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Junctophilin

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https://www.readbyqxmd.com/read/29440728/highly-variable-contractile-performance-correlates-with-myocyte-content-in-trabeculae-from-failing-human-hearts
#1
Michelle L Munro, Xin Shen, Marie Ward, Peter N Ruygrok, David J Crossman, Christian Soeller
Heart failure (HF) is defined by compromised contractile function and is associated with changes in excitation-contraction (EC) coupling and cardiomyocyte organisation. Tissue level changes often include fibrosis, while changes within cardiomyocytes often affect structures critical to EC coupling, including the ryanodine receptor (RyR), the associated protein junctophilin-2 (JPH2) and the transverse tubular system architecture. Using a novel approach, we aimed to directly correlate the influence of structural alterations with force development in ventricular trabeculae from failing human hearts...
February 13, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29368397/l-arginine-ingestion-inhibits-eccentric-contraction-induced-proteolysis-and-force-deficit-via-s-nitrosylation-of-calpain
#2
Keita Kanzaki, Daiki Watanabe, Chihiro Aibara, Yuki Kawakami, Takashi Yamada, Yoshitaka Takahashi, Masanobu Wada
It has been shown that calpains are involved in the proteolysis of muscle proteins that occurs with eccentric contraction (ECC) and that exogenously applied nitric oxide decreases the calpain-mediated proteolysis. The aim of this study was to examine the effects of ingestion of l-arginine (ARG), a nitric oxide precursor, on ECC-related calpain activation. In the first and second experiments, male Wistar rats were given ARG in water for 7 days starting from 3 days before the ECC protocol (average ingestion, ~600 mg kg-body wt-1  day-1 )...
January 2018: Physiological Reports
https://www.readbyqxmd.com/read/29320748/true-molecular-scale-visualization-of-variable-clustering-properties-of-ryanodine-receptors
#3
Isuru Jayasinghe, Alexander H Clowsley, Ruisheng Lin, Tobias Lutz, Carl Harrison, Ellen Green, David Baddeley, Lorenzo Di Michele, Christian Soeller
Signaling nanodomains rely on spatial organization of proteins to allow controlled intracellular signaling. Examples include calcium release sites of cardiomyocytes where ryanodine receptors (RyRs) are clustered with their molecular partners. Localization microscopy has been crucial to visualizing these nanodomains but has been limited by brightness of markers, restricting the resolution and quantification of individual proteins clustered within. Harnessing the remarkable localization precision of DNA-PAINT (<10 nm), we visualized punctate labeling within these nanodomains, confirmed as single RyRs...
January 9, 2018: Cell Reports
https://www.readbyqxmd.com/read/29208631/the-drosophila-junctophilin-gene-is-functionally-equivalent-to-its-four-mammalian-counterparts-and-is-a-modifier-of-a-huntingtin-poly-q-expansion-and-the-notch-pathway
#4
Eduardo Calpena, Víctor López Del Amo, Mouli Chakraborty, Beatriz Llamusí, Rubén Artero, Carmen Espinós, Máximo I Galindo
Members of the Junctophilin (JPH) protein family have emerged as key actors in all excitable cells, with crucial implications for human pathophysiology. In mammals, this family consists of four members (JPH1-JPH4) that are differentially expressed throughout excitable cells. The analysis of knockout mice lacking JPH subtypes has demonstrated their essential contribution to physiological functions in skeletal and cardiac muscles and in neurons. Moreover, mutations in the human JPH2 gene are associated with hypertrophic and dilated cardiomyopathies; mutations in JPH3 are responsible for the neurodegenerative Huntington's disease-like-2 (HDL2), whereas JPH1 acts as a genetic modifier in Charcot-Marie-Tooth 2K peripheral neuropathy...
January 17, 2018: Disease Models & Mechanisms
https://www.readbyqxmd.com/read/29066237/huntington-s-disease-like-2-with-an-expansion-mutation-of-the-junctophilin-3-gene-first-reported-case-from-botswana
#5
C Ocampo, R Daimari, A A Oyekunle
Huntington's disease-like 2 (HDL2) is a rare autosomal dominant progressive neurodegenerative disorder commonly seen in adults. It was first described in a large African-American family in the United States. HDL2 clinically resembles Huntington's disease (HD) and causes adult-onset relentlessly progressive movement, emotional and cognitive dysfunction. Onset is usually in the fourth decade with slow progression to death. We present a 47-year-old male Botswana native, with a four-year-history of chorea, slurred speech, mood instability, cognitive impairment and weight loss...
