Variants Cause Atrioventricular Node Dysfunction and Arrhythmogenic Changes in Cardiac Electrophysiology and Intracellular Calcium Handling in Zebrafish.

Popeye domain-containing (POPDC) proteins selectively bind cAMP and mediate cellular responses to sympathetic nervous system (SNS) stimulation. The first discovered human genetic variant () is associated with atrioventricular (AV) block, which is exacerbated by increased SNS activity. Zebrafish carrying the homologous mutation () display a similar phenotype to humans.

Genomic and physiological analyses of the zebrafish atrioventricular canal reveal molecular building blocks of the secondary pacemaker region.

The atrioventricular canal (AVC) is the site where key structures responsible for functional division between heart regions are established, most importantly, the atrioventricular (AV) conduction system and cardiac valves. To elucidate the mechanism underlying AVC development and function, we utilized transgenic zebrafish line sqet31Et expressing EGFP in the AVC to isolate this cell population and profile its transcriptome at 48 and 72 hpf. The zebrafish AVC transcriptome exhibits hallmarks of mammalian AV node, including the expression of genes implicated in its development and those encoding connexins forming low conductance gap junctions.

Editor's Highlight: Transgenic Zebrafish Reporter Lines as Alternative In Vivo Organ Toxicity Models.

Organ toxicity, particularly liver toxicity, remains one of the major reasons for the termination of drug candidates in the development pipeline as well as withdrawal or restrictions of marketed drugs. A screening-amenable alternative in vivo model such as zebrafish would, therefore, find immediate application in the early prediction of unacceptable organ toxicity. To identify highly upregulated genes as biomarkers of toxic responses in the zebrafish model, a set of well-characterized reference drugs that cause drug-induced liver injury (DILI) in the clinic were applied to zebrafish larvae and adults.

Synthesis and Antibacterial Study of Sulfobetaine/Quaternary Ammonium-Modified Star-Shaped Poly[2-(dimethylamino)ethyl methacrylate]-Based Copolymers with an Inorganic Core.

Cationic polymethacrylates are interesting candidates for bacterial disinfectants since they can be made in large-scale by various well-established polymerization techniques such as atom transfer radical polymerization (ATRP). However, they are usually toxic or ineffective in serum and various strategies to improve their biocompatibility or nonfouling property have often resulted in compromised bactericidal activity. Also, star-shaped polymers are less explored than linear polymers for application as antibacterial compounds.

Development of the cardiac conduction system in zebrafish.

The cardiac conduction system (CCS) propagates and coordinates the electrical excitation that originates from the pacemaker cells, throughout the heart, resulting in rhythmic heartbeat. Its defects result in life-threatening arrhythmias and sudden cardiac death. Understanding of the factors involved in the formation and function of the CCS remains incomplete.

Humanizing the zebrafish liver shifts drug metabolic profiles and improves pharmacokinetics of CYP3A4 substrates.

Understanding and predicting whether new drug candidates will be safe in the clinic is a critical hurdle in pharmaceutical development, that relies in part on absorption, distribution, metabolism, excretion and toxicology studies in vivo. Zebrafish is a relatively new model system for drug metabolism and toxicity studies, offering whole organism screening coupled with small size and potential for high-throughput screening. Through toxicity and absorption analyses of a number of drugs, we find that zebrafish is generally predictive of drug toxicity, although assay outcomes are influenced by drug lipophilicity which alters drug uptake.

POPDC1(S201F) causes muscular dystrophy and arrhythmia by affecting protein trafficking.

The Popeye domain-containing 1 (POPDC1) gene encodes a plasma membrane-localized cAMP-binding protein that is abundantly expressed in striated muscle. In animal models, POPDC1 is an essential regulator of structure and function of cardiac and skeletal muscle; however, POPDC1 mutations have not been associated with human cardiac and muscular diseases. Here, we have described a homozygous missense variant (c.

The Popeye Domain Containing Genes and cAMP Signaling.

3'-5'-cyclic adenosine monophosphate (cAMP) is a second messenger, which plays an important role in the heart. It is generated in response to activation of G-protein-coupled receptors (GPCRs). Initially, it was thought that protein kinase A (PKA) exclusively mediates cAMP-induced cellular responses such as an increase in cardiac contractility, relaxation, and heart rate.

The cAMP-binding Popdc proteins have a redundant function in the heart.

Popdc (Popeye-domain-containing) genes encode membrane-bound proteins and are abundantly present in cardiac myocytes and in skeletal muscle fibres. Functional analysis of Popdc1 (Bves) and Popdc2 in mice and of popdc2 in zebrafish revealed an overlapping role for proper electrical conduction in the heart and maintaining structural integrity of skeletal muscle. Popdc proteins mediate cAMP signalling and modulate the biological activity of interacting proteins.

The Popeye domain containing genes: essential elements in heart rate control.

The Popeye domain containing (Popdc) gene family displays preferential expression in skeletal muscle and heart. Only recently a significant gain in the understanding of the function of Popdc genes in the heart has been obtained. The Popdc genes encode membrane proteins harboring an evolutionary conserved Popeye domain, which functions as a binding domain for cyclic adenosine monophosphate (cAMP).

