An intense stimulus can cause death of odontoblasts and initiate odontoblastic differentiation of stem/progenitor cell populations of dental pulp cells (DPCs), which is followed by reparative dentin formation. However, the mechanism of odontoblastic differentiation during reparative dentin formation remains unclear. This study was to determine the role of β-catenin, a key player in tooth development, in reparative dentin formation, especially in odontoblastic differentiation. We found that β-catenin was expressed in odontoblast-like cells and DPCs beneath the perforation site during reparative dentin formation after direct pulp capping. The expression of β-catenin was also significantly upregulated during odontoblastic differentiation of in vitro cultured DPCs. The expression pattern of runt-related transcription factor 2 (Runx2) was similar to that of β-catenin. Immunofluorescence staining indicated that Runx2 was also expressed in β-catenin–positive odontoblast-like cells and DPCs during reparative dentin formation. Knockdown of β-catenin disrupted odontoblastic differentiation, which was accompanied by a reduction in β-catenin binding to the Runx2 promoter and diminished expression of Runx2. In contrast, lithium chloride (LiCl) induced accumulation of β-catenin produced the opposite effect to that caused by β-catenin knockdown. In conclusion, it was reported in this study for the first time that β-catenin can enhance the odontoblastic differentiation of DPCs through activation of Runx2, which might be the mechanism involved in odontoblastic differentiation during reparative dentin formation.

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Process research and development of the first fully synthetic broad spectrum 7-fluorotetracycline in clinical development is described. The process utilizes two key intermediates in a convergent approach. The key transformation is a Michael–Dieckmann reaction between a suitable substituted aromatic moiety and a key cyclohexenone derivative. Subsequent deprotection and acylation provide the desired active pharmaceutical ingredient in good overall yield.

A robust, cost effective and high yielding manufacturing process for enantiomerically enriched (S)-allylic amine 3, a key intermediate for fully synthetic tetracyclines have been developed.Two novel and scalable asymmetric vinylations resulting in high to excellent stereoselectivity have been developed for the key step. The final product is purified by an efficient crystallization of a L-tartaric salt. The process described has been used to manufacture ~350 kg of the tartaric salt of 3 with 99.0% ee in 8 steps (35% overall yield) from cheap and readily available dimethyl maleate.