The root is crucial for the physiological function of the tooth, and a healthy root allows an artificial crown to function as required clinically. Tooth crown development has been studied intensively during the last f...The root is crucial for the physiological function of the tooth, and a healthy root allows an artificial crown to function as required clinically. Tooth crown development has been studied intensively during the last few decades, but root development remains not well understood. Here we review the root development processes, including cell fate determination, induction of odontoblast and cementoblast differentiation, interaction of root epithelium and mesenchyme, and other molecular mechanisms. This review summarizes our current understanding of the signaling cascades and mechanisms involved in root development. It also sets the stage for de novo tooth regeneration.展开更多
The interaction between Hertwig's epithelial root sheath(HERS) and the adjacent mesenchyme is vitally important in mouse tooth root development. We previously generated odontoblast-specific Ctnnb1(encoding β-cate...The interaction between Hertwig's epithelial root sheath(HERS) and the adjacent mesenchyme is vitally important in mouse tooth root development. We previously generated odontoblast-specific Ctnnb1(encoding β-catenin) deletion mice, and demonstrated that odontoblast β-catenin signaling regulates odontoblast proliferation and differentiation. However, the role of odontoblast β-catenin signaling in regulation of HERS behavior has not been fully investigated. Here, using the same odontoblast-specific Ctnnb1 deletion mice, we found that ablation of β-catenin signaling in odontoblasts led to aberrant HERS formation. Mechanistically, odontoblast-specific Ctnnb1 deletion resulted in elevated bone morphogenetic protein 7(Bmp7) expression and reduced expression of noggin and follistatin, both of which encode extracellular inhibitors of BMPs. Furthermore, the levels of phosphorylated Smad1/5/8 were increased in HERS cells. In vitro tissue culture confirmed that BMP7 treatment disrupted the HERS structure. Taken together, we demonstrated that odontoblast β-catenin signaling may act through regulation of BMP signaling to maintain the integrity of HERS cells.展开更多
Occlusion is commenced by contact of a tooth with an opposing tooth and is the mechanical force working against the periodontal ligament (PDL). Our recent study indicated that occlusion regulated tooth root elongation...Occlusion is commenced by contact of a tooth with an opposing tooth and is the mechanical force working against the periodontal ligament (PDL). Our recent study indicated that occlusion regulated tooth root elongation occurs during root development in rat molars. Using a non-occlusal model established to directly examine the effects of the absence of occlusion in developing first molars of upper jaw, histological analysis was performed to count the number of HERS cells, with Microarray used to analyse gene expression profiles. HERS cell numbers in normal molars decreased significantly more than those in experimental molars. In microarray data, a total of 59 genes showed significant differences (fold change > 2.0). Expressions of 55 genes in the experimental molars, which included PLAP-1/asporin and periostin, were significantly decreased than those in normal molars. These data indicate that occlusion during root development leads to a decrease in the number of HERS cells, and that the aforementioned genes may play an essential role in normal root formation.展开更多
目的:通过追踪观察小鼠细胞牙骨质发育过程中的组织形态和细胞活性改变,探讨源于上皮根鞘断裂的上皮性细胞是否参与细胞牙骨质的发育。方法:选取出生后15、19、25 d BALB/c小鼠的下颌第一磨牙根尖1/3区细胞牙骨质,细胞角蛋白14(CK 14)...目的:通过追踪观察小鼠细胞牙骨质发育过程中的组织形态和细胞活性改变,探讨源于上皮根鞘断裂的上皮性细胞是否参与细胞牙骨质的发育。方法:选取出生后15、19、25 d BALB/c小鼠的下颌第一磨牙根尖1/3区细胞牙骨质,细胞角蛋白14(CK 14)标记追踪上皮根鞘断裂后的上皮性细胞;TUNEL(Td T-mediated-d UTP nick end labeling,TUNEL)法检测细胞牙骨质在发育过程中的细胞凋亡情况;透射电镜观察细胞牙骨质发育的超微结构。结果:细胞凋亡检测结果显示,细胞牙骨质形成过程中可见大量被埋入或正被埋入细胞呈现凋亡阳性表达;免疫组化染色结果显示,其中部分细胞呈CK14阳性表达;透射电镜观察结果显示,细胞牙骨质形成过程中上皮性细胞被其外侧成牙骨质细胞分泌的基质包围。结论:来源上皮根鞘断裂的上皮性细胞可能作为牙骨质细胞参与细胞牙骨质的形成。展开更多
基金supported by grants from the NIDCR, NIH (DE012711 and DE014078) to Yang ChaiNational Natural Science Foundation of China (81170943)+1 种基金Beijing Natural Science Foundation (7122051)Funding for Talents in Beijing (D) (2010D003034000012) to Xiao-Feng Huang
文摘The root is crucial for the physiological function of the tooth, and a healthy root allows an artificial crown to function as required clinically. Tooth crown development has been studied intensively during the last few decades, but root development remains not well understood. Here we review the root development processes, including cell fate determination, induction of odontoblast and cementoblast differentiation, interaction of root epithelium and mesenchyme, and other molecular mechanisms. This review summarizes our current understanding of the signaling cascades and mechanisms involved in root development. It also sets the stage for de novo tooth regeneration.
