Differential regulation of connexin 26 and 43 in murine neocortical precursors

Proliferating cells of the developing murine neocortex couple together into clusters during neurogenesis. Previously, we have shown that these cluster s contain neural precursors in all phases of the cell cycle except M phase, and that they extend a nestin-expressing process from the cluster to the p ial surface. In addition, coupling within neocortical cell clusters is a dy namic process related to the cell cycle, with maximal coupling in S/G2 phas e, uncoupling in M phase and then recoupling during G1 and S phases of the cell cycle, in the present study, we use immunohistochemistry to demonstrat e that cycling neocortical cells as well as radial glial cells express the gap junction proteins connexin 26 and connexin 43. Furthermore, we demonstr ate that biocytin labeled clusters extend processes to the pial surface tha t express the glial cell antigen RC2. Lastly, by combining bromodeoxyuridin e and connexin immunohistochemistry on acutely dissociated neocortical cell s, we show that the percentage of cycling cells immunoreactive to connexin 26 and connexin 43 changes through the cell cycle. These results indicate t hat radial glial cells as well as neural precursors couple into clusters, a nd suggest that through differential regulation of connexins, neocortical p recursors may compartmentalize as they progress through the cell cycle.