scholarly journals MyoR Modulates Cardiac Conduction by Repressing Gata4

2014 ◽  
Vol 35 (4) ◽  
pp. 649-661 ◽  
Author(s):  
John P. Harris ◽  
Minoti Bhakta ◽  
Svetlana Bezprozvannaya ◽  
Lin Wang ◽  
Christina Lubczyk ◽  
...  
Keyword(s):  
Transcriptional Repression ◽  
Atrioventricular Node ◽  
Electrical Activation ◽  
Cardiac Conduction ◽  
Specific Gene ◽  
Dependent Manner ◽  
Regulatory Circuit ◽  
Genetic Deletion ◽  
Repression Domain ◽  
Av Delay

The cardiac conduction system coordinates electrical activation through a series of interconnected structures, including the atrioventricular node (AVN), the central connection point that delays impulse propagation to optimize cardiac performance. Although recent studies have uncovered important molecular details of AVN formation, relatively little is known about the transcriptional mechanisms that regulate AV delay, the primary function of the mature AVN. We identify here MyoR as a novel transcription factor expressed in Cx30.2+cells of the AVN. We show that MyoR specifically inhibits a Cx30.2 enhancer required for AVN-specific gene expression. Furthermore, we demonstrate that MyoR interacts directly with Gata4 to mediate transcriptional repression. Our studies reveal that MyoR contains two nonequivalent repression domains. While the MyoR C-terminal repression domain inhibits transcription in a context-dependent manner, the N-terminal repression domain can function in a heterologous context to convert the Hand2 activator into a repressor. In addition, we show that genetic deletion of MyoR in mice increases Cx30.2 expression by 50% and prolongs AV delay by 13%. Taken together, we conclude that MyoR modulates a Gata4-dependent regulatory circuit that establishes proper AV delay, and these findings may have wider implications for the variability of cardiac rhythm observed in the general population.

scholarly journals A Novel Transcriptional Repression Domain Mediates p21WAF1/CIP1 Induction of p300 Transactivation

2000 ◽  
Vol 20 (8) ◽  
pp. 2676-2686 ◽  
Author(s):  
Andrew W. Snowden ◽  
Lisa A. Anderson ◽  
Gill A. Webster ◽  
Neil D. Perkins
Keyword(s):  
Cell Cycle ◽  
Transcriptional Activation ◽  
Transcriptional Repression ◽  
Kinase Inhibitor ◽  
Core Promoter ◽  
Dependent Manner ◽  
Creb Binding Protein ◽  
Cycle Dependent ◽  
Repression Domain

ABSTRACT The transcriptional coactivators p300 and CREB binding protein (CBP) are important regulators of the cell cycle, differentiation, and tumorigenesis. Both p300 and CBP are targeted by viral oncoproteins, are mutated in certain forms of cancer, are phosphorylated in a cell cycle-dependent manner, interact with transcription factors such as p53 and E2F, and can be found complexed with cyclinE-Cdk2 in vivo. Moreover, p300-deficient cells show defects in proliferation. Here we demonstrate that transcriptional activation by both p300 and CBP is stimulated by coexpression of the cyclin-dependent kinase inhibitor p21WAF/CIP1. Significantly this stimulation is independent of both the inherent histone acetyltransferase (HAT) activity of p300 and CBP and of the previously reported carboxyl-terminal binding site for cyclinE-Cdk2. Rather, we describe a previously uncharacterized transcriptional repression domain (CRD1) within p300. p300 transactivation is stimulated through derepression of CRD1 by p21. Significantly p21 regulation of CRD1 is dependent on the nature of the core promoter. We suggest that CRD1 provides a novel mechanism through which p300 and CBP can switch activities between the promoters of genes that stimulate growth and those that enhance cell cycle arrest.

scholarly journals Necroptosis protects against exacerbation of acute pancreatitis

2021 ◽  
Vol 12 (6) ◽  
Author(s):  
Michittra Boonchan ◽  
Hideki Arimochi ◽  
Kunihiro Otsuka ◽  
Tomoko Kobayashi ◽  
Hisanori Uehara ◽  
...  
Keyword(s):  
Acute Pancreatitis ◽  
Necrotizing Pancreatitis ◽  
Neutrophil Infiltration ◽  
Dependent Manner ◽  
Protective Effects ◽  
Interacting Protein ◽  
Inflammatory Conditions ◽  
Edematous Pancreatitis ◽  
Genetic Deletion ◽  
Dose Dependent

