scholarly journals Loss of H2A.Z Is Not Sufficient to Determine Transcriptional Activity of Snf2-Related CBP Activator Protein or p400 Complexes

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Tamara A. Bowman ◽  
Madeline M. Wong ◽  
Linda K. Cox ◽  
Joseph J. Baldassare ◽  
John C. Chrivia
Keyword(s):  
Transcriptional Activity ◽  
Protein Complexes ◽  
Regulation Of Transcription ◽  
Wild Type ◽  
Transcript Levels ◽  
Activator Protein ◽  
Nucleosome Density

The p400 and SRCAP (Snf2-related CBP activator protein) complexes remodel chromatin by catalyzing deposition of histone H2A.Z into nucleosomes. This remodeling activity has been proposed as a basis for regulation of transcription by these complexes. Transcript levels ofp21orSp1mRNAs after knockdown of p400 or SRCAP reveals that each regulates transcription of these promoters differently. In this study, we asked whether deposition of H2A.Z within specific nucleosomes by p400 or SRCAP dictates transcriptional activity. Our data indicates that nucleosome density at specificp21orSp1promoter positions is not altered by the loss of either remodeling complex. However, knockdown of SRCAP or p400 reduces deposition of H2A.Z∼50% into allp21andSp1promoter nucleosomes. Thus, H2A.Z deposition is not targeted to specific nucleosomes. These results indicate that the deposition of H2A.Z by the p400 or SRCAP complexes is not sufficient to determine how each regulates transcription. This conclusion is further supported by studies that demonstrate a SRCAPΔATPmutant unable to deposit H2A.Z has similar transcriptional activity as wild-type SRCAP.

scholarly journals Transcriptional Activity of the Telomeric Retrotransposon HeT-A in Drosophila melanogaster Is Stimulated as a Consequence of Subterminal Deficiencies at Homologous and Nonhomologous Telomeres

2007 ◽  
Vol 27 (13) ◽  
pp. 4991-5001 ◽  
Author(s):  
Radmila Capkova Frydrychova ◽  
Harald Biessmann ◽  
Alexander Y. Konev ◽  
Mikhail D. Golubovsky ◽  
Jessica Johnson ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Promoter Activity ◽  
Transcriptional Activity ◽  
Position Effect ◽  
Wild Type ◽  
Global Effect ◽  
Transcript Levels ◽  
Telomere Position Effect

ABSTRACT Drosophila melanogaster telomeres have two DNA domains: a terminal array of retrotransposons and a subterminal repetitive telomere-associated sequence (TAS), a source of telomere position effect (TPE). We reported previously that deletion of the 2L TAS array leads to dominant suppression of TPE by stimulating in trans expression of a telomeric transgene. Here, we compared the transcript activities of a w transgene inserted between the retrotransposon and TAS arrays at the 2L telomere in genotypes with different lengths of the 2L TAS. In contrast to individuals bearing a wild-type 2L homologue, flies with a TAS deficiency showed a significant increase in the level of telomeric w transcript during development, especially in pupae. Moreover, we identified a read-through w transcript initiated from a retrotransposon promoter in the terminal array. Read-through transcript levels also significantly increased with the presence of a 2L TAS deficiency in trans, indicating a stimulating force of the TAS deficiency on retrotransposon promoter activity. The read-through transcript contributes to total w transcript, although most w transcript originates at the w promoter. While silencing of transgenes in nonhomologous telomeres is suppressed by 2L TAS deficiencies, suggesting a global effect, the overall level of HeT-A transcripts is not increased under similar conditions.

