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Basic Science

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19 papers 0 to 25 followers
Hanting Yang, Miaohui Hu, Jianli Guo, Xiaomin Ou, Tanxi Cai, Zhenfeng Liu
Intracellular Ca(2+) signalling processes are fundamental to muscle contraction, neurotransmitter release, cell growth and apoptosis. Release of Ca(2+) from the intracellular stores is supported by a series of ion channels in sarcoplasmic or endoplasmic reticulum (SR/ER). Among them, two isoforms of the trimeric intracellular cation (TRIC) channel family, named TRIC-A and TRIC-B, modulate the release of Ca(2+) through the ryanodine receptor or inositol triphosphate receptor, and maintain the homeostasis of ions within SR/ER lumen...
October 3, 2016: Nature
Adam S Helms, Francisco J Alvarado, Jaime Yob, Vi T Tang, Francis Pagani, Mark W Russell, Héctor H Valdivia, Sharlene M Day
BACKGROUND: -Aberrant calcium signaling may contribute to arrhythmias and adverse remodeling in hypertrophic cardiomyopathy (HCM). Mutations in sarcomere genes may distinctly alter calcium handling pathways. METHODS: -We analyzed gene expression, protein levels, and functional assays for calcium regulatory pathways in human HCM surgical samples with (n=25) and without (n=10) sarcomere mutations compared with control hearts (n=8). RESULTS: -Gene expression and protein levels for calsequestrin, L-type calcium channel, sodium-calcium exchanger, phospholamban (PLN), calcineurin, and calcium/calmodulin-dependent protein kinase type II (CaMKII) were similar in HCM compared to controls...
September 29, 2016: Circulation
Swapan Mallick, Heng Li, Mark Lipson, Iain Mathieson, Melissa Gymrek, Fernando Racimo, Mengyao Zhao, Niru Chennagiri, Susanne Nordenfelt, Arti Tandon, Pontus Skoglund, Iosif Lazaridis, Sriram Sankararaman, Qiaomei Fu, Nadin Rohland, Gabriel Renaud, Yaniv Erlich, Thomas Willems, Carla Gallo, Jeffrey P Spence, Yun S Song, Giovanni Poletti, Francois Balloux, George van Driem, Peter de Knijff, Irene Gallego Romero, Aashish R Jha, Doron M Behar, Claudio M Bravi, Cristian Capelli, Tor Hervig, Andres Moreno-Estrada, Olga L Posukh, Elena Balanovska, Oleg Balanovsky, Sena Karachanak-Yankova, Hovhannes Sahakyan, Draga Toncheva, Levon Yepiskoposyan, Chris Tyler-Smith, Yali Xue, M Syafiq Abdullah, Andres Ruiz-Linares, Cynthia M Beall, Anna Di Rienzo, Choongwon Jeong, Elena B Starikovskaya, Ene Metspalu, Jüri Parik, Richard Villems, Brenna M Henn, Ugur Hodoglugil, Robert Mahley, Antti Sajantila, George Stamatoyannopoulos, Joseph T S Wee, Rita Khusainova, Elza Khusnutdinova, Sergey Litvinov, George Ayodo, David Comas, Michael F Hammer, Toomas Kivisild, William Klitz, Cheryl A Winkler, Damian Labuda, Michael Bamshad, Lynn B Jorde, Sarah A Tishkoff, W Scott Watkins, Mait Metspalu, Stanislav Dryomov, Rem Sukernik, Lalji Singh, Kumarasamy Thangaraj, Svante Pääbo, Janet Kelso, Nick Patterson, David Reich
Here we report the Simons Genome Diversity Project data set: high quality genomes from 300 individuals from 142 diverse populations. These genomes include at least 5.8 million base pairs that are not present in the human reference genome. Our analysis reveals key features of the landscape of human genome variation, including that the rate of accumulation of mutations has accelerated by about 5% in non-Africans compared to Africans since divergence. We show that the ancestors of some pairs of present-day human populations were substantially separated by 100,000 years ago, well before the archaeologically attested onset of behavioural modernity...
