30 results on '"David Y. Chiang"'
Search Results
2. Targeting the Microtubule EB1-CLASP2 Complex Modulates Na(V)1.5 at Intercalated Discs
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Mischa Klerk, Calum A. MacRae, Marta Pérez-Hernández, Elisabeth M. Lodder, Paul W. Burridge, Christiaan C. Veerman, Isabella Mengarelli, Richard Redon, Vincent Portero, Gerard A Marchal, Carol Ann Remme, Mario Delmar, Franck Potet, Flavien Charpentier, Kaomei Guan, Svitlana Podliesna, Nuo Yu, Carlos G. Vanoye, Alfred Lewis George, David Y. Chiang, Niels Galjart, Simona Casini, Mariam Jouni, Arie O. Verkerk, Eli Rothenberg, Connie R. Bezzina, Cardiology, Graduate School, ACS - Heart failure & arrhythmias, Human Genetics, Medical Biology, APH - Methodology, and Cell biology
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biology ,Physiology ,Chemistry ,cardiac ,Sodium channel ,Myocardium ,Fluorescence recovery after photobleaching ,Nav1.5 ,biology.organism_classification ,electrophysiology ,zebrafish ,Article ,Sodium Channels ,Cell biology ,Microtubule ,Cytoplasm ,GSK-3 ,biology.protein ,microscopy ,Cardiology and Cardiovascular Medicine ,Induced pluripotent stem cell ,Zebrafish ,myocyte, cardiac ,myocyte ,microtubule - Abstract
Rationale: Loss-of-function of the cardiac sodium channel Na V 1.5 causes conduction slowing and arrhythmias. Na V 1.5 is differentially distributed within subcellular domains of cardiomyocytes, with sodium current ( I Na ) being enriched at the intercalated discs (ID). Various pathophysiological conditions associated with lethal arrhythmias display ID-specific I Na reduction, but the mechanisms underlying microdomain-specific targeting of Na V 1.5 remain largely unknown. Objective: To investigate the role of the microtubule plus-end tracking proteins EB1 (end-binding protein 1) and CLASP2 (cytoplasmic linker associated protein 2) in mediating Na V 1.5 trafficking and subcellular distribution in cardiomyocytes. Methods and Results: EB1 overexpression in human-induced pluripotent stem cell-derived cardiomyocytes resulted in enhanced whole-cell I Na , increased action potential upstroke velocity ( V max ), and enhanced Na V 1.5 localization at the plasma membrane as detected by multicolor stochastic optical reconstruction microscopy. Fluorescence recovery after photobleaching experiments in HEK293A cells demonstrated that EB1 overexpression promoted Na V 1.5 forward trafficking. Knockout of MAPRE1 in human induced pluripotent stem cell-derived cardiomyocytes led to reduced whole-cell I Na , decreased V max , and action potential duration (APD) prolongation. Similarly, acute knockout of the MAPRE1 homolog in zebrafish ( mapre1b ) resulted in decreased ventricular conduction velocity and V max as well as increased APD. Stochastic optical reconstruction microscopy imaging and macropatch I Na measurements showed that subacute treatment (2–3 hours) with SB216763 (SB2), a GSK3β (glycogen synthase kinase 3β) inhibitor known to modulate CLASP2-EB1 interaction, reduced GSK3β localization and increased Na V 1.5 and I Na preferentially at the ID region of wild-type murine ventricular cardiomyocytes. By contrast, SB2 did not affect whole cell I Na or Na V 1.5 localization in cardiomyocytes from Clasp2 -deficient mice, uncovering the crucial role of CLASP2 in SB2-mediated modulation of Na V 1.5 at the ID. Conclusions: Our findings demonstrate the modulatory effect of the microtubule plus-end tracking protein EB1 on Na V 1.5 trafficking and function, and identify the EB1-CLASP2 complex as a target for preferential modulation of I Na within the ID region of cardiomyocytes.
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- 2021
3. BS-513-02 GENOME-WIDE ASSOCIATION ANALYSES IDENTIFY NOVEL BRUGADA SYNDROME RISK LOCI AND HIGHLIGHT A NEW MECHANISM OF SODIUM CHANNEL REGULATION IN DISEASE SUSCEPTIBILITY
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Julien Barc, Rafik Tadros, Charlotte Glinge, David Y. Chiang, Mariam jouni, Floriane Simonet, Michael Tanck, Alfred L. George, Calum A. MacRae, Paul Burridge, Christian Dina, Vincent Probst, Arthur A.M. Wilde, Jean-Jacques Schott, Richard Redon, and Connie R. Bezzina
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Physiology (medical) ,Cardiology and Cardiovascular Medicine - Published
- 2022
4. Abstract 16184: Lamin A Deficiency Leads to Electrophysiological and Nuclear Abnormalities Reminiscent of Atrial Cardiomyopathy in Zebrafish
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Kenshi Hayashi, Aparna Mahadevan, Wandi Zhu, Calum A. MacRae, Tuomas Kiviniemi, E. Buys, Micah L Burch, Wei Dai, Jing Liu, Ryota Teramoto, Manu Beerens, Ashmita Kc, David Y. Chiang, and Masahiro Satoh
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Pathology ,medicine.medical_specialty ,biology ,business.industry ,Cardiomyopathy ,Atrial fibrillation ,Gene mutation ,medicine.disease ,biology.organism_classification ,LMNA ,Physiology (medical) ,Cardiac conduction ,Medicine ,Cardiology and Cardiovascular Medicine ,business ,Gene ,Zebrafish ,Lamin - Abstract
Introduction: Mutations in the lamin A/C ( LMNA ) gene have been causally linked to atrial arrhythmias and cardiac conduction disease (CCD) in young adults. However, the mechanism by which the laminopathy leads to perturbed cardiac electrophysiology has not been fully elucidated. Hypothesis: We hypothesize that protein-truncating variants in LMNA will impair the mechano-protection force in the nuclear envelope and will lead to early-onset cardiomyocyte degeneration and CCD. Methods: In a multi-regional registry of early-onset CCD and atrial fibrillation in Japan, we performed whole-exome DNA sequencing of 23 probands. Using CRISPR/Cas9, we generated indels of candidate gene homologues in zebrafish and characterized cardiac physiology using optical mapping technology and immunohistochemistry. Results: Among all probands, our study revealed four rare nonsense variants in the nuclear protein-coding genes. We focused on a LMNA protein-truncating variant, c.339dupT (p.K114X fsX1), and created a variant in the zebrafish lmna that produced a similar truncation. Lmna -/- zebrafish larvae showed shortened atrial action potential duration (APD) (msec.) compared to wild-type controls (162 ± 19 vs 227 ± 79, p lmna -/- embryos exhibited prolonged APD (399 ± 51 vs 322 ± 47, p lmna -/- zebrafish displayed significantly decreased cell numbers and smaller cell size compared to those of controls, which in turn developed into abnormal nuclear structures in adult. Conclusions: These findings suggest that lamin A is a prerequisite for proper atrial cardiomyocyte morphology in embryonic zebrafish, and is indispensable for correct cardiac electrophysiology and -conduction.
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- 2020
5. Loss of SPEG Inhibitory Phosphorylation of Ryanodine Receptor Type-2 Promotes Atrial Fibrillation
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Ann P. Quick, Issam Abu-Taha, Dobromir Dobrev, Eleonora Corradini, Xander H.T. Wehrens, Stephan E. Lehnart, Katherina M. Alsina, Oliver Moore, Dennis Uhlenkamp, Hannah M. Campbell, Sören Brandenburg, Tarah A. Word, Markus Kamler, David Y. Chiang, Satadru K. Lahiri, Brian Martin, Albert J. R. Heck, Mohit Hulsurkar, Carlos F. Kramm, Hui-Bin Liu, Sub Biomol.Mass Spectrometry & Proteom., Afd Biomol.Mass Spect. and Proteomics, and Biomolecular Mass Spectrometry and Proteomics
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Male ,medicine.medical_specialty ,Diastole ,Medizin ,chemistry.chemical_element ,Muscle Proteins ,030204 cardiovascular system & hematology ,Calcium ,Protein Serine-Threonine Kinases ,Inhibitory postsynaptic potential ,Ryanodine receptor 2 ,Article ,03 medical and health sciences ,Mice ,0302 clinical medicine ,Physiology (medical) ,Internal medicine ,Atrial Fibrillation ,Medicine ,Animals ,Humans ,Calcium Signaling ,Phosphorylation ,Myosin-Light-Chain Kinase ,030304 developmental biology ,Mice, Knockout ,0303 health sciences ,business.industry ,Ryanodine receptor ,Endoplasmic reticulum ,Myocardium ,Atrial fibrillation ,Ryanodine Receptor Calcium Release Channel ,medicine.disease ,musculoskeletal system ,Sarcoplasmic Reticulum ,Endocrinology ,chemistry ,cardiovascular system ,Female ,Cardiology and Cardiovascular Medicine ,business - Abstract
Background: Enhanced diastolic calcium (Ca 2+ ) release through ryanodine receptor type-2 (RyR2) has been implicated in atrial fibrillation (AF) promotion. Diastolic sarcoplasmic reticulum Ca 2+ leak is caused by increased RyR2 phosphorylation by PKA (protein kinase A) or CaMKII (Ca 2+ /calmodulin-dependent kinase-II) phosphorylation, or less dephosphorylation by protein phosphatases. However, considerable controversy remains regarding the molecular mechanisms underlying altered RyR2 function in AF. We thus aimed to determine the role of SPEG (striated muscle preferentially expressed protein kinase), a novel regulator of RyR2 phosphorylation, in AF pathogenesis. Methods: Western blotting was performed with right atrial biopsies from patients with paroxysmal AF. SPEG atrial knockout mice were generated using adeno-associated virus 9. In mice, AF inducibility was determined using intracardiac programmed electric stimulation, and diastolic Ca 2+ leak in atrial cardiomyocytes was assessed using confocal Ca 2+ imaging. Phosphoproteomics studies and Western blotting were used to measure RyR2 phosphorylation. To test the effects of RyR2-S2367 phosphorylation, knockin mice with an inactivated S2367 phosphorylation site (S2367A) and a constitutively activated S2367 residue (S2367D) were generated by using CRISPR-Cas9. Results: Western blotting revealed decreased SPEG protein levels in atrial biopsies from patients with paroxysmal AF in comparison with patients in sinus rhythm. SPEG atrial-specific knockout mice exhibited increased susceptibility to pacing-induced AF by programmed electric stimulation and enhanced Ca 2+ spark frequency in atrial cardiomyocytes with Ca 2+ imaging, establishing a causal role for decreased SPEG in AF pathogenesis. Phosphoproteomics in hearts from SPEG cardiomyocyte knockout mice identified RyR2-S2367 as a novel kinase substrate of SPEG. Western blotting demonstrated that RyR2-S2367 phosphorylation was also decreased in patients with paroxysmal AF. RyR2-S2367A mice exhibited an increased susceptibility to pacing-induced AF, and aberrant atrial sarcoplasmic reticulum Ca 2+ leak, as well. In contrast, RyR2-S2367D mice were resistant to pacing-induced AF. Conclusions: Unlike other kinases (PKA, CaMKII) that increase RyR2 activity, SPEG phosphorylation reduces RyR2-mediated sarcoplasmic reticulum Ca 2+ release. Reduced SPEG levels and RyR2-S2367 phosphorylation typified patients with paroxysmal AF. Studies in S2367 knockin mouse models showed a causal relationship between reduced S2367 phosphorylation and AF susceptibility. Thus, modulating SPEG activity and phosphorylation levels of the novel S2367 site on RyR2 may represent a novel target for AF treatment.