AbstractThe sensing of various extrinsic stimuli triggers the receptor-interacting protein kinase-3 (RIPK3)-mediated signaling pathway, which leads to mixed-lineage kinase-like (MLKL) phosphorylation followed by necroptosis. Although necroptosis is a form of cell death and is involved in inflammatory conditions, the roles of necroptosis in acute pancreatitis (AP) remain unclear. In the current study, we administered caerulein to Ripk3- or Mlkl-deficient mice (Ripk3−/− or Mlkl−/− mice, respectively) and assessed the roles of necroptosis in AP. We found that Ripk3−/− mice had significantly more severe pancreatic edema and inflammation associated with macrophage and neutrophil infiltration than control mice. Consistently, Mlkl−/− mice were more susceptible to caerulein-induced AP, which occurred in a time- and dose-dependent manner, than control mice. Mlkl−/− mice exhibit weight loss, edematous pancreatitis, necrotizing pancreatitis, and acinar cell dedifferentiation in response to tissue damage. Genetic deletion of Mlkl resulted in downregulation of the antiapoptotic genes Bclxl and Cflar in association with increases in the numbers of apoptotic cells, as detected by TUNEL assay. These findings suggest that RIPK3 and MLKL-mediated necroptosis exerts protective effects in AP and caution against the use of necroptosis inhibitors for AP treatment.

Optical mapping of atrioventricular node reveals a conduction barrier between atrial and nodal cells

1998 ◽  
Vol 274 (3) ◽  
pp. H829-H845 ◽  
Author(s):  
Bum-Rak Choi ◽  
Guy Salama
Keyword(s):  
Action Potentials ◽  
Imaging Techniques ◽  
Atrioventricular Node ◽  
Small Cells ◽  
Av Node ◽  
Propagation Pattern ◽  
Voltage Sensitive Dyes ◽  
Decremental Conduction ◽  
Microelectrode Techniques ◽  
Av Delay

The mechanisms responsible for atrioventricular (AV) delay remain unclear, in part due to the inability to map electrical activity by conventional microelectrode techniques. In this study, voltage-sensitive dyes and imaging techniques were refined to detect action potentials (APs) from the small cells comprising the AV node and to map activation from the “compact” node. Optical APs (124) were recorded from 5 × 5 mm (∼0.5-mm depth) AV zones of perfused rabbit hearts stained with a voltage-sensitive dye. Signals from the node exhibited a set of three spikes; the first and third ( peaks I and III) were coincident with atrial (A) and ventricular (V) electrograms, respectively. The second spike ( peak II) represented the firing of midnodal (N) and/or lower nodal (NH) cell APs as indicated by their small amplitude, propagation pattern, location determined from superimposition of activation maps and histological sections of the node region, dependence on depth of focus, and insensitivity to tetrodotoxin (TTX). AV delays consisted of τ1 (49.5 ± 6.59 ms, 300-ms cycle length), the interval between peaks I and II (perhaps AN to N cells), and τ2 (57.57 ± 5.15 ms), the interval between peaks II and III (N to V cells). The conductance time across the node was 10.33 ± 3.21 ms, indicating an apparent conduction velocity (ΘN) of 0.162 ± 0.02 m/s ( n = 9) that was insensitive to TTX. In contrast, τ1 correlated with changes in AV node delays (measured with surface electrodes) caused by changes in heart rate or perfusion with acetylcholine. The data provide the first maps of activation across the AV node and demonstrate that ΘN is faster than previously presumed. These findings are inconsistent with theories of decremental conduction and prove the existence of a conduction barrier between the atrium and the AV node that is an important determinant of AV node delay.

scholarly journals Cardiac Cell Type-Specific Gene Regulatory Programs and Disease Risk Association

2020 ◽  
Author(s):  
James D. Hocker ◽  
Olivier B. Poirion ◽  
Fugui Zhu ◽  
Justin Buchanan ◽  
Kai Zhang ◽  
...  
Keyword(s):  
Cardiovascular Disease ◽  
Disease Risk ◽  
Cardiovascular Disease Risk ◽  
Cell Types ◽  
Regulatory Elements ◽  
Specific Gene ◽  
Dependent Manner ◽  
Cardiac Cell ◽  
Risk Variants ◽  
Gene Regulatory

