Deletion or mutation of dentin matrix protein 1 （DMP1） leads to hypophosphatemic rickets and defects within the dentin. However, it is largely unknown if this pathological change is a direct role of DMP1 or an indir...Deletion or mutation of dentin matrix protein 1 （DMP1） leads to hypophosphatemic rickets and defects within the dentin. However, it is largely unknown if this pathological change is a direct role of DMP1 or an indirect role of phosphate （Pi） or both. It has also been previously shown that Klotho-deficient mice, which displayed a high Pi level due to a failure of Pi excretion, causes mild defects in the dentinal structure. This study was to address the distinct roles of DMP1 and Pi homeostasis in cell differentiation, apoptosis and mineralization of dentin and enamel. Our working hypothesis was that a stable Pi homeostasis is critical for postnatal tooth formation, and that DMP1 has an antiapoptotic role in both amelogenesis and dentinogenesis. To test this hypothesis, Dmpl-null （Dmpl-/-）, Klotho-deficient （kl/kl）, Dmpl/Klotho-double-deficient （Dmpl-/-/kl/kl） and wild-type （WT） mice were killed at the age of 6 weeks. Combinations of X-ray, microcomputed tomography （I^CT）, scanning electron microscopy （SEM）, histology, apoptosis and immunohistochemical methods were used for characterization of dentin, enamel and pulp structures in these mutant mice. Our results showed that Dmpl-/- （a low Pi level） or kl/kl（a high Pi level） mice displayed mild dentin defects such as thin dentin and a reduction of dentin tubules. Neither deficient mouse line exhibited any apparent changes in enamel or pulp structure. However, the double-deficient mice （a high Pi level） displayed severe defects in dentin and enamel structures, including loss of dentinal tubules and enamel prisms, as well as unexpected ectopic ossification within the pulp root canal. TUNEL assay showed a sharp increase in apoptotic cells in ameloblasts and odontoblasts. Based on the above findings, we conclude that DMP1 has a protective role for odontoblasts and ameloblasts in a pro-apoptotic environment （a high Pi level）.展开更多
several heat shock proteins have been investigated in relation to tooth development, no available information is available about the spatial and temporal expression pattern of heat shock protein 60 （Hsp 60）. To char...several heat shock proteins have been investigated in relation to tooth development, no available information is available about the spatial and temporal expression pattern of heat shock protein 60 （Hsp 60）. To characterize Hsp 60 expression in the structures of the developing tooth germ, we used Western blotting, immunohistochemistry and in situ hybridization. Hsp 60 was present in high amounts in the inner and outer enamel epithelia, enamel knot （EK） and stratum intermedium （SI）. Hsp 60 also appeared in odontoblasts beginning in the bell stage. To obtain data on the possible effect of Hsp 60 on isolated lower incisors from mice, we performed in vitro culturing. To investigate the effect of exogenous Hsp 60 on the cell cycle during culturing, we used the 5-bromo-2- deoxyuridine （BrdU） incorporation test on dental cells. Exogenously administered Hsp 60 caused bluntness at the apical part of the 16.5-day-old tooth germs, but it did not influence the proliferation rate of dental cells. We identified the expression of Hsp 60 in the developing tooth germ, which was present in high concentrations in the inner and outer enamel epithelia, EK, SI and odontoblasts. High concentration of exogenous Hsp 60 can cause abnormal morphology of the tooth germ, but it did not influence the proliferation rate of the dental cells. Our results suggest that increased levels of Hsp 60 may cause abnormalities in the morphological development of the tooth germ and support the data on the significance of Hsp during the developmental processes.展开更多
