Bailly A, Späth G, Bender V, Weiss M C
Unité de Génétique de la Différenciation, URA 1773 du CNRS, Institut Pasteur, 75724 Paris Cedex 15, France.
J Cell Sci. 1998 Aug;111 ( Pt 16):2411-21. doi: 10.1242/jcs.111.16.2411.
Tagged versions of HNF4 or HNF1alpha cDNAs in expression vectors have been introduced by transient and stable transfection into three cell lines of hepatic origin that all fail to express these two liver-enriched transcription factors and hepatic functions. C2 and H5 cells are dedifferentiated rat hepatoma variants and WIF12-E cells are human fibroblast-rat hepatoma hybrids with a reduced complement of human chromosomes. Transfectants were analyzed for the expression state of the endogenous genes coding for these transcription factors and for hepatic functions. Each cell line showed a different response to the forced expression of the transcription factors. In C2 cells, no measurable effect was observed, either upon transitory or stable expression. H5 cells reexpressed the endogenous HNF4 gene only upon transient HNF1alpha transfection, and the endogenous HNF1alpha gene only in stable HNF4 transfectants. WIF12-E cells responded to the forced transient or stable expression of either HNF1alpha or HNF4 by cross-activation of the corresponding endogenous gene. In addition, the stable transfectants reexpress HNF3alpha and C/EBPalpha, as well as all of the hepatic functions examined. Hybrid cells similar to WIF12-E had previously been observed to show pleiotropic reexpression of the hepatic phenotype in parallel with loss of human chromosome 2. For the stable WIF12-E transfectants, it was verified that reexpression of the hepatic phenotype was not due to loss of human chromosome 2. The demonstration of reciprocal cross-regulation between HNF4 and HNF1alpha in transient as well as stable transfectants implies that direct effects are involved.
已通过瞬时转染和稳定转染将表达载体中带有标签的HNF4或HNF1α cDNA导入三种肝源性细胞系，这些细胞系均无法表达这两种肝脏富集转录因子及肝功能。C2和H5细胞是去分化的大鼠肝癌变体，WIF12 - E细胞是人类成纤维细胞 - 大鼠肝癌杂交细胞，其人类染色体的互补成分减少。分析转染子中编码这些转录因子的内源性基因的表达状态以及肝功能。每个细胞系对转录因子的强制表达表现出不同的反应。在C2细胞中，无论是瞬时表达还是稳定表达，均未观察到可测量的效应。H5细胞仅在瞬时转染HNF1α时重新表达内源性HNF4基因，仅在稳定转染HNF4时重新表达内源性HNF1α基因。WIF12 - E细胞通过相应内源性基因的交叉激活对HNF1α或HNF4的强制瞬时或稳定表达做出反应。此外，稳定转染子重新表达HNF3α和C/EBPα以及所有检测的肝功能。此前观察到类似于WIF12 - E的杂交细胞在人类染色体2丢失的同时多效性地重新表达肝表型。对于稳定的WIF12 - E转染子，已证实肝表型的重新表达并非由于人类染色体2的丢失。在瞬时和稳定转染子中HNF4和HNF1α之间相互交叉调节的证明意味着涉及直接效应。