An ER–Golgi Tethering Factor SLOH4/MIP3 Is Involved in Long-term Heat Tolerance of Arabidopsis

2020 ◽  
Author(s):  
Kazuho Isono ◽  
Ryo Tsukimoto ◽  
Satoshi Iuchi ◽  
Akihisa Shinozawa ◽  
Izumi Yotsui ◽  
...  
Keyword(s):  
Heat Stress ◽  
Heat Tolerance ◽  
Secretory Proteins ◽  
Wild Type ◽  
Additional Function ◽  
Transcript Levels ◽  
Unfolded Protein ◽  
In The Wild ◽  
Protein Response

Abstract Plants are often exposed not only to short-term (S-) heat stress but also to diurnal long-term (L-) heat stress over several consecutive days. To reveal the mechanisms underlying L-heat stress tolerance, we here used a forward genetic screening for sensitive to long-term heat (sloh) mutants and isolated sloh4. The mutant was hypersensitive to L- but not S-heat stress. The causal gene of sloh4 was identical to MIP3 encoding a member of the MAIGO2 (MAG2) tethering complex, which is composed of the MAG2, MIP1, MIP2, and MIP3 subunits and is localized at the endoplasmic reticulum (ER) membrane. Although sloh4/mip3 was hypersensitive to L-heat stress, the sensitivity of the mag2-3 and mip1–1 mutants was similar to that of the wild type. Under L-heat stress, the ER stress and the following unfolded protein response (UPR) were more pronounced in sloh4 than in the wild type. Transcript levels of bZIP60-regulated UPR genes were strongly increased in sloh4 under L-heat stress. Two processes known to be mediated by INOSITOL REQUIRING ENZYME1 (IRE1)—accumulation of the spliced bZIP60 transcript and a decrease in the transcript levels of PR4 and PRX34, encoding secretory proteins—were observed in sloh4 in response to L-heat stress. These findings suggest that misfolded proteins generated in sloh4 under L-heat stress may be recognized by IRE1 but not bZIP28, resulting in initiation of the UPR via activated bZIP60. Therefore, it would be possible that only MIP3 in MAG2 complex has an additional function in L-heat tolerance, which is not related to the ER–Golgi vesicle tethering.

scholarly journals The AML-associated K313 mutation enhances C/EBPα activity by leading to C/EBPα overexpression

2021 ◽  
Vol 12 (7) ◽  
Author(s):  
Ian Edward Gentle ◽  
Isabel Moelter ◽  
Mohamed Tarek Badr ◽  
Konstanze Döhner ◽  
Michael Lübbert ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Culture ◽  
Transcription Factor ◽  
Transcription Factors ◽  
Transcriptional Activity ◽  
Target Gene ◽  
Wild Type ◽  
Elevated Expression ◽  
Factor C ◽  
Acute Myeloid

AbstractMutations in the transcription factor C/EBPα are found in ~10% of all acute myeloid leukaemia (AML) cases but the contribution of these mutations to leukemogenesis is incompletely understood. We here use a mouse model of granulocyte progenitors expressing conditionally active HoxB8 to assess the cell biological and molecular activity of C/EBPα-mutations associated with human AML. Both N-terminal truncation and C-terminal AML-associated mutations of C/EBPα substantially altered differentiation of progenitors into mature neutrophils in cell culture. Closer analysis of the C/EBPα-K313-duplication showed expansion and prolonged survival of mutant C/EBPα-expressing granulocytes following adoptive transfer into mice. C/EBPα-protein containing the K313-mutation further showed strongly enhanced transcriptional activity compared with the wild-type protein at certain promoters. Analysis of differentially regulated genes in cells overexpressing C/EBPα-K313 indicates a strong correlation with genes regulated by C/EBPα. Analysis of transcription factor enrichment in the differentially regulated genes indicated a strong reliance of SPI1/PU.1, suggesting that despite reduced DNA binding, C/EBPα-K313 is active in regulating target gene expression and acts largely through a network of other transcription factors. Strikingly, the K313 mutation caused strongly elevated expression of C/EBPα-protein, which could also be seen in primary K313 mutated AML blasts, explaining the enhanced C/EBPα activity in K313-expressing cells.

