Burdsal C A, Flannery M L, Pedersen R A
Department Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118, USA.
Dev Biol. 1998 Jun 15;198(2):231-44.
We have developed an in vitro differentiation assay to characterize the ability of peptide growth factors to induce differentiation in mouse epiblast. We report that culturing explants of mouse anterior epiblast, a tissue normally fated to give rise to neuroectoderm and surface ectoderm, in a serum-free, chemically defined medium with 10-50 ng/ml of FGF-2 induced gross changes in cell morphology. Treated cells adopted an elongated, flattened morphology but did not migrate from the explant. Instead, FGF-2-treated cells condensed into multicellular mounds or ridges. Immunocytochemistry showed that cells in treated explants expressed vimentin and in situ hybridization demonstrated that FGF-2 induced the expression of brachyury, goosecoid, and myo-D in regions of treated explants displaying morphological differentiation. Control explants cultured with platelet-derived growth factor AA (PDGF AA), transforming growth factor-beta 1 (TGF-beta 1), or in defined medium alone showed no morphological or biochemical differentiation. These results indicate that FGF-2 altered the fate of mouse anterior epiblast from ectoderm to mesoderm in vitro. Cell migration, which is characteristic of primitive streak mesoderm in vivo, was not induced by FGF-2 in these assays. However, the changes in morphology and the expression of mesodermal genes in vitro do support an early role for FGF signaling in the induction of mouse primitive streak mesoderm, as well as in later patterning events during embryogenesis.
我们开发了一种体外分化测定法，以表征肽生长因子诱导小鼠外胚层分化的能力。我们报告称，在含有10 - 50 ng/ml FGF - 2的无血清、化学成分明确的培养基中培养小鼠前外胚层（一种通常注定会产生神经外胚层和表面外胚层的组织）外植体，会诱导细胞形态发生显著变化。经处理的细胞呈现出细长、扁平的形态，但并未从外植体迁移。相反，FGF - 2处理的细胞凝聚成多细胞丘或脊。免疫细胞化学显示，处理过的外植体中的细胞表达波形蛋白，原位杂交表明，FGF - 2在显示形态分化的处理过的外植体区域诱导了短尾、鹅膏菌素和肌分化抗原（Myo - D）的表达。用血小板衍生生长因子AA（PDGF AA）、转化生长因子 - β1（TGF - β1）培养的对照外植体，或仅在限定培养基中培养的对照外植体，均未显示出形态或生化分化。这些结果表明，FGF - 2在体外改变了小鼠前外胚层从外胚层到中胚层的命运。在这些测定中，FGF - 2并未诱导细胞迁移，而细胞迁移是体内原始条纹中胚层的特征。然而，体外形态的变化和中胚层基因的表达确实支持了FGF信号在诱导小鼠原始条纹中胚层以及胚胎发育后期模式形成事件中的早期作用。
