scholarly journals Electrophysiological phenotyping in genetically engineered mice

2003 ◽  
Vol 13 (3) ◽  
pp. 207-216 ◽  
Author(s):  
Charles I. Berul
Keyword(s):  
Molecular Mechanisms ◽  
Heart Defects ◽  
Gene Mutations ◽  
Genetically Engineered ◽  
Experimental Methodology ◽  
Cardiac Conduction ◽  
Disease States ◽  
Genetically Engineered Mice ◽  
Study Techniques

Advances in transgene and gene targeting technology have enabled sophisticated manipulation of the mouse genome, providing important insights into the molecular mechanisms underlying cardiac conduction, arrhythmogenesis, and sudden cardiac death. The mouse is currently the principal mammalian model for studying biological processes, particularly related to cardiac pathophysiology. Murine models have been engineered harboring gene mutations leading to inherited structural and electrical disorders of the heart due to transcription factor mutations, connexin protein defects, and G protein and ion channelopathies. These mutations lead to phenotypes reminiscent of human clinical disease states including congenital heart defects, cardiomyopathies, and long-QT syndrome, creating models of human electrophysiological disease. Functional analyses of the underlying molecular mechanisms of resultant phenotypes require appropriate and sophisticated experimental methodology. This paper reviews current in vivo murine electrophysiology study techniques and genetic mouse models pertinent to human arrhythmia disorders.

Cardiac function in genetically engineered mice with altered adrenergic receptor signaling

1997 ◽  
Vol 272 (4) ◽  
pp. H1553-H1559 ◽  
Author(s):  
H. A. Rockman ◽  
W. J. Koch ◽  
R. J. Lefkowitz
Keyword(s):  
Cardiac Function ◽  
G Protein ◽  
Adrenergic Receptors ◽  
Current Knowledge ◽  
Tissue Perfusion ◽  
Genetically Engineered ◽  
Disease States ◽  
Genetically Engineered Mice ◽  
G Protein Coupled

In disease states such as heart failure, catecholamines released from sympathetic nerve endings and the adrenal medulla play a central role in the adaptive and maladaptive physiological response to altered tissue perfusion. G protein-coupled receptors are importantly involved in myocardial growth and the regulation of contractility. The adrenergic receptors themselves are regulated by a set of specific kinases, termed the G protein-coupled receptor kinases. The study of complex systems in vivo has recently been advanced by the development of transgenic and gene-targeted "knockout" mouse models. Combining transgenic technology with sophisticated physiological measurements of cardiac function is an extremely powerful strategy for studying the regulation of myocardial contractility in normal animals and in models of disease states. The purpose of this review is to summarize current knowledge about the regulation of cardiovascular homeostasis involving signaling pathways through stimulation of adrenergic receptors.

scholarly journals Characterization and visualization of murine coagulation factor VIII-producing cells in vivo

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Morisada Hayakawa ◽  
Asuka Sakata ◽  
Hiroko Hayakawa ◽  
Hikari Matsumoto ◽  
Takafumi Hiramoto ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Factor Viii ◽  
Fluorescent Protein ◽  
Coagulation Factor ◽  
Coagulation Factors ◽  
Genetically Engineered ◽  
Coagulation Factor Viii ◽  
Liver Sinusoidal Endothelial Cells ◽  
Genetically Engineered Mice

AbstractCoagulation factors are produced from hepatocytes, whereas production of coagulation factor VIII (FVIII) from primary tissues and cell species is still controversial. Here, we tried to characterize primary FVIII-producing organ and cell species using genetically engineered mice, in which enhanced green fluorescent protein (EGFP) was expressed instead of the F8 gene. EGFP-positive FVIII-producing cells existed only in thin sinusoidal layer of the liver and characterized as CD31high, CD146high, and lymphatic vascular endothelial hyaluronan receptor 1 (Lyve1)+. EGFP-positive cells can be clearly distinguished from lymphatic endothelial cells in the expression profile of the podoplanin− and C-type lectin-like receptor-2 (CLEC-2)+. In embryogenesis, EGFP-positive cells began to emerge at E14.5 and subsequently increased according to liver maturation. Furthermore, plasma FVIII could be abolished by crossing F8 conditional deficient mice with Lyve1-Cre mice. In conclusion, in mice, FVIII is only produced from endothelial cells exhibiting CD31high, CD146high, Lyve1+, CLEC-2+, and podoplanin− in liver sinusoidal endothelial cells.

scholarly journals miR-146a is a significant brake on autoimmunity, myeloproliferation, and cancer in mice

