Astrocyte cultures from conditional connexin43-deficient mice.

Connexin43 (Cx43) mainly provides the molecular basis for astrocytic gap junctions. Interastrocytic coupling is thought to mediate extracellular ion homeostasis, long-range signaling, and neuroprotection in the brain. Cx43 has been implicated in astrocytic growth control and is also expressed in other cell types in the brain, such as leptomeningeal and vascular cells. Cx43 function has been studied in astrocyte cultures of Cx43-deficient mice, which lack Cx43 in all cell types. We have generated conditionally deficient mice with an astrocyte-directed inactivation of Cx43, which leaves expression in other cell types unaffected. Other connexins have been detected in astrocytes. For the study of astrocytes lacking Cx45 and Cx26 in vitro, which deficiencies are embryonic lethal, conditionally deficient astrocyte cultures are essential. In the present study, we describe the developmental kinetics of Cx43 inactivation and loss of intercellular communication in astrocyte cultures derived from conditional Cx43-deficient mice. Conditional ablation of Cx43 is efficient, reaches a plateau at 4 weeks in culture, but retains Cx43 expression in contaminating nonastrocytic cells. Our findings indicate that conditional knockout astrocytes are a promising tool for the study of embryonic lethal genes in astrocyte cultures. Copyright 2004 Wiley-Liss, Inc.