ABSTRACTBackgroundCis-regulatory elements such as enhancers and promoters are crucial for directing gene expression in the human heart. Dysregulation of these elements can result in many cardiovascular diseases that are major leading causes of morbidity and mortality worldwide. In addition, genetic variants associated with cardiovascular disease risk are enriched within cis-regulatory elements. However, the location and activity of these cis-regulatory elements in individual cardiac cell types remains to be fully defined.MethodsWe performed single nucleus ATAC-seq and single nucleus RNA-seq to define a comprehensive catalogue of candidate cis-regulatory elements (cCREs) and gene expression patterns for the distinct cell types comprising each chamber of four non-failing human hearts. We used this catalogue to computationally deconvolute dynamic enhancers in failing hearts and to assign cardiovascular disease risk variants to cCREs in individual cardiac cell types. Finally, we applied reporter assays, genome editing and electrophysiogical measurements in in vitro differentiated human cardiomyocytes to validate the molecular mechanisms of cardiovascular disease risk variants.ResultsWe defined >287,000 candidate cis-regulatory elements (cCREs) in human hearts at single-cell resolution, which notably revealed gene regulatory programs controlling specific cell types in a cardiac region/structure-dependent manner and during heart failure. We further report enrichment of cardiovascular disease risk variants in cCREs of distinct cardiac cell types, including a strong enrichment of atrial fibrillation variants in cardiomyocyte cCREs, and reveal 38 candidate causal atrial fibrillation variants localized to cardiomyocyte cCREs. Two such risk variants residing within a cardiomyocyte-specific cCRE at the KCNH2/HERG locus resulted in reduced enhancer activity compared to the non-risk allele. Finally, we found that deletion of the cCRE containing these variants decreased KCNH2 expression and prolonged action potential repolarization in an enhancer dosage-dependent manner.ConclusionsThis comprehensive atlas of human cardiac cCREs provides the foundation for not only illuminating cell type-specific gene regulatory programs controlling human hearts during health and disease, but also interpreting genetic risk loci for a wide spectrum of cardiovascular diseases.

scholarly journals Herpes simplex virus ICP27 regulates alternative pre-mRNA polyadenylation and splicing in a sequence-dependent manner

2016 ◽  
Vol 113 (43) ◽  
pp. 12256-12261 ◽  
Author(s):  
Shuang Tang ◽  
Amita Patel ◽  
Philip R. Krause
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Splice Site ◽  
Alternative Polyadenylation ◽  
Common Mechanism ◽  
Specific Gene ◽  
Dependent Manner ◽  
Splice Sites ◽  
Cellular Genes ◽  
Simplex Virus

The herpes simplex virus (HSV) infected cell culture polypeptide 27 (ICP27) protein is essential for virus infection of cells. Recent studies suggested that ICP27 inhibits splicing in a gene-specific manner via an unknown mechanism. Here, RNA-sequencing revealed that ICP27 not only inhibits splicing of certain introns in <1% of cellular genes, but also can promote use of alternative 5′ splice sites. In addition, ICP27 induced expression of pre-mRNAs prematurely cleaved and polyadenylated from cryptic polyadenylation signals (PAS) located in intron 1 or 2 of ∼1% of cellular genes. These previously undescribed prematurely cleaved and polyadenylated pre-mRNAs, some of which contain novel ORFs, were typically intronless, <2 Kb in length, expressed early during viral infection, and efficiently exported to cytoplasm. Sequence analysis revealed that ICP27-targeted genes are GC-rich (as are HSV genes), contain cytosine-rich sequences near the 5′ splice site, and have suboptimal splice sites in the impacted intron, suggesting that a common mechanism is shared between ICP27-mediated alternative polyadenylation and splicing. Optimization of splice site sequences or mutation of nearby cytosines eliminated ICP27-mediated splicing inhibition, and introduction of C-rich sequences to an ICP27-insensitive splicing reporter conferred this phenotype, supporting the inference that specific gene sequences confer susceptibility to ICP27. Although HSV is the first virus and ICP27 is the first viral protein shown to activate cryptic PASs in introns, we suspect that other viruses and cellular genes also encode this function.

