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

Abstract

The oncogenes (v- onc genes) of rapidly transforming retroviruses have homologs (c- onc genes) in the genomes of normal cells. In this study, we characterized and quantitated transcription from four c- onc genes, 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 cloned onc probes showed that c- myb , c- myc , and c- src each give rise to a single mature transcript, whereas c- erb gives 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- src was quantitated by a “dot-blot” hybridization assay. We found that c- myc , c- erb , and c- src transcription could be detected in nearly all cells and tissues examined, whereas c- myb transcription was detected only in some hemopoietic cells; these cells, however, belong to several different lineages. Thus, in no case was expression of a c- onc gene restricted to a single cell lineage. There appeared to be a correlation between levels of c- myb expression and hemopoietic activity of the tissues and cells examined, which suggests that c- myb may be expressed primarily in immature hemopoietic cells. An examination of c- onc RNA levels in target cells and tissues for viruses carrying the corresponding v- onc genes revealed no obvious correlation, direct or inverse, between susceptibility to transformation by a given v- onc gene and expression of the homologous c- onc gene.