Lukinmaa P L, Vaahtokari A, Vainio S, Sandberg M, Waltimo J, Thesleff I
Department of Oral Pathology, University of Helsinki, Finland.
Matrix. 1993 Nov;13(6):503-15. doi: 10.1016/s0934-8832(11)80116-2.
The expression of pro-alpha 1(III) and pro-alpha 1(I) collagen mRNAs in mouse and human dental tissues during tooth development and after its completion was analyzed by in situ hybridization, with use of [35S]-labeled RNA probes. The expression of pro-alpha 1(III) mRNA was also compared to that of the protein product, as localized by immunostaining with polyclonal antibodies to type III collagen and the N-terminal propeptide of type III procollagen. Contrary to many previous reports, our results suggest that odontoblasts express type III collagen. While pro-alpha 1(III) transcripts were less intensely expressed in odontoblasts than pro-alpha 1(I) transcripts, the amounts of both mRNAs increased in odontoblasts with progressing dentin formation, and decreased toward its completion. In contrast to pro-alpha 1(III) mRNA, pro-alpha 1(I) mRNA was still detectable in odontoblasts of fully developed teeth. Type III collagen immunoreactivity was observed in the early predentin, and again in predentin toward the completion of dentinogenesis, when mRNA was no longer detected. Also in the pulp, the protein product, unlike pro-alpha 1(III) mRNA, was relatively strongly expressed. Hence, these immunostaining patterns were inversely related to the expression of pro-alpha 1(III) mRNA, suggesting accumulation of the protein. The mesenchymal cells, when condensed in the region of the future mandibular bone, expressed pro-alpha 1(III) mRNA intensely, whereas osteoblasts expressed pro-alpha 1(I) but not pro-alpha 1(III) transcripts strongly. Cell type- and developmental stage-related differences in the expression of the two mRNAs suggest that type I/type III collagen ratio influences the structure of dental tissues.
利用[35S]标记的RNA探针，通过原位杂交分析了小鼠和人类牙齿组织在牙齿发育期间及发育完成后I型前胶原α1（pro-alpha 1(I)）和III型前胶原α1（pro-alpha 1(III)）mRNA的表达情况。还将pro-alpha 1(III) mRNA的表达与蛋白产物的表达进行了比较，蛋白产物通过用针对III型胶原和III型前胶原N端前肽的多克隆抗体进行免疫染色来定位。与许多先前的报道相反，我们的结果表明成牙本质细胞表达III型胶原。虽然pro-alpha 1(III)转录本在成牙本质细胞中的表达强度低于pro-alpha 1(I)转录本，但随着牙本质形成的进展，两种mRNA在成牙本质细胞中的含量均增加，并在牙本质形成完成时减少。与pro-alpha 1(III) mRNA不同，在完全发育的牙齿的成牙本质细胞中仍可检测到pro-alpha 1(I) mRNA。在早期前期牙本质中观察到III型胶原免疫反应性，在牙本质形成接近完成时的前期牙本质中再次观察到，此时mRNA不再被检测到。同样在牙髓中，与pro-alpha 1(III) mRNA不同，蛋白产物表达相对较强。因此，这些免疫染色模式与pro-alpha 1(III) mRNA的表达呈负相关，表明蛋白发生了积累。间充质细胞在未来下颌骨区域聚集时，强烈表达pro-alpha 1(III) mRNA，而成骨细胞强烈表达pro-alpha 1(I)转录本，但不表达pro-alpha 1(III)转录本。两种mRNA表达的细胞类型和发育阶段相关差异表明I型/III型胶原比例影响牙齿组织的结构。
