Molecular Cloning and Analysis of an eIF-4A-related Rat Liver Nuclear Protein. J Biol Chem. 1992 Jun 25;267(18):12928-35. (original) (raw)
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Nucleic acids …, 2001
Hepatocyte nuclear factor-4 (HNF4) regulates gene expression by binding to direct repeat motifs of the RG(G/T)TCA sequence separated by one nucleotide (DR1). In this study we demonstrate that endogenous HNF4 present in rat liver nuclear extracts, as well as purified recombinant HNF4, activates transcription from naked DNA templates containing multiple copies of the DR1 element linked to the adenovirus major late promoter. Recombinant HNF4 also activates transcription from the rat cellular retinol binding protein II (CRBPII) promoter in vitro. The region between –105 and –63 bp of this promoter is essential for HNF-mediated transactivation. The addition of a peptide containing the LXXLL motif abolished HNF4-mediated transactivation in vitro suggesting that LXXLL-containing protein factor(s) are involved in HNF4-mediated transactivation in rat liver nuclear extracts. This is the first report on transactivation by HNF4 in a cell-free system derived from rat liver nuclei.
The protein composition of the hepatocyte nuclear matrix is differentiation-stage specific
… of Biochemistry and …, 2000
The protein composition of hepatocyte nuclear matrices was examined in rats from the 16th day of gestation to 75 days after birth (adult). An overall increase in size of the nuclear matrix was accompanied by quantitative and qualitative changes in its protein content. Quantitative changes of the major proteins of the peripheral lamina surrounding the isolated nuclear matrix were detected. By Western analysis we established that in pre-and postnatal nuclear matrices the relative concentrations of lamin C were greater than lamin A. After birth, the relative concentrations of both lamins progressively increased. In the adult nuclear matrix, the concentration of lamin A was greater than lamin C. In contrast, the relative concentrations of lamin B remained unchanged throughout development and growth. The relative concentrations of two nuclear matrixassociated regulatory proteins studied changed with development and growth: transcription factor C/EBP® isoforms, which were detected during the gestation period, increased notably after the rst postnatal day, attaining a maximum at the adult stage; the high concentrations of the proliferating cell nuclear antigen (PCNA) perceptibly decreased after the 21st prenatal day. Changes in the composition of the nuclear matrix protein suggest that this structure coordinates nuclear functioning during cell differentiation.
Biochemical Journal, 1998
Hepatocyte nuclear factor 6 (HNF-6) is the prototype of a family of tissue-specific transcription factors characterized by a bipartite DNA-binding domain consisting of a single cut domain and a novel type of homeodomain. We have previously cloned rat cDNA species coding for two isoforms, HNF-6α (465 residues) and β (491 residues), which differ only by the length of the spacer between the two DNA-binding domains. We have now localized the rat Hnf6 gene to chromosome 8q24–q31 by Southern blotting of DNA from somatic cell hybrids and by fluorescence in situhybridization. Cloning and sequencing of the rat gene showed that the two HNF-6 isoforms are generated by alternative splicing of three exons that are more than 10 kb apart from each other. Exon 1 codes for the N-terminal part and the cut domain, exon 2 codes for the 26 HNF-6β-specific amino acids, and exon 3 codes for the homeodomain and the C-terminal amino acids. The transcription initiation site was mapped by ribonuclease protect...
Gene regulation in rodent hepatocytes during development, differentiation and disease
European Journal of Biochemistry, 1993
The expression of genes in the liver is mostly controlled at the transcriptional level and depends on the regulatory interactions between cis-acting sequences and trans-acting molecules. Proximal promoters and distant enhancers in combination with a number of hepatocyte-enriched DNA-binding proteins and general transcription factors interact specifically with these elements and control the expression of liver-specific genes. Hepatocyte-enriched regulatory proteins have been isolated from liver nuclear extracts, characterized, and their corresponding genes have been cloned. These include the hepatocyte nuclear factors 1, 3, 4 (HNF-1,3,4), some members of the CAAATIenhancer binding protein (CEBP) family, and D site binding protein (DBP). These factors belong to larger families and are able to form heterodimers, perhaps with the exception of the HNF-3 family, with other members of the same family. Interestingly, the majority of the genes encoding such proteins are themselves regulated at the transcriptional level, although both transcriptional and post-transcriptional events modulate their expression during development, hepatocyte differentiation and disease, suggesting that a transcriptional cascade may play a critical role in mammalian liver development and differentiation. Cellular proliferation and differentiation during development is controlled by many regulatory processes. These include the selective induction, expression and regulation of the activity of genes which are likely to encode for DNAbinding proteins or proteins that interact with them and control the transcription of several other genes. Thus a cascade of transcriptional activities is initiated that will direct development and differentiation to the adult phenotype [l -31. The study of liver development and differentiation offers many opportunities to address these questions at the molecular level. Rodent liver organogenesis has been thoroughly studied at the cellular level. It is now known that at day eight of embryonal development the endodermal cells of the developing foregut are induced by the precardiac mesenchyme and approximately one day later the hepatic endoderm will emerge from the gut endoderm. Subsequently the primary liver diverticulum invades the mesenchyme of the septum transversum. During this stage, proliferation and differentiation of the hepatic endoderm into hepatoblasts occurs.
