scholarly journals Age-dependent changes in electrophysiology and calcium handling – implications for pediatric cardiac research

2019 ◽  
Author(s):  
Luther M. Swift ◽  
Morgan Burke ◽  
Devon Guerrelli ◽  
Manelle Ramadan ◽  
Marissa Reilly ◽  
...  
Keyword(s):  
Postnatal Development ◽  
Cardiac Electrophysiology ◽  
Calcium Handling ◽  
Cell Coupling ◽  
Altered Expression ◽  
Expression Of Genes ◽  
Age Dependent ◽  
Genes Encoding ◽  
Cardiac Maturation

ABSTRACTRationaleThe heart continues to develop and mature after birth and into adolescence. Accordingly, cardiac maturation is likely to include a progressive refinement in both organ morphology and function during the postnatal period. Yet, age-dependent changes in cardiac electrophysiology and calcium handling have not yet been fully characterized.ObjectiveThe objective of this study, was to examine the relationship between cardiac maturation, electrophysiology, and calcium handling throughout postnatal development in a rat model.MethodsPostnatal rat cardiac maturation was determined by measuring the expression of genes involved in cell-cell coupling, electrophysiology, and calcium handling. In vivo electrocardiograms were recorded from neonatal, juvenile, and adult animals. Simultaneous dual optical mapping of transmembrane voltage and calcium transients was performed on isolated, Langendorff-perfused rat hearts (postnatal day 0–3, 4-7, 8-14, adult).ResultsYounger, immature hearts displayed slowed electrical conduction, prolonged action potential duration and increased ventricular refractoriness. Slowed calcium handling in the immature heart increased the propensity for calcium transient alternans which corresponded to alterations in the expression of genes encoding calcium handling proteins. Developmental changes in cardiac electrophysiology were associated with the altered expression of genes encoding potassium channels and intercalated disc proteins.ConclusionUsing an intact whole heart model, this study highlights chronological changes in cardiac electrophysiology and calcium handling throughout postnatal development. Results of this study can serve as a comprehensive baseline for future studies focused on pediatric cardiac research, safety assessment and/or preclinical testing using rodent models.

scholarly journals Age-dependent changes in electrophysiology and calcium handling: implications for pediatric cardiac research

2020 ◽  
Vol 318 (2) ◽  
pp. H354-H365 ◽  
Author(s):  
Luther M. Swift ◽  
Morgan Burke ◽  
Devon Guerrelli ◽  
Marissa Reilly ◽  
Manelle Ramadan ◽  
...  
Keyword(s):  
Heart Rate ◽  
Postnatal Development ◽  
Cardiac Electrophysiology ◽  
Disease Modeling ◽  
Calcium Transient ◽  
Atrioventricular Conduction ◽  
Calcium Handling ◽  
Multiparametric Imaging ◽  
Whole Heart

Rodent models are frequently employed in cardiovascular research, yet our understanding of pediatric cardiac physiology has largely been deduced from more simplified two-dimensional cell studies. Previous studies have shown that postnatal development includes an alteration in the expression of genes and proteins involved in cell coupling, ion channels, and intracellular calcium handling. Accordingly, we hypothesized that postnatal cell maturation is likely to lead to dynamic alterations in whole heart electrophysiology and calcium handling. To test this hypothesis, we employed multiparametric imaging and electrophysiological techniques to quantify developmental changes from neonate to adult. In vivo electrocardiograms were collected to assess changes in heart rate, variability, and atrioventricular conduction (Sprague-Dawley rats). Intact, whole hearts were transferred to a Langendorff-perfusion system for multiparametric imaging (voltage, calcium). Optical mapping was performed in conjunction with an electrophysiology study to assess cardiac dynamics throughout development. Postnatal age was associated with an increase in the heart rate (181 ± 34 vs. 429 ± 13 beats/min), faster atrioventricular conduction (94 ± 13 vs. 46 ± 3 ms), shortened action potentials (APD80: 113 ± 18 vs. 60 ± 17 ms), and decreased ventricular refractoriness (VERP: 157 ± 45 vs. 57 ± 14 ms; neonatal vs. adults, means ± SD, P < 0.05). Calcium handling matured with development, resulting in shortened calcium transient durations (168 ± 18 vs. 117 ± 14 ms) and decreased propensity for calcium transient alternans (160 ± 18- vs. 99 ± 11-ms cycle length threshold; neonatal vs. adults, mean ± SD, P < 0.05). Results of this study can serve as a comprehensive baseline for future studies focused on pediatric disease modeling and/or preclinical testing. NEW & NOTEWORTHY This is the first study to assess cardiac electrophysiology and calcium handling throughout postnatal development, using both in vivo and whole heart models.