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- 2020
6. Identification of Racial Inequities in Access to Specialized Inpatient Heart Failure Care at an Academic Medical Center
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Catherine Meador, Viswatej Avutu, Emily Cetrone, Alec Petersen, Alexander B. Stone, George Huang, Rebecca Zon, Aaron J. Cohen, Aileen Wright, Jacqueline Greb, Sam A. Tanyos, Thomas Gilliland, Sheridan Reiger, David B. Duong, Alissa Cooper, An Tran, Michelle Rengarajan, Pablo Sanchez, Robert J. Glynn, Kenneth Barshop, Aaron J. Deutsch, Christine E. Ryan, Heather Burrell Ward, Molly Plovanich, Siobhan Case, Mark Ferreira, Chijioke Nze, Rose M. Kakoza, Justin Tuwatananurak, Steven M. Blum, Zachary Hermes, Hans Stabenau, Yi Lu, Elisa Walsh, Bradford Diephuis, Anish Mehta, Alexander P. Boardman, Jennifer Schulte, Daniel C. Pipilas, Laura Kolbe, Hallie Rozansky, Stephanie Lin-Beckford, Alexandra Charrow, Khameer Kidia, Matthew E. Growdon, Joshua Lang, Lindsay N. Warner, Eleni Stavrou, Caroline Wunsch, Andrew Ben Shorten, James W. Smithy, Evan Shannon, Michael Pardo, Wai-Ying Yau, Caitlin Drescher, Natalie Fedotova, Patricia Foo, Michelle Morse, Kristine Torres-Lockhart, Ramkumar V. Venkateswaran, Stephen Tsaur, Mariel Bailey, Cristina Thomas, Andrew Stergachis, Abraar Karan, Eldrin F. Lewis, Tamara Feingold-Link, Sanjay Salgado, Sungat Grewal, Mariya Kalashnikova, Kevin Ma, Devin Worster, Marisa L. Winkler, Gregory Snyder, Brian W. Powers, Stanley Jablonski, Jennifer Yeh, Joseph Loscalzo, Kaeleen Boden, Joel T. Katz, Julia Beamesderfer, Douglas Jacobs, Stephanie Rico, Nareh Marukian, Lauren Sinnenberg, Sohan Japa, Zachary Lee, Emily Murphy, Siddharth Patel, Aaron Richterman, Robert Boxer, Anna Reichardt, Wilfredo R. Matias, Christine A. Eckhardt, Jyotsna Mullur, Priscilla Wang, Cindy Y. Chang, Alexandra Bachorik, Omar Bayomy, Katherine J. Greco, Cynthia K. Hahn, Maria A Yialamas, Emilie Mitten, Diana Lopez, Michael B. Foote, Neha Limaye, Katherine C. Brooks, Erika J Haydu, Robert S. Stern, Erik Andrews, Emily Baumrin, Julia Loewenthal, Neil Shaw, Idil Kore, Melissa G. Lechner, Richard W. Joseph, Jessica S. Little, Alexis Roy, Nina Jain, Jamila Wynter, Lindsay Wahl, Scott M Knowles, Constantinos Michaelidis, Nicholas Yozamp, Laura Horton, Jordan Wengrod, Sarah Brown, Michael McLaughlin, Meghan Rudder, Ranjani Logaraj, Haley Thun, Noreen Okwara, Daniel Kellner, Lauren A. Eberly, Anastasia Vishnevetsky, Ayrenne Adams, Ian McConnell, Denis Balaban, Scott Lee, Erica Pimenta, Nicholas S. Downing, Matthew Lawlor, Sarah Royston, Anirudh Sreekrishnan, Salina Bakshi, Marina Zambrotta, Zachary E. Holcomb, Frances Wallace, Tomas Cordova, Kathryn B. Holroyd, Rafael Paez, Christina Meade, Daniel Loriaux, Devin Clark, Omar Badri, Anita Rao, Alisa A. Mueller, Shervin Tabrizi, David D. Berg, Yiannis Koullias, Ifedayo O. Kuye, Nora Becker, Daniel Kang, Herrick N Fisher, Kay Everett, Rachael Rosales, C. Nicholas Cuneo, Peter Dorschner, Abirami Natarajan, Jeffrey L. Wong, Kristin M. D’Silva, Samantha Abel, Lisa S. Rotenstein, Brendan John Guercio, Geneva DeGregorio, June-Ho Kim, Benjamin Grin, Ross England, Mattheus Ramsis, Emily C. Cleveland Manchanda, Alsina Alejandro de Feria, Daniel Yazdi, Sanjay Divakaran, Frederick D. Tsai, Haiyan Ramirez Batlle, Bram Wispelwey, Robert A. Bonacci, April Wall, Denise Pong, Idalid Franco, Michelle Nsahlai, Chase Yarbrough, Carolyn Treasure, Lachelle D. Weeks, Joseph Anaya, Benjamin Atkinson, Jennifer Goldsmith, Jessica N. Williams, Brian Hasselfeld, Ellen H. Nagami, Katie Baird, Evan Tschirhart, Berman Adam N., Jared R. Mayers, Peter Olds, Ken Lee, Scott A. Elman, Neil Kalwani, David Y. Chiang, Kipp Weiskopf, Regan H. Marsh, Jacob Mirsky, Kirsti Campbell, William Shrauner, Elizabeth Messenger, Anne G. Beckett, Marla Lipsyc, Aswin Sekar, Benjamin N. Rome, Sarah E. Earp, Nicholas P. Semenkovich, Karen Deffenbacher, Laura Phelan, Ersilia M. DeFilippis, Gordon Hildick-Smith, Amir Munir, and Peter Dunbar
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business.industry ,media_common.quotation_subject ,030204 cardiovascular system & hematology ,medicine.disease ,Racism ,Health equity ,Article ,03 medical and health sciences ,Identification (information) ,0302 clinical medicine ,Heart failure ,Hospital admission ,Medicine ,Center (algebra and category theory) ,030212 general & internal medicine ,Medical emergency ,Cardiology and Cardiovascular Medicine ,business ,media_common - Abstract
Background: Racial inequities for patients with heart failure (HF) have been widely documented. HF patients who receive cardiology care during a hospital admission have better outcomes. It is unknown whether there are differences in admission to a cardiology or general medicine service by race. This study examined the relationship between race and admission service, and its effect on 30-day readmission and mortality Methods: We performed a retrospective cohort study from September 2008 to November 2017 at a single large urban academic referral center of all patients self-referred to the emergency department and admitted to either the cardiology or general medicine service with a principal diagnosis of HF, who self-identified as white, black, or Latinx. We used multivariable generalized estimating equation models to assess the relationship between race and admission to the cardiology service. We used Cox regression to assess the association between race, admission service, and 30-day readmission and mortality. Results: Among 1967 unique patients (66.7% white, 23.6% black, and 9.7% Latinx), black and Latinx patients had lower rates of admission to the cardiology service than white patients (adjusted rate ratio, 0.91; 95% CI, 0.84–0.98, for black; adjusted rate ratio, 0.83; 95% CI, 0.72–0.97 for Latinx). Female sex and age >75 years were also independently associated with lower rates of admission to the cardiology service. Admission to the cardiology service was independently associated with decreased readmission within 30 days, independent of race. Conclusions: Black and Latinx patients were less likely to be admitted to cardiology for HF care. This inequity may, in part, drive racial inequities in HF outcomes.