Anti-wear performance of human enamel in the mouth is closely related to the lubrication of salivary pellicle.It is well known that the inorganic hydroxyapatite(HA)of the enamel plays an important role in the adsorpti...Anti-wear performance of human enamel in the mouth is closely related to the lubrication of salivary pellicle.It is well known that the inorganic hydroxyapatite(HA)of the enamel plays an important role in the adsorption and pellicle-forming of salivary proteins on the enamel,but the role of enamel matrix proteins remains unclear.In this study,the adsorption and lubrication behavior of salivary proteins on original,heated,and deproteinated enamel surfaces was comparatively investigated using an atomic force microscopy and nano-indentation/scratch techniques.Compared with that on the original enamel surface,the adsorption and lubrication behavior of salivary proteins remains almost unchanged on the heated enamel surface(where the enamel matrix proteins are denatured but the size of HA crystalline nanoparticles keeps constant)but exhibits an obvious compromise on the deproteinated enamel surface(where the enamel matrix proteins are removed and agglomeration of HA crystallites occurs).The HA agglomeration weakens the electrostatic interaction of enamel surfaces with salivary proteins to cause a distinct negative influence on the adsorption and pellicle-forming of salivary proteins.Further,the negative effect is confirmed with a quartz crystal microbalance with dissipation.In summary,by regulating enamel nanostructure for appropriate electrostatic interactions between salivary proteins and enamel surfaces,the enamel matrix proteins play an essential role in the adsorption and pellicle-forming of salivary proteins on human enamel,and then contribute to saliva lubrication,which provides the enamel with an anti-wear mechanism.The findings will promote and assist the design of enamel-inspired anti-wear materials.展开更多
背景:釉基质衍生物已经在临床上用于治疗严重的牙周炎,发现其可促进牙周组织修复、再生,但其中的机制还未阐明。目的:探讨釉基质衍生物对牙周膜干细胞分化和增殖的作用。方法:分离培养人牙周膜干细胞,检测其克隆形成率、表面抗原表达情...背景:釉基质衍生物已经在临床上用于治疗严重的牙周炎,发现其可促进牙周组织修复、再生,但其中的机制还未阐明。目的:探讨釉基质衍生物对牙周膜干细胞分化和增殖的作用。方法:分离培养人牙周膜干细胞,检测其克隆形成率、表面抗原表达情况,鉴定其多向分化潜能。将不同质量浓度的釉基质衍生物(20,50或100 mg/L)作用于牙周膜干细胞培养2,4周,用Trichrome和Von Kosa’s染色法检测牙周膜干细胞胶原合成及矿化结节形成情况,Real time RT-PCR方法检测成骨分化相关基因Ⅰ型胶原、骨钙素、RUX2的表达,MTT法和生长率法检测牙周膜干细胞的增殖情况。结果与结论:牙周膜干细胞呈梭形,其克隆形成率较牙周膜细胞高,表面抗原CD105,CD29,CD45,CD44的表达率分别为99.8%,99.7%,1.26%,98.8%,具备多向分化潜能。釉基质衍生物呈现一定的时间剂量效应关系促进牙周膜干细胞胶原合成及矿化结节形成,促进成骨分化相关基因Ⅰ型胶原、骨钙素、RUX2的表达,促进牙周膜干细胞的增殖,可能在牙周组织修复、再生中发挥作用。展开更多
基金supported by NIH grants Jian-Quan Feng (DE018486) and to Chun-Lin Qin (DE005092)State Key Laboratory of Oral Diseases Open Funding (SKLODOF2010-03) to Jian-Quan Feng
文摘Deletion or mutation of dentin matrix protein 1 （DMP1） leads to hypophosphatemic rickets and defects within the dentin. However, it is largely unknown if this pathological change is a direct role of DMP1 or an indirect role of phosphate （Pi） or both. It has also been previously shown that Klotho-deficient mice, which displayed a high Pi level due to a failure of Pi excretion, causes mild defects in the dentinal structure. This study was to address the distinct roles of DMP1 and Pi homeostasis in cell differentiation, apoptosis and mineralization of dentin and enamel. Our working hypothesis was that a stable Pi homeostasis is critical for postnatal tooth formation, and that DMP1 has an antiapoptotic role in both amelogenesis and dentinogenesis. To test this hypothesis, Dmpl-null （Dmpl-/-）, Klotho-deficient （kl/kl）, Dmpl/Klotho-double-deficient （Dmpl-/-/kl/kl） and wild-type （WT） mice were killed at the age of 6 weeks. Combinations of X-ray, microcomputed tomography （I^CT）, scanning electron microscopy （SEM）, histology, apoptosis and immunohistochemical methods were used for characterization of dentin, enamel and pulp structures in these mutant mice. Our results showed that Dmpl-/- （a low Pi level） or kl/kl（a high Pi level） mice displayed mild dentin defects such as thin dentin and a reduction of dentin tubules. Neither deficient mouse line exhibited any apparent changes in enamel or pulp structure. However, the double-deficient mice （a high Pi level） displayed severe defects in dentin and enamel structures, including loss of dentinal tubules and enamel prisms, as well as unexpected ectopic ossification within the pulp root canal. TUNEL assay showed a sharp increase in apoptotic cells in ameloblasts and odontoblasts. Based on the above findings, we conclude that DMP1 has a protective role for odontoblasts and ameloblasts in a pro-apoptotic environment （a high Pi level）.