September 21, 2016: Nature
Meital Ben-Ari, Shulamit Naor, Naama Zeevi-Levin, Revital Schick, Ronen Ben Jehuda, Irina Reiter, Amit Raveh, Inna Grijnevitch, Omri Barak, Michael R Rosen, Amir Weissman, Ofer Binah
BACKGROUND: Previous studies proposed that throughout differentiation of human induced Pluripotent Stem Cell-derived cardiomyocytes (iPSC-CMs), only 3 types of action potentials (APs) exist: nodal-, atrial-, and ventricular-like. OBJECTIVES: To investigate whether there are precisely 3 phenotypes or a continuum exists among them, we tested 2 hypotheses: (1) During culture development a cardiac precursor cell is present that-depending on age-can evolve into the 3 phenotypes...
September 14, 2016: Heart Rhythm: the Official Journal of the Heart Rhythm Society
Mei Methawasin, Joshua G Strom, Rebecca E Slater, Vanessa Fernandez, Chandra Saripalli, Henk Granzier
BACKGROUND: Left ventricular (LV) stiffening contributes to heart failure with preserved ejection fraction (HFpEF), a syndrome with no effective treatment options. Increasing the compliance of titin in the heart has become possible recently through inhibition of the splicing factor RNA binding motif-20. Here, we investigated the effects of increasing the compliance of titin in mice with diastolic dysfunction. METHODS: Mice in which the RNA recognition motif (RRM) of one of the RNA binding motif-20 alleles was floxed and that expressed the MerCreMer transgene under control of the αMHC promoter (referred to as cRbm20(ΔRRM) mice) were used...
October 11, 2016: Circulation
Peidong Han, Joshua Bloomekatz, Jie Ren, Ruilin Zhang, Jonathan D Grinstein, Long Zhao, C Geoffrey Burns, Caroline E Burns, Ryan M Anderson, Neil C Chi
Many organs are composed of complex tissue walls that are structurally organized to optimize organ function. In particular, the ventricular myocardial wall of the heart comprises an outer compact layer that concentrically encircles the ridge-like inner trabecular layer. Although disruption in the morphogenesis of this myocardial wall can lead to various forms of congenital heart disease and non-compaction cardiomyopathies, it remains unclear how embryonic cardiomyocytes assemble to form ventricular wall layers of appropriate spatial dimensions and myocardial mass...
June 30, 2016: Nature
Christian Dina, Nabila Bouatia-Naji, Nathan Tucker, Francesca N Delling, Katelynn Toomer, Ronen Durst, Maelle Perrocheau, Leticia Fernandez-Friera, Jorge Solis, Thierry Le Tourneau, Ming-Huei Chen, Vincent Probst, Yohan Bosse, Philippe Pibarot, Diana Zelenika, Mark Lathrop, Serge Hercberg, Ronan Roussel, Emelia J Benjamin, Fabrice Bonnet, Su Hao Lo, Elena Dolmatova, Floriane Simonet, Simon Lecointe, Florence Kyndt, Richard Redon, Hervé Le Marec, Philippe Froguel, Patrick T Ellinor, Ramachandran S Vasan, Patrick Bruneval, Roger R Markwald, Russell A Norris, David J Milan, Susan A Slaugenhaupt, Robert A Levine, Jean-Jacques Schott, Albert A Hagege, Xavier Jeunemaitre
Nonsyndromic mitral valve prolapse (MVP) is a common degenerative cardiac valvulopathy of unknown etiology that predisposes to mitral regurgitation, heart failure and sudden death. Previous family and pathophysiological studies suggest a complex pattern of inheritance. We performed a meta-analysis of 2 genome-wide association studies in 1,412 MVP cases and 2,439 controls. We identified 6 loci, which we replicated in 1,422 cases and 6,779 controls, and provide functional evidence for candidate genes. We highlight LMCD1 (LIM and cysteine-rich domains 1), which encodes a transcription factor and for which morpholino knockdown of the ortholog in zebrafish resulted in atrioventricular valve regurgitation...
October 2015: Nature Genetics
Alan G Hinnebusch, Ivaylo P Ivanov, Nahum Sonenberg
The eukaryotic 5' untranslated region (UTR) is critical for ribosome recruitment to the messenger RNA (mRNA) and start codon choice and plays a major role in the control of translation efficiency and shaping the cellular proteome. The ribosomal initiation complex is assembled on the mRNA via a cap-dependent or cap-independent mechanism. We describe various mechanisms controlling ribosome scanning and initiation codon selection by 5' upstream open reading frames, translation initiation factors, and primary and secondary structures of the 5'UTR, including particular sequence motifs...