基金supported by grants from the State Key Program of the National Natural Science Foundation of China(81030018)the National Basic Research Program of China(2012CB966904)the National Natural Science Foundation of China(30900863,81241062)
文摘The interaction between Hertwig's epithelial root sheath(HERS) and the adjacent mesenchyme is vitally important in mouse tooth root development. We previously generated odontoblast-specific Ctnnb1(encoding β-catenin) deletion mice, and demonstrated that odontoblast β-catenin signaling regulates odontoblast proliferation and differentiation. However, the role of odontoblast β-catenin signaling in regulation of HERS behavior has not been fully investigated. Here, using the same odontoblast-specific Ctnnb1 deletion mice, we found that ablation of β-catenin signaling in odontoblasts led to aberrant HERS formation. Mechanistically, odontoblast-specific Ctnnb1 deletion resulted in elevated bone morphogenetic protein 7(Bmp7) expression and reduced expression of noggin and follistatin, both of which encode extracellular inhibitors of BMPs. Furthermore, the levels of phosphorylated Smad1/5/8 were increased in HERS cells. In vitro tissue culture confirmed that BMP7 treatment disrupted the HERS structure. Taken together, we demonstrated that odontoblast β-catenin signaling may act through regulation of BMP signaling to maintain the integrity of HERS cells.
文摘Occlusion is commenced by contact of a tooth with an opposing tooth and is the mechanical force working against the periodontal ligament (PDL). Our recent study indicated that occlusion regulated tooth root elongation occurs during root development in rat molars. Using a non-occlusal model established to directly examine the effects of the absence of occlusion in developing first molars of upper jaw, histological analysis was performed to count the number of HERS cells, with Microarray used to analyse gene expression profiles. HERS cell numbers in normal molars decreased significantly more than those in experimental molars. In microarray data, a total of 59 genes showed significant differences (fold change > 2.0). Expressions of 55 genes in the experimental molars, which included PLAP-1/asporin and periostin, were significantly decreased than those in normal molars. These data indicate that occlusion during root development leads to a decrease in the number of HERS cells, and that the aforementioned genes may play an essential role in normal root formation.
文摘目的:通过追踪观察小鼠细胞牙骨质发育过程中的组织形态和细胞活性改变,探讨源于上皮根鞘断裂的上皮性细胞是否参与细胞牙骨质的发育。方法:选取出生后15、19、25 d BALB/c小鼠的下颌第一磨牙根尖1/3区细胞牙骨质,细胞角蛋白14(CK 14)标记追踪上皮根鞘断裂后的上皮性细胞;TUNEL(Td T-mediated-d UTP nick end labeling,TUNEL)法检测细胞牙骨质在发育过程中的细胞凋亡情况;透射电镜观察细胞牙骨质发育的超微结构。结果:细胞凋亡检测结果显示,细胞牙骨质形成过程中可见大量被埋入或正被埋入细胞呈现凋亡阳性表达;免疫组化染色结果显示,其中部分细胞呈CK14阳性表达;透射电镜观察结果显示,细胞牙骨质形成过程中上皮性细胞被其外侧成牙骨质细胞分泌的基质包围。结论:来源上皮根鞘断裂的上皮性细胞可能作为牙骨质细胞参与细胞牙骨质的形成。
