Rahm M, Hultgårdh-Nilsson A, Jiang W Q, Sejersen T, Ringertz N R
Department of Medical Cell Genetics, Karolinska Institutet, Stockholm, Sweden.
J Cell Physiol. 1990 Jun;143(3):475-82. doi: 10.1002/jcp.1041430311.
The subcellular localization of the c-fos proto-oncogene product was studied in the G1, S, G2, 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 co-transfected mouse Swiss 3T3 fibroblasts were used. During G1, S, and G2, 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 immunofluorescence 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 nucleus was fragmented into micronuclei containing single, or groups of, chromosomes. Immunofluorescence 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.
通过间接免疫荧光法研究了细胞周期的G1、S、G2和有丝分裂期c-fos原癌基因产物的亚细胞定位。为进行这些分析，使用了转染c-fos的L6J1大鼠骨骼肌成肌细胞和传代培养的成年大鼠主动脉平滑肌细胞，以及共转染c-fos和c-myc的小鼠瑞士3T3成纤维细胞。在G1、S和G2期，c-fos蛋白均匀分布于细胞核中，核仁除外。在有丝分裂前期，c-fos抗原与浓缩的染色体解离，弥散分布于细胞质中，直至末期，此时它似乎再次与重新组装的细胞核中的染色质相关联。当将c-fos产物的亚核分布与用荧光染料Hoechst染色的紧密堆积的DNA的分布进行比较时，发现了一种反比关系。Hoechst DNA荧光较弱的分散染色质区域显示出比含有较高浓度DNA的区域更强的fos免疫荧光。c-fos抗原的定位与参与转录和剪接的小核核糖核蛋白复合物典型抗原的定位部分重叠。为了检查c-fos蛋白是否会优先结合特定的间期染色体，将细胞核破碎成含有单个或成组染色体的微核。免疫荧光分析表明，大多数微核是fos阳性的。结合其他核抗原讨论了c-fos原癌基因产物的可能作用。