2011 ◽  
Vol 208 (6) ◽  
pp. 1189-1201 ◽  
Author(s):  
Mark P. Boldin ◽  
Konstantin D. Taganov ◽  
Dinesh S. Rao ◽  
Lili Yang ◽  
Jimmy L. Zhao ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Immune Cell ◽  
Myeloid Cell ◽  
Genetically Engineered ◽  
Biological Processes ◽  
Targeted Deletion ◽  
Genetically Engineered Mice ◽  
Immune Defects ◽  
Molecular Brake

Excessive or inappropriate activation of the immune system can be deleterious to the organism, warranting multiple molecular mechanisms to control and properly terminate immune responses. MicroRNAs (miRNAs), ∼22-nt-long noncoding RNAs, have recently emerged as key posttranscriptional regulators, controlling diverse biological processes, including responses to non-self. In this study, we examine the biological role of miR-146a using genetically engineered mice and show that targeted deletion of this gene, whose expression is strongly up-regulated after immune cell maturation and/or activation, results in several immune defects. Collectively, our findings suggest that miR-146a plays a key role as a molecular brake on inflammation, myeloid cell proliferation, and oncogenic transformation.

Prenatal ethanol exposure impairs the conduction delay at the atrioventricular junction in the looping heart

2021 ◽  
Author(s):  
Shan Ling ◽  
Michael W Jenkins ◽  
Michiko Watanabe ◽  
Stephanie M Ford ◽  
Andrew M Rollins
Keyword(s):  
Heart Development ◽  
Molecular Mechanisms ◽  
Early Stage ◽  
Heart Defects ◽  
Ethanol Exposure ◽  
Cardiac Conduction ◽  
Conduction Delay ◽  
Prenatal Ethanol Exposure ◽  
Endocardial Cushions ◽  
Atrioventricular Junction

The etiology of ethanol-related congenital heart defects has been the focus of much study, but most research has concentrated on cellular and molecular mechanisms. We have shown with optical coherence tomography (OCT) that ethanol exposure led to increased retrograde flow and smaller atrioventricular (AV) cushions compared to controls. Since AV cushions play a role in patterning the conduction delay at the atrioventricular junction (AVJ), this study aims to investigate whether ethanol exposure alters the AVJ conduction in early looping hearts and whether this alteration is related to the decreased cushion size. Quail embryos were exposed to a single dose of ethanol at gastrulation, and Hamburger-Hamilton stage 19 - 20 hearts were dissected for imaging. Cardiac conduction was measured using an optical mapping microscope and we imaged the endocardial cushions using OCT. Our results showed that, compared with controls, ethanol-exposed embryos exhibited abnormally fast AVJ conduction and reduced cushion size. However, this increased conduction velocity (CV) did not strictly correlate with decreased cushion volume and thickness. By matching the CV map to the cushion size map, we found that the slowest conduction location was consistently at the atrial side of the AVJ, which had the thinner cushions, not at the thickest cushion location at the ventricular side as expected. Our findings reveal regional differences in the AVJ myocardium even at this early stage in heart development. These findings reveal the early steps leading to the heterogeneity and complexity of conduction at the mature AVJ, a site where arrhythmias can be initiated.

scholarly journals Anisotropic Cardiac Conduction

2020 ◽  
Vol 9 (4) ◽  
pp. 202-210
Author(s):  
Irum Kotadia ◽  
John Whitaker ◽  
Caroline Roney ◽  
Steven Niederer ◽  
Mark O’Neill ◽  
...  
Keyword(s):  
Gap Junction ◽  
Cardiac Tissue ◽  
Diffusion Tensor ◽  
Interstitial Fibrosis ◽  
Cardiac Conduction ◽  
Principal Mechanism ◽  
Disease States ◽  
And Function ◽  
Anisotropic Conduction

Anisotropy is the property of directional dependence. In cardiac tissue, conduction velocity is anisotropic and its orientation is determined by myocyte direction. Cell shape and size, excitability, myocardial fibrosis, gap junction distribution and function are all considered to contribute to anisotropic conduction. In disease states, anisotropic conduction may be enhanced, and is implicated, in the genesis of pathological arrhythmias. The principal mechanism responsible for enhanced anisotropy in disease remains uncertain. Possible contributors include changes in cellular excitability, changes in gap junction distribution or function and cellular uncoupling through interstitial fibrosis. It has recently been demonstrated that myocyte orientation may be identified using diffusion tensor magnetic resonance imaging in explanted hearts, and multisite pacing protocols have been proposed to estimate myocyte orientation and anisotropic conduction in vivo. These tools have the potential to contribute to the understanding of the role of myocyte disarray and anisotropic conduction in arrhythmic states.

