Transcripts from the Cellular Homologs of Retroviral Oncogenes: Distribution Among Chicken Tissues

Abstract

The oncogenes (v-oncgenes) of rapidly transforming retroviruses have homologs (c-oncgenes) in the genomes of normal cells. In this study, we characterized and quantitated transcription from four c-oncgenes, c-myb, c-myc, c-erb, and c-src, in a variety of chicken cells and tissues. Electrophoretic analysis of polyadenylated RNA, followed by transfer to nitrocellulose and hybridization to clonedoncprobes showed that c-myb, c-myc, and c-srceach give rise to a single mature transcript, whereas c-erbgives rise to multiple transcripts (B. Vennstrom and J. M. Bishop, Cell, in press) which vary in abundance among different cells and tissues. Transcription from c-myb, c-myc, c-erb, and c-srcwas quantitated by a “dot-blot” hybridization assay. We found that c-myc, c-erb, and c-srctranscription could be detected in nearly all cells and tissues examined, whereas c-mybtranscription was detected only in some hemopoietic cells; these cells, however, belong to several different lineages. Thus, in no case was expression of a c-oncgene restricted to a single cell lineage. There appeared to be a correlation between levels of c-mybexpression and hemopoietic activity of the tissues and cells examined, which suggests that c-mybmay be expressed primarily in immature hemopoietic cells. An examination of c-oncRNA levels in target cells and tissues for viruses carrying the corresponding v-oncgenes revealed no obvious correlation, direct or inverse, between susceptibility to transformation by a given v-oncgene and expression of the homologous c-oncgene.