Retrovirus-induced interference with collagen I gene expression in Mov13 fibroblasts is maintained in the absence of DNA methylation

1991 ◽  
Vol 11 (1) ◽  
pp. 47-54
Author(s):  
H Chan ◽  
S Hartung ◽  
M Breindl
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Chromatin Structure ◽  
Transcriptional Activity ◽  
Xenopus Laevis Oocytes ◽  
Regulatory Sequences ◽  
Type I ◽  
Wild Type ◽  
Col1a1 Gene

We have studied the role of DNA methylation in repression of the murine alpha 1 type I collagen (COL1A1) gene in Mov13 fibroblasts. In Mov13 mice, a retroviral provirus has inserted into the first intron of the COL1A1 gene and blocks its expression at the level of transcriptional initiation. We found that regulatory sequences in the COL1A1 promoter region that are involved in the tissue-specific regulation of the gene are unmethylated in collagen-expressing wild-type fibroblasts and methylated in Mov13 fibroblasts, confirming and extending earlier observations. To directly assess the role of DNA methylation in the repression of COL1A1 gene transcription, we treated Mov13 fibroblasts with the demethylating agent 5-azacytidine. This treatment resulted in a demethylation of the COL1A1 regulatory sequences but failed to activate transcription of the COL1A1 gene. Moreover, the 5-azacytidine treatment induced a transcription-competent chromatin structure in the retroviral sequences but not in the COL1A1 promoter. In DNA transfection and microinjection experiments, we found that the provirus interfered with transcriptional activity of the COL1A1 promoter in Mov13 fibroblasts but not in Xenopus laevis oocytes. In contrast, the wild-type COL1A1 promoter was transcriptionally active in Mov13 fibroblasts. These experiments showed that the COL1A1 promoter is potentially transcriptionally active in the presence of proviral sequences and that Mov13 fibroblasts contain the trans-acting factors required for efficient COL1A1 gene expression. Our results indicate that the provirus insertion in Mov13 can inactivate COL1A1 gene expression at several levels. It prevents the developmentally regulated establishment of a transcription-competent methylation pattern and chromatin structure of the COL1A1 domain and, in the absence of DNA methylation, appears to suppress the COL1A1 promoter in a cell-specific manner, presumably by assuming a dominant chromatin structure that may be incompatible with transcriptional activity of flanking cellular sequences.

Interactions Between Leukotriene C4 and Interleukin 13 Signaling Pathways in a Mouse Model of Airway Disease

2006 ◽  
Vol 130 (4) ◽  
pp. 440-446
Author(s):  
Jaime Chavez ◽  
Hays W. J. Young ◽  
David B. Corry ◽  
Michael W. Lieberman
Keyword(s):  
Signaling Pathways ◽  
Airway Disease ◽  
Lavage Fluid ◽  
Airway Responsiveness ◽  
Leukotriene C4 ◽  
Wild Type ◽  
Transcript Levels ◽  
Interleukin 13 ◽  
Deficient Mice ◽  
Intranasal Instillation

Abstract Context.—During an asthmatic episode, leukotriene C4 (LTC4) and interleukin 13 (IL-13) are released into the airways and are thought to be central mediators of the asthmatic response. However, little is known about how these molecules interact or affect each other's signaling pathway. Objective.—To determine if the LTC4 and IL-13 signaling pathways interact with each other's pathways. Design.—We examined airway responsiveness, cysteinyl LTs (Cys-LTs), and Cys-LT and IL-13 receptor transcript levels in wild-type mice and in mice that were deficient in γ-glutamyl leukotrienase (an enzyme that converts LTC4 to LTD4), STAT6 (signal transducer and activator of transcription 6 [a critical molecule in IL-13 signaling]), and IL-4Rα (a subunit of the IL-13 receptor). Results.—Wild-type (C57BL/129SvEv) and γ-glutamyl leukotrienase–deficient mice showed increased airway responsiveness after intranasal instillation of IL-13; similar results were observed after intranasal instillation of IL-13 or LTC4 in a second wild-type strain (BALB/c). Interleukin 13 treatment reduced levels of Cys-LTs in bronchoalveolar lavage fluid. This change was unaccompanied by changes in other arachidonic acid metabolites or in RNA transcript levels of enzymes associated with Cys-LT synthesis. Interleukin 13 treatment also increased transcript levels of the Cys-LT 1 and Cys-LT 2 receptors, while LTC4 increased transcript levels of the α1 chain of the IL-13 receptor. Furthermore, IL-4Rα–deficient mice had increased airway responsiveness to LTC4 but not to IL-13, whereas STAT6-deficient mice failed to respond to either agonist. Conclusions.—These findings indicate that LTC4 and IL-13 are dependent on or signal through STAT6 to increase airway responsiveness and that both agonists regulate expression of each other's receptors.