scholarly journals In vivo transcriptome analysis provides insights into host-dependent expression of virulence factors by Yersinia entomophaga MH96, during infection of Galleria mellonella

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Amber R Paulson ◽  
Maureen O’Callaghan ◽  
Xue-Xian Zhang ◽  
Paul B Rainey ◽  
Mark R H Hurst
Keyword(s):  
Galleria Mellonella ◽  
Functional Enrichment ◽  
Natural Environments ◽  
Insecticidal Toxin ◽  
Heat Stable ◽  
Expression Of Genes ◽  
Genes Encoding ◽  
Cell Densities

Abstract The function of microbes can be inferred from knowledge of genes specifically expressed in natural environments. Here, we report the in vivo transcriptome of the entomopathogenic bacterium Yersinia entomophaga MH96, captured during initial, septicemic, and pre-cadaveric stages of intrahemocoelic infection in Galleria mellonella. A total of 1285 genes were significantly upregulated by MH96 during infection; 829 genes responded to in vivo conditions during at least one stage of infection, 289 responded during two stages of infection, and 167 transcripts responded throughout all three stages of infection compared to in vitro conditions at equivalent cell densities. Genes upregulated during the earliest infection stage included components of the insecticidal toxin complex Yen-TC (chi1, chi2, and yenC1), genes for rearrangement hotspot element containing protein yenC3, cytolethal distending toxin cdtAB, and vegetative insecticidal toxin vip2. Genes more highly expressed throughout the infection cycle included the putative heat-stable enterotoxin yenT and three adhesins (usher-chaperone fimbria, filamentous hemagglutinin, and an AidA-like secreted adhesin). Clustering and functional enrichment of gene expression data also revealed expression of genes encoding type III and VI secretion system-associated effectors. Together these data provide insight into the pathobiology of MH96 and serve as an important resource supporting efforts to identify novel insecticidal agents.

scholarly journals Ablation of sarcolipin results in atrial remodeling

2012 ◽  
Vol 302 (12) ◽  
pp. C1762-C1771 ◽  
Author(s):  
Lai-Hua Xie ◽  
Mayilvahanan Shanmugam ◽  
Ji Yeon Park ◽  
Zhenghang Zhao ◽  
Hairuo Wen ◽  
...  
Keyword(s):  
Interstitial Fibrosis ◽  
Calcium Transient ◽  
Atrial Remodeling ◽  
Atrial Myocytes ◽  
Long Term Effects ◽  
Sodium Calcium Exchanger ◽  
Altered Expression ◽  
Expression Of Genes ◽  
Genes Encoding ◽  
Intracellular Ca

Sarcolipin (SLN) is a key regulator of sarco(endo)plasmic reticulum (SR) Ca2+-ATPase (SERCA), and its expression is altered in diseased atrial myocardium. To determine the precise role of SLN in atrial Ca2+ homeostasis, we developed a SLN knockout ( sln−/−) mouse model and demonstrated that ablation of SLN enhances atrial SERCA pump activity. The present study is designed to determine the long-term effects of enhanced SERCA activity on atrial remodeling in the sln−/− mice. Calcium transient measurements show an increase in atrial SR Ca2+ load and twitch Ca2+ transients. Patch-clamping experiments demonstrate activation of the forward mode of sodium/calcium exchanger, increased L-type Ca2+ channel activity, and prolongation of action potential duration at 90% repolarization in the atrial myocytes of sln−/− mice. Spontaneous Ca2+ waves, delayed afterdepolarization, and triggered activities are frequent in the atrial myocytes of sln−/− mice. Furthermore, loss of SLN in atria is associated with increased interstitial fibrosis and altered expression of genes encoding collagen and other extracellular matrix proteins. Our results also show that the sln−/− mice are susceptible to atrial arrhythmias upon aging. Together, these findings indicate that ablation of SLN results in increased SERCA activity and SR Ca2+ load, which, in turn, could cause abnormal intracellular Ca2+ handling and atrial remodeling.