June 17, 2016: Science
Hengtao Zhang, Albert Y Sun, Jong J Kim, Victoria Graham, Elizabeth A Finch, Igor Nepliouev, Guiling Zhao, Tianyu Li, W J Lederer, Jonathan A Stiber, Geoffrey S Pitt, Nenad Bursac, Paul B Rosenberg
Cardiac pacemaking is governed by specialized cardiomyocytes located in the sinoatrial node (SAN). SAN cells (SANCs) integrate voltage-gated currents from channels on the membrane surface (membrane clock) with rhythmic Ca(2+) release from internal Ca(2+) stores (Ca(2+) clock) to adjust heart rate to meet hemodynamic demand. Here, we report that stromal interaction molecule 1 (STIM1) and Orai1 channels, key components of store-operated Ca(2+) entry, are selectively expressed in SANCs. Cardiac-specific deletion of STIM1 in mice resulted in depletion of sarcoplasmic reticulum (SR) Ca(2+) stores of SANCs and led to SAN dysfunction, as was evident by a reduction in heart rate, sinus arrest, and an exaggerated autonomic response to cholinergic signaling...
October 13, 2015: Proceedings of the National Academy of Sciences of the United States of America
Sathya D Unudurthi, Roseanne M Wolf, Thomas J Hund
Normal heart rhythm (sinus rhythm) depends on regular activity of the sinoatrial node (SAN), a heterogeneous collection of specialized myocytes in the right atrium. SAN cells, in general, possess a unique electrophysiological profile that promotes spontaneous electrical activity (automaticity). However, while automaticity is required for normal pacemaking, it is not necessarily sufficient. Less appreciated is the importance of the elaborate structure of the SAN complex for proper pacemaker function. Here, we review the important structural features of the SAN with a focus on how these elements help manage a precarious balance between electrical charge generated by the SAN ("source") and the charge needed to excite the surrounding atrial tissue ("sink")...
2014: Frontiers in Physiology
J C Denyer, H F Brown
1. A method has been developed for isolating calcium-tolerant, single rabbit sinoatrial node cells which maintain their natural shape following isolation. The majority of viable, spontaneously active cells were elongated and measured about 100 microns in length. 2. Staining fixed cells with Haematoxylin-Eosin revealed that a 'cell' with projections was usually an aggregate of more than one cell. 3. Single, elongated, spontaneously active cells were current and voltage clamped using the whole-cell configuration of the patch-clamp recording technique...
September 1990: Journal of Physiology
Xun Lan, Jonathan K Pritchard
Gene duplication is a fundamental process in genome evolution. However, most young duplicates are degraded by loss-of-function mutations, and the factors that allow some duplicate pairs to survive long-term remain controversial. One class of models to explain duplicate retention invokes sub- or neofunctionalization, whereas others focus on sharing of gene dosage. RNA-sequencing data from 46 human and 26 mouse tissues indicate that subfunctionalization of expression evolves slowly and is rare among duplicates that arose within the placental mammals, possibly because tandem duplicates are coregulated by shared genomic elements...
May 20, 2016: Science
Nan Cao, Yu Huang, Jiashun Zheng, C Ian Spencer, Yu Zhang, Ji-Dong Fu, Baoming Nie, Min Xie, Mingliang Zhang, Haixia Wang, Tianhua Ma, Tao Xu, Guilai Shi, Deepak Srivastava, Sheng Ding
Reprogramming somatic fibroblasts into alternative lineages would provide a promising source of cells for regenerative therapy. However, transdifferentiating human cells into specific homogeneous, functional cell types is challenging. Here we show that cardiomyocyte-like cells can be generated by treating human fibroblasts with a combination of nine compounds that we term 9C. The chemically induced cardiomyocyte-like cells uniformly contracted and resembled human cardiomyocytes in their transcriptome, epigenetic, and electrophysiological properties...
