Intracellular distribution of the c-fos antigen during the cell cycle

✍ Scribed by Magnus Rahm; Anna Hultgardh-Nilsson; Wei-Qin Jiang; Thomas Sejersen; Nils R. Ringertz

• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 987 KB
• Volume: 143
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.1041430311

✦ Synopsis

The subcellular localization of the c-fos proto-oncogene product was studied in the G,, 5, G, , and mitotic phases of the cell cycle by indirect immunofluorescence. For these analyses c-fos transfected L6J1 rat skeletal myoblasts and adult rat aortic smooth muscle cells in secondary culture, and c-fos-and c-myc cotransfected mouse Swiss 373 fibroblasts were used. During G,, S, and G, , the c-fos protein was evenly distributed in the nucleus, with exclusion of the nucleoli. In mitotic prophase the c-fos antigen was dissociated from the condensed chromosomes and became diffusely distributed in the cell cytoplasm, where it remained until telophase, when, again, it appeared to be associated with chromatin in the re-assembling nucleus. When comparing the subnuclear distribution of the c-fos product with that of densely packed DNA, stained with the fluorochrome Hoechst, an inverse relationship was found. Dispersed chromatin regions with weak Hoechst DNA fluorescence showed a stronger fos irnmunofluorescence than regions that contained a higher concentration of DNA. The localization of c-fos antigen partially overlapped with that of antigens typical of small nuclear ribonucleoprotein complexes participating in transcription and splicing.

To examine if the c-fos protein would bind preferentially to specific interphase chromosomes the nucleu3 was fragmented into micronuclei containing single, or groups of, chromosomes. lmmunofluorescence analysis showed that the majority of micronuclei were fos-positive. Possible roles of the c-fos proto-oncogene product are discussed in relation to other nuclear antigens.