Tissue-specific post-transcriptional regulation of c-myc expression in normal and H-2K/human c-myc transgenic mice.
We show that the steady-state levels of c-myc mRNAs vary considerably in different organs of normal adult mice, maximal expression being observed in lymphoid organs and minimal expression in liver and brain. Nuclear run-on analysis of c-myc gene transcription in adult liver and spleen reveals that the difference in c-myc gene expression in these two organs is due to differential post-transcriptional control. Moreover, these nuclear run-on assays indicate that no premature termination of c-myc gene transcription takes place in the nuclei of the three adult tissues analysed. In fetal liver development, we observe a decrease in c-myc mRNA, but this is not due to changes in transcriptional activity implicating post-transcriptional regulatory mechanisms. Our studies of c-myc gene expression in organs of H-2K/myc transgenic mice, harboring an H-2K promoter driven human c-myc gene, confirm that the in vivo c-myc regulation is mainly post-transcriptional and shows that sequences shared by the murine and human c-myc proto-oncogenes are involved in this control.
Morello
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Department of Immunology, Institut Pasteur, Paris, France.
Asselin
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C
Lavenu
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Marcu
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KB
Babinet
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C
D000818:Animals; D002454:Cell Differentiation; D005786:Gene Expression Regulation / Q000187:drug effects; D006183:H-2 Antigens / Q000235:genetics; D008070:Lipopolysaccharides / Q000494:pharmacology; D008099:Liver / Q000502:physiology; D051379:Mice; D008822:Mice, Transgenic; D011401:Promoter Regions, Genetic; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D016271:Proto-Oncogene Proteins c-myc; D011519:Proto-Oncogenes; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000235:genetics*; D013045:Species Specificity; D014158:Transcription, Genetic / Q000187:drug effects
D006183:H-2 Antigens; D008070:Lipopolysaccharides; D011518:Proto-Oncogene Proteins; D016271:Proto-Oncogene Proteins c-myc; D012333:RNA, Messenger