scholarly journals Dual Functional States of R406W-Desmin Assembly Complexes Cause Cardiomyopathy With Severe Intercalated Disc Derangement in Humans and in Knock-In Mice

Circulation ◽  
2020 ◽  
Vol 142 (22) ◽  
pp. 2155-2171
Author(s):  
Harald Herrmann ◽  
Eva Cabet ◽  
Nicolas R. Chevalier ◽  
Julia Moosmann ◽  
Dorothea Schultheis ◽  
...  
Keyword(s):  
Connexin 43 ◽  
Molecular Mechanisms ◽  
Cell Transfection ◽  
Intercalated Disc ◽  
Dual Functional ◽  
Intercalated Discs ◽  
Cardiac Phenotype ◽  
Functional States ◽  
Explanted Heart

Background: Mutations in the human desmin gene cause myopathies and cardiomyopathies. This study aimed to elucidate molecular mechanisms initiated by the heterozygous R406W-desmin mutation in the development of a severe and early-onset cardiac phenotype. Methods: We report an adolescent patient who underwent cardiac transplantation as a result of restrictive cardiomyopathy caused by a heterozygous R406W-desmin mutation. Sections of the explanted heart were analyzed with antibodies specific to 406W-desmin and to intercalated disc proteins. Effects of the R406W mutation on the molecular properties of desmin were addressed by cell transfection and in vitro assembly experiments. To prove the genuine deleterious effect of the mutation on heart tissue, we further generated and analyzed R405W-desmin knock-in mice harboring the orthologous form of the human R406W-desmin. Results: Microscopic analysis of the explanted heart revealed desmin aggregates and the absence of desmin filaments at intercalated discs. Structural changes within intercalated discs were revealed by the abnormal organization of desmoplakin, plectin, N-cadherin, and connexin-43. Next-generation sequencing confirmed the DES variant c.1216C>T (p.R406W) as the sole disease-causing mutation. Cell transfection studies disclosed a dual behavior of R406W-desmin with both its integration into the endogenous intermediate filament system and segregation into protein aggregates. In vitro, R406W-desmin formed unusually thick filaments that organized into complex filament aggregates and fibrillar sheets. In contrast, assembly of equimolar mixtures of mutant and wild-type desmin generated chimeric filaments of seemingly normal morphology but with occasional prominent irregularities. Heterozygous and homozygous R405W-desmin knock-in mice develop both a myopathy and a cardiomyopathy. In particular, the main histopathologic results from the patient are recapitulated in the hearts from R405W-desmin knock-in mice of both genotypes. Moreover, whereas heterozygous knock-in mice have a normal life span, homozygous animals die at 3 months of age because of a smooth muscle-related gastrointestinal phenotype. Conclusions: We demonstrate that R406W-desmin provokes its severe cardiotoxic potential by a novel pathomechanism, where the concurrent dual functional states of mutant desmin assembly complexes underlie the uncoupling of desmin filaments from intercalated discs and their structural disorganization.

Gap junctions–guards of excitability

2015 ◽  
Vol 43 (3) ◽  
pp. 508-512 ◽  
Author(s):  
Line Waring Stroemlund ◽  
Christa Funch Jensen ◽  
Klaus Qvortrup ◽  
Mario Delmar ◽  
Morten Schak Nielsen
Keyword(s):  
Sodium Channel ◽  
Crucial Role ◽  
Connexin 43 ◽  
Current Evidence ◽  
Intercalated Disc ◽  
Intercalated Discs ◽  
Cardiac Sodium Channel ◽  
Junctional Protein ◽  
Gap Junctional

Cardiomyocytes are connected by mechanical and electrical junctions located at the intercalated discs (IDs). Although these structures have long been known, it is becoming increasingly clear that their components interact. This review describes the involvement of the ID in electrical disturbances of the heart and focuses on the role of the gap junctional protein connexin 43 (Cx43). Current evidence shows that Cx43 plays a crucial role in organizing microtubules at the intercalated disc and thereby regulating the trafficking of the cardiac sodium channel NaV1.5 to the membrane.

