305 research outputs found
Molecular mechanisms and functional consequences of the regulation of the MHC Class II transcription activator (CIITA)
No full textPhosphorylation of CIITA directs its oligomerization, accumulation and increased activity on MHCII promoters
No full textThe class II transactivator (CIITA) is the master regulator
of major histocompatibility complex class II
(MHCII) transcription. Its activity is regulated at the
post-transcriptional level by phosphorylation and oligomerization.
This aggregation mapped to and depended on the phosphorylation of residues between
positions 253 and 321 in CIITA, which resulted in a
dramatic accumulation of the protein and increased
expression of MHCII genes in human promonocytic
U937 cells, which represent immature antigen-presenting
cells. Thus, the post-transcriptional modification
of CIITA plays an important role in the immune
response
Major histocompatibility complex class II transcriptional platform: assembly of nuclear factor Y and regulatory factor X (RFX) on DNA requires RFX5 dimers
No full textMajor histocompatibility complex class II (MHC-II) genes are regulated in a B-cell-specific and gamma
interferon-inducible manner. Conserved upstream sequences (CUS) in their compact promoters bind nuclear
factor Y (NFY) and regulatory factor X (RFX) complexes. These DNA-bound proteins form a platform that
attracts the class II transactivator, which initiates and elongates MHC-II transcription. In this report, we
analyzed the complex assembly of these DNA-bound proteins. First, we found that NFY can interact with RFX
in cells. In particular, NFYA and NFYC bound RFXANK/B in vitro. Next, RFX5 formed dimers in vivo and in
vitro. Within a leucine-rich stretch N-terminal to the DNA-binding domain in RFX5, the leucine at position 66
was found to be critical for this self-association. Mutant RFX5 proteins that could not form dimers also did
not support the formation of higher-order DNA-protein complexes on CUS in vitro or MHC-II transcription
in vivo. We conclude that the MHC-II transcriptional platform begins to assemble off CUS and then binds DNA
via multiple, spatially constrained interactions. These findings offer one explanation of why in the Bare
Lymphocyte Syndrome, which is a congenital severe combined immunodeficiency, MHC-II promoters are bare
when any subunit of RFX is mutated or missing
MHC class II enhanceosome: how is the class II transactivator recruited to DNA-bound activators?
No full textMHC class II (MHCII) determinants play a crucial role in the immune response by presenting
antigenic peptides to T cells. Their expression is controlled from compact promoters at the
transcriptional level. Pre-assembled regulatory factor X (RFX) and nuclear factor Y (NFY)
complexes form a platform on DNA. The class II transactivator (CIITA) can then be recruited
through multiple protein±protein interactions. In this report, we de®ned domains of CIITA that
are responsible for its interactions with these DNA-bound factors. Furthermore, using DNA-af®nity
precipitation, we demonstrated that although CIITA binds at least ®ve activators, RFX5, RFXAP,
RFXANK/B, NFYB and NFYC, its assembly on the promoter requires the addition of nuclear
extracts. We conclude that not only does the platform bind DNA via multiple, spatially
constrained nteractions, but that it can recruit only modi®ed and/or complexed CIITA to MHCII
promoters
Abnormal expression of dysferlin in skeletal muscle and monocytes supports primary dysferlinopathy in patients with one mutated allele
No full textBackground: In some cases, a definitive confirmation of dysferlinopathy cannot be achieved by DNA test, because the mutation is detected in one allele only. Patients and methods: Dysferlin expression in skeletal muscle and peripheral blood monocytes (PBM) was studied by Western blot in two unrelated adult patients. The comparative CT method (ΔΔCT) was used to calculate relative changes in dysferlin mRNA determined from real-time quantitative PCR experiments. The dysferlin gene was studied by direct sequencing of cDNA and genomic DNA and by Multiplex Ligation-dependent Probe Amplification (MLPA) analysis. Results: A comparable severe reduction in dysferlin was demonstrated in both skeletal muscle and PBM. The expression of dysferlin mRNA was significantly reduced. A novel mutation in exon 47 (c.5289G>C) of the dysferlin gene in the heterozygous state, causing an amino acid change (p.Glu1763Asp), was detected in both patients. The MLPA analysis did not reveal any deletion or duplication. Conclusions: Dysferlin and/or dysferlin mRNA abnormalities are diagnostic for dysferlinopathy when mutational analysis detects a mutation in one allele only. Analysis of dysferlin mRNA can be helpful for distinguishing symptomatic heterozygotes from such patients. © 2010 The Author(s). European Journal of Neurology © 2010 EFNS
