Genesis and Regulation of the Heart Automaticity

2008 ◽  
Vol 88 (3) ◽  
pp. 919-982 ◽  
Author(s):  
Matteo E. Mangoni ◽  
Joël Nargeot
Keyword(s):  
Ion Channels ◽  
Current Knowledge ◽  
Genetically Engineered ◽  
Cardiac Cells ◽  
Mouse Strains ◽  
Cellular Mechanisms ◽  
Cardiac Pacemaking ◽  
Intracellular Ca ◽  
Cardiac Automaticity

The heart automaticity is a fundamental physiological function in higher organisms. The spontaneous activity is initiated by specialized populations of cardiac cells generating periodical electrical oscillations. The exact cascade of steps initiating the pacemaker cycle in automatic cells has not yet been entirely elucidated. Nevertheless, ion channels and intracellular Ca2+ signaling are necessary for the proper setting of the pacemaker mechanism. Here, we review the current knowledge on the cellular mechanisms underlying the generation and regulation of cardiac automaticity. We discuss evidence on the functional role of different families of ion channels in cardiac pacemaking and review recent results obtained on genetically engineered mouse strains displaying dysfunction in heart automaticity. Beside ion channels, intracellular Ca2+ release has been indicated as an important mechanism for promoting automaticity at rest as well as for acceleration of the heart rate under sympathetic nerve input. The potential links between the activity of ion channels and Ca2+ release will be discussed with the aim to propose an integrated framework of the mechanism of automaticity.

scholarly journals Cardiac Transmembrane Ion Channels and Action Potentials: Cellular Physiology and Arrhythmogenic Behavior

2020 ◽  
Author(s):  
András Varró ◽  
Jakub Tomek ◽  
Norbert Nagy ◽  
Laszlo Virag ◽  
Elisa Passini ◽  
...  
Keyword(s):  
Ion Channel ◽  
Action Potentials ◽  
Cardiac Electrophysiology ◽  
Current Knowledge ◽  
Animal Experiments ◽  
Cardiac Cells ◽  
Cellular Mechanisms ◽  
Electrophysiological Properties ◽  
Channel Expression ◽  
Ionic Mechanisms

Cardiac arrhythmias are among the leading causes of mortality. They often arise from alterations in the electrophysiological properties of cardiac cells, and their underlying ionic mechanisms. It is therefore critical to further unravel the patho-physiology of the ionic basis of human cardiac electrophysiology in health and disease. In the first part of this review, current knowledge on the differences in ion channel expression and properties of the ionic processes that determine the morphology and properties of cardiac action potentials and calcium dynamics from cardiomyocytes in different regions of the heart are described. Then the cellular mechanisms promoting arrhythmias in congenital or acquired conditions of ion channel function (electrical remodelling) are discussed. The focus is human relevant findings obtained with clinical, experimental and computational studies, given that interspecies differences make the extrapolation from animal experiments to the human clinical settings difficult. Deepening the understanding of the diverse patholophysiology of human cellular electrophysiology will help developing novel and effective antiarrhythmic strategies for specific subpopulations and disease conditions.

scholarly journals Phagocytosis: A Fundamental Process in Immunity

2017 ◽  
Vol 2017 ◽  
pp. 1-18 ◽  
Author(s):  
Carlos Rosales ◽  
Eileen Uribe-Querol
Keyword(s):  
Immune Responses ◽  
Host Response ◽  
Current Knowledge ◽  
General View ◽  
Cellular Mechanisms ◽  
Complex Process ◽  
Fundamental Process ◽  
Target Particle ◽  
Acquired Immune Responses