scholarly journals Effects of Cordycepin in Cordyceps militaris during Its Infection to Silkworm Larvae

2021 ◽  
Vol 9 (4) ◽  
pp. 681
Author(s):  
Tatsuya Kato ◽  
Konomi Nishimura ◽  
Ahmad Suparmin ◽  
Kazuho Ikeo ◽  
Enoch Y. Park
Keyword(s):  
Cordyceps Militaris ◽  
Silkworm Larvae ◽  
Gene Encoding ◽  
Biosynthesis Gene Cluster ◽  
Expression Of Genes ◽  
Cuticular Proteins ◽  
Genes Encoding ◽  
Fat Bodies ◽  
In Vivo Growth

Cordyceps militaris produces cordycepin, a secondary metabolite that exhibits numerous bioactive properties. However, cordycepin pharmacology in vivo is not yet understood. In this study, the roles of cordycepin in C. militaris during its infection were investigated. After the injection of conidia, C. militaris NBRC100741 killed silkworm larvae more rapidly than NBRC103752. At 96 and 120 h, Cmcns genes (Cmcns1–4), which are part of the cordycepin biosynthesis gene cluster, were expressed in fat bodies and cuticles. Thus, cordycepin may be produced in the infection of silkworm larvae. Further, cordycepin enhanced pathogenicity toward silkworm larvae of Metarhizium anisopliae and Beauveria bassiana, that are also entomopathogenic fungi and do not produce cordycepin. In addition, by RNA-seq analysis, the increased expression of the gene encoding a lipoprotein 30K-8 (Bmlp20, KWMTBOMO11934) and decreased expression of genes encoding cuticular proteins (KWMTBOMO13140, KWMTBOMO13167) and a serine protease inhibitor (serpin29, KWMTBOMO08927) were observed when cordycepin was injected into silkworm larvae. This result suggests that cordycepin may aid the in vivo growth of C. militaris in silkworm larvae by the influence of the expression of some genes in silkworm larvae.

scholarly journals Nrg1 Is a Transcriptional Repressor for Glucose Repression of STA1 Gene Expression inSaccharomyces cerevisiae

1999 ◽  
Vol 19 (3) ◽  
pp. 2044-2050 ◽  
Author(s):  
Seok Hee Park ◽  
Sang Seok Koh ◽  
Jae Hwan Chun ◽  
Hye Jin Hwang ◽  
Hyen Sam Kang
Keyword(s):  
Gene Expression ◽  
Zinc Finger Protein ◽  
Glucose Repression ◽  
Transcriptional Repressor ◽  
Dependent Manner ◽  
Expression Of Genes ◽  
Dnase I Footprinting ◽  
Genes Encoding

ABSTRACT Expression of genes encoding starch-degrading enzymes is regulated by glucose repression in the yeast Saccharomyces cerevisiae. We have identified a transcriptional repressor, Nrg1, in a genetic screen designed to reveal negative factors involved in the expression of STA1, which encodes a glucoamylase. TheNRG1 gene encodes a 25-kDa C2H2zinc finger protein which specifically binds to two regions in the upstream activation sequence of the STA1 gene, as judged by gel retardation and DNase I footprinting analyses. Disruption of theNRG1 gene causes a fivefold increase in the level of theSTA1 transcript in the presence of glucose. The expression of NRG1 itself is inhibited in the absence of glucose. DNA-bound LexA-Nrg1 represses transcription of a target gene 10.7-fold in a glucose-dependent manner, and this repression is abolished in bothssn6 and tup1 mutants. Two-hybrid and glutathione S-transferase pull-down experiments show an interaction of Nrg1 with Ssn6 both in vivo and in vitro. These findings indicate that Nrg1 acts as a DNA-binding repressor and mediates glucose repression of the STA1 gene expression by recruiting the Ssn6-Tup1 complex.

