Nucleic Acids Research, 1988, Vol. 16, No. 23 11171-11186
© 1988
MOLECULAR BIOLOGY |
Alternate structures and stabilities of c-myc RNA in a hursal lymphoma cell line
1Oncology Division, Health Sciences Center T17, Room 080, State University of New York at Stony Brook, Stony Brook, NY 11794-8174, USA 2Graduate Genetics Program, Health Sciences Center T17, Room 080, State University of New York at Stony Brook, Stony Brook, NY 11794–8174, USA
To whom correspondence should be addressed
Received August 4, 1988. Revised November 3, 1988. Accepted November 3, 1988.
A bursal lymphoma cell line, BK25, had been shown to be haploid at the c-myc locus and to have undergone an alteration of chromatin structure upstream from the c-myc coding region. In BK25 DNA at least the 3' half of an ALV provirus is integrated l60bp upstream from exon 2. As a result of this integration event, the first and second exons are separated by at least 17kb. Approximately 90% of c-myc transcription begins in the promoter of the ALV proviral long terminal repeat (LTR) and this mRNA has a half-life of 
25 minutes in actinomycin D chase experiments. Approximately 10% of c-myc transcription initiates at the normal promoter of c-myc. The latter message has an unusually long half-life of >100 minutes. By contrast, in MSB-1 cells, which lack any c-myc rearrangments, transcription begins at the normal promoter in exon 1 and c-myc RNA has a half-life of 15 minutes. These results suggest that factors in addition to the structure of the 5' end of chicken c-myc RNA determine its stability in vivo.