June 3, 2016: Science
Malou van den Boogaard, Phil Barnett, Vincent M Christoffels
The electrical activity of the heart depends on the correct interplay between key transcription factors and cis-regulatory elements, which together regulate the proper heterogeneous expression of genes encoding for ion channels and other proteins. Genome-wide association studies of ECG parameters implicated genetic variants in the genes for these factors and ion channels modulating conduction and depolarization. Here, we review recent insights into the regulation of localized expression of ion channel genes and the mechanism by which a single-nucleotide polymorphism (SNP) associated with alterations in cardiac conduction patterns in humans affects the transcriptional regulation of the sodium channel genes, SCN5A and SCN10A...
April 2014: Trends in Cardiovascular Medicine
Willem M H Hoogaars, Angela Engel, Janynke F Brons, Arie O Verkerk, Frederik J de Lange, L Y Elaine Wong, Martijn L Bakker, Danielle E Clout, Vincent Wakker, Phil Barnett, Jan Hindrik Ravesloot, Antoon F M Moorman, E Etienne Verheijck, Vincent M Christoffels
The sinoatrial node initiates the heartbeat and controls the rate and rhythm of contraction, thus serving as the pacemaker of the heart. Despite the crucial role of the sinoatrial node in heart function, the mechanisms that underlie its specification and formation are not known. Tbx3, a transcriptional repressor required for development of vertebrates, is expressed in the developing conduction system. Here we show that Tbx3 expression delineates the sinoatrial node region, which runs a gene expression program that is distinct from that of the bordering atrial cells...
May 1, 2007: Genes & Development
Maria Manukyan, Prim B Singh
Induced pluripotent stem (iPS) cells have provided a rational means of obtaining histo-compatible tissues for 'patient-specific' regenerative therapies (Hanna et al. 2010; Yamanaka & Blau 2010). Despite the obvious potential of iPS cell-based therapies, there are certain problems that must be overcome before these therapies can become safe and routine (Ohi et al. 2011; Pera 2011). As an alternative, we have recently explored the possibility of using 'epigenetic rejuvenation', where the specialized functions of an old cell are rejuvenated in the absence of any change in its differentiated state (Singh & Zacouto 2010)...
May 2012: Genes to Cells: Devoted to Molecular & Cellular Mechanisms
Kazutoshi Takahashi, Koji Tanabe, Mari Ohnuki, Megumi Narita, Tomoko Ichisaka, Kiichiro Tomoda, Shinya Yamanaka
Successful reprogramming of differentiated human somatic cells into a pluripotent state would allow creation of patient- and disease-specific stem cells. We previously reported generation of induced pluripotent stem (iPS) cells, capable of germline transmission, from mouse somatic cells by transduction of four defined transcription factors. Here, we demonstrate the generation of iPS cells from adult human dermal fibroblasts with the same four factors: Oct3/4, Sox2, Klf4, and c-Myc. Human iPS cells were similar to human embryonic stem (ES) cells in morphology, proliferation, surface antigens, gene expression, epigenetic status of pluripotent cell-specific genes, and telomerase activity...
November 30, 2007: Cell
Kazutoshi Takahashi, Shinya Yamanaka
Differentiated cells can be reprogrammed to an embryonic-like state by transfer of nuclear contents into oocytes or by fusion with embryonic stem (ES) cells. Little is known about factors that induce this reprogramming. Here, we demonstrate induction of pluripotent stem cells from mouse embryonic or adult fibroblasts by introducing four factors, Oct3/4, Sox2, c-Myc, and Klf4, under ES cell culture conditions. Unexpectedly, Nanog was dispensable. These cells, which we designated iPS (induced pluripotent stem) cells, exhibit the morphology and growth properties of ES cells and express ES cell marker genes...
August 25, 2006: Cell
Xiao-Hua Zhang, Martin Morad
Derivation of cardiomyocyte cell lines from human fibroblasts (induced pluripotent stem cells, iPSCs) has made it possible not only to investigate the electrophysiological and Ca(2+) signaling properties of these cells, but also to determine the altered electrophysiological and Ca(2+)-signaling profiles of such cells lines derived from patients expressing mutation-inducing pathologies. This approach has the potential of generating in vitro human models of cardiovascular diseases where cellular pathology can be investigated in detail and possibly specific pharmacotherapy developed...
March 2016: Cell Calcium
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