DOWN-REGULATION OF ENDOTHELIN RECEPTOR MESSENGER-RNA SYNTHESIS IN C6 RAT ASTROCYTOMA-CELLS BY PERSISTENT MEASLES-VIRUS AND CANINE-DISTEMPER VIRUS-INFECTIONS

Persistent infections of C6 rat astrocytoma cells with measles (subacute sclerosing panencephalitis [SSPE]) virus (C6/SSPE cells) or canine distemper virus (C6/CDV cells) cause a loss of endothelin-1 (ET-1) binding to its specific receptors (ETR(A) type) and subsequent ET-1-induced Ca2+ signaling. It was the aim of this study to investigate the underlying mechanism of this phenomenon in more detail. By using an RNase protection assay, it was found that ETR(A) mRNA disappears, whereas other cellular mRNA species, e.g., beta-actin mRNA, were not influenced. The data show that the loss of the ET-1 signaling pathway in C6/SSPE and C6/CDV cells is due to a receptor downregulation at the transcriptional level.