Abstract 181: Myozap Deficiency Promotes Adverse Remodeling And Cardiomyopathy In Response To Biomechanical Stress

2014 ◽  
Vol 115 (suppl_1) ◽  
Author(s):  
Ashraf Y Rangrez ◽  
Derk Frank ◽  
Reza Poyanmehr ◽  
Alexander Bernt ◽  
Norbert Frey
Keyword(s):  
Heart Failure ◽  
Body Weight ◽  
Connexin 43 ◽  
Left Ventricular ◽  
Transverse Aortic Constriction ◽  
Aortic Constriction ◽  
Protein Aggregate ◽  
Biomechanical Stress ◽  
Cardiac Phenotype

Background: Myozap is a new addition to the list of intercalated disc (ID) proteins, which we previously identified using a bioinformatics screen. In vitro characterization of Myozap revealed that it activates Rho-dependent SRF signaling. Moreover, cardiac restricted overexpression of Myozap in mice resulted in protein aggregate-associated cardiomyopathy, whereas, knockdown of its ortholog in Zebrafish led to severe contractile dysfunction and cardiomyopathy. The objective of the current study was to elucidate the cardiac consequences of targeted deletion of Myozap in mice. Methods and Results: We generated a Myozap null mutant (MZP-ko) by global deletion of Myozap in mice. Unchallenged MZP-ko mice did not exhibit a baseline cardiac phenotype. However, upon biomechanical stress due to TAC (transverse aortic constriction), deficiency for Myozap led to accelerated cardiac hypertrophy (significant increases in the heart to body weight, left ventricular to body weight ratios) and fibrosis, accompanied by “super”-induction of the hypertrophic gene program (ANF/BNP). Moreover, MZP-ko mice revealed a severe reduction of fractional shortening and signs heart failure (increased lung/body weights) as well as a markedly increased mortality in response to TAC). Additional molecular data exhibited a significant decrease in the levels of native and phosphorylated Connexin 43 after transverse aortic constriction (TAC) in MZP-ko mice compared to wildtype animals. Finally, we observed a downregulation of dysbindin, a novel interaction partner of Myozap and known inducer of ERK1/2 signaling in TAC operated MZP-ko mice. Consistently, activation of ERK1/2 in response to TAC was blunted compared to wild-type littermates. Conclusions: We here show that myozap deficiency in vivo leads to a maladaptative response to increased biomechanical stress associated with cardiomyopathy, heart failure and cardiac death. Mechanistically, this phenotype can at least in part be explained by the interruption of the interaction between myozap and dysbindin with subsequent loss of ERK1/2 activation. Taken into a larger perspective, our data imply an essential role of the ID and its associated proteins in cardiac remodeling.

Abstract 18420: Myozap-deficiency Inhibits SRF Signaling and Causes Severe Cardiomyopathy in Response to Pathological Biomechanical Stress in vivo

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Ashraf Y Rangrez ◽  
Derk Frank ◽  
Reza Poyanmehr ◽  
Alexander Bernt ◽  
Matthias Eden ◽  
...  
Keyword(s):  
Heart Failure ◽  
Cardiac Hypertrophy ◽  
Connexin 43 ◽  
Target Genes ◽  
Clinical Signs ◽  
Structural Defects ◽  
Intercalated Disc ◽  
Biomechanical Stress ◽  
Cardiac Phenotype

Background: We recently showed that the intercalated disc (ID) protein Myozap activates Rho-dependent SRF signaling both in vitro, and in vivo. Conversely, knockdown of its ortholog in Zebrafish led to severe contractile dysfunction and cardiomyopathy. Methods and Results: We generated a Myozap null mutant (MZP-ko) by global deletion of Myozap in mice. The absence of Myozap caused neither structural defects nor a baseline cardiac phenotype and led only to mild cardiac hypertrophy upon aging. Of note, induction of SRF target genes and the activation of SRF per se were markedly inhibited in MZP-ko mice. Nevertheless, biomechanical stress induced by transverse aortic constriction (TAC) triggered an excessive increase in cardiac hypertrophy (43% or 36% increased heart wt:body wt or LV wt:body wt ratios, p<0.001), an increased cell surface area, as well as accelerated fibrosis, followed by “super”- induction of the hypertrophic gene program (ANF/BNP). Moreover, MZP-ko mice revealed a severe reduction of fractional shortening (average %FS for MZP-ko 14.5% compared to 33.5% for wild-type littermates, p<0.001) and clinical signs of heart failure (54% increase in lung/body weights, p<0.001) which also caused a profound increase in mortality in response to TAC. Furthermore, expression of other ID proteins like N-Cadherin, Desmoplakin and Connexin 43 was found significantly altered upon pressure overload in MZP-ko mice. Finally, we observed a downregulation of Dysbindin, a novel interaction partner of Myozap and known inducer of ERK1/2 signaling in TAC operated MZP-ko mice. Consistently, activation of ERK1/2 was blunted in MZP-ko mice after TAC. Conclusions: We here show that myozap deficiency in vivo inhibits SRF- and ERK1/2-signaling leading to a maladaptative response to increased biomechanical stress, followed by cardiomyopathy, heart failure and cardiac death. Moreover, myozap deficiency severely altered the expression of its direct ID interaction partners such as Dysbindin and Desmoplakin. In a broader perspective, our data identify signaling at the level of the intercalated disc as a critical component of cardiac remodeling.