scholarly journals SIRT1 Suppresses Activator Protein-1 Transcriptional Activity and Cyclooxygenase-2 Expression in Macrophages

2009 ◽  
Vol 285 (10) ◽  
pp. 7097-7110 ◽  
Author(s):  
Ran Zhang ◽  
Hou-Zao Chen ◽  
Jin-Jing Liu ◽  
Yu-Yan Jia ◽  
Zhu-Qin Zhang ◽  
...  
Keyword(s):  
Transcriptional Activity ◽  
Cyclooxygenase 2 ◽  
Activator Protein 1 ◽  
Activator Protein

scholarly journals Unexpected Specificity within Dynamic Transcriptional Protein-Protein Complexes

2020 ◽  
Author(s):  
Matthew J. Henley ◽  
Brian M. Linhares ◽  
Brittany S. Morgan ◽  
Tomasz Cierpicki ◽  
Carol A. Fierke ◽  
...  
Keyword(s):  
Molecular Recognition ◽  
Electrostatic Interactions ◽  
Protein Complexes ◽  
Critical Role ◽  
Gene Activation ◽  
Disordered Proteins ◽  
Conformational Ensemble ◽  
Regulation Of Transcription ◽  
Protein Protein Interaction ◽  
Eukaryotic Gene

AbstractA key functional event in eukaryotic gene activation is the formation of dynamic protein-protein interaction networks between transcriptional activators and transcriptional coactivators. Seemingly incongruent with the tight regulation of transcription, many biochemical and biophysical studies suggest that activators use nonspecific hydrophobic and/or electrostatic interactions to bind to coactivators, with few if any specific contacts. Here a mechanistic dissection of a set of representative dynamic activator•coactivator complexes, comprised of the ETV/PEA3 family of activators and the coactivator Med25, reveals a different molecular recognition model. The data demonstrate that small sequence variations within an activator family significantly redistribute the conformational ensemble of the complex while not affecting overall affinity, and distal residues within the activator—not often considered as contributing to binding—play a key role in mediating conformational redistribution. The ETV/PEA3•Med25 ensembles are directed by specific contacts between the disordered activator and the Med25 interface, which is facilitated by structural shifts of the coactivator binding surface. Taken together, these data highlight the critical role coactivator plasticity plays in recognition of disordered activators, and indicates that molecular recognition models of disordered proteins must consider the ability of the binding partners to mediate specificity.

scholarly journals Identification and Functional Analysis of a Novel CTNNB1 Mutation in Pediatric Medulloblastoma

Cancers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 421
Author(s):  
Lide Alaña ◽  
Caroline E. Nunes-Xavier ◽  
Laura Zaldumbide ◽  
Idoia Martin-Guerrero ◽  
Lorena Mosteiro ◽  
...  
Keyword(s):  
Functional Analysis ◽  
Transcriptional Activity ◽  
Nuclear Accumulation ◽  
Wild Type ◽  
Osteosarcoma Cells ◽  
Human Osteosarcoma ◽  
Pediatric Medulloblastoma ◽  
Human Osteosarcoma Cells ◽  
The Central Nervous System ◽  
Ctnnb1 Mutation

Medulloblastoma is the primary malignant tumor of the Central Nervous System (CNS) most common in pediatrics. We present here, the histological, molecular, and functional analysis of a cohort of 88 pediatric medulloblastoma tumor samples. The WNT-activated subgroup comprised 10% of our cohort, and all WNT-activated patients had exon 3 CTNNB1 mutations and were immunostained for nuclear β-catenin. One novel heterozygous CTNNB1 mutation was found, which resulted in the deletion of β-catenin Ser37 residue (ΔS37). The ΔS37 β-catenin variant ectopically expressed in U2OS human osteosarcoma cells displayed higher protein expression levels than wild-type β-catenin, and functional analysis disclosed gain-of-function properties in terms of elevated TCF/LEF transcriptional activity in cells. Our results suggest that the stabilization and nuclear accumulation of ΔS37 β-catenin contributed to early medulloblastoma tumorigenesis.

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