scholarly journals Myofilament Glycation in Diabetes Reduces Contractility by Inhibiting Tropomyosin Movement, is Rescued by cMyBPC Domains

2021 ◽  
Author(s):  
Maria Papadaki ◽  
Theerachat Kampaengsri ◽  
Samantha K Barrick ◽  
Stuart A. Campbell ◽  
Samantha P Harris ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Calcium Sensitivity ◽  
Myosin Binding Protein ◽  
Myosin Binding Protein C ◽  
Developing Heart ◽  
Calcium Desensitization ◽  
Promising Therapeutic Target ◽  
Patients With Diabetes ◽  
Experimental Findings

Diabetes doubles the risk of developing heart failure (HF). As the prevalence of diabetes grows, so will HF unless the mechanisms connecting these diseases can be identified. Methylglyoxal (MG) is a glycolysis by-product that forms irreversible modifications on lysine and arginine, called glycation. We previously found that myofilament MG glycation causes sarcomere contractile dysfunction and is increased in patients with diabetes and HF. The aim of this study was to discover the molecular mechanisms by which MG glycation of myofilament proteins cause sarcomere dysfunction and to identify therapeutic avenues to compensate. In humans with type 2 diabetes without HF, we found increased glycation of sarcomeric actin compared to non-diabetics and it correlated with decreased calcium sensitivity. Depressed calcium sensitivity is pathogenic for HF, therefore myofilament glycation represents a promising therapeutic target to inhibit the development of HF in diabetics. To identify possible therapeutic targets, we further defined the molecular actions of myofilament glycation. Skinned myocytes exposed to 100 uM MG exhibited decreased calcium sensitivity, maximal calcium-activated force, and crossbridge kinetics. Replicating MG's functional affects using a computer simulation of sarcomere function predicted simultaneous decreases in tropomyosin's blocked-to-closed rate transition and crossbridge duty cycle were consistent with all experimental findings. Stopped-flow experiments and ATPase activity confirmed MG decreased the blocked-to-closed transition rate. Currently, no therapeutics target tropomyosin, so as proof-of-principal, we used a n-terminal peptide of myosin-binding protein C, previously shown to alter tropomyosin's position on actin. C0C2 completely rescued MG-induced calcium desensitization, suggesting a possible treatment for diabetic HF.

scholarly journals Diabetic Endothelial Cells Differentiated From Patient iPSCs Show Dysregulated Glycine Homeostasis and Senescence Associated Phenotypes

2021 ◽  
Vol 9 ◽  
Author(s):  
Liping Su ◽  
Xiaocen Kong ◽  
Sze Jie Loo ◽  
Yu Gao ◽  
Jean-Paul Kovalik ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Endothelial Dysfunction ◽  
Pluripotent Stem Cells ◽  
Molecular Mechanisms ◽  
Cell Transfer ◽  
Angiogenic Potential ◽  
Patients With Diabetes ◽  
Induced Pluripotent

Induced pluripotent stem cells derived cells (iPSCs) not only can be used for personalized cell transfer therapy, but also can be used for modeling diseases for drug screening and discovery in vitro. Although prior studies have characterized the function of rodent iPSCs derived endothelial cells (ECs) in diabetes or metabolic syndrome, feature phenotypes are largely unknown in hiPSC-ECs from patients with diabetes. Here, we used hiPSC lines from patients with type 2 diabetes mellitus (T2DM) and differentiated them into ECs (dia-hiPSC-ECs). We found that dia-hiPSC-ECs had disrupted glycine homeostasis, increased senescence, and impaired mitochondrial function and angiogenic potential as compared with healthy hiPSC-ECs. These signature phenotypes will be helpful to establish dia-hiPSC-ECs as models of endothelial dysfunction for understanding molecular mechanisms of disease and for identifying and testing new targets for the treatment of endothelial dysfunction in diabetes.

scholarly journals Fast skeletal myosin-binding protein-C regulates fast skeletal muscle contraction

2021 ◽  
Vol 118 (17) ◽  
pp. e2003596118
Author(s):  
Taejeong Song ◽  
James W. McNamara ◽  
Weikang Ma ◽  
Maicon Landim-Vieira ◽  
Kyoung Hwan Lee ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein C ◽  
Binding Protein ◽  
Calcium Sensitivity ◽  
Fast Skeletal Muscle ◽  
Myosin Binding Protein ◽  
Myosin Binding Protein C ◽  
Skeletal Myosin ◽  
Myosin Binding ◽  
Edl Muscle