scholarly journals iASPP, a previously unidentified regulator of desmosomes, prevents arrhythmogenic right ventricular cardiomyopathy (ARVC)-induced sudden death

2015 ◽  
Vol 112 (9) ◽  
pp. E973-E981 ◽  
Author(s):  
Mario Notari ◽  
Ying Hu ◽  
Gopinath Sutendra ◽  
Zinaida Dedeić ◽  
Min Lu ◽  
...  
Keyword(s):  
Right Ventricular ◽  
Molecular Mechanisms ◽  
Arrhythmogenic Right Ventricular Cardiomyopathy ◽  
Spontaneous Mutation ◽  
Ventricular Cardiomyopathy ◽  
Intercalated Discs ◽  
Frequent Mutations ◽  
Filament Networks

Desmosomes are anchoring junctions that exist in cells that endure physical stress such as cardiac myocytes. The importance of desmosomes in maintaining the homeostasis of the myocardium is underscored by frequent mutations of desmosome components found in human patients and animal models. Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a phenotype caused by mutations in desmosomal components in ∼50% of patients, however, the causes in the remaining 50% of patients still remain unknown. A deficiency of inhibitor of apoptosis-stimulating protein of p53 (iASPP), an evolutionarily conserved inhibitor of p53, caused by spontaneous mutation recently has been associated with a lethal autosomal recessive cardiomyopathy in Poll Hereford calves and Wa3 mice. However, the molecular mechanisms that mediate this putative function of iASPP are completely unknown. Here, we show that iASPP is expressed at intercalated discs in human and mouse postmitotic cardiomyocytes. iASPP interacts with desmoplakin and desmin in cardiomyocytes to maintain the integrity of desmosomes and intermediate filament networks in vitro and in vivo. iASPP deficiency specifically induces right ventricular dilatation in mouse embryos at embryonic day 16.5. iASPP-deficient mice with exon 8 deletion (Ppp1r13lΔ8/Δ8) die of sudden cardiac death, displaying features of ARVC. Intercalated discs in cardiomyocytes from four of six human ARVC cases show reduced or loss of iASPP. ARVC-derived desmoplakin mutants DSP-1-V30M and DSP-1-S299R exhibit weaker binding to iASPP. These data demonstrate that by interacting with desmoplakin and desmin, iASPP is an important regulator of desmosomal function both in vitro and in vivo. This newly identified property of iASPP may provide new molecular insight into the pathogenesis of ARVC.

High resolution mapping of nucleic acid containing complexes in vitro and in situ

1996 ◽  
Vol 54 ◽  
pp. 48-49
Author(s):  
D. P. Bazett-Jones ◽  
M. J. Hendzel
Keyword(s):  
Nucleic Acid ◽  
High Resolution ◽  
Transcription Initiation ◽  
Molecular Mechanisms ◽  
Heavy Atom ◽  
Regulation Of Transcription ◽  
High Exposure ◽  
Resolution Mapping ◽  
Tata Sequence

Structural analysis of combinations of nucleosomes and transcription factors on promoter and enhancer elements is necessary in order to understand the molecular mechanisms responsible for the regulation of transcription initiation. Such complexes are often not amenable to study by high resolution crystallographic techniques. We have been applying electron spectroscopic imaging (ESI) to specific problems in molecular biology related to transcription regulation. There are several advantages that this technique offers in studies of nucleoprotein complexes. First, an intermediate level of spatial resolution can be achieved because heavy atom contrast agents are not necessary. Second, mass and stoichiometric relationships of protein and nucleic acid can be estimated by phosphorus detection, an element in much higher proportions in nucleic acid than protein. Third, wrapping or bending of the DNA by the protein constituents can be observed by phosphorus mapping of the complexes. Even when ESI is used with high exposure of electrons to the specimen, important macromolecular information may be provided. For example, an image of the TATA binding protein (TBP) bound to DNA is shown in the Figure (top panel). It can be seen that the protein distorts the DNA away from itself and much of its mass sits off the DNA helix axis. Moreover, phosphorus and mass estimates demonstrate whether one or two TBP molecules interact with this particular promoter TATA sequence.