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- 2019
7. SPEG (Striated Muscle Preferentially Expressed Protein Kinase) Is Essential for Cardiac Function by Regulating Junctional Membrane Complex Activity
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Ann P. Quick, Xander H.T. Wehrens, David Y. Chiang, Maha Khalid, Leonne E Philippen, David L. Beavers, Qiongling Wang, Giselle Barreto-Torres, Jordan Showell, Mark McCauley, Hannah M. Campbell, Julia O. Reynolds, Guoliang Wang, and Arjen Scholten
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0301 basic medicine ,Myosin light-chain kinase ,Physiology ,Junctional membrane complex ,HEK 293 cells ,030204 cardiovascular system & hematology ,Biology ,Cell biology ,03 medical and health sciences ,030104 developmental biology ,0302 clinical medicine ,Membrane protein ,Biochemistry ,Phosphorylation ,Myocyte ,Cardiology and Cardiovascular Medicine ,Protein kinase A ,Calcium signaling - Abstract
Rationale: Junctional membrane complexes (JMCs) in myocytes are critical microdomains, in which excitation–contraction coupling occurs. Structural and functional disruption of JMCs underlies contractile dysfunction in failing hearts. However, the role of newly identified JMC protein SPEG (striated muscle preferentially expressed protein kinase) remains unclear. Objective: To determine the role of SPEG in healthy and failing adult hearts. Methods and Results: Proteomic analysis of immunoprecipitated JMC proteins ryanodine receptor type 2 and junctophilin-2 (JPH2) followed by mass spectrometry identified the serine–threonine kinase SPEG as the only novel binding partner for both proteins. Real-time polymerase chain reaction revealed the downregulation of SPEG mRNA levels in failing human hearts. A novel cardiac myocyte-specific Speg conditional knockout (MCM- Speg fl/fl ) model revealed that adult-onset SPEG deficiency results in heart failure (HF). Calcium (Ca 2+ ) and transverse-tubule imaging of ventricular myocytes from MCM- Speg fl/fl mice post HF revealed both increased sarcoplasmic reticulum Ca 2+ spark frequency and disrupted JMC integrity. Additional studies revealed that transverse-tubule disruption precedes the development of HF development in MCM- Speg fl/fl mice. Although total JPH2 levels were unaltered, JPH2 phosphorylation levels were found to be reduced in MCM- Speg fl/fl mice, suggesting that loss of SPEG phosphorylation of JPH2 led to transverse-tubule disruption, a precursor of HF development in SPEG-deficient mice. Conclusions: The novel JMC protein SPEG is downregulated in human failing hearts. Acute loss of SPEG in mouse hearts causes JPH2 dephosphorylation and transverse-tubule loss associated with downstream Ca 2+ mishandling leading to HF. Our study suggests that SPEG could be a novel target for the treatment of HF.
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- 2017
8. DISRUPTION OF LAMIN A LEADS TO EARLY-ONSET CARDIAC CONDUCTION DYSFUNCTION IN ZEBRAFISH MODELS OF LAMINOPATHY
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Kenshi Hayashi, Manu Beerens, Yao Zu, E. Buys, Micah L Burch, Calum A. MacRae, Tuomas Kiviniemi, Ryota Teramoto, Akihiro Nomura, Aaron P. Kithcart, Masayuki Takamura, and David Y. Chiang
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congenital, hereditary, and neonatal diseases and abnormalities ,integumentary system ,biology ,Mechanism (biology) ,business.industry ,Laminopathy ,Dilated cardiomyopathy ,medicine.disease ,biology.organism_classification ,Cell biology ,LMNA ,embryonic structures ,Cardiac conduction ,medicine ,Cardiology and Cardiovascular Medicine ,business ,Zebrafish ,Lamin ,Early onset - Abstract
Mutations in the lamin A/C ( LMNA ) gene have been causally linked to dilated cardiomyopathy with conduction disease. However, the mechanism by which the laminopathy leads to electrophysiological disorders has not been fully elucidated. In a multi-regional registry of early-onset cardiac conduction
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- 2020
9. Oxidized CaMKII (Ca 2+ /Calmodulin-Dependent Protein Kinase II) Is Essential for Ventricular Arrhythmia in a Mouse Model of Duchenne Muscular Dystrophy
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Na Li, Ann P. Quick, Shuyi Cao, Guoliang Wang, Julia O. Reynolds, Qiongling Wang, David L. Beavers, George G. Rodney, Xander H.T. Wehrens, Mark E. Anderson, and David Y. Chiang
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0301 basic medicine ,mdx mouse ,medicine.medical_specialty ,Duchenne muscular dystrophy ,030204 cardiovascular system & hematology ,Ventricular tachycardia ,03 medical and health sciences ,0302 clinical medicine ,Calcium imaging ,Physiology (medical) ,Internal medicine ,Ca2+/calmodulin-dependent protein kinase ,medicine ,chemistry.chemical_classification ,Reactive oxygen species ,NADPH oxidase ,biology ,business.industry ,medicine.disease ,030104 developmental biology ,Endocrinology ,chemistry ,cardiovascular system ,biology.protein ,Cardiology and Cardiovascular Medicine ,business ,Homeostasis - Abstract
Background: Duchenne muscular dystrophy patients are prone to ventricular arrhythmias, which may be caused by abnormal calcium (Ca 2+ ) homeostasis and elevated reactive oxygen species. CaMKII (Ca 2+ /calmodulin-dependent protein kinase II) is vital for normal Ca 2+ homeostasis, but excessive CaMKII activity contributes to abnormal Ca 2+ homeostasis and arrhythmias in cardiomyocytes. Reactive oxygen species induce CaMKII to become autonomously active. We hypothesized that genetic inhibition of CaMKII oxidation (ox-CaMKII) in a mouse model of Duchenne muscular dystrophy can alleviate abnormal Ca 2+ homeostasis, thus, preventing ventricular arrhythmia. The objective of this study was to test if selective loss of ox-CaMKII affects ventricular arrhythmias in the mdx mouse model of Duchenne muscular dystrophy. Methods and Results: 5-(6)-Chloromethyl-2,7-dichlorodihydrofluorescein diacetate staining revealed increased reactive oxygen species production in ventricular myocytes isolated from mdx mice, which coincides with elevated ventricular ox-CaMKII demonstrated by Western blotting. Genetic inhibition of ox-CaMKII by knockin replacement of the regulatory domain methionines with valines (MM-VV [CaMKII M281/282V]) prevented ventricular tachycardia in mdx mice. Confocal calcium imaging of ventricular myocytes isolated from mdx :MM-VV mice revealed normalization of intracellular Ca 2+ release events compared with cardiomyocytes from mdx mice. Abnormal action potentials assessed by optical mapping in mdx mice were also alleviated by genetic inhibition of ox-CaMKII. Knockout of the NADPH oxidase regulatory subunit p47 phox normalized elevated ox-CaMKII, repaired intracellular Ca 2+ homeostasis, and rescued inducible ventricular arrhythmias in mdx mice. Conclusions: Inhibition of reactive oxygen species or ox-CaMKII protects against proarrhythmic intracellular Ca 2+ handling and prevents ventricular arrhythmia in a mouse model of Duchenne muscular dystrophy.
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- 2018
10. Rearrangement of the Protein Phosphatase 1 Interactome During Heart Failure Progression
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Katherina M. Alsina, Albert J. R. Heck, Julia O. Reynolds, Xiaolu Pan, David Y. Chiang, Satadru K. Lahiri, Larry D. Scott, Martin Fitzpatrick, Li Ni, Xander H.T. Wehrens, and Eleonora Corradini
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0301 basic medicine ,Male ,animal structures ,Time Factors ,Protein subunit ,Genetic Vectors ,macromolecular substances ,030204 cardiovascular system & hematology ,Proteomics ,Interactome ,Article ,Muscle hypertrophy ,Pathogenesis ,03 medical and health sciences ,0302 clinical medicine ,Physiology (medical) ,Protein Phosphatase 1 ,Medicine ,Animals ,Humans ,Myocytes, Cardiac ,Calcium Signaling ,Protein Interaction Maps ,RNA, Small Interfering ,Heart Failure ,Gene knockdown ,business.industry ,Endoplasmic reticulum ,Protein phosphatase 1 ,Dependovirus ,Cell biology ,Mice, Inbred C57BL ,Disease Models, Animal ,030104 developmental biology ,Disease Progression ,Female ,RNA Interference ,Cardiology and Cardiovascular Medicine ,business ,HeLa Cells ,Protein Binding - Abstract
Background: Heart failure (HF) is a complex disease with a rising prevalence despite advances in treatment. Protein phosphatase 1 (PP1) has long been implicated in HF pathogenesis, but its exact role is both unclear and controversial. Most previous studies measured only the PP1 catalytic subunit (PP1c) without investigating its diverse set of interactors, which confer localization and substrate specificity to the holoenzyme. In this study, we define the PP1 interactome in cardiac tissue and test the hypothesis that this interactome becomes rearranged during HF progression at the level of specific PP1c interactors. Methods: Mice were subjected to transverse aortic constriction and grouped on the basis of ejection fraction into sham, hypertrophy, moderate HF (ejection fraction, 30%–40%), and severe HF (ejection fraction Results: Seventy-one and 98 PP1c interactors were quantified from mouse cardiac and HeLa lysates, respectively, including many novel interactors and protein complexes. This represents the largest reproducible PP1 interactome data set ever captured from any tissue, including both primary and secondary/tertiary interactors. Nine PP1c interactors with changes in their binding to PP1c were strongly associated with HF progression, including 2 known (Ppp1r7 and Ppp1r18) and 7 novel interactors. Within the entire cardiac PP1 interactome, Ppp1r7 had the highest binding to PP1c. Cardiac-specific knockdown in mice led to cardiac dysfunction and disruption of calcium release from the sarcoplasmic reticulum. Conclusions: PP1 is best studied at the level of its interactome, which undergoes significant rearrangement during HF progression. The 9 key interactors that are associated with HF progression may represent potential targets in HF therapy. In particular, Ppp1r7 may play a central role in regulating the PP1 interactome by acting as a competitive molecular “sponge” of PP1c.