One hundred years have passed since the death of Élie Metchnikoff (1845–1916). He was the first to observe the uptake of particles by cells and realized the importance of this process for the host response to injury and infection. He also was a strong advocate of the role of phagocytosis in cellular immunity, and with this he gave us the basis for our modern understanding of inflammation and the innate and acquired immune responses. Phagocytosis is an elegant but complex process for the ingestion and elimination of pathogens, but it is also important for the elimination of apoptotic cells and hence fundamental for tissue homeostasis. Phagocytosis can be divided into four main steps: (i) recognition of the target particle, (ii) signaling to activate the internalization machinery, (iii) phagosome formation, and (iv) phagolysosome maturation. In recent years, the use of new tools of molecular biology and microscopy has provided new insights into the cellular mechanisms of phagocytosis. In this review, we present a general view of our current knowledge on phagocytosis. We emphasize novel molecular findings, particularly on phagosome formation and maturation, and discuss aspects that remain incompletely understood.

scholarly journals Genetic neuroscience of mammalian learning and memory

2003 ◽  
Vol 358 (1432) ◽  
pp. 787-795 ◽  
Author(s):  
Susumu Tonegawa ◽  
Kazu Nakazawa ◽  
Matthew A. Wilson
Keyword(s):  
Cell Types ◽  
Genetically Engineered ◽  
Mouse Strains ◽  
Cellular Mechanisms ◽  
Genetic Manipulations ◽  
Adult Mice ◽  
Multiple Levels ◽  
Primary Research Interest

Our primary research interest is to understand the molecular and cellular mechanisms on neuronal circuitry underlying the acquisition, consolidation and retrieval of hippocampus-dependent memory in rodents. We study these problems by producing genetically engineered (i.e. spatially targeted and/or temporally restricted) mice and analysing these mice by multifaceted methods including molecular and cellular biology, in vitro and in vivo physiology and behavioural studies. We attempt to identify deficits at each of the multiple levels of complexity in specific brain areas or cell types and deduce those deficits that underlie specific learning or memory. We will review our recent studies on the acquisition, consolidation and recall of memories that have been conducted with mouse strains in which genetic manipulations were targeted to specific types of cells in the hippocampus or forebrain of young adult mice.

scholarly journals Pleiotropic Role of Notch Signaling in Human Skin Diseases

2020 ◽  
Vol 21 (12) ◽  
pp. 4214 ◽  
Author(s):  
Rossella Gratton ◽  
Paola Maura Tricarico ◽  
Chiara Moltrasio ◽  
Ana Sofia Lima Estevão de Oliveira ◽  
Lucas Brandão ◽  
...  
Keyword(s):  
Notch Signaling ◽  
Human Skin ◽  
Hidradenitis Suppurativa ◽  
Target Genes ◽  
Skin Diseases ◽  
Current Knowledge ◽  
Cellular Mechanisms ◽  
Degos Disease ◽  
Cellular Pathways

Notch signaling orchestrates the regulation of cell proliferation, differentiation, migration and apoptosis of epidermal cells by strictly interacting with other cellular pathways. Any disruption of Notch signaling, either due to direct mutations or to an aberrant regulation of genes involved in the signaling route, might lead to both hyper- or hypo-activation of Notch signaling molecules and of target genes, ultimately inducing the onset of skin diseases. The mechanisms through which Notch contributes to the pathogenesis of skin diseases are multiple and still not fully understood. So far, Notch signaling alterations have been reported for five human skin diseases, suggesting the involvement of Notch in their pathogenesis: Hidradenitis Suppurativa, Dowling Degos Disease, Adams–Oliver Syndrome, Psoriasis and Atopic Dermatitis. In this review, we aim at describing the role of Notch signaling in the skin, particularly focusing on the principal consequences associated with its alterations in these five human skin diseases, in order to reorganize the current knowledge and to identify potential cellular mechanisms in common between these pathologies.

scholarly journals Role of Hedgehog Signaling in Vasculature Development, Differentiation, and Maintenance

2019 ◽  
Vol 20 (12) ◽  
pp. 3076 ◽  
Author(s):  
Candice Chapouly ◽  
Sarah Guimbal ◽  
Pierre-Louis Hollier ◽  
Marie-Ange Renault
Keyword(s):  
Hedgehog Signaling ◽  
Current Knowledge ◽  
Vascular Biology ◽  
Cerebrovascular Diseases ◽  
Future Research ◽  
Cellular Mechanisms ◽  
Vascular Integrity ◽  
Hh Signaling ◽  
Vessel Integrity