Fast skeletal myosin-binding protein-C (fMyBP-C) is one of three MyBP-C paralogs and is predominantly expressed in fast skeletal muscle. Mutations in the gene that encodes fMyBP-C, MYBPC2, are associated with distal arthrogryposis, while loss of fMyBP-C protein is associated with diseased muscle. However, the functional and structural roles of fMyBP-C in skeletal muscle remain unclear. To address this gap, we generated a homozygous fMyBP-C knockout mouse (C2−/−) and characterized it both in vivo and in vitro compared to wild-type mice. Ablation of fMyBP-C was benign in terms of muscle weight, fiber type, cross-sectional area, and sarcomere ultrastructure. However, grip strength and plantar flexor muscle strength were significantly decreased in C2−/− mice. Peak isometric tetanic force and isotonic speed of contraction were significantly reduced in isolated extensor digitorum longus (EDL) from C2−/− mice. Small-angle X-ray diffraction of C2−/− EDL muscle showed significantly increased equatorial intensity ratio during contraction, indicating a greater shift of myosin heads toward actin, while MLL4 layer line intensity was decreased at rest, indicating less ordered myosin heads. Interfilament lattice spacing increased significantly in C2−/− EDL muscle. Consistent with these findings, we observed a significant reduction of steady-state isometric force during Ca2+-activation, decreased myofilament calcium sensitivity, and sinusoidal stiffness in skinned EDL muscle fibers from C2−/− mice. Finally, C2−/− muscles displayed disruption of inflammatory and regenerative pathways, along with increased muscle damage upon mechanical overload. Together, our data suggest that fMyBP-C is essential for maximal speed and force of contraction, sarcomere integrity, and calcium sensitivity in fast-twitch muscle.

scholarly journals Cannabinoid Type-2 Receptor Agonist, JWH133 May Be a Possible Candidate for Targeting Infection, Inflammation, and Immunity in COVID-19

Immuno ◽  
2021 ◽  
Vol 1 (3) ◽  
pp. 285-304
Author(s):  
Niraj Kumar Jha ◽  
Charu Sharma ◽  
Mohamed Fizur Nagoor Meeran ◽  
Saurabh Kumar Jha ◽  
Vivek Dhar Dwivedi ◽  
...  
Keyword(s):  
Immune Modulation ◽  
Molecular Mechanisms ◽  
Inflammatory Responses ◽  
Endocannabinoid System ◽  
Cb2 Receptor ◽  
Promising Therapeutic Target ◽  
Safety Studies ◽  
Anti Inflammatory ◽  
Preclinical And Clinical Studies

The COVID-19 pandemic, caused by SARS-CoV-2, is a deadly disease affecting millions due to the non-availability of drugs and vaccines. The majority of COVID-19 drugs have been repurposed based on antiviral, immunomodulatory, and antibiotic potential. The pathogenesis and advanced complications with infection involve the immune-inflammatory cascade. Therefore, a therapeutic strategy could reduce infectivity, inflammation, and immune modulation. In recent years, modulating the endocannabinoid system, particularly activation of the cannabinoid type 2 (CB2) receptor is a promising therapeutic target for modulation of immune-inflammatory responses. JWH133, a selective, full functional agonist of the CB2 receptor, has been extensively studied for its potent anti-inflammatory, antiviral, and immunomodulatory properties. JWH133 modulates numerous signaling pathways and inhibits inflammatory mediators, including cytokines, chemokines, adhesion molecules, prostanoids, and eicosanoids. In this study, we propose that JWH133 could be a promising candidate for targeting infection, immunity, and inflammation in COVID-19, due to its pharmacological and molecular mechanisms in numerous preclinical efficacy and safety studies, along with its immunomodulatory, anti-inflammatory, organoprotective, and antiviral properties. Thus, JWH133 should be investigated in preclinical and clinical studies for its potential as an agent or adjuvant with other agents for its effect on viremia, infectivity, immune modulation, resolution of inflammation, reduction in severity, and progression of complications in COVID-19. JWH133 is devoid of psychotropic effects due to CB2 receptor selectivity, has negligible toxicity, good bioavailability and druggable properties, including pharmacokinetic and physicochemical effects. We believe that JWH133 could be a promising drug and may inspire further studies for an evidence-based approach against COVID-19.

scholarly journals Protein kinase A changes calcium sensitivity but not crossbridge kinetics in human cardiac myofibrils

