Poulin M L, Patrie K M, Botelho M J, Tassava R A, Chiu I M
Department of Molecular Genetics, Ohio State University, Davis Medical Research Center, Columbus 43210.
Development. 1993 Oct;119(2):353-61. doi: 10.1242/dev.119.2.353.
Two closely related fibroblast growth factor receptors, FGFR1 and FGFR2, have been cloned from a newt (Notophthalmus viridescens) limb blastema cDNA library. Sequence analysis revealed that we have isolated both the bek and KGFR variants of FGFR2. These two variants differ only in the second half of the last of their three Ig-like domains. The expression patterns of FGFR1 and FGFR2 during limb regeneration have been determined by in situ hybridization. During the preblastema stages of regeneration, FGFR2 expression is observed in the basal layer of the wound epithelium and in the cells of the periosteum. As regeneration progresses to the blastema stages, FGFR2 expression continues to be observed in the basal layer of the wound epithelium with additional hybridization seen in the blastema mesenchyme closely associated with the bisected bones. From the early bud to the mid-bud blastema stage, FGFR1 expression is observed throughout the blastema mesenchyme but, unlike FGFR2, is distinctly absent from the wound epithelium. In the differentiation stages of regeneration, the mesenchymal expression of FGFR2 becomes restricted to the cells of the condensing cartilage and later to the perichondrium. During these later stages of regeneration, the wound epithelium hybridization to the FGFR2 probe is no longer observed. The expression patterns of these receptors suggest that FGFR1 and FGFR2 have distinct roles in limb regeneration, despite their sharing a number of the FGF ligands. Further investigation regarding the potential sources of the FGF ligands will help establish the role that FGFs and FGFRs play in limb regeneration.
从蝾螈（绿红东美螈）肢体芽基cDNA文库中克隆出了两种密切相关的成纤维细胞生长因子受体，即FGFR1和FGFR2。序列分析表明，我们已分离出FGFR2的bek和KGFR变体。这两种变体仅在其三个免疫球蛋白样结构域中最后一个结构域的后半部分有所不同。通过原位杂交确定了FGFR1和FGFR2在肢体再生过程中的表达模式。在再生的芽基前期阶段，在伤口上皮的基底层和骨膜细胞中观察到FGFR2表达。随着再生进展到芽基阶段，在伤口上皮的基底层持续观察到FGFR2表达，在与被切断的骨骼紧密相关的芽基间充质中也观察到额外的杂交信号。从早期芽到中期芽基阶段，在整个芽基间充质中观察到FGFR1表达，但与FGFR2不同的是，在伤口上皮中明显没有表达。在再生的分化阶段，FGFR2的间充质表达局限于凝聚软骨的细胞，随后局限于软骨膜。在再生的这些后期阶段，不再观察到伤口上皮与FGFR2探针的杂交。这些受体的表达模式表明，尽管FGFR1和FGFR2共享许多FGF配体，但它们在肢体再生中具有不同的作用。关于FGF配体潜在来源的进一步研究将有助于确定FGF和FGFR在肢体再生中所起的作用。
