Biomedical subjects

L Rogge

Publications and source records attributed to L Rogge.

27 records · Page 2Linked to original sources

PubMed1990

Nuclear factor I acts as a transcription factor on the MMTV promoter but competes with steroid hormone receptors for DNA binding.

Several steroid hormones induce transcription of the mouse mammary tumor virus (MMTV) promoter, through an interaction of their respective receptors with the hormone responsive elements (HREs) in the long terminal repeat (LTR) region. The molecular mechanism underlying transcriptional activation is not known, but binding of nuclear factor I (NFI) to a site adjacent to the HRE appears to be required for efficient transcription of the MMTV promoter. In JEG-3 choriocarcinoma cells the MMTV promoter is transcribed inefficiently, even after transfection of the receptor cDNA and treatment with glucocorticoids or progestins. These cells contain low levels of NFI as cotransfection of NFI cDNA enhances MMTV transcription and this effect is inhibited by mutation of the NFI binding site. In DNA binding experiments with purified NFI from pig liver, the glucocorticoid and progesterone receptors do not co-operate but rather compete with NFI for binding to their respective sites on the LTR. Similar results are obtained with a functional recombinant NFI synthesized in vitro. Competition for DNA binding is probably due to steric hindrance as the DNase I footprints of the hormone receptors and NFI do overlap. These results suggest that, though NFI acts as a transcription factor on the MMTV promoter, transcriptional activation does not take place through a direct facilitation of DNA binding of NFI by steroid hormone receptors.

Animals↗

PubMed1989

Hydroxyl radical footprints reveal novel structural features around the NF I binding site in adenovirus DNA.

We have identified a number of as yet unknown structural abnormalities of the NF I-DNA binding site within the inverted terminal repetition of adenovirus DNA by probing it with a hydroxyl radical footprinting technique. NF I binding alters the accessibility of the deoxyribose moieties to hydroxyl radicals both at the 3' and at the 5' side of the recognition sequence 5'-TGG(N)6GCCAA-3'. A smooth bend at the 5' side of the binding sequence is already present in naked linear DNA and it is further enhanced by protein binding. This could be demonstrated not only by hydroxyl radical footprinting but also by studying the temperature dependent mobility during gel electrophoresis of DNA fragments carrying the NF I binding site at circularly permutated positions. We propose that the bent conformation at this site is responsible for facilitating protein/DNA interactions.

Adenoviruses, Human↗

PubMed1989

Structural and functional organization of a porcine gene coding for nuclear factor I.

This paper describes the structure of a 70-kb porcine gene for nuclear factor I, including its promoter region, comprising a total of 11 exons. Different mRNAs that we have isolated as cDNAs from both porcine liver and human HeLa cells presumably are generated from this gene by differential splicing events. One cDNA species from porcine liver that lacks exon 9 carries coding information for a protein of 439 amino acids. The in vitro translated protein displays all the properties of an NFI-like protein with high affinity toward the sequence element TGG(N)6GCCAA, as shown by gel shift analysis, and no or little affinity toward CCAAT box containing sequences. Cotranslation experiments with full-length and truncated variants of the protein demonstrate that it binds as a dimer to its cognate DNA recognition sequence. Its DNA-binding domain which is retained in all cDNA clones was mapped by deletion analysis to the 250 N-terminal amino acids of the protein. No structural homologies are observed between this protein and other known DNA-binding proteins; instead, the protein contains a novel alpha-helical sequence motif consisting of several lysine residues spaced at intervals of seven amino acids which we have termed the "lysine helix". The C-terminal portion of the protein derived from full-length cDNAs encodes a short amino acid sequence which is identical with the heptapeptide repeat CT7 observed in the C-terminal domain of the largest subunits of yeast and mouse RNA polymerase II. This region is removed by differential splicing in some of the NFI/CTF cDNAs and thus may be of functional significance.

Amino Acid Sequence↗

PubMed1989

Clusters of nuclear factor I binding sites identify enhancers of several papillomaviruses but alone are not sufficient for enhancer function.

The long control region (LCR) of human papillomaviruses (HPV) encompasses 5-12% of the viral genome and contains an intricate network of cis responsive elements. In the LCR of seven unrelated HPV-types, namely HPV-1, 6, 8, 11, 16, 18 and 33, we have identified clusters of 4 to 7 5-TTGGC-3 motifs suggesting nuclear factor I (NFI) binding sites. We randomly selected 20 (out of a total of 38) of these motifs and showed that pure NFI from porcine liver protects virtually the same nucleotides as a factor present in crude HeLa nuclear extracts. The footprints obtained with HeLa extracts in the LCR of HPV-16 are eliminated in competition experiments by an oligonucleotide representing the palindromic adenovirus NFI binding site. Restriction fragments from the genome of HPV-11, 16 and 18, which contain this cluster of NFI binding sites associated with binding sites of unrelated transcription factors, function as transcriptional enhancers. In contrast, a fragment from HPV-8 exhibiting exclusively NFI binding sites, or polymerized NFI sites from HPV-16, are functionally inactive. NFI seems to be necessary but not sufficient for HPV enhancer activation.

