Specifically binds to the upstream regulatory region of type I IFN and IFN-inducible MHC class I genes (the interferon consensus sequence (ICS)) and represses those genes. Also acts as an activator for several genes including H4 and IL7. Constitutively binds to the ISRE promoter to activate IL7. Involved in cell cycle regulation through binding the site II (HiNF-M) promoter region of H4 and activating transcription during cell growth. Antagonizes IRF1 transcriptional activation.
IRFs constitute a family of transcription factors involved in IFN signaling and in the development and differentiation of the immune system. IRFs activities are regulated at transcriptional level (such as IRF1) and post-translational modifications (such as IRF3 and IRF7). Here we show that IRF2 interacts with the SUMO-E3 ligase PIASy and is sumoylated in vivo. Mutagenesis analysis suggests that IRF2 contains three sumoylation sites. Sumoylation of IRF2 has no significant effects on its nuclear localization and DNA-binding activity, but increases its ability to inhibit IRF1 transcriptional activity and decreases its ability to activate the ISRE and H4 promoters. Our findings suggest that sumoylation of IRF2 regulates its transcriptional activities.
Intestinal epithelial cell-derived interleukin (IL)-7 functions as a pleiotropic and nonredundant cytokine in the human intestinal mucosa; however, the molecular basis of its production has remained totally unknown. We here showed that human intestinal epithelial cells both constitutively and when induced by gamma interferon (IFN-gamma) produced IL-7, while several other factors we tested had no effect. Transcriptional regulation via an IFN regulatory factor element (IRF-E) on the 5' flanking region, which lacks canonical core promoter sequences, was pivotal for both modes of IL-7 expression. IRF-1 and IRF-2, the latter of which is generally known as a transcriptional repressor, were shown to interact with IRF-E and transactivate IL-7 gene expression in an IFN-gamma-inducible and constitutive manner, respectively. Indeed, tetracycline-inducible expression experiments revealed that both of these IRF proteins up-regulated IL-7 protein production, and their exclusive roles were further confirmed by small interfering RNA-mediated gene silencing systems. Moreover, these IRFs displayed distinct properties concerning the profile of IL-7 transcripts upon activation and expression patterns within human colonic epithelial tissues. These results suggest that the functional interplay between IRF-1 and IRF-2 serves as an elaborate and cooperative mechanism for timely as well as continuous regulation of IL-7 production that is essential for local immune regulation within human intestinal mucosa.
We have previously shown that interferon regulatory factor-2 (IRF-2) is acetylated by p300 and PCAF in vivo and in vitro. In this study we identified, by mass spectrometry, two lysine residues in the DNA binding domain (DBD), Lys-75 and Lys-78, to be the major acetylation sites in IRF-2. Although acetylation of IRF-2 did not alter DNA binding activity in vitro, mutation of Lys-75 diminished the IRF-2-dependent activation of histone H4 promoter activity. Acetylation of IRF-2 and IRF-2-stimulated H4 promoter activity were inhibited by the adenovirus E1A, indicating the involvement of p300/CBP. Mutation of Lys-78, a residue conserved throughout the IRF family members, led to the abrogation of DNA binding activity independently of acetylation. H4 is transcribed only in rapidly growing cells and its promoter activity is dependent on cell growth. Consistent with a role for acetylated IRF-2 in cell growth control, IRF-2 was acetylated only in growing NIH 3T3 cells, but not in growth-arrested counterparts. Chromatin immunoprecipitation assays showed that IRF-2 interacted with p300 and bound to the endogenous H4 promoter only in growing cells, although the levels of total IRF-2 were comparable in both growing and growth-arrested cells. These results indicate that IRF-2 is acetylated in a cell growth-dependent manner, which enables it to contribute to transcription of cell growth-regulated promoters.