January 2018: Journal of Clinical Neuroscience: Official Journal of the Neurosurgical Society of Australasia
https://www.readbyqxmd.com/read/29055091/functional-interaction-of-junctophilin-2-with-small-conductance-ca-2-activated-potassium-channel-subtype-2-sk2-in-mouse-cardiac-myocytes
#6
H K Fan, T X Luo, W D Zhao, Y H Mu, Y Yang, W J Guo, H Y Tu, Q Zhang
AIM: Junctophilins (JPs), a protein family of the junctional membrane complex, maintain the close conjunction between cell surface and intracellular membranes in striate muscle cells mediating the crosstalk between extracellular Ca2+ entry and intracellular Ca2+ release. The small-conductance Ca2+ -activated K+ channels are activated by the intracellular calcium and play an essential role in the cardiac action potential profile. Molecular mechanisms of regulation of the SK channels are still uncertain...
March 2018: Acta Physiologica
https://www.readbyqxmd.com/read/29045568/loss-of-protein-kinase-novel-1-pkn1-is-associated-with-mild-systolic-and-diastolic-contractile-dysfunction-increased-phospholamban-thr17-phosphorylation-and-exacerbated-ischaemia-reperfusion-injury
#7
Asvi A Francois, Kofo Obasanjo-Blackshire, James E Clark, Andrii Boguslavskyi, Mark R Holt, Peter J Parker, Michael S Marber, Richard J Heads
Aims: PKN1 is a stress-responsive protein kinase acting downstream of small GTP-binding proteins of the Rho/Rac family. The aim was to determine its role in endogenous cardioprotection. Methods and results: Hearts from PKN1 knockout (KO) or wild type (WT) littermate control mice were perfused in Langendorff mode and subjected to global ischaemia and reperfusion (I/R). Myocardial infarct size was doubled in PKN1 KO hearts compared to WT hearts. PKN1 was basally phosphorylated on the activation loop Thr778 PDK1 target site which was unchanged during I/R...
January 1, 2018: Cardiovascular Research
https://www.readbyqxmd.com/read/28763026/genome-wide-analysis-reveals-extensive-changes-in-lncrnas-during-skeletal-muscle-development-in-hu-sheep
#8
Caifang Ren, Mingtian Deng, Yixuan Fan, Hua Yang, Guomin Zhang, Xu Feng, Fengzhe Li, Dan Wang, Feng Wang, Yanli Zhang
As an important type of noncoding RNA molecules, long non-coding RNAs (lncRNAs) act as versatile players in various biological processes. However, little is known about lncRNA regulators during sheep muscle growth. To explore functional lncRNAs during sheep muscle growth, we systematically investigated lncRNAs using strand-specific Ribo-Zero RNA sequencing at three key developmental stages in Hu sheep. A total of 6924 lncRNAs were obtained, and the differentially expressed lncRNAs and genes were screened from (control vs...
August 1, 2017: Genes
https://www.readbyqxmd.com/read/28706255/mitsugumin-29-regulates-t-tubule-architecture-in-the-failing-heart
#9
Robert N Correll, Jeffrey M Lynch, Tobias G Schips, Vikram Prasad, Allen J York, Michelle A Sargent, Didier X P Brochet, Jianjie Ma, Jeffery D Molkentin
Transverse tubules (t-tubules) are uniquely-adapted membrane invaginations in cardiac myocytes that facilitate the synchronous release of Ca(2+) from internal stores and subsequent myofilament contraction, although these structures become disorganized and rarefied in heart failure. We previously observed that mitsugumin 29 (Mg29), an important t-tubule organizing protein in skeletal muscle, was induced in the mouse heart for the first time during dilated cardiomyopathy with heart failure. Here we generated cardiac-specific transgenic mice expressing Mg29 to model this observed induction in the failing heart...
July 13, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28656064/epigenomic-and-functional-characterization-of-junctophilin-3-jph3-as-a-novel-tumor-suppressor-being-frequently-inactivated-by-promoter-cpg-methylation-in-digestive-cancers
#10
Xiaotong Hu, Yeye Kuang, Lili Li, Haimei Tang, Qinglan Shi, Xingsheng Shu, Yanjiao Zhang, Francis Kl Chan, Qian Tao, Chao He
Junctophilin (JPH) proteins stabilize junctional membrane complexes between plasma membrane and endoplasmic reticulum, also implicated in some human diseases. JPH3 mutations are linked to Huntington's disease-like 2 syndrome. Through epigenomic study of a colon cancer cell line pair (HCT116 and DKO), we identified JPH3 as a methylated novel tumor suppressor gene (TSG) candidate at 16q24. We further studied its epigenetic alterations and functions in digestive tumorigenesis. JPH3 expression at the RNA level was found to be frequently silenced or reduced in colorectal and gastric cancers due to its promoter CpG methylation, which is associated with tumor progression and poor survival of digestive cancer patients...
