Bani-Yaghoub M, Underhill T M, Naus C C
Department of Anatomy & Cell Biology, University of Western Ontario, London, Canada.
Dev Genet. 1999;24(1-2):69-81. doi: 10.1002/(SICI)1520-6408(1999)24:1/2<69::AID-DVG8>3.0.CO;2-M.
During embryonic development, cells not only increase in number, they also undergo specialization and differentiate into diverse cell types that are organized into different tissues and organs. Nervous system development, for example, involves a complex series of events such as neuronal and astroglial differentiation that are coordinated among adjacent cells. The organization of growth and differentiation may be mediated, at least partly, by exchange of small ions and molecules via intercellular gap junction channels. These structures are mode of connexons (hemichannels), which are hexameric assemblies of the gap junction proteins, connexins. We investigated the role of intercellular communication in neuronal and astroglial differentiation by using a gap junction blocking agent, carbenoxolone (CBX), in comparison to its inactive (control) analog, glycyrrhizic acid (GZA). We used the mouse P19 embryonal carcinoma cell line, which differentiates into neurons and astrocytes upon retinoic acid (RA) induction. Our results show that both GZA- and CBX-treated cells express alpha 1 connexin (connexin43). The level of alpha 1 connexin decreases upon RA induction. CBX treated cells show significant reduction in both neuronal (5-fold) and astrocytic (13-fold) differentiation compared with those of control. These results clearly indicate that the blockage of gap junction-mediated intercellular communication interferes with differentiation of P19 cells into neurons and astrocytes.
在胚胎发育过程中，细胞不仅数量增加，还会经历特化并分化为不同的细胞类型，这些细胞类型会组织成不同的组织和器官。例如，神经系统发育涉及一系列复杂的事件，如神经元和星形胶质细胞的分化，这些事件在相邻细胞之间相互协调。生长和分化的组织可能至少部分地由小离子和分子通过细胞间缝隙连接通道的交换介导。这些结构是连接子（半通道）的形式，连接子是缝隙连接蛋白连接蛋白的六聚体组装。我们使用缝隙连接阻断剂甘草次酸（CBX）及其无活性（对照）类似物甘草酸（GZA），研究了细胞间通讯在神经元和星形胶质细胞分化中的作用。我们使用了小鼠P19胚胎癌细胞系，该细胞系在视黄酸（RA）诱导下分化为神经元和星形胶质细胞。我们的结果表明，GZA和CBX处理的细胞均表达α1连接蛋白（连接蛋白43）。RA诱导后，α1连接蛋白水平降低。与对照组相比，CBX处理的细胞在神经元（5倍）和星形胶质细胞（13倍）分化方面均显著降低。这些结果清楚地表明，缝隙连接介导的细胞间通讯的阻断会干扰P19细胞向神经元和星形胶质细胞的分化。