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- 2018
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11. Novel role of the protein phosphatase 1 regulatory subunit PPP1R3A in atrial fibrillation
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Barbara Langer, Samuel K. Buxton, David Y. Chiang, Mohit Hulsurkar, Dobromir Dobrev, Katherina M. Alsina, Albert J. R. Heck, Niels van der Sangen, Chunxia Yao, and Xander H.T. Wehrens
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Chemistry ,Protein subunit ,medicine ,Medizin ,Atrial fibrillation ,Protein phosphatase 1 ,Cardiology and Cardiovascular Medicine ,medicine.disease ,Molecular Biology ,Molecular biology - Published
- 2018
12. Identification of microRNA–mRNA dysregulations in paroxysmal atrial fibrillation
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Min Zhang, Niels Voigt, David Y. Chiang, Na Li, James F. Martin, Xander H.T. Wehrens, Dobromir Dobrev, Katherina M. Alsina, and Heinz Jakob
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Male ,medicine.medical_specialty ,Paroxysmal atrial fibrillation ,Medizin ,Bioinformatics ,Article ,Pathogenesis ,Internal medicine ,Atrial Fibrillation ,microRNA ,Humans ,Medicine ,RNA, Messenger ,Epigenetics ,Aged ,Messenger RNA ,business.industry ,Microarray analysis techniques ,Gene Expression Profiling ,Atrial fibrillation ,Middle Aged ,Microarray Analysis ,medicine.disease ,Gene expression profiling ,MicroRNAs ,Endocrinology ,Female ,Cardiology and Cardiovascular Medicine ,business - Abstract
The molecular mechanisms underlying the early development of atrial fibrillation (AF) remain poorly understood. Emerging evidence suggests that abnormal epigenetic modulation via microRNAs (miRNAs) might be involved in the pathogenesis of paroxysmal AF (pAF).To identify key molecular changes associated with pAF, we conducted state-of-the-art transcriptomic studies to identify the abnormal miRNA-mRNA interactions potentially driving AF development.High-quality total RNA including miRNA was isolated from atrial biopsies of age-matched and sex-matched pAF patients and control patients in sinus rhythm (SR; n=4 per group) and used for RNA-sequencing and miRNA microarray. Results were analyzed bioinformatically and validated using quantitative real-time (qRT)-PCR and 3'UTR luciferase reporter assays.113 genes and 49 miRNAs were differentially expressed (DE) in pAF versus SR patients. Gene ontology analysis revealed that most of the DE genes were involved in the "gonadotropin releasing hormone receptor pathway" and "p53 pathway". Of these DE genes, bioinformatic analyses identified 23 pairs of putative miRNA-mRNA interactions that were altered in pAF (involving 15 miRNAs and 17 mRNAs). Using qRT-PCR and 3'UTR luciferase reporter assays, the interaction between upregulation of miR-199a-5p and downregulation of FKBP5 was confirmed in samples from pAF patients.Our combined transcriptomic analysis and miRNA microarray study of atrial samples from pAF patients revealed novel pathways and miRNA-mRNA regulations that may be relevant in the development of pAF. Future studies are required to investigate the potential involvement of the gonadotropin releasing hormone receptor and p53 pathways in AF pathogenesis.
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- 2015
13. CaMKII inhibition rescues proarrhythmic phenotypes in the model of human ankyrin-B syndrome
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Peter J. Mohler, Na Li, Sean T. DeGrande, Derek Nixon, Olha M. Koval, Qiongling Wang, Mark E. Anderson, Xander H.T. Wehrens, Patrick J. Wright, Jerald W. Curran, Thomas J. Hund, David Y. Chiang, and Farshid Kashef
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Ankyrins ,medicine.medical_specialty ,Patch-Clamp Techniques ,Immunoblotting ,Ryanodine receptor 2 ,Sudden death ,Afterdepolarization ,Mice ,Physiology (medical) ,Ca2+/calmodulin-dependent protein kinase ,Internal medicine ,medicine ,Animals ,Humans ,Myocytes, Cardiac ,Ryanodine receptor ,business.industry ,Cardiac arrhythmia ,Arrhythmias, Cardiac ,Protein phosphatase 2 ,medicine.disease ,Mice, Inbred C57BL ,Disease Models, Animal ,Phenotype ,Endocrinology ,Ventricular Fibrillation ,Ventricular fibrillation ,cardiovascular system ,Calcium-Calmodulin-Dependent Protein Kinase Type 2 ,Cardiology and Cardiovascular Medicine ,business - Abstract
BACKGROUND Cardiovascular disease is a leading cause of death worldwide. Arrhythmias are associated with significant morbidity and mortality related to cardiovascular disease. Recent work illustrates that many cardiac arrhythmias are initiated by a pathologic imbalance between kinase and phosphatase activities in excitable cardiomyocytes. OBJECTIVE To test the relationship between myocyte kinase/phosphatase imbalance and cellular and whole animal arrhythmia phenotypes associated with ankyrin-B cardiac syndrome. METHODS By using a combination of biochemical, electrophysiological, and in vivo approaches, we tested the ability of calcium/calmodulin-dependent kinase (CaMKII) inhibition to rescue imbalance in kinase/phosphatase pathways associated with human ankyrin-B-associated cardiac arrhythmia. RESULTS The cardiac ryanodine receptor (RyR 2 ), a validated target of kinase/phosphatase regulation in myocytes, displays abnormal CaMKII-dependent phosphorylation (pS2814 hyperphosphorylation) in ankyrin-B +/− heart. Notably, RyR 2 dysregulation is rescued in myocytes from ankyrin-B +/− mice overexpressing a potent CaMKII-inhibitory peptide (AC3I), and aberrant RyR 2 open probability observed in ankyrin-B +/− hearts is normalized by treatment with the CaMKII inhibitor KN-93. CaMKII inhibition is sufficient to rescue abnormalities in ankyrin-B +/− myocyte electrical dysfunction including cellular afterdepolarizations, and significantly blunts whole animal cardiac arrhythmias and sudden death in response to elevated sympathetic tone. CONCLUSIONS These findings illustrate the complexity of the molecular components involved in human arrhythmia and define regulatory elements of the ankyrin-B pathway in pathophysiology. Furthermore, the findings illustrate the potential impact of CaMKII inhibition in the treatment of a congenital form of human cardiac arrhythmia.
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- 2012
14. Regulating the Regulator: Insights into the Cardiac Protein Phosphatase 1 Interactome
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Dobromir Dobrev, Xander H.T. Wehrens, David Y. Chiang, and Albert J. R. Heck
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0301 basic medicine ,Protein subunit ,Phosphatase ,Regulator ,Medizin ,macromolecular substances ,030204 cardiovascular system & hematology ,Biology ,Proteomics ,Interactome ,Article ,03 medical and health sciences ,0302 clinical medicine ,Protein Phosphatase 1 ,Atrial Fibrillation ,Protein Interaction Mapping ,Animals ,Humans ,Molecular Biology ,Heart Failure ,Kinase ,Myocardium ,Computational Biology ,Protein phosphatase 1 ,Heart ,Cell biology ,030104 developmental biology ,Cardiology and Cardiovascular Medicine ,Carrier Proteins ,Function (biology) ,Protein Binding - Abstract
Reversible phosphorylation of proteins is a delicate yet dynamic balancing act between kinases and phosphatases, the disturbance of which underlies numerous disease processes. While our understanding of protein kinases has grown tremendously over the past decades, relatively little is known regarding protein phosphatases. This may be because protein kinases are great in number and relatively specific in function, and thereby amenable to be studied in isolation, whereas protein phosphatases are much less abundant and more unspecific in their function. To achieve subcellular localization and substrate specificity, phosphatases depend on partnering with a large number of regulatory subunits, protein scaffolds and/or other interactors. This added layer of complexity presents a significant barrier to their study, but holds the key to unexplored opportunities for novel pharmacologic intervention. In this review we focus on the serine/threonine protein phosphatase type-1 (PP1), which plays an important role in cardiac physiology and pathophysiology. Although much work has been done to investigate the role of PP1 in cardiac diseases including atrial fibrillation and heart failure, most of these studies were limited to examining and manipulating the catalytic subunit(s) of PP1 without adequately considering the PP1 interactors, which give specificity to PP1’s functions. To complement these studies, three unbiased methods have been developed and applied to the mapping of the PP1 interactome: bioinformatics approaches, yeast two-hybrid screens, and affinity-purification mass spectrometry. The application of these complementary methods has the potential to generate a detailed cardiac PP1 interactome, which is an important step in identifying novel and targeted pharmacological interventions.