The research of the molecular mechanisms of endothelial dysfunction in vitro

2019 ◽  
Vol XIV (1) ◽  
Author(s):  
R.E. Kalinin ◽  
I.A. Suchkov ◽  
N.V. Korotkova ◽  
N.D. Mzhavanadze
Keyword(s):  
Endothelial Dysfunction ◽  
Molecular Mechanisms

Natural products from the traditional Moroccan pharmacopoeia: A potential lead for the prevention and treatment of COVID-19

2020 ◽  
Vol 11 (SPL1) ◽  
pp. 1278-1285
Author(s):  
Mohamed Yafout ◽  
Amine Ousaid ◽  
Ibrahim Sbai El Otmani ◽  
Youssef Khayati ◽  
Amal Ait Haj Said
Keyword(s):  
Medicinal Plants ◽  
Plant Extracts ◽  
Molecular Mechanisms ◽  
Scientific Literature ◽  
Treatment Protocol ◽  
World Health ◽  
The World ◽  
Health Organization ◽  
Promising Source

The new SARS-CoV-2 belonging to the coronaviruses family has caused a pandemic affecting millions of people around the world. This pandemic has been declared by the World Health Organization as an international public health emergency. Although several clinical trials involving a large number of drugs are currently underway, no treatment protocol for COVID-19 has been officially approved so far. Here we demonstrate through a search in the scientific literature that the traditional Moroccan pharmacopoeia, which includes more than 500 medicinal plants, is a fascinating and promising source for the research of natural molecules active against SARS-CoV-2. Multiple in-silico and in-vitro studies showed that some of the medicinal plants used by Moroccans for centuries possess inhibitory activity against SARS-CoV or SARS-CoV-2. These inhibitory activities are achieved through the different molecular mechanisms of virus penetration and replication, or indirectly through stimulation of immunity. Thus, the potential of plants, plant extracts and molecules derived from plants that are traditionally used in Morocco and have activity against SARS-CoV-2, could be explored in the search for a preventive or curative treatment against COVID-19. Furthermore, safe plants or plant extracts that are proven to stimulate immunity could be officially recommended by governments as nutritional supplements.

Therapeutic Application of Diacylglycerol Oil for Obesity: Serotonin Hypothesis

2012 ◽  
Vol 2 (1) ◽  
pp. 1 ◽  
Author(s):  
Hidekatsu Yanai ◽  
Hiroshi Yoshida ◽  
Yuji Hirowatari ◽  
Norio Tada
Keyword(s):  
Energy Expenditure ◽  
Molecular Mechanisms ◽  
Uncoupling Protein ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Serotonin Release ◽  
Intestinal Cell ◽  
Therapeutic Application ◽  
Postprandial Triglyceride

Characteristics for the serum lipid abnormalities in the obesity/metabolic syndrome are elevated fasting, postprandial triglyceride (TG), and decreased high-density lipoprotein-cholesterol (HDL-C). Diacylglycerol (DAG) oil ingestion has been reported to ameliorate postprandial hyperlipidemia and prevent obesity by increasing energy expenditure, due to the intestinal physiochemical dynamics that differ from triacylglycerol (TAG). Our study demonstrated that DAG suppresses postprandial increase in TG-rich lipoprotein, very low-density lipoprotein (VLDL), and insulin, as compared with TAG in young, healthy individuals. Interestingly, our study also presented that DAG significantly increases plasma serotonin, which is mostly present in the intestine, and mediates thermogenesis, proposing a possible mechanism for a postprandial increase in energy expenditure by DAG. Our other study demonstrated that DAG suppresses postprandial increase in TG, VLDL-C, and remnant-like particle-cholesterol, in comparison with TAG in an apolipoprotein C-II deficient subject, suggesting that DAG suppresses postprandial TG-rich lipoprotein independently of lipoprotein lipase. Further, to understand the molecular mechanisms for DAG-mediated increase in serotonin and energy expenditure, we studied the effects of 1-monoacylglycerol and 2-monoacylglycerol, distinct digestive products of DAG and TAG, respectively, on serotonin release from the Caco-2 cells, the human intestinal cell line. We also studied effects of 1- and 2-monoacylglycerol, and serotonin on the expression of mRNA associated with β-oxidation, fatty acids metabolism, and thermogenesis, in the Caco-2 cells. 1-monoacylglycerol significantly increased serotonin release from the Caco-2 cells, compared with 2-monoacylglycerol by approximately 40%. The expression of mRNA of acyl-CoA oxidase (ACO), fatty acid translocase (FAT), and uncoupling protein-2 (UCP-2), was significantly higher in 1-MOG-treated Caco-2 cells, than 2-MOG-treated cells. The expression of mRNA of ACO, medium-chain acyl-CoA dehydrogenase, FAT, and UCP-2, was significantly elevated in serotonin-treated Caco-2 cells, compared to cells incubated without serotonin. In conclusion, our clinical and in vitro studies suggested a possible therapeutic application of DAG for obesity, and obesity-related metabolic disorders.Key words: Diacylglycerol, intestine, obesity, serotonin, thermogenesis

