Chuĭkin I A, Lianguzova M S, Pospelov V A
Tsitologiia. 2004;46(12):1080-90.
Retinoic acid (RA) causes differentiation of mouse F9 embryonic carcinoma cell line into primitive and parietal (with dibutiril-cAMP) endoderm. The role of AP-1 transcription factor during RA-induced differentiation was studied in F9 cell line. It was shown that differentiated cells acquired protein complexes, which are specifically bound to well characterized AP-1 32P-labeled binding sites from collagenase (Col-AP-1) and c-jun (Jun2-AP-1) promoters. These complexes contain c-Fos/c-Jun with Col-AP-1 site and c-Jun/ATF-2 with Jun2-AP-1 site as revealed by supershift analysis. DNA-binding activity of these complexes is high in parietal endoderm but low-detectable in undifferentiated cells. DNA-binding activity of AP-1 transcription factor correlates with increased expression of c-fos and c-jun genes. RT-PCR analysis showed an increase in steady-state level of c-fos and c-jun gene transcription at the stage of parietal endoderm (terminally differentiated F9 cells). Transcription of immediate early c-fos and c-jun genes and DNA-binding activity of c-Fos/c-Jun complex are serum dependent. The rate of c-fos and c-jun gene transcription and DNA-binding activity of c-Fos/c-Jun complex decreased in serum-starved cells, but was rapidly induced upon stimulation with serum. Undifferentiated F9 cells contain a very low level of c-fos mRNA, with may be a consequence of repressive chromatin structure in promoter region. Histone deacetylase (HDAC) activity is necessary to restrict expression of specific number of genes, also HDAC inhibitors are well known inductors of differentiation and anticancer agents. Frow cytometry analysis showed a decreased rate of proliferation of F9 cells after their incubation with HDAC inhibitors, sodium butirate and trichostatin A. Also, these ihibitors induced the transcription of c-fos gene. So, we conclude that HDAC activity may be necessary to sustain a high proliferative rate of undifferentiated F9 cells.
视黄酸（RA）可使小鼠F9胚胎癌细胞系分化为原始内胚层和壁内胚层（与二丁酰环磷腺苷共同作用）。在F9细胞系中研究了AP-1转录因子在RA诱导分化过程中的作用。结果表明，分化细胞获得了蛋白质复合物，这些复合物能特异性结合来自胶原酶（Col-AP-1）和c-jun（Jun2-AP-1）启动子的、特征明确的AP-1 32P标记结合位点。超迁移分析显示，这些复合物在Col-AP-1位点含有c-Fos/c-Jun，在Jun2-AP-1位点含有c-Jun/ATF-2。这些复合物的DNA结合活性在壁内胚层中较高，而在未分化细胞中难以检测到。AP-1转录因子的DNA结合活性与c-fos和c-jun基因表达的增加相关。RT-PCR分析表明，在壁内胚层阶段（终末分化的F9细胞），c-fos和c-jun基因转录的稳态水平增加。即刻早期c-fos和c-jun基因的转录以及c-Fos/c-Jun复合物的DNA结合活性依赖于血清。在血清饥饿的细胞中，c-fos和c-jun基因的转录速率以及c-Fos/c-Jun复合物的DNA结合活性降低，但在用血清刺激后迅速被诱导。未分化的F9细胞中c-fos mRNA水平极低，这可能是启动子区域抑制性染色质结构的结果。组蛋白去乙酰化酶（HDAC）活性对于限制特定数量基因的表达是必要的，HDAC抑制剂也是众所周知的分化诱导剂和抗癌剂。流式细胞术分析显示，F9细胞与HDAC抑制剂丁酸钠和曲古抑菌素A孵育后增殖速率降低。此外，这些抑制剂诱导了c-fos基因的转录。因此，我们得出结论，HDAC活性可能是维持未分化F9细胞高增殖速率所必需的。