- Published
- 2016
15. Relation of Cardiac Dysfunction to Rhythm Abnormalities in Patients With Duchenne or Becker Muscular Dystrophies
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Hugh D. Allen, Ricardo H. Pignatelli, Yunfei Wang, Santiago O. Valdes, Timothy Lotze, David Y. Chiang, Christina Y. Miyake, and Jeffrey J. Kim
- Subjects
musculoskeletal diseases ,Cardiac function curve ,Adult ,Cardiomyopathy, Dilated ,Male ,congenital, hereditary, and neonatal diseases and abnormalities ,medicine.medical_specialty ,Adolescent ,Duchenne muscular dystrophy ,030204 cardiovascular system & hematology ,Ventricular tachycardia ,03 medical and health sciences ,Young Adult ,0302 clinical medicine ,Heart Conduction System ,Heart Rate ,Internal medicine ,Heart rate ,medicine ,Humans ,cardiovascular diseases ,Muscular dystrophy ,Child ,Retrospective Studies ,Ejection fraction ,business.industry ,Arrhythmias, Cardiac ,medicine.disease ,Muscular Dystrophy, Duchenne ,Echocardiography ,Child, Preschool ,cardiovascular system ,Cardiology ,Female ,Supraventricular tachycardia ,Electrical conduction system of the heart ,Cardiology and Cardiovascular Medicine ,business ,030217 neurology & neurosurgery ,Follow-Up Studies - Abstract
The association between systolic cardiac dysfunction and arrhythmia development in patients with Duchenne muscular dystrophy (DMD) or Becker muscular dystrophy (BMD) is generally assumed but has not been extensively studied. The purpose of this study was to describe arrhythmias in patients with DMD and BMD in the present era and determine whether arrhythmia development is associated with cardiac dysfunction. This is a single-center retrospective review of 237 Holters from 91 patients with DMD (mean = 17 ± 4 years, range 3 to 27 years) and 64 Holters from 21 patients with BMD (mean = 18 ± 7 years, range 4 to 31 years) with corresponding echocardiography. Holters were stratified by age of patient at the time of study and ejection fraction: normal (≥55%), mild (55% and ≥45%), moderate (45% and ≥30%), and severe (30%). Arrhythmias included frequent atrial and ventricular premature complexes (10/hr), couplets, and runs of supraventricular and ventricular tachycardias. Arrhythmias occurred in 44% of DMD and 57% of BMD patients and were significantly associated with decrease in cardiac function. Clinically significant arrhythmias (supraventricular tachycardia and ventricular tachycardia) occurred in 10% of all Holters obtained in patients with DMD and 25% of all Holters obtained in patients with BMD. Subgroup analysis of Holters from patients with DMD demonstrated that arrhythmias increased with decreasing ejection fraction regardless of age, but that age was also a significant predictor of arrhythmia development. In conclusion, among patients with DMD or BMD, arrhythmias increase with development of cardiac dysfunction.
- Published
- 2015
16. P304Reprogramming of the protein phosphatase 1 interactome during heart failure progression
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Xht Wehrens, Satadru K. Lahiri, Ajr Heck, Eleonora Corradini, Martin Fitzpatrick, Larry D. Scott, David Y. Chiang, Li Ni, Julia O. Reynolds, and Katherina M. Alsina
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Physiology ,Physiology (medical) ,Heart failure ,medicine ,Protein phosphatase 1 ,Biology ,Cardiology and Cardiovascular Medicine ,medicine.disease ,Interactome ,Cell biology - Published
- 2018
17. Expression and function of Kv1.1 potassium channels in human atria from patients with atrial fibrillation
- Author
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Dierk Thomas, Constanze Schmidt, Xiaobo Zhou, Mark McCauley, Na Li, Niels Voigt, David Y. Chiang, Edward Glasscock, Darlene G. Skapura, Jeffrey L. Noebels, Cristina E. Molina, Dobromir Dobrev, Xander H.T. Wehrens, and Qiang Sun
- Subjects
Male ,Cardiac function curve ,medicine.medical_specialty ,Patch-Clamp Techniques ,Physiology ,Immunoblotting ,Medizin ,Dendrotoxin ,Biology ,Real-Time Polymerase Chain Reaction ,Article ,Mice ,Fibrosis ,Physiology (medical) ,Internal medicine ,Atrial Fibrillation ,medicine ,Animals ,Humans ,Myocyte ,Myocytes, Cardiac ,Heart Atria ,Patch clamp ,Aged ,Mice, Knockout ,Reverse Transcriptase Polymerase Chain Reaction ,Atrial fibrillation ,Voltage-gated potassium channel ,Middle Aged ,medicine.disease ,Immunohistochemistry ,Potassium channel ,Mice, Inbred C57BL ,Endocrinology ,cardiovascular system ,Cardiology ,Female ,Kv1.1 Potassium Channel ,Cardiology and Cardiovascular Medicine - Abstract
Voltage-gated Kv1.1 channels encoded by the Kcna1 gene are traditionally regarded as being neural-specific with no known expression or intrinsic functional role in the heart. However, recent studies in mice reveal low-level Kv1.1 expression in heart and cardiac abnormalities associated with Kv1.1-deficiency suggesting that the channel may have a previously unrecognized cardiac role. Therefore, this study tests the hypothesis that Kv1.1 channels are associated with arrhythmogenesis and contribute to intrinsic cardiac function. In intra-atrial burst pacing experiments, Kcna1-null mice exhibited increased susceptibility to atrial fibrillation (AF). The atria of Kcna1-null mice showed minimal Kv1 family ion channel remodeling and fibrosis as measured by qRT-PCR and Masson's trichrome histology, respectively. Using RT-PCR, immunocytochemistry, and immunoblotting, KCNA1 mRNA and protein were detected in isolated mouse cardiomyocytes and human atria for the first time. Patients with chronic AF (cAF) showed no changes in KCNA1 mRNA levels relative to controls; however, they exhibited increases in atrial Kv1.1 protein levels, not seen in paroxysmal AF patients. Patch-clamp recordings of isolated human atrial myocytes revealed significant dendrotoxin-K (DTX-K)-sensitive outward current components that were significantly increased in cAF patients, reflecting a contribution by Kv1.1 channels. The concomitant increases in Kv1.1 protein and DTX-K-sensitive currents in atria of cAF patients suggest that the channel contributes to the pathological mechanisms of persistent AF. These findings provide evidence of an intrinsic cardiac role of Kv1.1 channels and indicate that they may contribute to atrial repolarization and AF susceptibility.
- Published
- 2015
18. Loss-of-Function SCN5A Mutations Associated With Sinus Node Dysfunction, Atrial Arrhythmias, and Poor Pacemaker Capture
- Author
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Melissa Domino, Xander H.T. Wehrens, Melissa Smith, Caridad M. de la Uz, Yuxin Fan, Christina Y. Miyake, David Y. Chiang, Jeffrey J. Kim, Santiago O. Valdes, and Jeffrey W. Orcutt
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Adult ,Male ,medicine.medical_specialty ,Pacemaker, Artificial ,Adolescent ,medicine.disease_cause ,Article ,Sick sinus syndrome ,NAV1.5 Voltage-Gated Sodium Channel ,Physiology (medical) ,Internal medicine ,medicine ,Humans ,Child ,Loss function ,Brugada syndrome ,Genetic testing ,Retrospective Studies ,Sick Sinus Syndrome ,Mutation ,medicine.diagnostic_test ,business.industry ,Infant, Newborn ,Infant ,Retrospective cohort study ,Arrhythmias, Cardiac ,Middle Aged ,medicine.disease ,Surgery ,medicine.anatomical_structure ,Ventricle ,Child, Preschool ,Cardiology ,Female ,Implant ,Cardiology and Cardiovascular Medicine ,business - Abstract
Background— Cardiac device implantation can be complicated by inability to adequately place leads because of significant lead capture issues. This study sought to determine whether there are genetic bases that underlie poor lead capture. Methods and Results— Retrospective review of all patients with structurally normal hearts who underwent new device implantation at Texas Children’s Hospital between 2009 and 2014 was performed. Patients with inability to capture at 10 V or a final capture threshold ≥3 V at 0.4 ms during implant were analyzed. Among a total of 136 patients (median age, 13 years; range, 3 days to 46 years), 11 patients (8.1%) who underwent dual chamber device implantation had elevated thresholds in the atria (4), ventricle (3), or both chambers (4; atrial-lead threshold, 4.7±4.3 versus 0.7±0.3 V; ventricular-lead, 3.0±3.3 versus 0.7±0.3 V). All 11 patients presented with sinus node dysfunction and 10 had atrial arrhythmias. At implant, inability to find atrial capture was seen in 4 patients. Three demonstrated intermittent complete loss of ventricular capture after implantation: 1 has recurrent syncope, 2 eventually died. Genetic testing performed in 10 demonstrated 7 patients with 6 distinct SCN5A mutations, all predicted to be severe loss-of-function mutations by bioinformatic analyses. In the remaining patients, although putative pathogenic mutations were not found, multiple SCN5A polymorphisms were identified in 2 and a desmin mutation in 1. Conclusions— This study suggests that significant capture issues at implant may be because of loss-of-function SCN5A mutations, providing new insights into SCN5A function. Recognition of this association may be critical for planning device implantation strategies and patient follow-up.