scholarly journals YtxR, a Conserved LysR-Like Regulator That Induces Expression of Genes Encoding a Putative ADP-Ribosyltransferase Toxin Homologue in Yersinia enterocolitica

2006 ◽  
Vol 188 (23) ◽  
pp. 8033-8043 ◽  
Author(s):  
Grace L. Axler-DiPerte ◽  
Virginia L. Miller ◽  
Andrew J. Darwin
Keyword(s):  
Yersinia Enterocolitica ◽  
Transcription Initiation ◽  
Photorhabdus Luminescens ◽  
Expression Of Genes ◽  
Dnase I Footprinting ◽  
Genes Encoding ◽  
Adp Ribosyltransferase ◽  
Insight Into

ABSTRACT Yersinia enterocolitica causes human gastroenteritis, and many isolates have been classified as either “American” or “non-American” strains based on their geographic prevalence and virulence properties. In this study we describe identification of a transcriptional regulator that controls expression of the Y. enterocolitica ytxAB genes. The ytxAB genes have the potential to encode an ADP-ribosylating toxin with similarity to pertussis toxin. However, a ytxAB null mutation did not affect virulence in mice. Nevertheless, the ytxAB genes are conserved in many Y. enterocolitica strains. Interestingly, American and non-American strains have different ytxAB alleles encoding proteins that are only 50 to 60% identical. To obtain further insight into the ytxAB locus, we investigated whether it is regulated as part of a known or novel regulon. Transposon mutagenesis identified a LysR-like regulator, which we designated YtxR. Expression of ytxR from a nonnative promoter increased Φ(ytxA-lacZ) operon fusion expression up to 35-fold. YtxR also activated expression of its own promoter. DNase I footprinting showed that a His6-YtxR fusion protein directly interacted with the ytxA and ytxR control regions at similar distances upstream of their probable transcription initiation sites, identified by primer extension. Deletion analysis demonstrated that removal of the regions protected by His6-YtxR in vitro eliminated YtxR-dependent induction in vivo. The ytxAB locus is not present in most Yersinia species. In contrast, ytxR is conserved in multiple Yersinia species, as well as in the closely related organisms Photorhabdus luminescens and Photorhabdus asymbiotica. These observations suggest that YtxR may play a conserved role involving regulation of other genes besides ytxAB.

scholarly journals RhoGDIα-dependent balance between RhoA and RhoC is a key regulator of cancer cell tumorigenesis

2011 ◽  
Vol 22 (17) ◽  
pp. 3263-3275 ◽  
Author(s):  
T. T. Giang Ho ◽  
Audrey Stultiens ◽  
Johanne Dubail ◽  
Charles M. Lapière ◽  
Betty V. Nusgens ◽  
...  
Keyword(s):  
Tumor Growth ◽  
Cancer Progression ◽  
Dynamic Balance ◽  
Cellular Functions ◽  
Expression Of Genes ◽  
Genes Encoding ◽  
Interfering Rna

RhoGTPases are key signaling molecules regulating main cellular functions such as migration, proliferation, survival, and gene expression through interactions with various effectors. Within the RhoA-related subclass, RhoA and RhoC contribute to several steps of tumor growth, and the regulation of their expression affects cancer progression. Our aim is to investigate their respective contributions to the acquisition of an invasive phenotype by using models of reduced or forced expression. The silencing of RhoC, but not of RhoA, increased the expression of genes encoding tumor suppressors, such as nonsteroidal anti-inflammatory drug–activated gene 1 (NAG-1), and decreased migration and the anchorage-independent growth in vitro. In vivo, RhoC small interfering RNA (siRhoC) impaired tumor growth. Of interest, the simultaneous knockdown of RhoC and NAG-1 repressed most of the siRhoC-related effects, demonstrating the central role of NAG-1. In addition of being induced by RhoC silencing, NAG-1 was also largely up-regulated in cells overexpressing RhoA. The silencing of RhoGDP dissociation inhibitor α (RhoGDIα) and the overexpression of a RhoA mutant unable to bind RhoGDIα suggested that the effect of RhoC silencing is indirect and results from the up-regulation of the RhoA level through competition for RhoGDIα. This study demonstrates the dynamic balance inside the RhoGTPase network and illustrates its biological relevance in cancer progression.

