Cha, a basic helix-loop-helix transcription factor involved in the regulation of upstream stimulatory factor activity.
Journal - The Journal of biological chemistry (United States )
We report here the characterization of Cha, a transcription factor of the basic helix-loop-helix (bHLH) family. The basic region of Cha shares DNA-interacting amino acids with members of class C bHLH transcription factors. In addition, the HLH region of Cha presents a Myc-type dimerization domain signature required for heterodimer formation between members of this class. Cha protein and mRNA were ubiquitously expressed in many human tissues. Electrophoretic mobility shift assays showed that Cha and upstream stimulatory factor (USF)-1 formed a complex that specifically bound to E-box DNA elements. Moreover, pull-down and co-immunoprecipitation experiments showed an interaction between Cha and USF-1. Cha did not bind to E-box DNA elements and required USF-1 for protein-DNA complex formation. Moreover, Cha inhibited USF-1-stimulated transcription of CD2 (a USF-1-dependent gene) and E-box promoter reporter plasmids. Chromatin immunoprecipitation assays showed that Cha occupied the CD2 promoter in resting, but not in mitogen-stimulated, T cells. Finally, Cha mRNA and protein expression were high in resting T cells and absent in mitogen-activated T cells and inversely correlated with CD2 expression. Contrarily, overexpression of Cha in T cells significantly reduced CD2 expression. In summary, our results indicated that Cha is a new bHLH transcription factor that negatively regulates USF-dependent transcription.
|ISSN : ||0021-9258|
|Mesh Heading : ||Amino Acid Sequence Animals Antigens, CD2 Base Sequence Basic Helix-Loop-Helix Transcription Factors COS Cells Cells, Cultured Chromatin Cloning, Molecular DNA, Complementary Dimerization Flow Cytometry Helix-Loop-Helix Motifs Humans Jurkat Cells Models, Genetic Molecular Sequence Data Plasmids Precipitin Tests Promoter Regions, Genetic Protein Binding Protein Structure, Tertiary RNA, Messenger Recombinant Proteins Sequence Homology, Amino Acid T-Lymphocytes Time Factors Tissue Distribution Transcription Factors Transcription, Genetic Upstream Stimulatory Factors biosynthesis metabolism metabolism metabolism metabolism metabolism metabolism|
|Mesh Heading Relevant : ||DNA-Binding Proteins Gene Expression Regulation biosynthesis chemistry genetics physiology|
African swine fever virus IAP-like protein induces the activation of nuclear factor kappa B.
Journal - Journal of virology (United States )
African swine fever virus (ASFV) encodes a homologue of the inhibitor of apoptosis (IAP) that promotes cell survival by controlling the activity of caspase-3. Here we show that ASFV IAP is also able to activate the transcription factor NF-kappaB. Thus, transient transfection of the viral IAP increases the activity of an NF-kappaB reporter gene in a dose-responsive manner in Jurkat cells. Similarly, stably transfected cells expressing ASFV IAP have elevated basal levels of c-rel, an NF-kappaB-dependent gene. NF-kappaB complexes in the nucleus were increased in A224L-expressing cells compared with control cells upon stimulation with phorbol myristate acetate (PMA) plus ionomycin. This resulted in greater NF-kappaB-dependent promoter activity in ASFV IAP-expressing than in control cells, both in basal conditions and after PMA plus ionophore stimulation. The elevated NF-kappaB activity seems to be the consequence of higher IkappaB kinase (IKK) basal activity in these cells. The NF-kappaB-inducing activity of ASFV IAP was abrogated by an IKK-2 dominant negative mutant and enhanced by expression of tumor necrosis factor receptor-associated factor 2.
|ISSN : ||0022-538X|
|Mesh Heading : ||African Swine Fever Virus Animals Humans I-kappa B Proteins Inhibitor of Apoptosis Proteins Insect Proteins Jurkat Cells NF-kappa B Proteins TNF Receptor-Associated Factor 2 Transfection genetics metabolism genetics metabolism|
|Mesh Heading Relevant : ||Gene Expression Regulation metabolism metabolism metabolism|
Competence to develop sensory organs is temporally and spatially regulated in Drosophila epidermal primordia.
