Schmidt J W, Brugge J S, Nelson W J
Department of Molecular and Cellular Physiology, Standard University School of Medicine, California 94305-5426.
J Cell Biol. 1992 Feb;116(4):1019-33. doi: 10.1083/jcb.116.4.1019.
P19 embryonal carcinoma cells provide an in vitro model system to analyze the events involved in neural differentiation. These multipotential stem cells can be induced by retinoic acid (RA) to differentiate into neural cells. We have investigated the ability of several variant forms of the protein-tyrosine kinase (PTK) pp60src to modulate cell fate determination in this system. Normally, P19 cells are induced to differentiate along a neural lineage when allowed to form extensive cell-cell contacts in large multicellular aggregates during exposure to RA. Through analysis of markers of epithelial (keratin and desmosomal proteins) and neuronal (neurofilament) cells we have found that RA-induced P19 cells transiently express epithelial markers before neuronal differentiation. Under these inductive conditions, expression of pp60v-src or expression of the neuronal variant pp60c-src+ inhibited neuronal differentiation, and resulted in maintained expression of an epithelial phenotype. Morphological analysis showed that expression of pp60src PTKs results in decreased cell-cell adhesion during the critical cell aggregation stage of the neural differentiation procedure. The effects of pp60v-src on cell fate and cell-cell adhesion could be mimicked by direct modulation of Ca+(+)-dependent cell-cell contact during RA induction of normal P19 cells. We conclude that the neural lineage of P19 cells includes an early epithelial intermediate and suggest that tyrosine phosphorylation can modulate cell fate determination during an early cell-cell adhesion-dependent event in neurogenesis.
P19胚胎癌细胞提供了一个体外模型系统，用于分析神经分化过程中涉及的事件。这些多能干细胞可被视黄酸（RA）诱导分化为神经细胞。我们研究了蛋白酪氨酸激酶（PTK）pp60src的几种变体形式在该系统中调节细胞命运决定的能力。正常情况下，当P19细胞在暴露于RA期间在大型多细胞聚集体中形成广泛的细胞间接触时，它们会被诱导沿神经谱系分化。通过分析上皮细胞（角蛋白和桥粒蛋白）和神经元细胞（神经丝）的标志物，我们发现RA诱导的P19细胞在神经元分化之前短暂表达上皮标志物。在这些诱导条件下，pp60v-src的表达或神经元变体pp60c-src+的表达抑制了神经元分化，并导致上皮表型的持续表达。形态学分析表明，pp60src PTK的表达导致神经分化过程关键的细胞聚集阶段细胞间黏附减少。在正常P19细胞的RA诱导过程中，通过直接调节Ca+(+)-依赖性细胞间接触，可以模拟pp60v-src对细胞命运和细胞间黏附的影响。我们得出结论，P19细胞的神经谱系包括一个早期上皮中间阶段，并表明酪氨酸磷酸化可以在神经发生早期细胞间黏附依赖性事件中调节细胞命运决定。
