Gap junction blockage interferes with neuronal and astroglial differentiation of mouse P19 embryonal carcinoma cells

During embryonic development, cells not only increase in number, they also undergo specialization and differentiate into diverse cell types that are o rganized into different tissues and organs. Nervous system development, for example, involves a complex series of events such as neuronal and astrogli al differentiation that are coordinated among adjacent cells. The organizat ion of growth and differentiation may be mediated, at least partly, by exch ange of small ions and molecules via intercellular gap junction channels. T hese structures are made of connexons (hemichannels), which are hexameric a ssemblies 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 mous e P19 embryonal carcinoma cell line, which differentiates into neurons and astrocytes upon retinoic acid IRA) induction. Our results show that both GZ A- and CBX-treated cells express alpha(1) connexin (connexin43). The level of alpha(1) connexin decreases upon RA induction. CBX treated cells show si gnificant reduction in both neuronal (5-fold) and astrocytic (13-fold) diff erentiation compared with those of control. These results clearly indicate that the blockage of gap junction-mediated intercellular communication inte rferes with differentiation of P10 cells into neurons and astrocytes. (C) 1 999 Wiley-Liss, Inc.