The role of Hedgehog (Hh) signaling in vascular biology has first been highlighted in embryos by Pepicelli et al. in 1998 and Rowitch et al. in 1999. Since then, the proangiogenic role of the Hh ligands has been confirmed in adults, especially under pathologic conditions. More recently, the Hh signaling has been proposed to improve vascular integrity especially at the blood–brain barrier (BBB). However, molecular and cellular mechanisms underlying the role of the Hh signaling in vascular biology remain poorly understood and conflicting results have been reported. As a matter of fact, in several settings, it is currently not clear whether Hh ligands promote vessel integrity and quiescence or destabilize vessels to promote angiogenesis. The present review relates the current knowledge regarding the role of the Hh signaling in vasculature development, maturation and maintenance, discusses the underlying proposed mechanisms and highlights controversial data which may serve as a guideline for future research. Most importantly, fully understanding such mechanisms is critical for the development of safe and efficient therapies to target the Hh signaling in both cancer and cardiovascular/cerebrovascular diseases.

scholarly journals Molecular Crosstalking among Noncoding RNAs: A New Network Layer of Genome Regulation in Cancer

2017 ◽  
Vol 2017 ◽  
pp. 1-17 ◽  
Author(s):  
Marco Ragusa ◽  
Cristina Barbagallo ◽  
Duilia Brex ◽  
Angela Caponnetto ◽  
Matilde Cirnigliaro ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Structural Integrity ◽  
Current Knowledge ◽  
Noncoding Rnas ◽  
Special Focus ◽  
Cellular Mechanisms ◽  
Protein Coding ◽  
The Past ◽  
Higher Eukaryotes

Over the past few years, noncoding RNAs (ncRNAs) have been extensively studied because of the significant biological roles that they play in regulation of cellular mechanisms. ncRNAs are associated to higher eukaryotes complexity; accordingly, their dysfunction results in pathological phenotypes, including cancer. To date, most research efforts have been mainly focused on how ncRNAs could modulate the expression of protein-coding genes in pathological phenotypes. However, recent evidence has shown the existence of an unexpected interplay among ncRNAs that strongly influences cancer development and progression. ncRNAs can interact with and regulate each other through various molecular mechanisms generating a complex network including different species of RNAs (e.g., mRNAs, miRNAs, lncRNAs, and circRNAs). Such a hidden network of RNA-RNA competitive interactions pervades and modulates the physiological functioning of canonical protein-coding pathways involved in proliferation, differentiation, and metastasis in cancer. Moreover, the pivotal role of ncRNAs as keystones of network structural integrity makes them very attractive and promising targets for innovative RNA-based therapeutics. In this review we will discuss: (1) the current knowledge on complex crosstalk among ncRNAs, with a special focus on cancer; and (2) the main issues and criticisms concerning ncRNAs targeting in therapeutics.

scholarly journals Cellular mechanisms involved in CO2 and acid signaling in chemosensitive neurons

2004 ◽  
Vol 287 (6) ◽  
pp. C1493-C1526 ◽  
Author(s):  
Robert W. Putnam ◽  
Jessica A. Filosa ◽  
Nicola A. Ritucci
Keyword(s):  
Brain Stem ◽  
Neuronal Response ◽  
Taste Receptor ◽  
Cellular Mechanisms ◽  
Signaling Mechanisms ◽  
Intrapulmonary Chemoreceptors ◽  
Intracellular Ca ◽  
Different Levels ◽  
Carotid Body Glomus Cells

