxic effect to cultured MDPC-23 cells.     

牙本质磷蛋白mRNA原位杂交方法的建立

目的:建立检测牙本质磷蛋白(DPP)mRNA表达的原位杂交方法。方法:选用发育各阶段的牙胚、牙齿和体外培养的MDPC-23成牙本质细胞为对象,采用地高辛标记的寡核苷酸探针的原位杂交方法。结果:DPP mRNA在牙胚与牙齿中的成牙本质细胞、前成釉细胞和体外培养的成牙本质细胞存在阳性表达。结论:设计的探针敏感性高,特异性高,所建立的原位杂交方法是研究牙本质发育和损伤修复的良好方法。     

Smad2、3在人牙髓组织中的表达及意义

目的：观察转化生长因子β特异的细胞内信号转导分子Smad2、3在牙髓组织中的表达及其变化,探讨Smad2、3在牙髓损伤修复中的作用。方法：用免疫组化方法检测Smad2、3在正常、龋坏及炎症牙髓组织中的表达。结果：Smad2,3在正常和龋环牙髓的成本本质细胞层呈强阳性表达,在下方的多细胞区及中心部牙髓有阳性或弱阳性表达,炎症牙随浸润的炎细胞中Smad2、3呈强阳性表达,各类牙髓中Smad2的表达较Smad3略强。结论：Smad2、3在正常、龋坏及炎症牙髓组织中有表达,提示Smad2、3可能在TGF－β调节牙髓细胞增殖、分化的信号转导途径中发挥一定的作用。     

Transforming growth factor beta2 regulates growth and differentiation of pulp cells via ALK5/Smad2/3

Transforming growth factor beta (TGF-beta) may regulate the biological activities of dental pulp cells. We found that human dental pulp cells expressed TGF-beta1, TGF-beta2, and a little amount of TGF-beta3 messenger RNA (mRNA). The exposure of pulp cells to TGF-beta2 induced the phosphorylation of Smad2/3, Smad1/5/8, and extracellular regulated-kinase 1/2 (ERK1/2) as observed by Western blotting. Exposure to TGF-beta2 decreased the alkaline phosphatase (ALP) mRNA expression and enzyme activity. Pretreatment of pulp cells with SB431542 (an inhibitor of TGF-beta ALK-4, ALK-5, and ALK-7 receptors) but not U0126 (a MEK1 inhibitor) prevented the inhibition of viable cell number, ALP activity, and mRNA expression by TGF-beta2 in dental pulp cells. These results suggest that TGF-beta may affect the growth and differentiation of dental pulp cells via an autocrine fashion by activation of the ALK/Smad2/3-signal transduction pathways. TGF-beta2 possibly regulates the differentiation of pulp cell at specific stages synergistically with other factors.