Genes & Development, 1991
Hepatocyte nuclear factor 1 (HNF-1) is a transcriptional regulatory protein possibly involved in the activation of many liver-specifically expressed genes. HNF-1 mRNA is restricted to a small number of tissues, suggesting that the HNF-1 gene itself is regulated at the transcriptional level. We have isolated and characterized the promoter region of this gene and have determined its transcriptional potential in several cell types by cell-free transcription and transient transfection experiments. In in vitro transcription assays, an HNF-1 promoter is active in nuclear extracts from liver and kidney, two tissues that contain HNF-1, but silent in nuclear extracts from spleen and lung, which are devoid of this transcription factor. Likewise, in transfection experiments, HNF-1 promoter-chloramphenicol acetyltransferase (CAT) fusion genes are expressed in Hep G2 cells, which express HNF-1, but not in mouse L cells or Hela cells, which do not express HNF-1. In both cell-free transcription and transient transfection assays, a relatively short promoter segment located between positions -82 and -40 is necessary and sufficient to direct cell type-specific HNF-1 transcription. This region contains a single site for a DNA-binding protein that has been tentatively identified as hepatocyte nuclear factor 4, a member of the steroid hormone receptor family. Cold Spring Harbor Laboratory Press on July 15, 2016 -Published by genesdev.cshlp.org Downloaded from 2226 GENES & DEVELOPMENT Cold Spring Harbor Laboratory Press on July 15, 2016 -Published by genesdev.cshlp.org Downloaded from 2230 GENES & DEVELOPMENT Cold Spring Harbor Laboratory Press on July 15, 2016 -Published by genesdev.cshlp.org Downloaded from Tissue-specific HNF-1 transcription Discussion Access the most recent version at doi: 1991 5: 2225-2234 Genes Dev. J M Tian and U Schibler factor 1 may involve hepatocyte nuclear factor 4. Tissue-specific expression of the gene encoding hepatocyte nuclear References http://genesdev.cshlp.org/content/5/12a/2225.full.html#ref-list-1
Developmentally regulated mRNAs in mouse liver
Proceedings of the National Academy of Sciences, 1982
The mouse liver contains a group of 10-12 different tissue-specific mRNAs, each present at an average concentration of 12,000-15,000 copies per cell [Hastie, N. D. & Bishop, J. 0. (1976) Cell 9, 761-774]. We have determined, by translation in vitro, that these mRNAs are developmentally regulated in the liver. We have also used specific cloned probes to quantitate the developmental time course of expression of five different abundant liver mRNAs. We have found that there are at least three periods during liver development when specific abundant mRNAs are first detectable: prior to 14 days postconception, at birth, and during the onset of sexual maturity. These results indicate that all the members of this mRNA group are not under common developmental regulation. One of the abundant liver mRNAs (p54 mRNA) increases more than 1000-fold in the liver 1 day before birth. We discuss factors that may be involved in the developmental regulation of expression of the genes encoding these mRNAs.
Nucleic Acids Research, 1989
The proximal promoter region of the human transferrin gene contains an hepatocyte-specific cis-element (PRI, nucleotides -76 to -51) whose DNA sequence is homologous to a sequence (nucleotides -89 to -68) present in the transcriptionally essential 5' region of the human antithrombin III gene and to another hepatocyte-specific sequence (A domain) of the human a 1 -antitrypsin gene promoter. The results reported here lead to the conclusion that the liver trans-acting factor Tf-LF1, binding to the transferrin PRI cis-element interacts with the homologous antithrombin III region, but is different from the transcription factor LF-A1 interacting with the A domain of the a l-antitrypsin promoter.