Corporate Risk Management in Slovenian Firms
No full textIn today’s competitive environment the modern firm increasingly focuses on identifying, measuring and managing various risk exposures. Risk management is interwoven with the firm’s business strategy and impacts considerably on its competitive position. Thus, management should develop an integrated approach to address it. Although hedging using derivatives accounts for just one part of such an approach, the article solely covers financial risk management using derivatives. Namely, it is found that even Slovenian blue-chip firms still have room to improve as they have only recently started to use derivatives. The article reviews some of the most interesting characteristics and practices of modern Slovenian financial risk management departments and provides a practically oriented case-study which describes the important steps a risk manager must take to hedge commodity price exposure.risk management, derivatives, corporate finance, hedging accounting, reporting, supervision, auditing
Therapeutic perspectives of epigenetically active nutrients
No full textMany nutrients are known for a wide range of activities in prevention and alleviation of various diseases. Recently, their potential role in epigenetics regulating human health has become evident, although specific mechanisms are still unclear. Thus, nutriepigenetics/nutriepigenomics has emerged as a new and promising field in current epigenetics research in the past few years. In particular, polyphenols, as part of the central dynamic interaction between the genome and the environment with specificity at physiological concentrations, are well known to affect mechanisms underlying human health. This review summarizes the effects of dietary compounds on epigenetic mechanisms in the regulation of gene expression including expression of enzymes and other molecules responsible for drug absorption, distribution, metabolism, and excretion in cancer, metabolic syndrome, neurodegenerative disorders, and hormonal dysfunctions
"Cystic Fibrosis gene mutations and linked RFLPs in the Slovenian population"
No full textThe authors used polymerase chain reaction to analyse 56 Slovenian cystic fibrosis (CF) chromosomes for the presence of delta F508 and eight other most frequent mutations located in exons 7,11 and 20 (R347P, R334W, G551D, R553X, S549RA, S549RT, S549I and S1255X) of the CF gene. We also determined the frequency of haplotypes associated with CF for six linked RFLP markers (MetD/TaqI, MetH/TaqI, XV-2c/TaqI, KM-19/PstI, MP6d9/MspI and J3.11/MspI) in 27 Slovenian CF families. delta F508 mutation was present in 55.4 percent of the CF chromosomes. No case of the other mutations were detected in the sample of tested CF chromosomes. A very high degree of association (0.88) has been found between DNA marker MetH and CF (as measured by the Yule's association coefficient) in our population. Using the RFLP markers XV-2c and KM-19, we found that 85% of delta F508 mutated chromosomes have a single 1 2 (B) haplotype, and that this haplotype is present on only 15.4 percent of CF chromosomes without this deletion
Ets-1 activates the DRA promoter in B cells.
No full textInternational audienceThe X box in promoters of class II major histocompatibility complex genes plays a crucial role in the B-cell-specific and gamma interferon-inducible expression of these genes. The sequence TTCC is located in the pyrimidine tract which extends 5' to and partially overlaps the X box of the DRA promoter. This sequence resembles the core binding site for the Ets family of DNA-binding proteins. In this study, we demonstrate that mutations within the pyrimidine tract which change the TTCC motif, but do not affect the binding of regulatory factor X to the X box, decrease the activity of the DRA promoter in B cells. Furthermore, using electrophoretic mobility shift assays and cotransfection experiments, we demonstrate that Ets-1, but not Ets-2 or PU.1, functionally interacts with the pyrimidine tract and activates the DRA promoter
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