Journal - The EMBO journal (ENGLAND )
The Drosophila adult cuticle displays a stereotyped pattern of sensory organs (SOs). Its deployment requires the expression of the achaete (ac) and scute (sc) genes. Their products confer to cells of epidermal primordia (imaginal discs and histoblasts) the ability to become SO precursors (SOPs). In imaginal discs, ac and sc expression is spatially restricted to cell clusters within which one or a few cells become SOP(s). With the help of ubiquitous sc expression provided at different developmental times by a heat shock-sc (HSSC) chimeric gene, we have analyzed the response of epidermal primordia to the proneural action of the sc product, and have tested whether the patterned distribution of ac/sc products is necessary to position SOs correctly within the epidermis. Each primordium responds to HSSC expression by developing SOs only during a characteristic developmental period. In the absence of the endogenous ac and sc genes, most SOs induced by HSSC are of the correct type and are located in wild type positions. These results indicate that the capacity of primordia to respond to sc is temporally and spatially regulated, that specification of the type of SO does not depend on ac/sc, and that SO positioning utilizes topological information independent of the spatially restricted distribution of ac/sc products.
|ISSN : ||0261-4189|
|Mesh Heading : ||Abdomen Age Factors Animals Drosophila melanogaster Epidermis Extremities Gene Expression Regulation Plasmids RNA, Messenger Sense Organs Thorax Wing anatomy & histology genetics|
|Mesh Heading Relevant : ||embryology embryology embryology|
African Swine Fever Virus IAP-Like Protein Induces the Activation of Nuclear Factor Kappa B
Journal - Journal of Virology
African swine fever virus (ASFV) encodes a homologue of the inhibitor of apoptosis (IAP) that promotes cell survival by controlling the activity of caspase-3. Here we show that ASFV IAP is also able to activate the transcription factor NF-?B. Thus, transient transfection of the viral IAP increases the activity of an NF-?B reporter gene in a dose-responsive manner in Jurkat cells. Similarly, stably transfected cells expressing ASFV IAP have elevated basal levels of c-rel, an NF-?B-dependent gene. NF-?B complexes in the nucleus were increased in A224L-expressing cells compared with control cells upon stimulation with phorbol myristate acetate (PMA) plus ionomycin. This resulted in greater NF-?B-dependent promoter activity in ASFV IAP-expressing than in control cells, both in basal conditions and after PMA plus ionophore stimulation. The elevated NF-?B activity seems to be the consequence of higher I?B kinase (IKK) basal activity in these cells. The NF-?B-inducing activity of ASFV IAP was abrogated by an IKK-2 dominant negative mutant and enhanced by expression of tumor necrosis factor receptor-associated factor 2.
Antibodies to an Epitope from the Cha Human Autoantigen Are Markers of Chagas' Disease
Journal - Clinical and Diagnostic Laboratory Immunology
Chagas' disease is a prevalent disease in South America that is thought to have an autoimmune etiology. We previously identified human Cha as a new autoantigen recognized by chagasic sera. Those sera recognized an epitope spanning amino acids 120 to 129 of Cha, named R3. In the present study we have used the synthetic R3 peptide for the detection of serum immunoglobulin G antibodies from patients at different stages of Chagas' disease, including a therapeutically treated group. The immunoreactivity with R3 by enzyme-linked immunosorbent assay (ELISA) showed 92.4% sensitivity and 100% specificity for Chagas' disease sera. This sensitivity and specificity were higher than for any other autoantigen described to date. No anti-R3 antibodies were detected in sera from Leishmania-infected or idiopathic dilated cardiomyopathy patients or healthy controls from the same areas. Moreover, anti-R3 antibody reactivity detected by ELISA correlated with conventional serological tests as indirect immunofluorescence and ELISA assays with Trypanosoma cruzi extracts and other diagnostic tests as indirect hemagglutination. The levels of anti-R3 antibodies increased with progression and symptomatology of Chagas' disease. More interestingly, a statistically significant fall in anti-R3 antibody titer was observed in patients treated with antiparasitic drugs. Those results suggest that the presence of anti-R3 antibodies is a highly specific marker of Chagas' disease and that R3 ELISA could be helpful in the diagnosis and monitoring of this disease.