2017: Theranostics
https://www.readbyqxmd.com/read/28566298/colchicine-depolymerizes-microtubules-increases-junctophilin-2-and-improves-right-ventricular-function-in-experimental-pulmonary-arterial-hypertension
#11
Kurt W Prins, Lian Tian, Danchen Wu, Thenappan Thenappan, Joseph M Metzger, Stephen L Archer
BACKGROUND: Pulmonary arterial hypertension (PAH) is a lethal disease characterized by obstructive pulmonary vascular remodeling and right ventricular (RV) dysfunction. Although RV function predicts outcomes in PAH, mechanisms of RV dysfunction are poorly understood, and RV-targeted therapies are lacking. We hypothesized that in PAH, abnormal microtubular structure in RV cardiomyocytes impairs RV function by reducing junctophilin-2 (JPH2) expression, resulting in t-tubule derangements...
May 31, 2017: Journal of the American Heart Association
https://www.readbyqxmd.com/read/28473402/post-myocardial-infarction-t-tubules-form-enlarged-branched-structures-with-dysregulation-of-junctophilin-2-and-bridging-integrator-1-bin-1
#12
Christian Pinali, Nadim Malik, J Bernard Davenport, Laurence J Allan, Lucy Murfitt, Mohammad M Iqbal, Mark R Boyett, Elizabeth J Wright, Rachel Walker, Yu Zhang, Halina Dobryznski, Cathy M Holt, Ashraf Kitmitto
BACKGROUND: Heart failure is a common secondary complication following a myocardial infarction (MI), characterized by impaired cardiac contraction and t-tubule (t-t) loss. However, post-MI nano-scale morphological changes to the remaining t-ts are poorly understood. METHOD AND RESULTS: We utilized a porcine model of MI, using a nonlethal microembolization method to generate controlled microinfarcts. Using serial block face scanning electron microscopy, we report that post-MI, after mild left-ventricular dysfunction has developed, t-ts are not only lost in the peri-infarct region, but also the remnant t-ts form enlarged, highly branched disordered structures, containing a dense intricate inner membrane...
May 4, 2017: Journal of the American Heart Association
https://www.readbyqxmd.com/read/28447290/regulation-of-cardiomyocyte-t-tubular-structure-opportunities-for-therapy
#13
REVIEW
Ornella Manfra, Michael Frisk, William E Louch
PURPOSE OF REVIEW: Membrane invaginations called t-tubules play an integral role in triggering cardiomyocyte contraction, and their disruption during diseases such as heart failure critically impairs cardiac performance. In this review, we outline the growing understanding of the malleability of t-tubule structure and function, and highlight emerging t-tubule regulators which may be exploited for novel therapies. RECENT FINDINGS: New technologies are revealing the nanometer scale organization of t-tubules, and their functional junctions with the sarcoplasmic reticulum called dyads, which generate Ca2+ sparks...
June 2017: Current Heart Failure Reports
https://www.readbyqxmd.com/read/28393127/novel-junctophilin-2-mutation-a405s-is-associated-with-basal-septal-hypertrophy-and-diastolic-dysfunction
#14
Ann P Quick, Andrew P Landstrom, Qiongling Wang, David L Beavers, Julia O Reynolds, Giselle Barreto-Torres, Viet Tran, Jordan Showell, Leonne E Philippen, Shaine A Morris, Darlene Skapura, J Martijn Bos, Steen E Pedersen, Robia G Pautler, Michael J Ackerman, Xander H T Wehrens
BACKGROUND: Hypertrophic cardiomyopathy (HCM), defined as asymmetric left ventricular hypertrophy, is a leading cause of cardiac death in the young. Perturbations in calcium (Ca(2+)) handling proteins have been implicated in the pathogenesis of HCM. JPH2-encoded junctophilin 2 is a major component of the junctional membrane complex, the subcellular microdomain involved in excitation-contraction coupling. We hypothesized that a novel JPH2 mutation identified in patients with HCM is causally linked to HCM, and alters intracellular Ca(2+) signaling in a pro-hypertrophic manner...