scholarly journals Human Cytomegalovirus Immediate-Early Protein IE2 Tethers a Transcriptional Repression Domain to p53

1996 ◽  
Vol 271 (7) ◽  
pp. 3534-3540 ◽  
Author(s):  
Hsiu-Lan Tsai ◽  
Guang-Hsiung Kou ◽  
Shan-Chun Chen ◽  
Cheng-Wen Wu ◽  
Young-Sun Lin
Keyword(s):  
Human Cytomegalovirus ◽  
Transcriptional Repression ◽  
Immediate Early ◽  
Early Protein ◽  
Repression Domain

scholarly journals PARP1-dependent recruitment of the FBXL10-RNF68-RNF2 ubiquitin ligase to sites of DNA damage controls H2A.Z loading

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Gergely Rona ◽  
Domenico Roberti ◽  
Yandong Yin ◽  
Julia K Pagan ◽  
Harrison Homer ◽  
...  
Keyword(s):  
Dna Damage ◽  
Homologous Recombination ◽  
Ubiquitin Ligase ◽  
Transcriptional Repression ◽  
Genotoxic Stress ◽  
Strand Break ◽  
Homologous Recombination Repair ◽  
Dependent Manner ◽  
Ubiquitin Ligase Complex ◽  
Recombination Repair

The mammalian FBXL10-RNF68-RNF2 ubiquitin ligase complex (FRRUC) mono-ubiquitylates H2A at Lys119 to repress transcription in unstressed cells. We found that the FRRUC is rapidly and transiently recruited to sites of DNA damage in a PARP1- and TIMELESS-dependent manner to promote mono-ubiquitylation of H2A at Lys119, a local decrease of H2A levels, and an increase of H2A.Z incorporation. Both the FRRUC and H2A.Z promote transcriptional repression, double strand break signaling, and homologous recombination repair (HRR). All these events require both the presence and activity of the FRRUC. Moreover, the FRRUC and its activity are required for the proper recruitment of BMI1-RNF2 and MEL18-RNF2, two other ubiquitin ligases that mono-ubiquitylate Lys119 in H2A upon genotoxic stress. Notably, whereas H2A.Z is not required for H2A mono-ubiquitylation, impairment of the latter results in the inhibition of H2A.Z incorporation. We propose that the recruitment of the FRRUC represents an early and critical regulatory step in HRR.

Nucleosomal location of the STE6 TATA box and Mat alpha 2p-mediated repression

1994 ◽  
Vol 14 (6) ◽  
pp. 4002-4010
Author(s):  
H G Patterton ◽  
R T Simpson
Keyword(s):  
Reporter Gene ◽  
Tata Box ◽  
Chromatin Domain ◽  
Specific Gene ◽  
Multicopy Plasmid ◽  
Alpha Cells ◽  
Lacz Reporter ◽  
Lacz Reporter Gene ◽  
Histone Octamer ◽  
Repression Domain

It has been proposed that yeast MATa cell-specific genes are repressed in MAT alpha cells by the Mat alpha 2p repressor-directed placement of a nucleosome in a position that incorporates the TATA box of the MATa-specific gene close to the nucleosomal pseudodyad. In this study, we address this proposal directly with a series of plasmids designed to place the MATa-specific STE6 TATA box at different locations in a nucleosome and in the internucleosomal linker. These plasmids contain different lengths of synthetic random DNA between the Mat alpha 2p operator and the TATA box of the STE6 promoter, which is located upstream of a lacZ reporter gene in a multicopy plasmid. We show that in MAT alpha cells, a nucleosome is retained in an identical translational frame relative to the Mat alpha 2p operator in all the constructs investigated, irrespective of the sequence of the DNA wrapped onto the histone octamer. This result shows that the nucleosomal organization of the STE6 promoter in MAT alpha cells is not conferred by the sequence of the promoter itself. No expression of the lacZ reporter gene was detectable in MAT alpha cells in any of the constructs, even with the TATA box located in a short internucleosomal linker. These data indicate that repression of MATa-specific genes in MAT alpha cells does not require the precise translational placement of the TATA box close to the nucleosomal pseudodyad; the gene remains repressed when the TATA box is located within the investigated 250-bp region in the organized chromatin domain abutting the Mat alpha 2p operator in MAT alpha cells and may remain repressed with the TATA box located anywhere within this organized repression domain.

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