Maximal transcription of a prototypical cell cycle controlled histone H4 gene requires a proliferation-specific in vivo genomic protein/DNA interaction element, Site II. Three sequence-specific transcription factors interact with overlapping recognition motifs within Site II: interferon regulatory factor IRF-2 (HiNF-M), the putative H4 subtype-specific protein H4TF-2 (HiNF-P), and HiNF-D which represents a complex of the homeodomain protein CDP/cut, CDC2, cyclin A and pRB. However, natural sequence variation in the Site II sequences of different human H4 genes abolishes binding of specific trans-acting factors; the functional consequences of these variations have not been investigated. To address the precise contribution of H4 promoter factors to the level of H4 gene transcription, we performed a systematic mutational analysis of Site II transcriptional motifs. These mutants were tested for ability to bind each of the Site II cognate proteins, and subsequently evaluated for ability to confer H4 transcriptional activity using chimeric H4 promoter/CAT fusion constructs in different cell types. We also analyzed the effect of over-expressing IRF-2 on CAT reporter gene expression driven by mutant H4 promoters and assessed H4 transcriptional control in cells nullizygous for IRF-1 and IRF-2. Our results show that the recognition sequence for IRF-2 (HiNF-M) is the dominant component of Site II and modulates H4 gene transcription levels by 3 fold. However, the overlapping recognition sequences for IRF-2 (HiNF-M), H4TF-2 (HiNF-P) and CDP/cut (HiNF-D) together modulate H4 gene transcription levels by at least an order of magnitude. Thus, maximal activation of H4 gene transcription during the cell cycle in vivo requires the integrated activities of multiple transcription factors at Site II. We postulate that the composite organization of Site II supports responsiveness to multiple signalling pathways modulating the activities of H4 gene transcription factors during the cell cycle. Variations in Site II sequences among different H4 genes may accommodate differential regulation of H4 gene expression in cells and tissues with unique phenotypic properties.
Maximal transcription of a prototypical cell cycle controlled histone H4 gene requires a proliferation-specific in vivo genomic protein/DNA interaction element, Site II. Three sequence-specific transcription factors interact with overlapping recognition motifs within Site II: interferon regulatory factor IRF-2 (HiNF-M), the putative H4 subtype-specific protein H4TF-2 (HiNF-P), and HiNF-D which represents a complex of the homeodomain protein CDP/cut, CDC2, cyclin A and pRB. However, natural sequence variation in the Site II sequences of different human H4 genes abolishes binding of specific trans-acting factors; the functional consequences of these variations have not been investigated. To address the precise contribution of H4 promoter factors to the level of H4 gene transcription, we performed a systematic mutational analysis of Site II transcriptional motifs. These mutants were tested for ability to bind each of the Site II cognate proteins, and subsequently evaluated for ability to confer H4 transcriptional activity using chimeric H4 promoter/CAT fusion constructs in different cell types. We also analyzed the effect of over-expressing IRF-2 on CAT reporter gene expression driven by mutant H4 promoters and assessed H4 transcriptional control in cells nullizygous for IRF-1 and IRF-2. Our results show that the recognition sequence for IRF-2 (HiNF-M) is the dominant component of Site II and modulates H4 gene transcription levels by 3 fold. However, the overlapping recognition sequences for IRF-2 (HiNF-M), H4TF-2 (HiNF-P) and CDP/cut (HiNF-D) together modulate H4 gene transcription levels by at least an order of magnitude. Thus, maximal activation of H4 gene transcription during the cell cycle in vivo requires the integrated activities of multiple transcription factors at Site II. We postulate that the composite organization of Site II supports responsiveness to multiple signalling pathways modulating the activities of H4 gene transcription factors during the cell cycle. Variations in Site II sequences among different H4 genes may accommodate differential regulation of H4 gene expression in cells and tissues with unique phenotypic properties.
Interacting selectively and non-covalently with any protein or protein complex (a complex of two or more proteins that may include other nonprotein molecules).
Evidence
1:
Inferred from Physical InteractionIntAct
To systematically investigate innate immune signaling networks regulating production of type I interferon, we analyzed protein complexes formed after microbial recognition. Fifty-eight baits were associated with 260 interacting proteins forming a human innate immunity interactome for type I interferon (HI5) of 401 unique interactions; 21% of interactions were modulated by RNA, DNA, or LPS. Overexpression and depletion analyses identified 22 unique genes that regulated NF-κB and ISRE reporter activity, viral replication, or virus-induced interferon production. Detailed mechanistic analysis defined a role for mind bomb (MIB) E3 ligases in K63-linked ubiquitination of TBK1, a kinase that phosphorylates IRF transcription factors controlling interferon production. Mib genes selectively controlled responses to cytosolic RNA. MIB deficiency reduced antiviral activity, establishing the role of MIB proteins as positive regulators of antiviral responses. The HI5 provides a dynamic physical and regulatory network that serves as a resource for mechanistic analysis of innate immune signaling.
