Transcriptional and posttranscriptional regulation of the proliferating cell nuclear antigen gene.
The steady-state mRNA levels of the proliferating cell nuclear antigen (PCNA) gene are growth regulated. In a previous paper (L. Ottavio, C.-D. Chang, M. G. Rizzo, S. Travali, C. Casadevall, and R. Baserga, Mol. Cell. Biol. 10:303-309, 1990), we reported that introns (especially intron 4) participate in growth regulation of the PCNA gene. We have now investigated the role of the 5'-flanking sequence of the human PCNA gene stably transfected into BALB/c 3T3 cells. Promoters of different lengths (from -2856 to -45 upstream of the cap site) were tested. All promoters except the AatII promoter (-45), including a short HpaII promoter (-210), were sufficient for a response to serum, platelet-derived growth factor, and to a lesser extent epidermal growth factor. No construct responded to insulin or platelet-poor plasma. The AatII promoter had little detectable activity. Transcriptional activity was also determined in BALB/c 3T3 cells carrying various constructs of the human PCNA gene by two methods: run-on transcription and reverse transcription-polymerase chain reaction (the latter measuring the heterogeneous nuclear RNA [hnRNA] steady-state levels). There was very little difference in the rate of transcription of the PCNA gene between G0 cells and serum-stimulated cells, although the levels of hnRNA were much higher after stimulation. In G0 cells carrying a human PCNA gene without introns 4 and 5, both transcription rate and hnRNA levels were high. Together with data on the mRNA half-life, these results suggest a posttranscriptional component in the regulation of PCNA mRNA levels after serum stimulation but a transcriptional regulation by intron 4.
Chang
C D
CD
Department of Pathology, Temple University Medical School, Philadelphia, Pennsylvania 19140.
Ottavio
L
L
Travali
S
S
Lipson
K E
KE
Baserga
R
R
D000818:Animals; D001324:Autoantigens / Q000235:genetics*; D002478:Cells, Cultured; D002872:Chromosome Deletion; D015342:DNA Probes; D005786:Gene Expression Regulation; D005796:Genes; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics*; D010957:Plasmids; D018809:Proliferating Cell Nuclear Antigen; D011401:Promoter Regions, Genetic; D012323:RNA Processing, Post-Transcriptional; D015183:Restriction Mapping; D014158:Transcription, Genetic; D014162:Transfection
D001324:Autoantigens; D015342:DNA Probes; D009687:Nuclear Proteins; D018809:Proliferating Cell Nuclear Antigen