Cardiac muscle diseases in genetically engineered mice: evolution of molecular physiology

1995 ◽  
Vol 269 (3) ◽  
pp. H755-H766 ◽  
Author(s):  
K. R. Chien
Keyword(s):  
Cardiac Muscle ◽  
Large Body ◽  
Genetically Engineered ◽  
Mouse Genetics ◽  
Model Systems ◽  
Molecular Physiology ◽  
Muscle Diseases ◽  
Recent Advances ◽  
Genetically Engineered Mice

Recent advances in molecular, cellular, and genetically based technologies now offer the possibility of generating genetically engineered mice that display physiological phenotypes with direct relevance to human pathophysiological states. The ability to create gene ablations, gene duplications, and gene modifications should allow the use of genetic approaches to map in vivo pathways responsible for complex physiological phenotypes. Recent work from our laboratory utilizing this approach to study cardiac muscle diseases in both the adult context (cardiac hypertrophy) and in the embryonic context (congenital ventricular defects) will be discussed, as well as the steps that led to the generation and characterization of these novel mouse model systems. A large body of work from independent laboratories now points to the inception of a new field of molecular physiology that will fuse mouse genetics and in vivo physiology using appropriate miniaturized physiological technology. Recent advances and prospects for future directions are summarized.

scholarly journals Impact of Resolvin E1 on Murine Neutrophil Phagocytosis in Type 2 Diabetes

2014 ◽  
Vol 83 (2) ◽  
pp. 792-801 ◽  
Author(s):  
Bruno S. Herrera ◽  
Hatice Hasturk ◽  
Alpdogan Kantarci ◽  
Marcelo O. Freire ◽  
Olivia Nguyen ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Transgenic Animals ◽  
Genetically Engineered ◽  
Mitogen Activated Protein Kinase ◽  
Air Pouch ◽  
Content Type ◽  
Genetically Engineered Mice ◽  
The Impact

Diabetic complications involve inflammation-mediated microvascular and macrovascular damage, disruption of lipid metabolism, glycosylation of proteins, and abnormalities of neutrophil-mediated events. Resolution of inflamed tissues to health and homeostasis is an active process mediated by endogenous lipid agonists, including lipoxins and resolvins. This proresolution system appears to be compromised in type 2 diabetes (T2D). The goal of this study was to investigate unresolved inflammation in T2D. Wild-type (WT) and genetically engineered mice, including T2D mice (db/db), transgenic mice overexpressing the human resolvin E1 (RvE1) receptor (ERV1), and a newly bred strain ofdb/ERV1mice, were used to determine the impact of RvE1 on the phagocytosis ofPorphyromonas gingivalisin T2D. Neutrophils were isolated and incubated with fluorescein isothiocyanate-labeledP. gingivalis, and phagocytosis was measured in a fluorochrome-based assay by flow cytometry. Mitogen-activated protein kinase (MAPK) (p42 and p44) and Akt (Thr308 and Ser473) phosphorylation was analyzed by Western blotting. The mouse dorsal air pouch model was used to evaluate thein vivoimpact of RvE1. Results revealed that RvE1 increased the neutrophil phagocytosis ofP. gingivalisin WT animals but had no impact indb/dbanimals. InERV1-transgenic andERV1-transgenic diabetic mice, phagocytosis was significantly increased. RvE1 decreased Akt and MAPK phosphorylation in the transgenic animals.In vivodorsal air pouch studies revealed that RvE1 decreases neutrophil influx into the pouch and increases neutrophil phagocytosis ofP. gingivalisin the transgenic animals; cutaneous fat deposition was reduced, as was macrophage infiltration. The results suggest that RvE1 rescues impaired neutrophil phagocytosis in obese T2D mice overexpressingERV1.

scholarly journals Genetically Altered Mouse Models: the Good, the Bad, and the Ugly

2003 ◽  
Vol 14 (3) ◽  
pp. 154-174 ◽  
Author(s):  
Tamizchelvi Thyagarajan ◽  
Satish Totey ◽  
Mary Jo S. Danton ◽  
Ashok B. Kulkarni
Keyword(s):  
Gene Targeting ◽  
Mouse Models ◽  
Molecular Mechanisms ◽  
Gene Knockout ◽  
Genetically Engineered ◽  
Murine Models ◽  
Functional Roles ◽  
Targeted Gene Disruption ◽  
Gene Knockout Mouse