Erratum in:
Immunity. 35(4), 647-8 (2011 Oct 28)
Evidence
2:
Inferred from Physical InteractionUniProtKB
Maximal transcription of a prototypical cell cycle controlled histone H4 gene requires a proliferation-specific in vivo genomic protein/DNA interaction element, Site II. Three sequence-specific transcription factors interact with overlapping recognition motifs within Site II: interferon regulatory factor IRF-2 (HiNF-M), the putative H4 subtype-specific protein H4TF-2 (HiNF-P), and HiNF-D which represents a complex of the homeodomain protein CDP/cut, CDC2, cyclin A and pRB. However, natural sequence variation in the Site II sequences of different human H4 genes abolishes binding of specific trans-acting factors; the functional consequences of these variations have not been investigated. To address the precise contribution of H4 promoter factors to the level of H4 gene transcription, we performed a systematic mutational analysis of Site II transcriptional motifs. These mutants were tested for ability to bind each of the Site II cognate proteins, and subsequently evaluated for ability to confer H4 transcriptional activity using chimeric H4 promoter/CAT fusion constructs in different cell types. We also analyzed the effect of over-expressing IRF-2 on CAT reporter gene expression driven by mutant H4 promoters and assessed H4 transcriptional control in cells nullizygous for IRF-1 and IRF-2. Our results show that the recognition sequence for IRF-2 (HiNF-M) is the dominant component of Site II and modulates H4 gene transcription levels by 3 fold. However, the overlapping recognition sequences for IRF-2 (HiNF-M), H4TF-2 (HiNF-P) and CDP/cut (HiNF-D) together modulate H4 gene transcription levels by at least an order of magnitude. Thus, maximal activation of H4 gene transcription during the cell cycle in vivo requires the integrated activities of multiple transcription factors at Site II. We postulate that the composite organization of Site II supports responsiveness to multiple signalling pathways modulating the activities of H4 gene transcription factors during the cell cycle. Variations in Site II sequences among different H4 genes may accommodate differential regulation of H4 gene expression in cells and tissues with unique phenotypic properties.
Interacting selectively and non-covalently with a DNA region that regulates a DNA-based process. Such processes include transcription, DNA replication, and DNA repair.
Interacting selectively and non-covalently with a specific DNA sequence in order to modulate transcription. The transcription factor may or may not also interact selectively with a protein or macromolecular complex.
Evidence
1:
Inferred from Mutant PhenotypeUniProtKB
Maximal transcription of a prototypical cell cycle controlled histone H4 gene requires a proliferation-specific in vivo genomic protein/DNA interaction element, Site II. Three sequence-specific transcription factors interact with overlapping recognition motifs within Site II: interferon regulatory factor IRF-2 (HiNF-M), the putative H4 subtype-specific protein H4TF-2 (HiNF-P), and HiNF-D which represents a complex of the homeodomain protein CDP/cut, CDC2, cyclin A and pRB. However, natural sequence variation in the Site II sequences of different human H4 genes abolishes binding of specific trans-acting factors; the functional consequences of these variations have not been investigated. To address the precise contribution of H4 promoter factors to the level of H4 gene transcription, we performed a systematic mutational analysis of Site II transcriptional motifs. These mutants were tested for ability to bind each of the Site II cognate proteins, and subsequently evaluated for ability to confer H4 transcriptional activity using chimeric H4 promoter/CAT fusion constructs in different cell types. We also analyzed the effect of over-expressing IRF-2 on CAT reporter gene expression driven by mutant H4 promoters and assessed H4 transcriptional control in cells nullizygous for IRF-1 and IRF-2. Our results show that the recognition sequence for IRF-2 (HiNF-M) is the dominant component of Site II and modulates H4 gene transcription levels by 3 fold. However, the overlapping recognition sequences for IRF-2 (HiNF-M), H4TF-2 (HiNF-P) and CDP/cut (HiNF-D) together modulate H4 gene transcription levels by at least an order of magnitude. Thus, maximal activation of H4 gene transcription during the cell cycle in vivo requires the integrated activities of multiple transcription factors at Site II. We postulate that the composite organization of Site II supports responsiveness to multiple signalling pathways modulating the activities of H4 gene transcription factors during the cell cycle. Variations in Site II sequences among different H4 genes may accommodate differential regulation of H4 gene expression in cells and tissues with unique phenotypic properties.