- Published
- 2015
19. Genetic Deletion of Rnd3/RhoE Results in Mouse Heart Calcium Leakage Through Upregulation of Protein Kinase A Signaling
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Xiangsheng Yang, Xander H.T. Wehrens, Tiannan Wang, Christina Y. Miyake, David Y. Chiang, Jiang Chang, Xi Lin, Qiongling Wang, Xun Ai, Qin Fu, Xiaojing Yue, and Guoliang Wang
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Male ,rho GTP-Binding Proteins ,medicine.medical_specialty ,Adrenergic receptor ,Physiology ,Biology ,Article ,Mice ,Downregulation and upregulation ,Internal medicine ,medicine ,Animals ,Myocytes, Cardiac ,Protein kinase A signaling ,Protein kinase A ,Cells, Cultured ,Mice, Knockout ,Ryanodine receptor ,Rnd3 ,Heart ,Actin cytoskeleton ,Cyclic AMP-Dependent Protein Kinases ,Rats ,Up-Regulation ,Cell biology ,Mice, Inbred C57BL ,Endocrinology ,Animals, Newborn ,Calcium ,Female ,Signal transduction ,Cardiology and Cardiovascular Medicine ,Gene Deletion ,Signal Transduction - Abstract
Rationale: Rnd3, a small Rho GTPase, is involved in the regulation of cell actin cytoskeleton dynamics, cell migration, and proliferation. The biological function of Rnd3 in the heart remains unexplored. Objective: To define the functional role of the Rnd3 gene in the animal heart and investigate the associated molecular mechanism. Methods and Results: By loss-of-function approaches, we discovered that Rnd3 is involved in calcium regulation in cardiomyocytes. Rnd3-null mice died at the embryonic stage with fetal arrhythmias. The deletion of Rnd3 resulted in severe Ca 2+ leakage through destabilized ryanodine receptor type 2 Ca 2+ release channels. We further found that downregulation of Rnd3 attenuated β 2 -adrenergic receptor lysosomal targeting and ubiquitination, which in turn resulted in the elevation of β 2 -adrenergic receptor protein levels leading to the hyperactivation of protein kinase A (PKA) signaling. The PKA activation destabilized ryanodine receptor type 2 channels. This irregular spontaneous Ca 2+ release can be curtailed by PKA inhibitor treatment. Increases in the PKA activity along with elevated cAMP levels were detected in Rnd3-null embryos, in neonatal rat cardiomyocytes, and noncardiac cell lines with Rnd3 knockdown, suggesting a general mechanism for Rnd3-mediated PKA signaling activation. β 2 -Adrenergic receptor blocker treatment reduced arrhythmia and improved cardiac function. Conclusions: Rnd3 is a novel factor involved in intracellular Ca 2+ homeostasis regulation in the heart. Deficiency of the protein induces ryanodine receptor type 2 dysfunction by a mechanism that attenuates Rnd3-mediated β 2 -adrenergic receptor ubiquitination, which leads to the activation of PKA signaling. Increased PKA signaling in turn promotes ryanodine receptor type 2 hyperphosphorylation, which contributes to arrhythmogenesis and heart failure.
- Published
- 2015
20. Loss of microRNA-106b-25 Cluster Promotes Atrial Fibrillation by Enhancing Ryanodine Receptor Type-2 Expression and Calcium Release
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Joel R. Neilson, Heinz Jakob, Na Li, Katherina M. Alsina, Xander H.T. Wehrens, David L. Beavers, James F. Martin, Dobromir Dobrev, David Y. Chiang, Niels Voigt, and Natee Kongchan
- Subjects
medicine.medical_specialty ,Time Factors ,Transcription, Genetic ,Medizin ,chemistry.chemical_element ,Action Potentials ,Down-Regulation ,Calcium ,Ryanodine receptor 2 ,Article ,Pathogenesis ,Downregulation and upregulation ,Physiology (medical) ,Internal medicine ,Atrial Fibrillation ,Medicine ,Animals ,Humans ,Calcium Signaling ,3' Untranslated Regions ,Calcium signaling ,Mice, Knockout ,business.industry ,Ryanodine receptor ,Endoplasmic reticulum ,Myocardium ,Atrial fibrillation ,Ryanodine Receptor Calcium Release Channel ,musculoskeletal system ,medicine.disease ,Up-Regulation ,Disease Models, Animal ,MicroRNAs ,Sarcoplasmic Reticulum ,Endocrinology ,chemistry ,Case-Control Studies ,Gene Knockdown Techniques ,cardiovascular system ,Cardiology and Cardiovascular Medicine ,business - Abstract
Background— Enhanced sarcoplasmic reticulum Ca 2+ -leak via ryanodine receptor type-2 (RyR2) contributes to the pathogenesis of atrial fibrillation (AF). Recent studies have shown that the level of RyR2 protein is elevated in atria of patients with paroxysmal AF, suggesting that microRNA-mediated post-transcriptional regulation of RyR2 might be an underlying mechanism. Bioinformatic analysis suggests that miR-106b and miR-93, members of the miR-106b-25 cluster, could bind to RyR2-3′-untranslated region and suppress its translation. Thus, we tested the hypothesis that loss of the miR-106b-25 cluster promotes AF via enhanced RyR2-mediated sarcoplasmic reticulum Ca 2+ -leak. Methods and Results— Quantitative real-time polymerase chain reaction showed that the levels of mature miR-106b, miR-93, and miR-25 were lower in atria of patients with paroxysmal AF when compared with patients in sinus rhythm. In vitro assay showed that miR-93 reduced RyR2-3′-untranslated region luciferase activity. Total RyR2 protein in atrial tissue of miR-106b-25 −/− mice was increased by 42% when compared with wild-type littermates but still maintained a normal subcellular distribution. Ca 2+ -spark frequency and total sarcoplasmic reticulum Ca 2+ -leak were increased in atrial myocytes of miR-106b-25 −/− mice. Telemetry ECG recordings revealed that miR-106b-25 −/− mice exhibited more frequent atrial ectopy and were also more susceptible to pacing-induced AF than wild-type littermates. Increased sarcoplasmic reticulum Ca 2+ -release and AF susceptibility in miR-106b-25 −/− mice were abolished by the RyR2 blocker K201. Conclusions— These results suggest that miR-106b-25 cluster–mediated post-transcriptional regulation of RyR2 is a potential molecular mechanism involved in paroxysmal AF pathogenesis. As such, the miR-106b-25 cluster could be a novel gene-therapy target in AF associated with enhanced RyR2 expression.
- Published
- 2014
21. Chronic Exercise
- Author
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David Y. Chiang, Na Li, and Xander H.T. Wehrens
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medicine.medical_specialty ,education.field_of_study ,business.industry ,Population ,Cardiac arrhythmia ,Atrial fibrillation ,030204 cardiovascular system & hematology ,medicine.disease ,3. Good health ,03 medical and health sciences ,0302 clinical medicine ,Internal medicine ,cardiovascular system ,medicine ,Cardiology ,In patient ,030212 general & internal medicine ,Cardiology and Cardiovascular Medicine ,education ,business - Abstract
Atrial fibrillation (AF) is the most common cardiac arrhythmia encountered in the clinical setting [(1)][1]. In the general population, the prevalence of AF increases with age, ranging from 0.5% in patients younger than 40 years to 5% in patients older than 65 years [(2)][2]. Less is known about the
- Published
- 2013
22. Emerging roles of junctophilin-2 in the heart and implications for cardiac diseases
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Xander H.T. Wehrens, David L. Beavers, David Y. Chiang, and Andrew P. Landstrom
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Cardiac function curve ,medicine.medical_specialty ,Heart Diseases ,Physiology ,Junctional membrane complex ,Biology ,Physiology (medical) ,Internal medicine ,JPH2 ,medicine ,Animals ,Humans ,Topical Review ,Excitation Contraction Coupling ,Endoplasmic reticulum ,Cardiac myocyte ,Hypertrophic cardiomyopathy ,Membrane Proteins ,Heart ,medicine.disease ,Endocrinology ,Intercellular Junctions ,Membrane protein ,Heart failure ,Calcium ,Cardiology and Cardiovascular Medicine ,Neuroscience - Abstract
Cardiomyocytes rely on a highly specialized subcellular architecture to maintain normal cardiac function. In a little over a decade, junctophilin-2 (JPH2) has become recognized as a cardiac structural protein critical in forming junctional membrane complexes (JMCs), which are subcellular domains essential for excitation–contraction coupling within the heart. While initial studies described the structure of JPH2 and its role in anchoring junctional sarcoplasmic reticulum and transverse-tubule (T-tubule) membrane invaginations, recent research has an expanded role of JPH2 in JMC structure and function. For example, JPH2 is necessary for the development of postnatal T-tubule in mammals. It is also critical for the maintenance of the complex JMC architecture and stabilization of local ion channels in mature cardiomyocytes. Loss of this function by mutations or down-regulation of protein expression has been linked to hypertrophic cardiomyopathy, arrhythmias, and progression of disease in failing hearts. In this review, we summarize current views on the roles of JPH2 within the heart and how JPH2 dysregulation may contribute to a variety of cardiac diseases.