Targeted gene disruption in mice is a powerful tool for generating murine models for human development and disease. While the human genome program has helped to generate numerous candidate genes, few genes have been characterized for their precise in vivo functions. Gene targeting has had an enormous impact on our ability to delineate the functional roles of these genes. Many gene knockout mouse models faithfully mimic the phenotypes of the human diseases. Because some models display an unexpected or no phenotype, controversy has arisen about the value of gene-targeting strategies. We argue in favor of gene-targeting strategies, provided they are used with caution, particularly in interpreting phenotypes in craniofacial and oral biology, where many genes have pleiotropic roles. The potential pitfalls are outweighed by the unique opportunities for developing and testing different therapeutic strategies before they are introduced into the clinic. In the future, we believe that genetically engineered animal models will be indispensable for gaining important insights into the molecular mechanisms underlying development, as well as disease pathogenesis, diagnosis, prevention, and treatment.

Selected Contribution: Pulmonary hypertension in mice following intermittent hypoxia

2001 ◽  
Vol 90 (6) ◽  
pp. 2502-2507 ◽  
Author(s):  
Karen A. Fagan
Keyword(s):  
Pulmonary Hypertension ◽  
Sleep Apnea ◽  
Intermittent Hypoxia ◽  
Systolic Pressure ◽  
Genetically Engineered ◽  
Systemic Hypertension ◽  
Pulmonary Hemodynamics ◽  
Genetically Engineered Mice ◽  
The Relationship

Sleep apnea (intermittent periods of hypoxia with or without hypercapnia) is associated with systemic hypertension and increased mortality from cardiovascular disease, but the relationship to pulmonary hypertension is uncertain. Previous studies on intermittent hypoxia (IH) in rats that demonstrated pulmonary hypertension utilized relatively long periods of hypoxia. Recent studies that utilized brief periods of hypoxia have conflicting reports of right ventricular (RV) hypertrophy. In addition, many studies have not measured pulmonary hemodynamics to asses the severity of pulmonary hypertension in vivo. Given the increasing availability of genetically engineered mice and the need to establish a rodent model of IH-induced pulmonary hypertension, we studied the effect of IH (2-min cycles of 10% and 21% O2, 8 h/day, 4 wk) on wild-type mice, correlating in vivo measurements of pulmonary hypertension with RV mass and pulmonary vascular remodeling. RV systolic pressure was increased after IH (36 ± 0.9 mmHg) compared with normoxia (29.5 ± 0.6) but was lower than continuous hypoxia (44.2 ± 3.4). RV mass [RV-to-(left ventricle plus septum) ratio] correlated with pressure measurements (IH = 0.27 ± 0.02, normoxia = 0.22 ± 0.01, and continuous hypoxia = 0.34 ± 0.01). Hematocrits were also elevated after IH and continuous hypoxia (56 ± 1.6 and 54 ± 1.1 vs. 44.3 ± 0.5%). Evidence of neomuscularization of the distal pulmonary circulation was found after IH and continuous hypoxia. We conclude that mice develop pulmonary hypertension following IH, representing a possible animal model of pulmonary hypertension in response to the repetitive hypoxia-reoxygenation of sleep apnea.

scholarly journals Generation and Characterization of Typhoid Toxin-Neutralizing Human Monoclonal Antibodies

2020 ◽  
Vol 88 (10) ◽  
Author(s):  
Xuyao Jiao ◽  
Sarah Smith ◽  
Gabrielle Stack ◽  
Qi Liang ◽  
Allan Bradley ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Typhoid Fever ◽  
Severe Disease ◽  
Genetically Engineered ◽  
Human Monoclonal Antibodies ◽  
Genetically Engineered Mice ◽  
Typhoid Toxin

ABSTRACT Typhoid toxin is a virulence factor of Salmonella enterica serovar Typhi, the causative agent of typhoid fever, and is thought to be responsible for the symptoms of severe disease. This toxin has a unique A2B5 architecture with two active subunits, the ADP ribosyl transferase PltA and the DNase CdtB, linked to a pentameric B subunit, which is alternatively made of PltB or PltC. Here, we describe the generation and characterization of typhoid toxin-neutralizing human monoclonal antibodies by immunizing genetically engineered mice that have a full set of human immunoglobulin variable region genes. We identified several monoclonal antibodies with strong in vitro and in vivo toxin-neutralizing activity and different mechanisms of toxin neutralization. These antibodies could serve as the basis for the development of novel therapeutic strategies against typhoid fever.

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