Up-regulation of c-myc gene expression following focal ischemia in the rat brain.
Changes in gene expression including that of c-fos occur following cerebral ischemia. Proto-oncogenes c-myc and s-myc and oncosuppressor gene p53 are known to induce apoptosis in some types of cells, whereas proto-oncogene bcl-2 inhibits apoptosis. Possible induction of mRNAs for c-myc, N-myc, s-myc, c-fos, p53 and bcl-2 was examined following focal ischemia in the rat anterior cortex, hippocampus, thalamus and cerebellum by Northern blot analysis. Animals were decapitated 1, 2, 6, 12, and 24 hours following the left middle cerebral artery (MCA) occlusion. In sham-operated control rats, the mRNAs for c-myc, N-myc, c-fos and p53 were present in the anterior cortex, hippocampus, thalamus on both sides, and in the cerebellum, whereas those for s-myc and bcl-2 were not. The c-myc gene expression was rapidly and markedly induced by the MCA occlusion in the ipsilateral anterior cortex, hippocampus and thalamus in a time-dependent manner. In these regions, the c-fos gene expression was also induced as early as 1 hour after the MCA occlusion. The p-53 mRNA was induced in the ipsilateral hippocampus at 24 hours after MCA occlusion. In contrast, mRNAs for N-myc, s-myc and bcl-2 were not induced following MCA occlusion. These results indicate a possibility that high-level expression of the c-myc gene may be involved in the ischemic cellular events including apoptosis.
Nakagomi
T
T
Department of Neurosurgery, Teikyo University School of Medicine, Tokyo, Japan.
Asai
A
A
Kanemitsu
H
H
Narita
K
K
Kuchino
Y
Y
Tamura
A
A
Kirino
T
T
D000818:Animals; D017209:Apoptosis / Q000502:physiology; D001157:Arterial Occlusive Diseases / Q000235:genetics / Q000503:physiopathology; D015152:Blotting, Northern; D001921:Brain / Q000098:blood supply / Q000166:cytology / Q000378:metabolism; D002545:Brain Ischemia / Q000235:genetics* / Q000503:physiopathology; D005786:Gene Expression Regulation / Q000502:physiology; D008297:Male; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D016159:Tumor Suppressor Protein p53 / Q000235:genetics; D015854:Up-Regulation / Q000502:physiology
D019253:Proto-Oncogene Proteins c-bcl-2; D016760:Proto-Oncogene Proteins c-fos; D016271:Proto-Oncogene Proteins c-myc; D012333:RNA, Messenger; D016159:Tumor Suppressor Protein p53