- Published
- 2014
23. Alterations in the interactome of serine/threonine protein phosphatase type-1 in atrial fibrillation patients
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Arjen Scholten, J. Mirjam A. Damen, David L. Beavers, Nicolas Lebesgue, Niels Voigt, Katherina M. Alsina, Xander H.T. Wehrens, Dobromir Dobrev, and David Y. Chiang
- Subjects
Proteomics ,animal structures ,Phosphatase ,Medizin ,macromolecular substances ,Pharmacology ,Interactome ,label-free quantification ,Mass Spectrometry ,Serine ,Mice ,Protein Phosphatase 1 ,Atrial Fibrillation ,Medicine ,Animals ,Humans ,Myocytes, Cardiac ,cardiovascular diseases ,Threonine ,PP1 regulatory subunits ,business.industry ,Cardiac arrhythmia ,Atrial fibrillation ,Protein phosphatase 1 ,medicine.disease ,Immunohistochemistry ,3. Good health ,cardiovascular system ,Cardiology and Cardiovascular Medicine ,business - Abstract
BackgroundAtrial fibrillation (AF) is the most common sustained cardiac arrhythmia, yet current pharmacological treatments are limited. Serine/threonine protein phosphatase type-1 (PP1), a major phosphatase in the heart, consists of a catalytic subunit (PP1c) and a large set of regulatory (R)-subunits that confer localization and substrate specificity to the holoenzyme. Previous studies suggest that PP1 is dysregulated in AF, but the mechanisms are unknown.ObjectivesThe purpose of this study was to test the hypothesis that PP1 is dysregulated in paroxysmal atrial fibrillation (PAF) at the level of its R-subunits.MethodsCardiac lysates were coimmunoprecipitated with anti-PP1c antibody followed by mass spectrometry–based, quantitative profiling of associated R-subunits. Subsequently, label-free quantification (LFQ) was used to evaluate altered R-subunit–PP1c interactions in PAF patients. R-subunits with altered binding to PP1c in PAF were further studied using bioinformatics, Western blotting (WB), immunocytochemistry, and coimmunoprecipitation.ResultsA total of 135 and 78 putative PP1c interactors were captured from mouse and human cardiac lysates, respectively, including many previously unreported interactors with conserved PP1c docking motifs. Increases in binding were found between PP1c and PPP1R7, cold-shock domain protein A (CSDA), and phosphodiesterase type-5A (PDE5A) in PAF patients, with CSDA and PDE5A being novel interactors validated by bioinformatics, immunocytochemistry, and coimmunoprecipitation. WB confirmed that these increases in binding cannot be ascribed to their changes in global protein expression alone.ConclusionsSubcellular heterogeneity in PP1 activity and downstream protein phosphorylation in AF may be attributed to alterations in PP1c–R-subunit interactions, which impair PP1 targeting to proteins involved in electrical and Ca2+ remodeling. This represents a novel concept in AF pathogenesis and may provide more specific drug targets for treating AF.
- Published
- 2014
24. Impaired local regulation of ryanodine receptor type 2 by protein phosphatase 1 promotes atrial fibrillation
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Dobromir Dobrev, Na Li, Katherina M. Alsina, Darlene G. Skapura, Julia O. Reynolds, Qiongling Wang, Xander H.T. Wehrens, Guoliang Wang, Niels Voigt, Ann P. Quick, and David Y. Chiang
- Subjects
Male ,medicine.medical_specialty ,Physiology ,Phosphatase ,Medizin ,Hyperphosphorylation ,Nerve Tissue Proteins ,macromolecular substances ,Biology ,environment and public health ,Ryanodine receptor 2 ,Mice ,Physiology (medical) ,Internal medicine ,Ca2+/calmodulin-dependent protein kinase ,Protein Phosphatase 1 ,Atrial Fibrillation ,medicine ,Animals ,Protein phosphorylation ,Calcium Signaling ,Phosphorylation ,Mice, Knockout ,Ryanodine receptor ,Myocardium ,Microfilament Proteins ,Protein phosphatase 1 ,Ryanodine Receptor Calcium Release Channel ,Original Articles ,musculoskeletal system ,Mice, Mutant Strains ,Mice, Inbred C57BL ,Disease Models, Animal ,Sarcoplasmic Reticulum ,Endocrinology ,Amino Acid Substitution ,cardiovascular system ,Female ,Mutant Proteins ,Cardiology and Cardiovascular Medicine ,tissues - Abstract
Aims Altered Ca2+ handling in atrial fibrillation (AF) has been associated with dysregulated protein phosphatase 1 (PP1) and subcellular heterogeneities in protein phosphorylation, but the underlying mechanisms remain unclear. This is due to a lack of investigation into the local , rather than global, regulation of PP1 on different subcellular targets such as ryanodine receptor type 2 (RyR2), especially in AF. Methods and results We tested the hypothesis that impaired local regulation of PP1 causes RyR2 hyperphosphorylation thereby promoting AF susceptibility. To specifically disrupt PP1's local regulation of RyR2, we used the spinophilin knockout (Sp−/−) mice ( Mus musculus ) since PP1 is targeted to RyR2 via spinophilin. Without spinophilin, the interaction between PP1 and RyR2 was reduced by 64%, while RyR2 phosphorylation was increased by 43% at serine (S)2814 but unchanged at S2808. Lipid bilayer experiments revealed that single RyR2 channels isolated from Sp−/− hearts had an increased open probability. Likewise, Ca2+ spark frequency normalized to sarcoplasmic reticulum Ca2+ content was also enhanced in Sp−/− atrial myocytes, but normalized by Ca2+/calmodulin-dependent protein kinase II (CaMKII) inhibitors KN-93 and AIP and also by genetic inhibition of RyR2 S2814 phosphorylation. Finally, Sp−/− mice exhibited increased atrial ectopy and susceptibility to pacing-induced AF, both of which were also prevented by the RyR2 S2814A mutation. Conclusion PP1 regulates RyR2 locally by counteracting CaMKII phosphorylation of RyR2. Decreased local PP1 regulation of RyR2 contributes to RyR2 hyperactivity and promotes AF susceptibility. This represents a novel mechanism for subcellular modulation of calcium channels and may represent a potential drug target of AF.
- Published
- 2014
25. Ryanodine receptor-mediated calcium leak drives progressive development of an atrial fibrillation substrate in a transgenic mouse model
- Author
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Na Li, Dobromir Dobrev, Wilhelm Schmitz, Jonathan L. Respress, Niels Voigt, Qiongling Wang, Sufen Wang, Valerie K. Jordan, Sameer Ather, Darlene G. Skapura, Frank U. Müller, Frank T. Horrigan, Xander H.T. Wehrens, Stanley Nattel, Liang Sun, David Y. Chiang, and Miguel Valderrábano
- Subjects
Genetically modified mouse ,Male ,medicine.medical_specialty ,Atrial enlargement ,Transgene ,Medizin ,Mice, Transgenic ,Ryanodine receptor 2 ,Article ,Mice ,Heart Conduction System ,Physiology (medical) ,Internal medicine ,Atrial Fibrillation ,Medicine ,Animals ,Myocytes, Cardiac ,Protein kinase A ,business.industry ,Ryanodine receptor ,Endoplasmic reticulum ,Age Factors ,Atrial fibrillation ,Ryanodine Receptor Calcium Release Channel ,medicine.disease ,Mice, Inbred C57BL ,Disease Models, Animal ,Sarcoplasmic Reticulum ,Endocrinology ,Disease Progression ,Calcium ,Female ,medicine.symptom ,Cardiology and Cardiovascular Medicine ,business ,Calcium-Calmodulin-Dependent Protein Kinase Type 2 - Abstract
Background— The progression of atrial fibrillation (AF) from paroxysmal to persistent forms remains a major clinical challenge. Abnormal sarcoplasmic reticulum (SR) Ca 2+ leak via the ryanodine receptor type 2 (RyR2) has been observed as a source of ectopic activity in various AF models. However, its potential role in progression to long-lasting spontaneous AF (sAF) has never been tested. This study was designed to test the hypothesis that enhanced RyR2-mediated Ca 2+ release underlies the development of a substrate for sAF and to elucidate the underlying mechanisms. Methods and Results— CREM-IbΔC-X transgenic (CREM) mice developed age-dependent progression from spontaneous atrial ectopy to paroxysmal and eventually long-lasting AF. The development of sAF in CREM mice was preceded by enhanced diastolic Ca 2+ release, atrial enlargement, and marked conduction abnormalities. Genetic inhibition of Ca 2+ /calmodulin-dependent protein kinase II–mediated RyR2-S2814 phosphorylation in CREM mice normalized open probability of RyR2 channels and SR Ca 2+ release, delayed the development of spontaneous atrial ectopy, fully prevented sAF, suppressed atrial dilation, and forestalled atrial conduction abnormalities. Hyperactive RyR2 channels directly stimulated the Ca 2+ -dependent hypertrophic pathway nuclear factor of activated T cell/Rcan1-4, suggesting a role for the nuclear factor of activated T cell/Rcan1-4 system in the development of a substrate for long-lasting AF in CREM mice. Conclusions— RyR2-mediated SR Ca 2+ leak directly underlies the development of a substrate for sAF in CREM mice, the first demonstration of a molecular mechanism underlying AF progression and sAF substrate development in an experimental model. Our work demonstrates that the role of abnormal diastolic Ca 2+ release in AF may not be restricted to the generation of atrial ectopy but extends to the development of atrial remodeling underlying the AF substrate.