Flavonoids as P-gp Inhibitors: A Systematic Review of SARs

2019 ◽  
Vol 26 (25) ◽  
pp. 4799-4831 ◽  
Author(s):  
Jiahua Cui ◽  
Xiaoyang Liu ◽  
Larry M.C. Chow
Keyword(s):  
Molecular Mechanisms ◽  
Metastatic Cancer ◽  
Drug Candidates ◽  
Chemical Structures ◽  
Transporter Family ◽  
Promising Area ◽  
New Generation ◽  
Nontoxic Inhibitors

P-glycoprotein, also known as ABCB1 in the ABC transporter family, confers the simultaneous resistance of metastatic cancer cells towards various anticancer drugs with different targets and diverse chemical structures. The exploration of safe and specific inhibitors of this pump has always been the pursuit of scientists for the past four decades. Naturally occurring flavonoids as benzopyrone derivatives were recognized as a class of nontoxic inhibitors of P-gp. The recent advent of synthetic flavonoid dimer FD18, as a potent P-gp modulator in reversing multidrug resistance both in vitro and in vivo, specifically targeted the pseudodimeric structure of the drug transporter and represented a new generation of inhibitors with high transporter binding affinity and low toxicity. This review concerned the recent updates on the structure-activity relationships of flavonoids as P-gp inhibitors, the molecular mechanisms of their action and their ability to overcome P-gp-mediated MDR in preclinical studies. It had crucial implications on the discovery of new drug candidates that modulated the efflux of ABC transporters and also provided some clues for the future development in this promising area.

Targeting PPARalpha in Alzheimer's Disease

2018 ◽  
Vol 15 (4) ◽  
pp. 345-354 ◽  
Author(s):  
Barbara D'Orio ◽  
Anna Fracassi ◽  
Maria Paola Cerù ◽  
Sandra Moreno
Keyword(s):  
Oxidative Stress ◽  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Molecular Mechanisms ◽  
Redox Homeostasis ◽  
Antioxidant Response ◽  
Peroxisome Proliferator ◽  
Prevailing Paradigm

Background: The molecular mechanisms underlying Alzheimer's disease (AD) are yet to be fully elucidated. The so-called “amyloid cascade hypothesis” has long been the prevailing paradigm for causation of disease, and is today being revisited in relation to other pathogenic pathways, such as oxidative stress, neuroinflammation and energy dysmetabolism. The peroxisome proliferator-activated receptors (PPARs) are expressed in the central nervous system (CNS) and regulate many physiological processes, such as energy metabolism, neurotransmission, redox homeostasis, autophagy and cell cycle. Among the three isotypes (α, β/δ, γ), PPARγ role is the most extensively studied, while information on α and β/δ are still scanty. However, recent in vitro and in vivo evidence point to PPARα as a promising therapeutic target in AD. Conclusion: This review provides an update on this topic, focussing on the effects of natural or synthetic agonists in modulating pathogenetic mechanisms at AD onset and during its progression. Ligandactivated PPARα inihibits amyloidogenic pathway, Tau hyperphosphorylation and neuroinflammation. Concomitantly, the receptor elicits an enzymatic antioxidant response to oxidative stress, ameliorates glucose and lipid dysmetabolism, and stimulates autophagy.

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