scholarly journals Relation between Biofilm and Virulence in Vibrio tapetis: A Transcriptomic Study

Pathogens ◽  
2018 ◽  
Vol 7 (4) ◽  
pp. 92 ◽  
Author(s):  
Sophie Rodrigues ◽  
Christine Paillard ◽  
Sabine Van Dillen ◽  
Ali Tahrioui ◽  
Jean-Marc Berjeaud ◽  
...  
Keyword(s):  
Pathogenic Bacteria ◽  
Cell System ◽  
Ruditapes Philippinarum ◽  
Differentially Expressed ◽  
Type Vi Secretion System ◽  
Altered Expression ◽  
Expression Of Genes ◽  
Polysaccharide Synthesis ◽  
Genes Encoding ◽  
Genetic Level

Marine pathogenic bacteria are able to form biofilms on many surfaces, such as mollusc shells, and they can wait for the appropriate opportunity to induce their virulence. Vibrio tapetis can develop such biofilms on the inner surface of shells of the Ruditapes philippinarum clam, leading to the formation of a brown conchiolin deposit in the form of a ring, hence the name of the disease: Brown Ring Disease. The virulence of V. tapetis is presumed to be related to its capacity to form biofilms, but the link has never been clearly established at the physiological or genetic level. In the present study, we used RNA-seq analysis to identify biofilm- and virulence-related genes displaying altered expression in biofilms compared to the planktonic condition. A flow cell system was employed to grow biofilms to obtain both structural and transcriptomic views of the biofilms. We found that 3615 genes were differentially expressed, confirming that biofilm and planktonic lifestyles are very different. As expected, the differentially expressed genes included those involved in biofilm formation, such as motility- and polysaccharide synthesis-related genes. The data show that quorum sensing is probably mediated by the AI-2/LuxO system in V. tapetis biofilms. The expression of genes encoding the Type VI Secretion System and associated exported proteins are strongly induced, suggesting that V. tapetis activates this virulence factor when living in biofilm.

scholarly journals mRNAs Encoding Telomerase Components and Regulators Are Controlled by UPF Genes in Saccharomyces cerevisiae

2003 ◽  
Vol 2 (1) ◽  
pp. 134-142 ◽  
Author(s):  
Jeffrey N. Dahlseid ◽  
Jodi Lew-Smith ◽  
Michael J. Lelivelt ◽  
Shinichiro Enomoto ◽  
Amanda Ford ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Telomere Length ◽  
Dna Sequences ◽  
Mrna Levels ◽  
Loss Of Function ◽  
Telomeric Silencing ◽  
Expression Of Genes ◽  
Mutant Strains ◽  
Genes Encoding

ABSTRACT Telomeres, the chromosome ends, are maintained by a balance of activities that erode and replace the terminal DNA sequences. Furthermore, telomere-proximal genes are often silenced in an epigenetic manner. In Saccharomyces cerevisiae, average telomere length and telomeric silencing are reduced by loss of function of UPF genes required in the nonsense-mediated mRNA decay (NMD) pathway. Because NMD controls the mRNA levels of several hundred wild-type genes, we tested the hypothesis that NMD affects the expression of genes important for telomere functions. In upf mutants, high-density oligonucleotide microarrays and Northern blots revealed that the levels of mRNAs were increased for genes encoding the telomerase catalytic subunit (Est2p), in vivo regulators of telomerase (Est1p, Est3p, Stn1p, and Ten1p), and proteins that affect telomeric chromatin structure (Sas2p and Orc5p). We investigated whether overexpressing these genes could mimic the telomere length and telomeric silencing phenotypes seen previously in upf mutant strains. Increased dosage of STN1, especially in combination with increased dosage of TEN1, resulted in reduced telomere length that was indistinguishable from that in upf mutants. Increased levels of STN1 together with EST2 resulted in reduced telomeric silencing like that of upf mutants. The half-life of STN1 mRNA was not altered in upf mutant strains, suggesting that an NMD-controlled transcription factor regulates the levels of STN1 mRNA. Together, these results suggest that NMD maintains the balance of gene products that control telomere length and telomeric silencing primarily by maintaining appropriate levels of STN1, TEN1, and EST2 mRNA.

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