基金supported by the European Union and the State of Hungary and co-financed by the European Social Fund in the framework of TA′MOP 4.2.4.A/2-11-12012-0001‘National Excellence Program’supported by a Ja′nos Bolyai fellowship from the Hungarian Academy of Science
文摘several heat shock proteins have been investigated in relation to tooth development, no available information is available about the spatial and temporal expression pattern of heat shock protein 60 （Hsp 60）. To characterize Hsp 60 expression in the structures of the developing tooth germ, we used Western blotting, immunohistochemistry and in situ hybridization. Hsp 60 was present in high amounts in the inner and outer enamel epithelia, enamel knot （EK） and stratum intermedium （SI）. Hsp 60 also appeared in odontoblasts beginning in the bell stage. To obtain data on the possible effect of Hsp 60 on isolated lower incisors from mice, we performed in vitro culturing. To investigate the effect of exogenous Hsp 60 on the cell cycle during culturing, we used the 5-bromo-2- deoxyuridine （BrdU） incorporation test on dental cells. Exogenously administered Hsp 60 caused bluntness at the apical part of the 16.5-day-old tooth germs, but it did not influence the proliferation rate of dental cells. We identified the expression of Hsp 60 in the developing tooth germ, which was present in high concentrations in the inner and outer enamel epithelia, EK, SI and odontoblasts. High concentration of exogenous Hsp 60 can cause abnormal morphology of the tooth germ, but it did not influence the proliferation rate of the dental cells. Our results suggest that increased levels of Hsp 60 may cause abnormalities in the morphological development of the tooth germ and support the data on the significance of Hsp during the developmental processes.
基金supported by National Natural Science Foundation of China(Nos.51675449 and 52105212)Sichuan Science and Technology Program(No.2023NSFSC0863)China Postdoctoral Science Foundation(No.2021M702712).
文摘Anti-wear performance of human enamel in the mouth is closely related to the lubrication of salivary pellicle.It is well known that the inorganic hydroxyapatite(HA)of the enamel plays an important role in the adsorption and pellicle-forming of salivary proteins on the enamel,but the role of enamel matrix proteins remains unclear.In this study,the adsorption and lubrication behavior of salivary proteins on original,heated,and deproteinated enamel surfaces was comparatively investigated using an atomic force microscopy and nano-indentation/scratch techniques.Compared with that on the original enamel surface,the adsorption and lubrication behavior of salivary proteins remains almost unchanged on the heated enamel surface(where the enamel matrix proteins are denatured but the size of HA crystalline nanoparticles keeps constant)but exhibits an obvious compromise on the deproteinated enamel surface(where the enamel matrix proteins are removed and agglomeration of HA crystallites occurs).The HA agglomeration weakens the electrostatic interaction of enamel surfaces with salivary proteins to cause a distinct negative influence on the adsorption and pellicle-forming of salivary proteins.Further,the negative effect is confirmed with a quartz crystal microbalance with dissipation.In summary,by regulating enamel nanostructure for appropriate electrostatic interactions between salivary proteins and enamel surfaces,the enamel matrix proteins play an essential role in the adsorption and pellicle-forming of salivary proteins on human enamel,and then contribute to saliva lubrication,which provides the enamel with an anti-wear mechanism.The findings will promote and assist the design of enamel-inspired anti-wear materials.
文摘背景:釉基质衍生物已经在临床上用于治疗严重的牙周炎,发现其可促进牙周组织修复、再生,但其中的机制还未阐明。目的:探讨釉基质衍生物对牙周膜干细胞分化和增殖的作用。方法:分离培养人牙周膜干细胞,检测其克隆形成率、表面抗原表达情况,鉴定其多向分化潜能。将不同质量浓度的釉基质衍生物(20,50或100 mg/L)作用于牙周膜干细胞培养2,4周,用Trichrome和Von Kosa’s染色法检测牙周膜干细胞胶原合成及矿化结节形成情况,Real time RT-PCR方法检测成骨分化相关基因Ⅰ型胶原、骨钙素、RUX2的表达,MTT法和生长率法检测牙周膜干细胞的增殖情况。结果与结论:牙周膜干细胞呈梭形,其克隆形成率较牙周膜细胞高,表面抗原CD105,CD29,CD45,CD44的表达率分别为99.8%,99.7%,1.26%,98.8%,具备多向分化潜能。釉基质衍生物呈现一定的时间剂量效应关系促进牙周膜干细胞胶原合成及矿化结节形成,促进成骨分化相关基因Ⅰ型胶原、骨钙素、RUX2的表达,促进牙周膜干细胞的增殖,可能在牙周组织修复、再生中发挥作用。