Interferon regulatory factor-1 (IRF-1), a transcriptional activator, and IRF-2, its antagonistic repressor, have been identified as regulators of type I interferon and interferon-inducible genes. The IRF-1 gene is itself interferon-inducible and hence may be one of the target genes critical for interferon action. When the IRF-2 gene was overexpressed in NIH 3T3 cells, the cells became transformed and displayed enhanced tumorigenicity in nude mice. This transformed phenotype was reversed by concomitant overexpression of the IRF-1 gene. Thus, restrained cell growth depends on a balance between these two mutually antagonistic transcription factors.
Interferon regulatory factor 1 (IRF-1) and IRF-2 are structurally similar DNA-binding factors which were originally identified as regulators of the type I interferon (IFN) system; the former functions as a transcriptional activator, and the latter represses IRF-1 function by competing for the same cis elements. More recent studies have revealed new roles of the two factors in the regulation of cell growth; IRF-1 and IRF-2 manifest antioncogenic and oncogenic activities, respectively. In this study, we determined the structures and chromosomal locations of the human IRF-1 and IRF-2 genes and further characterized the promoters of the respective genes. Comparison of exon-intron organization of the two genes revealed a common evolutionary structure, notably within the exons encoding the N-terminal portions of the two factors. We confirmed the chromosomal mapping of the human IRF-1 gene to 5q31.1 and newly assigned the IRF-2 gene to 4q35.1, using fluorescence in situ hybridization. The 5' regulatory regions of both genes contain highly GC-rich sequences and consensus binding sequences for several known transcription factors, including NF-kappa B. Interestingly, one IRF binding site was found within the IRF-2 promoter, and expression of the IRF-2 gene was affected by both transient and stable IRF-1 expression. In addition, one potential IFN-gamma-activated sequence was found within the IRF-1 promoter. Thus, these results may shed light on the complex gene network involved in regulation of the IFN system.
Maximal transcription of a prototypical cell cycle controlled histone H4 gene requires a proliferation-specific in vivo genomic protein/DNA interaction element, Site II. Three sequence-specific transcription factors interact with overlapping recognition motifs within Site II: interferon regulatory factor IRF-2 (HiNF-M), the putative H4 subtype-specific protein H4TF-2 (HiNF-P), and HiNF-D which represents a complex of the homeodomain protein CDP/cut, CDC2, cyclin A and pRB. However, natural sequence variation in the Site II sequences of different human H4 genes abolishes binding of specific trans-acting factors; the functional consequences of these variations have not been investigated. To address the precise contribution of H4 promoter factors to the level of H4 gene transcription, we performed a systematic mutational analysis of Site II transcriptional motifs. These mutants were tested for ability to bind each of the Site II cognate proteins, and subsequently evaluated for ability to confer H4 transcriptional activity using chimeric H4 promoter/CAT fusion constructs in different cell types. We also analyzed the effect of over-expressing IRF-2 on CAT reporter gene expression driven by mutant H4 promoters and assessed H4 transcriptional control in cells nullizygous for IRF-1 and IRF-2. Our results show that the recognition sequence for IRF-2 (HiNF-M) is the dominant component of Site II and modulates H4 gene transcription levels by 3 fold. However, the overlapping recognition sequences for IRF-2 (HiNF-M), H4TF-2 (HiNF-P) and CDP/cut (HiNF-D) together modulate H4 gene transcription levels by at least an order of magnitude. Thus, maximal activation of H4 gene transcription during the cell cycle in vivo requires the integrated activities of multiple transcription factors at Site II. We postulate that the composite organization of Site II supports responsiveness to multiple signalling pathways modulating the activities of H4 gene transcription factors during the cell cycle. Variations in Site II sequences among different H4 genes may accommodate differential regulation of H4 gene expression in cells and tissues with unique phenotypic properties.
Protein involved in the transfer of genetic information from DNA to messenger RNA (mRNA) by DNA-directed RNA polymerase. In the case of some RNA viruses, protein involved in the transfer of genetic information from RNA to messenger RNA (mRNA) by RNA-directed RNA polymerase.
A reference proteome is a set of protein sequences derived from a complete proteome which constitutes a defined standard for a particular user community. Reference proteomes are manually defined according to a number of criteria. They cover the proteomes of well- studied model organisms and other proteomes of interest for biomedical and biotechnological research. Reference proteomes have been selected to provide broad coverage of the tree of life, and constitute a representative cross-section of the taxonomic diversity to be found within UniProtKB.
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