- Published
- 2014
26. Cellular and molecular mechanisms of atrial arrhythmogenesis in patients with paroxysmal atrial fibrillation
- Author
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Jordi Heijman, Matthias Karck, Niels Voigt, Qiongling Wang, David Y. Chiang, Dobromir Dobrev, Na Li, Xander H.T. Wehrens, and Stanley Nattel
- Subjects
Male ,medicine.medical_specialty ,Patch-Clamp Techniques ,Medizin ,Article ,Sodium-Calcium Exchanger ,Membrane Potentials ,Sarcoplasmic Reticulum Calcium-Transporting ATPases ,Physiology (medical) ,Calcium-binding protein ,Internal medicine ,Atrial Fibrillation ,medicine ,Humans ,Atrial Appendage ,Computer Simulation ,Myocytes, Cardiac ,Sinus rhythm ,Calcium Signaling ,Heart Atria ,Patch clamp ,Cells, Cultured ,Aged ,Calcium signaling ,Sodium-calcium exchanger ,business.industry ,Endoplasmic reticulum ,Calcium-Binding Proteins ,Models, Cardiovascular ,Arrhythmias, Cardiac ,Ryanodine Receptor Calcium Release Channel ,Atrial fibrillation ,medicine.disease ,Sarcoplasmic Reticulum ,Electrophysiology ,Endocrinology ,Case-Control Studies ,Cardiology ,Calcium ,Female ,Cardiology and Cardiovascular Medicine ,business - Abstract
Background— Electrical, structural, and Ca 2+ -handling remodeling contribute to the perpetuation/progression of atrial fibrillation (AF). Recent evidence has suggested a role for spontaneous sarcoplasmic reticulum Ca 2+ -release events in long-standing persistent AF, but the occurrence and mechanisms of sarcoplasmic reticulum Ca 2+ -release events in paroxysmal AF (pAF) are unknown. Method and Results— Right-atrial appendages from control sinus rhythm patients or patients with pAF (last episode a median of 10–20 days preoperatively) were analyzed with simultaneous measurements of [Ca 2+ ] i (fluo-3-acetoxymethyl ester) and membrane currents/action potentials (patch-clamp) in isolated atrial cardiomyocytes, and Western blot. Action potential duration, L-type Ca 2+ current, and Na + /Ca 2+ -exchange current were unaltered in pAF, indicating the absence of AF-induced electrical remodeling. In contrast, there were increases in SR Ca 2+ leak and incidence of delayed after-depolarizations in pAF. Ca 2+ -transient amplitude and sarcoplasmic reticulum Ca 2+ load (caffeine-induced Ca 2+ -transient amplitude, integrated Na + /Ca 2+ -exchange current) were larger in pAF. Ca 2+ -transient decay was faster in pAF, but the decay of caffeine-induced Ca 2+ transients was unaltered, suggesting increased SERCA2a function. In agreement, phosphorylation (inactivation) of the SERCA2a-inhibitor protein phospholamban was increased in pAF. Ryanodine receptor fractional phosphorylation was unaltered in pAF, whereas ryanodine receptor expression and single-channel open probability were increased. A novel computational model of the human atrial cardiomyocyte indicated that both ryanodine receptor dysregulation and enhanced SERCA2a activity promote increased sarcoplasmic reticulum Ca 2+ leak and sarcoplasmic reticulum Ca 2+ -release events, causing delayed after-depolarizations/triggered activity in pAF. Conclusions— Increased diastolic sarcoplasmic reticulum Ca 2+ leak and related delayed after-depolarizations/triggered activity promote cellular arrhythmogenesis in pAF patients. Biochemical, functional, and modeling studies point to a combination of increased sarcoplasmic reticulum Ca 2+ load related to phospholamban hyperphosphorylation and ryanodine receptor dysregulation as underlying mechanisms.
- Published
- 2014
27. Junctophilin-2 is necessary for T-tubule maturation during mouse heart development
- Author
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Darlene G. Skapura, Xander H.T. Wehrens, Wei Wang, Andrew P. Landstrom, Long-Sheng Song, David Y. Chiang, Julia O. Reynolds, David L. Beavers, Sayali S. Dixit, and Michael J. Ackerman
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Genetically modified mouse ,medicine.medical_specialty ,Physiology ,Junctional membrane complex ,Biology ,T-tubule ,Contractility ,Mice ,Sarcolemma ,Physiology (medical) ,JPH2 ,Internal medicine ,medicine ,Animals ,Myocytes, Cardiac ,RNA, Small Interfering ,Heart Failure ,Gene knockdown ,Endoplasmic reticulum ,Membrane Proteins ,Heart ,Original Articles ,Cell biology ,Mice, Inbred C57BL ,medicine.anatomical_structure ,Endocrinology ,Calcium ,Cardiology and Cardiovascular Medicine - Abstract
Transverse tubules (TTs) provide the basic subcellular structures that facilitate excitation-contraction (EC) coupling, the essential process that underlies normal cardiac contractility. Previous studies have shown that TTs develop within the first few weeks of life in mammals but the molecular determinants of this development have remained elusive. This study aims to elucidate the role of junctophilin-2 (JPH2), a junctional membrane complex protein, in the maturation of TTs in car- diomyocytes. Methods and results Using a novel cardiac-specific short-hairpin-RNA-mediated JPH2 knockdown mouse model (Mus musculus; aMHC- shJPH2), we assessed the effects of the loss of JPH2 on the maturation of the ventricular TT structure. Between embryonic day (E) 10.5 and postnatal day (P) 10, JPH2 mRNA and protein levels were reduced by .70% inaMHC-shJPH2 mice. At P8 and P10, knockdown of JPH2 significantly inhibited the maturation of TTs, while expression levels of other genes impli- cated in TT development remained mostly unchanged. At the same time, intracellular Ca 2+ handling was disrupted in ventricular myocytes fromaMHC- shJPH2 mice, which developed heart failure by P10 marked by reduced ejection frac- tion, ventricular dilation, and premature death. In contrast, JPH2 transgenic mice exhibited accelerated TT maturation by P8. Conclusion Our findings suggest that JPH2 is necessary for TT maturation during postnatal cardiac development in mice. In particular, JPH2 may be critical in anchoring the invaginating sarcolemma to the sarcoplasmic reticulum, thereby enabling the maturation of the TT network.
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- 2013
28. Impaired local regulation of ryanodine receptor type-2 by protein phosphatase 1 promotes atrial fibrillation
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Na Li, Ann P. Quick, Guoliang Wang, Qiongling Wang, Darlene G. Skapura, Xander H.T. Wehrens, and David Y. Chiang
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medicine.medical_specialty ,Calmodulin ,biology ,Ryanodine receptor ,business.industry ,Phosphatase ,Protein phosphatase 1 ,musculoskeletal system ,Ryanodine receptor 2 ,Endocrinology ,Ca2+/calmodulin-dependent protein kinase ,Internal medicine ,cardiovascular system ,medicine ,biology.protein ,Phosphorylation ,Cardiology and Cardiovascular Medicine ,business ,Protein kinase A ,tissues - Abstract
Purpose: Atrial fibrillation (AF) is the most common cardiac arrhythmia with a growing prevalence yet current pharmaceutical treatments are ineffective. Previous studies suggest that protein phosphatase 1 (PP1) is dysregulated globally in AF patients but its local regulation on key Ca2+-handling proteins such as ryanodine receptor type-2 (RyR2) is not known. In this study we hypothesize that decreased PP1 regulation of RyR2 promotes AF through increasing Ca2+/calmodulin-dependent protein kinase II (CaMKII) phosphorylation of RyR2. Methods: To study the local regulation of RyR2 by PP1, we used spinophilin knockout mice (KO), since PP1 targets RyR2 via spinophilin. The interaction between RyR2 and PP1 was measured using co-immunoprecipitation while RyR2 phosphorylation level was quantified using Western blot. RyR2 activity was determined by measuring 1) single RyR2 channel activity in a lipid bilayer system and 2) Ca2+ sparks frequency in atrial myocytes loaded with Fluo4-AM. Baseline cardiac characteristics were determined using echocardiography and histological staining while AF inducibility was assessed by intracardiac electrophysiology study. Results: The interaction of PP1 with RyR2 was reduced by 55% in the KO hearts compared to WT (P
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- 2013
29. GW25-e5168 Impaired Post-Transcriptional Regulation of RyR2 by microRNA-106b-25 Cluster Promotes Atrial Fibrillation
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Na Li, James F. Martin, Dobromir Dobrev, Xander H.T. Wehrens, David Y. Chiang, and Niels Voigt
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medicine.medical_specialty ,Ryanodine receptor ,business.industry ,Endoplasmic reticulum ,Medizin ,Atrial fibrillation ,musculoskeletal system ,medicine.disease ,Ryanodine receptor 2 ,Pathogenesis ,Internal medicine ,microRNA ,cardiovascular system ,medicine ,Cardiology ,cardiovascular diseases ,business ,Cardiology and Cardiovascular Medicine ,Post-transcriptional regulation - Abstract
Atrial fibrillation (AF) is the most common sustained arrhythmia yet current pharmacological treatments are only moderately effective. Enhanced sarcoplasmic reticulum (SR) Ca2+ leak via ryanodine receptor type-2 (RyR2) contributes to AF pathogenesis and preliminary data in atrial samples from
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30. SEVERE LOSS-OF-FUNCTION SCN5A MUTATIONS ASSOCIATED WITH SINUS NODE DYSFUNCTION, ATRIAL ARRHYTHMIAS, AND POOR PACEMAKER CAPTURE
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Christina Y. Miyake, Caridad M. de la Uz, David Y. Chiang, Jeffrey J. Kim, Yuxin Fan, and Santiago O. Valdes
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medicine.medical_specialty ,congenital, hereditary, and neonatal diseases and abnormalities ,business.industry ,Node (networking) ,Atrial arrhythmias ,medicine.anatomical_structure ,Internal medicine ,medicine ,Cardiology ,cardiovascular system ,cardiovascular diseases ,Cardiology and Cardiovascular Medicine ,business ,Loss function ,Sinus (anatomy) - Full Text
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