Cancer research, 1979
The nuclear proteins of regenerating and fetal rat liver, slow growing Morris hepatoma 961 8A, and fast-growing Morris hepatoma 3924A, sequentially extracted from nuclei with (a) 0.075 M NaCl/0.O25 M EDTA, (b) 10 mMTnis,(c) 0.35 M NaCl, (d) 0.6 M NaCI, and (e) 3 M NaCI/7 M urea, were analyzed by two-dimensional, isoelectric-focusing sodium dodecyl sulfate gel electrophoresis. Many of the protein spots were common to these tissues as well as to the Novikoff hepatoma and normal liver. The protein patterns of the regenerating liver and slow growing 961 8A hepatoma were more similar to that of normal liver than to those of other tissues. Many similarities were found between the fetal liver and the fast-growing 3924A and Novikoff hepatomas. Four protein spots, 64/5.9, 60/6.3, 51 /5.3, and 38/7.3 (M.W. x 1O'3/pI), were only found in the fast-growing 3924A and Novikoff hepatomas. Proteins 79/6.4 and 61/7.2 were only found in the three hepatomas. Protein 37/6.3 was dense in the three hepatornas and much less dense in the regenerating and fetal livers. Two proteins, 28/5.0 and 27/ 4.9, were detected only in the fast-growing 3924A and Novikoft hepatomas and fetal liven. Proteins 125/8.2 and 98/8.4 were found in the fetal liver and the three hepatomas; these proteins may be â€ẫ€˜oncofetal' â€p roteins. Three proteins, 61 /5.5, 56/5.8, and 53/7.5, that were absent from other tissues were present in the regenerating liver, fast-growing 3924A and Novikoff hepatomas, fetal liver, and slow-growing 961 8A hepatoma. These proteins may be related to growth processes of normal and tumor tissues studied.
Tissue-specific regulation of mouse hepatocyte nuclear factor 4 expression
Molecular and cellular biology, 1994
Hepatocyte nuclear factor 4 (HNF-4) is a liver-enriched transcription factor and a member of the steroid hormone receptor superfamily. HNF-4 is required for the hepatoma-specific expression of HNF-1 alpha, another liver-enriched transcription factor, suggesting the early participation of HNF-4 in development. To prepare for further study of HNF-4 in development, the tissue-specific expression of the mouse HNF-4 gene was studied by analyzing the promoter region for required DNA elements. DNase-hypersensitive sites in the gene in liver and kidney tissues were found in regions both distal and proximal to the RNA start that were absent in tissues in which HNF-4 expression did not occur. By use of reporter constructs in transient-transfection assays and with transgenic mice, a region sufficient to drive liver-specific expression of HNF-4 was identified. While an HNF-1 binding site between bp -98 and -68 played an important role in the hepatoma-specific promoter activity of HNF-4 in trans...
Cancer research, 1991
Multiple a-fetoprotein (AFP) RNAs are expressed in the rat liver and are differentially regulated during development. We examined the expres sion and cellular distribution of the full-length AFP RNA (major form, 2.1 kilobases highly expressed in fetal liver) and 3 variants of 1.7, 1.4, and 1.0 kilobases in normal rat liver, during fetal development, in regeneration, and in carcinogenesis. The 1.7-kilobase variant is expressed only in developing liver (by 15 days of gestation) and is much less abundant than the major form. In adult normal liver the 1.4-and 1.0kilobase RNAs are the predominant forms. By cell separation studies we show that these variants are produced by parenchyma! and nonparenchymal cells in normal rat liver, and that the full-length AFP mRNA is detectable in normal nonparenchymal cells. We demonstrate by in situ hybridization that the 2.1-kilobase mRNA is expressed by some ductular cells and a few nondividing hepatocytes (approximately 1 in 20,000). Further studies revealed that (a) the 2.1-kilobase AFP mRNA encodes translation products of molecular weight 68,000 and 70,000, and probably has multiple sites for translation initiation; (b) the 1.4-kilobase AFP RNA variant in adult rat liver encodes translation products of molecular weight 58,000, 54,000, and 44,000; (c) the 2.1-kilobase AFP RNA increases in liver nonparenchymal cells after CCU injury (20-30-fold) and in galactosamine-injured liver (60-100-fold), while the 1.4-and 1.0kilobase variants change much less; and (</) after partial hepatectomy there are only small changes in any of the AFP RNAs, while during carcinogenesis oval cells contain large amounts of 2.1-kilobase AFP RNA and levels of the 1.4-and 1.0-kilobase species which are lower than those in normal liver. We suggest that after development synthesis of the fulllength RNA is not shut off in a small proportion of rat liver cells and that ductular cells that express this RNA may constitute a facultative liver stem cell compartment.