Odontoblast β-catenin signaling regulates fenestration of mouse Hertwig's epithelial root sheath

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 Ctnnbl （encodingβ-catenin） deletion mice, and demon- strated that odontoblast β-catenin signaling regulates odontoblast proliferation and differentiation. However, the role of odon- toblast β-catenin signaling in regulation of HERS behavior has not been fully investigated. Here, using the same odonto- blast-specific Ctnnbl deletion mice, we found that ablation of β-catenin signaling in odontoblasts led to aberrant HERS for- mation. Mechanistically, odontoblast-specific Ctnnbl deletion resulted in elevated bone morphogenetic protein 7 （Bmp7） ex- pression and reduced expression of noggin andfollistatin, both of which encode extracellular inhibitors of BMPs. Furthermore, the levels of phosphorylated Smadl/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 f3-catenin signaling may act through regula- tion of BMP signaling to maintain the integrity of HERS cells.

大鼠Hertwig's上皮根鞘细胞的分离培养

目的:建立大鼠Hertwig's上皮根鞘细胞分离、培养和纯化的方法。方法:分离出生后7dSD大鼠上下颌第一、二磨牙牙胚,切取牙冠颈部组织,酶消化法原代培养,利用差速传代纯化上皮细胞。用角蛋白14和波形丝蛋白染色确定细胞来源。结果:原代培养细胞为上皮和间充质混合细胞,经2～3次差速传代后可获得纯化的上皮根鞘细胞。免疫组化染色角蛋白14阳性,波形丝蛋白阴性。结论:利用酶消化法及差速传代法培养并获得纯化的上皮根鞘细胞。

Btbd7基因在SD乳鼠牙根发育中的表达

目的检测Btbd7基因在SD乳鼠牙根不同发育阶段的表达情况,以探讨其在牙根发育中的作用。方法制备出生后第8、11、15、19天含有下颌第一磨牙的SD乳鼠牙胚标本。常规HE染色观察SD乳鼠牙根不同发育阶段上皮根鞘的形态,免疫组化染色检测Btbd7基因表达情况。结果 Btbd7基因在SD乳鼠牙根发育期间高表达于上皮根鞘组织中,并且随着上皮根鞘的成熟而逐渐减少。结论 Btbd7基因在SD乳鼠牙根发育期间的上皮根鞘组织中呈时间-空间特异性表达,可能参与SD乳鼠磨牙牙根分支的形成。