Base Sequence↗

PubMed1988

Purification methods for the sequence-specific DNA-binding protein nuclear factor I (NFI)--generation of protein sequence information.

The paper describes a potent purification method, preparative gel retention, for the purification of sequence-specific DNA-binding proteins. This procedure exploits the sequence-specific DNA-binding affinity of such proteins for their enrichment, comparable to recognition site DNA affinity chromatography. The method was employed to obtain a pure preparation of nuclear factor I (NFI) from porcine liver from which sequences of partial peptides could be obtained. Oligonucleotide probes derived from these amino-acid sequences were used to identify genomic and cDNA clones of NFI.

Amino Acid Sequence↗

PubMed1988

Isolation and characterization of the porcine nuclear factor I (NFI) gene.

This study describes the isolation of a major portion of the gene for nuclear factor I (NFI) including its 5'-flanking region with transcriptional start sites. We screened a porcine liver, genomic DNA library in phage EMBL3A with synthetic oligonucleotides derived from tryptic and cyanogen-bromide peptide sequences obtained from purified NFI protein. The NFI gene is present as a single copy in porcine DNA.

Amino Acid Sequence↗

PubMed1988

A quantitative analysis of nuclear factor I/DNA interactions.

Nuclear factor I (NFI) was purified to homogeneity from porcine liver by DNA-affinity chromatography and displays a single band with a molecular weight of 36 kDa in SDS-polyacrylamide gels. The purified protein was used to determine absolute equilibrium binding constants by gel retardation techniques for a variety of DNA fragments with genuine or mutated NFI binding sites and a number of DNA fragments derived from various eukaryotic promoters carrying the CCAAT-box as a half-site for NFI binding. We present a model which allows prediction of the functional significance of mutated NFI binding-sites from sequence data. The data suggest that the single molecular species of NFI from porcine liver may not be able to recognize and activate the -CCAAT- promoter element in vivo without additional interactions, e.g. with other proteins.

Adenoviridae↗

PubMedDate not supplied

Proliferative responses to selected peptides of IA-2 in identical twins discordant for Type 1 diabetes.

BACKGROUND: The aim of the study was to define T lymphocyte reactivity to selected peptides of an islet antigen IA-2, associated with Type 1 diabetes. METHODS: We used 10 peptides selected from the IA-2 molecule due to their predicted ability to bind to HLA-DRB1*0401, a Type 1 diabetes-associated allele. We tested 21 identical twin pairs discordant for the disease and 15 control subjects and then followed them prospectively; seven non-diabetic twins developed diabetes. RESULTS: Twins of identical pairs tended to respond to different peptides suggesting that the T cell response is, to a degree, shaped by non-genetically determined factors (p<0. 0001). However, there was no difference in the T cell responses between diabetic twins and either their non-diabetic identical twins or control subjects and the response was heterogenous. T cell responses did not differ in those seven non-diabetic twins who developed diabetes from those twins who did not. T cell responses to peptide 11 (amino acids 502-514) was immunodominant in diabetic twins as well as their non-diabetic twins and controls; responses were not correlated with HLA, IA-2 antibodies, age or duration of disease. CONCLUSION: We conclude that T cell responses to selected IA-2 peptides are not genetically determined, heterogeneous, not strictly HLA controlled and did not distinguish diabetic or prediabetic twins from non-diabetic twins or controls. The identification of an immunodominant T cell response to IA-2 peptide 502-514 raises the possibility that this, or similar, epitopes may be of therapeutic value in disease prevention.

Adolescent↗

PubMedDate not supplied

Type I interferons and the Th1/Th2 paradigm.

During the past year significant advances have been made in our understanding of the factors contributing to the differentiation of CD4+ T helper cell subsets. These have been driven, in part, by the realization that cytokines from the innate immune response, such as interleukin-12 (IL-12) and interferons (IFNs), play a critical role in T cell subset differentiation. This review covers some of the most recent data concerning the divergent role that IFNs have in the differentiation of human versus mouse T helper cell subsets. In this review we discuss the molecular basis for the specie-specific effect of type I IFN on the selective induction of Th1 type immune responses. Furthermore, since IFN-beta is used in the treatment of multiple sclerosis (MS) we discuss the potential effects of such treatment and the value of the Th1/Th2 paradigm in MS.

Animals↗