Popeye domain-containing proteins and stress-mediated modulation of cardiac pacemaking.

An intricate network of ion channels and pumps are involved in generating a diastolic pacemaker potential, which is transmitted to the working myocardium with the help of the cardiac conduction system. The principles of cardiac pacemaking are reasonably well understood, however, the mechanism by which the heart increases its beating frequency in response to adrenergic stimulation has not been fully worked out. The Popeye domain-containing (Popdc) genes encode plasma membrane-localized proteins that are able to bind cAMP with high affinity; mice with null mutations in Popdc1 or 2 have a stress-induced pacemaker dysfunction.

RNA-binding protein RBM24 is required for sarcomere assembly and heart contractility.

Aims: The factors responsible for cardiomyopathy are not fully understood. Our studies of the transcriptome of human embryonic stem cell-derived cardiomyocytes identified novel genes up-regulated during cardiac differentiation, including RBM24. We therefore studied how its deficiency affected heart development.

The Popeye domain containing 2 (popdc2) gene in zebrafish is required for heart and skeletal muscle development.

The Popeye domain containing (Popdc) genes encode a family of transmembrane proteins with an evolutionary conserved Popeye domain. These genes are abundantly expressed in striated muscle tissue, however their function is not well understood. In this study we have investigated the role of the popdc2 gene in zebrafish.

Fish and Chips: a microfluidic perfusion platform for monitoring zebrafish development.

We have developed a multi-channel microfluidic perfusion platform for culturing zebrafish embryos and capturing live images of various tissues and organs inside the embryo. The Fish and Chips was micro-fabricated in silicon and glass for reproducibility and accuracy of the microfluidic structure. The microfluidic platform consists of three parts: a microfluidic gradient generator, a row of eight fish tanks, in which the fish embryos are individually placed, and eight output channels.

Target cell movement in tumor and cardiovascular diseases based on the epithelial-mesenchymal transition concept.

Epithelial-mesenchymal transition (EMT) is a fundamental mechanism in development driving body plan formation. EMT describes a transition process wherein polarized epithelial cells lose their characteristics and acquire a mesenchymal phenotype. The apico-basal polarity of epithelial cells is replaced by a front-rear polarity in mesenchymal cells which favor cell-extracellular matrix than intercellular adhesion.

Optogenetic in vivo cell manipulation in KillerRed-expressing zebrafish transgenics.

Background: KillerRed (KR) is a novel photosensitizer that efficiently generates reactive oxygen species (ROS) in KR-expressing cells upon intense green or white light illumination in vitro, resulting in damage to their plasma membrane and cell death.

Results: We report an in vivo modification of this technique using a fluorescent microscope and membrane-tagged KR (mem-KR)-expressing transgenic zebrafish. We generated several stable zebrafish Tol2 transposon-mediated enhancer-trap (ET) transgenic lines expressing mem-KR (SqKR series), and mapped the transposon insertion sites.

Zebrafish cardiac enhancer trap lines: new tools for in vivo studies of cardiovascular development and disease.

Using the transposon-mediated enhancer trap (ET), we generated 18 cardiac enhancer trap (CET) transgenic zebrafish lines. They exhibit EGFP expression in defined cell types--the endocardium, myocardium, and epicardium--or in anatomical regions of the heart--the atrium, ventricle, valves, or bulbus arteriosus. Most of these expression domains are maintained into adulthood.

Collective cell migration drives morphogenesis of the kidney nephron.

Tissue organization in epithelial organs is achieved during development by the combined processes of cell differentiation and morphogenetic cell movements. In the kidney, the nephron is the functional organ unit. Each nephron is an epithelial tubule that is subdivided into discrete segments with specific transport functions.

Expression of zebrafish nos2b surrounds oral cavity.

Inducible nitric oxide synthase (NOS2) catalyzes the production of nitric oxide (NO), and is one of the factors establishing innate immunity. In zebrafish, Nos2 is represented by nos2a and nos2b. Here, we report the cloning and expression pattern of the zebrafish nos2b gene, which does not seem to participate in induced immune response.

MAP-1 is a mitochondrial effector of Bax.

Apoptotic stimuli induce conformational changes in Bax and trigger its translocation from cytosol to mitochondria. Upon assembling into the mitochondrial membrane, Bax initiates a death program through a series of events, culminating in the release of apoptogenic factors such as cytochrome c. Although it is known that Bax is one of the key factors for integrating multiple death signals, the mechanism by which Bax functions in mitochondria remains controversial.

Expression pattern of neuronal nitric oxide synthase in embryonic zebrafish.

Nitric oxide synthase catalyzes the production of nitric oxide, a multifunctional signaling molecule that affects diverse aspects of animal physiology such as cell proliferation, differentiation, neurotransmission and apoptosis. Here, we report the cloning and expression pattern of the zebrafish nnos. This gene was mapped to zebrafish linkage group 5.