Cell coupling and Cx43 expression in embryonic mouse neural progenitor cells.
Embryonic neural progenitors isolated from the mouse striatal germinal zone grow in vitro as floating cell aggregates called neurospheres, which, upon adhesion, can be induced to differentiate into the three main cell types of the central nervous system (CNS), that is, astrocytes, neurons and oligodendrocytes. To study the possible role of connexins and junctional communication during differentiation of neural progenitors, we assessed cell-to-cell communication by microinjecting Lucifer Yellow into neurospheres at various times after adhesion. Cells located in neurospheres were strongly coupled, regardless of the differentiation time. Microinjections performed on the cell layers formed by differentiated cells migrating out of the neurosphere established that only astrocytes were coupled. These observations suggest the existence of at least three distinct communication compartments: coupled proliferating cells located in the sphere, uncoupled cells undergoing neuronal or oligodendrocytic differentiation and coupled differentiating astrocytes. A blockade of junctional communication by 18-beta-glycyrrhetinic acid (betaGA) reduced, in a concentration-dependent manner, the viability of undifferentiated neural progenitor cells. This effect appeared to be specific, inasmuch as it was reversible and that cell survival was not affected in the presence of the inactive analog glycyrrhyzic acid. Addition of betaGA to adherent neurospheres also decreased cell density and altered the morphology of differentiated cells. Cx43 was strongly expressed in either undifferentiated or differentiated neurospheres, where it was found both within the sphere and in astrocytes, the two cell populations that were dye coupled. Western blot analysis further showed that Cx43 phosphorylation was strongly increased in adherent neurospheres, suggesting a post-translational regulation during differentiation. These results point to a major role of cell-to-cell communication and Cx43 during the differentiation of neural progenitor cells in vitro.
Institut Pasteur, Unité de Neurovirologie et Régénération du Système Nerveux, 75015 Paris, France.
Nathalie
N
Duval
Danielle
D
Gomès
Viviane
V
Calaora
Alessandra
A
Calabrese
Paolo
P
Meda
Roberto
R
Bruzzone
D000818:Animals; D001921:Brain / Q000166:cytology / Q000196:embryology; D002448:Cell Adhesion / Q000502:physiology; D002450:Cell Communication / Q000502:physiology*; D018929:Cell Culture Techniques / Q000379:methods; D002454:Cell Differentiation / Q000502:physiology*; D002455:Cell Division / Q000502:physiology; D048429:Cell Size; D002470:Cell Survival; D002478:Cells, Cultured; D018031:Connexin 43 / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005456:Fluorescent Dyes; D006034:Glycyrrhetinic Acid / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D007365:Intercellular Junctions / Q000378:metabolism; D007546:Isoquinolines / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008845:Microinjections; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D011247:Pregnancy; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects / Q000502:physiology*
D018031:Connexin 43; D005456:Fluorescent Dyes; D007546:Isoquinolines; C017475:lucifer yellow; D006034:Glycyrrhetinic Acid