An increase in CO2/H+ is a major stimulus for increased ventilation and is sensed by specialized brain stem neurons called central chemosensitive neurons. These neurons appear to be spread among numerous brain stem regions, and neurons from different regions have different levels of chemosensitivity. Early studies implicated changes of pH as playing a role in chemosensitive signaling, most likely by inhibiting a K+ channel, depolarizing chemosensitive neurons, and thereby increasing their firing rate. Considerable progress has been made over the past decade in understanding the cellular mechanisms of chemosensitive signaling using reduced preparations. Recent evidence has pointed to an important role of changes of intracellular pH in the response of central chemosensitive neurons to increased CO2/H+ levels. The signaling mechanisms for chemosensitivity may also involve changes of extracellular pH, intracellular Ca2+, gap junctions, oxidative stress, glial cells, bicarbonate, CO2, and neurotransmitters. The normal target for these signals is generally believed to be a K+ channel, although it is likely that many K+ channels as well as Ca2+ channels are involved as targets of chemosensitive signals. The results of studies of cellular signaling in central chemosensitive neurons are compared with results in other CO2- and/or H+-sensitive cells, including peripheral chemoreceptors (carotid body glomus cells), invertebrate central chemoreceptors, avian intrapulmonary chemoreceptors, acid-sensitive taste receptor cells on the tongue, and pain-sensitive nociceptors. A multiple factors model is proposed for central chemosensitive neurons in which multiple signals that affect multiple ion channel targets result in the final neuronal response to changes in CO2/H+.

scholarly journals From syncitium to regulated pump: a cardiac muscle cellular update

2011 ◽  
Vol 35 (1) ◽  
pp. 22-27 ◽  
Author(s):  
Donna H. Korzick
Keyword(s):  
Cardiac Muscle ◽  
Intracellular Signaling ◽  
Ventricular Myocytes ◽  
Cellular Events ◽  
Intracellular Ca ◽  
Health And Disease ◽  
Cardiac Excitation ◽  
And Function ◽  
Cardiac Automaticity

The primary purpose of this article is to present a basic overview of some key teaching concepts that should be considered for inclusion in an six- to eight-lecture introductory block on the regulation of cardiac performance for graduate students. Within the context of cardiac excitation-contraction coupling, this review incorporates information on Ca2+ microdomains and local control theory, with particular emphasis on the role of Ca2+ sparks as a key regulatory component of ventricular myocyte contraction dynamics. Recent information pertaining to local Ca2+ cycling in sinoatrial nodal cells (SANCs) as a mechanism underlying cardiac automaticity is also presented as part of the recently described coupled-clock pacemaker system. The details of this regulation are emerging; however, the notion that the sequestration and release of Ca2+ from internal stores in SANCs (similar to that observed in ventricular myocytes) regulates the rhythmic excitation of the heart (i.e., membrane ion channels) is an important advancement in this area. The regulatory role of cardiac adrenergic receptors on cardiac rate and function is also included, and fundamental concepts related to intracellular signaling are discussed. An important point of emphasis is that whole organ cardiac dynamics can be traced back to cellular events regulating intracellular Ca2+ homeostasis and, as such, provides an important conceptual framework from which students can begin to think about whole organ physiology in health and disease. Greater synchrony of Ca2+-regulatory mechanisms between ventricular and pacemaker cells should enhance student comprehension of complex regulatory phenomenon in cardiac muscle.

scholarly journals Bioelectric State and Cell Cycle Control of Mammalian Neural Stem Cells

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Julieta Aprea ◽  
Federico Calegari
Keyword(s):  
Stem Cells ◽  
Membrane Potential ◽  
Ion Channels ◽  
Neural Stem Cells ◽  
Current Knowledge ◽  
Cell Cycle Control ◽  
Resting Membrane Potential ◽  
Excitable Cells ◽  
Proliferation And Differentiation

The concerted action of ion channels and pumps establishing a resting membrane potential has been most thoroughly studied in the context of excitable cells, most notably neurons, but emerging evidences indicate that they are also involved in controlling proliferation and differentiation of nonexcitable somatic stem cells. The importance of understanding stem cell contribution to tissue formation during embryonic development, adult homeostasis, and regeneration in disease has prompted many groups to study and manipulate the membrane potential of stem cells in a variety of systems. In this paper we aimed at summarizing the current knowledge on the role of ion channels and pumps in the context of mammalian corticogenesis with particular emphasis on their contribution to the switch of neural stem cells from proliferation to differentiation and generation of more committed progenitors and neurons, whose lineage during brain development has been recently elucidated.

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