February 2017: JACC. Basic to Translational Science
https://www.readbyqxmd.com/read/28356340/analysis-of-cardiac-myocyte-maturation-using-casaav-a-platform-for-rapid-dissection-of-cardiac-myocyte-gene-function-in-vivo
#15
REVIEW
Yuxuan Guo, Nathan J VanDusen, Lina Zhang, Weiliang Gu, Isha Sethi, Silvia Guatimosim, Qing Ma, Blake D Jardin, Yulan Ai, Donghui Zhang, Biyi Chen, Ang Guo, Guo-Cheng Yuan, Long-Sheng Song, William T Pu
RATIONALE: Loss-of-function studies in cardiac myocytes (CMs) are currently limited by the need for appropriate conditional knockout alleles. The factors that regulate CM maturation are poorly understood. Previous studies on CM maturation have been confounded by heart dysfunction caused by whole organ gene inactivation. OBJECTIVE: To develop a new technical platform to rapidly characterize cell-autonomous gene function in postnatal murine CMs and apply it to identify genes that regulate transverse tubules (T-tubules), a hallmark of mature CMs...
June 9, 2017: Circulation Research
https://www.readbyqxmd.com/read/28062939/early-transverse-tubule-development-begins-in-utero-in-the-sheep-heart
#16
Michelle L Munro, Christian Soeller
The ventricular cardiomyocytes of adult mammals contain invaginations of the plasma membrane known as transverse (t)-tubules. These regular structures are essential for the synchronisation of excitation-contraction (EC) coupling throughout the cell, which is a vital process for cardiac function. T-tubules form a close association with the sarcoplasmic reticulum (SR) to form junctions, where several key proteins involved in EC coupling are localised, including the SR calcium release channels-the ryanodine receptors (RyR)...
December 2016: Journal of Muscle Research and Cell Motility
https://www.readbyqxmd.com/read/27979982/role-of-calpain-in-eccentric-contraction-induced-proteolysis-of-ca-2-regulatory-proteins-and-force-depression-in-rat-fast-twitch-skeletal-muscle
#17
Keita Kanzaki, Daiki Watanabe, Mai Kuratani, Takashi Yamada, Satoshi Matsunaga, Masanobu Wada
The aim of this study was to examine the in vivo effects of eccentric contraction (ECC) on calpain-dependent proteolysis of Ca2+ -regulatory proteins and force production in fast-twitch skeletal muscles. Rat extensor digitorum longus muscles were exposed to 200 repeated ECC in situ and excised immediately [recovery 0 (REC0)] or 3 days [recovery 3 (REC3)] after cessation of ECC. Calpain inhibitor (CI)-treated rats were intraperitoneally injected with MDL-28170 before ECC and during REC3. Tetanic force was markedly reduced at REC0 and remained reduced at REC3...
February 1, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/27909078/a-nanoscale-view-of-junctophilin-2-and-ryanodine-receptors
#18
(no author information available yet)
No abstract text is available yet for this article.
December 1, 2016: Journal of Cell Science
https://www.readbyqxmd.com/read/27802169/junctophilin-2-in-the-nanoscale-organisation-and-functional-signalling-of-ryanodine-receptor-clusters-in-cardiomyocytes
#19
Michelle L Munro, Isuru D Jayasinghe, Qiongling Wang, Ann Quick, Wei Wang, David Baddeley, Xander H T Wehrens, Christian Soeller
Signalling nanodomains requiring close contact between the plasma membrane and internal compartments, known as 'junctions', are fast communication hubs within excitable cells such as neurones and muscle. Here, we have examined two transgenic murine models probing the role of junctophilin-2, a membrane-tethering protein crucial for the formation and molecular organisation of sub-microscopic junctions in ventricular muscle cells of the heart. Quantitative single-molecule localisation microscopy showed that junctions in animals producing above-normal levels of junctophilin-2 were enlarged, allowing the re-organisation of the primary functional protein within it, the ryanodine receptor (RyR; in this paper, we use RyR to refer to the myocardial isoform RyR2)...
December 1, 2016: Journal of Cell Science
https://www.readbyqxmd.com/read/27789286/effects-of-induced-na-ca-2-exchanger-overexpression-on-the-spatial-distribution-of-l-type-ca-2-channels-and-junctophilin-2-in-pressure-overloaded-hearts
#20
Yoshihiro Ujihara, Satoshi Mohri, Yuki Katanosaka
The Na(+)/Ca(2+) exchanger 1 (NCX1) is an essential Ca(2+) efflux system in cardiomyocytes. Although NCX1 is distributed throughout the sarcolemma, a subpopulation of NCX1 is localized to transverse (T)-tubules. There is growing evidence that T-tubule disorganization is a causal event that shifts the transition from hypertrophy to heart failure (HF). However, the detailed molecular mechanisms have not been clarified. Previously, we showed that induced NCX1 expression in pressure-overloaded hearts attenuates defective excitation-contraction coupling and HF progression...
November 25, 2016: Biochemical and Biophysical Research Communications
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