2011 ◽  
Vol 301 (1) ◽  
pp. H138-H146 ◽  
Author(s):  
John S. Walker ◽  
Lori A. Walker ◽  
Ken Margulies ◽  
Peter Buttrick ◽  
Pieter de Tombe
Keyword(s):  
Calcium Concentration ◽  
Troponin I ◽  
Calcium Sensitivity ◽  
Sarcomeric Proteins ◽  
Tension Development ◽  
Myosin Binding Protein ◽  
Myosin Binding Protein C ◽  
Crossbridge Kinetics ◽  
Myosin Binding ◽  
The Relationship

We investigated the effect of PKA treatment (1 U/ml) on the mechanical properties of isolated human cardiac myofibrils. PKA treatment was associated with significant incorporation of radiolabeled phosphate into several sarcomeric proteins including troponin I and myosin binding protein C and was also associated with a right shift in the tension-pCa relation (ΔpCa50 = 0.2 ± 0.1). PKA treatment also caused right shifts in the pCa dependence of the rate of tension development, tension redevelopment, and the linear and exponential phases of myofibril relaxation. However, there was no change in the same measures of crossbridge turnover when expressed as a function of tension. We conclude that the changes in crossbridge kinetics as a function of calcium concentration reflect a reduced tension due to a lower calcium sensitivity and that the relationship between crossbridge kinetics and tension was unchanged, indicating no direct effect of PKA treatment on crossbridge cycling.

scholarly journals Making waves: A proposed new role for myosin-binding protein C in regulating oscillatory contractions in vertebrate striated muscle

2020 ◽  
Vol 153 (3) ◽  
Author(s):  
Samantha P. Harris
Keyword(s):  
Protein C ◽  
Molecular Mechanisms ◽  
Striated Muscle ◽  
Binding Protein ◽  
Muscle Performance ◽  
Central Position ◽  
Myosin Binding Protein ◽  
Myosin Binding Protein C ◽  
Myosin Binding ◽  
Contraction And Relaxation

Myosin-binding protein C (MyBP-C) is a critical regulator of muscle performance that was first identified through its strong binding interactions with myosin, the force-generating protein of muscle. Almost simultaneously with its discovery, MyBP-C was soon found to bind to actin, the physiological catalyst for myosin’s activity. However, the two observations posed an apparent paradox, in part because interactions of MyBP-C with myosin were on the thick filament, whereas MyBP-C interactions with actin were on the thin filament. Despite the intervening decades since these initial discoveries, it is only recently that the dual binding modes of MyBP-C are becoming reconciled in models that place MyBP-C at a central position between actin and myosin, where MyBP-C alternately stabilizes a newly discovered super-relaxed state (SRX) of myosin on thick filaments in resting muscle and then prolongs the “on” state of actin on thin filaments in active muscle. Recognition of these dual, alternating functions of MyBP-C reveals how it is central to the regulation of both muscle contraction and relaxation. The purpose of this Viewpoint is to briefly summarize the roles of MyBP-C in binding to myosin and actin and then to highlight a possible new role for MyBP-C in inducing and damping oscillatory waves of contraction and relaxation. Because the contractile waves bear similarity to cycles of contraction and relaxation in insect flight muscles, which evolved for fast, energetically efficient contraction, the ability of MyBP-C to damp so-called spontaneous oscillatory contractions (SPOCs) has broad implications for previously unrecognized regulatory mechanisms in vertebrate striated muscle. While the molecular mechanisms by which MyBP-C can function as a wave maker or a wave breaker are just beginning to be explored, it is likely that MyBP-C dual interactions with both myosin and actin will continue to be important for understanding the new functions of this enigmatic protein.

scholarly journals THE ROLE OF GUT MICROBIOTA IN PATIENTS WITH DIABETES TYPE 2 AND INSULIN RESISTANCE

2021 ◽  
Author(s):  
Natia Katamadze ◽  
Tamar Kandashvili ◽  
David Metreveli ◽  
David Gordeladze
Keyword(s):  
Diabetes Mellitus ◽  
Gut Microbiota ◽  
Molecular Mechanisms ◽  
Early Stage ◽  
Diabetes Type 2 ◽  
Diabetes Type ◽  
Industrialized Countries ◽  
Common Chronic Disease ◽  
Patients With Diabetes

Diabetes mellitus is one of the most common chronic disease. In a number of developing and industrialized countries, diabetes mellitus has become an epidemic and is one of the leading causes of death. The rapid increase of cases of type 2 diabetes mellitus (T2DM) in the past decades has made it a widespread metabolic disorder. In recent years, an increasing understanding of how our microflora is linked to obesity-related T2DM has provided a new potential target for reducing the risk of T2DM. The aim of our project is to expand our view on the key roles of microflora during the onset and development of T2DM as well as its complications. Our aim was to study 2 groups of people with T2DM and Prediabetes in order to reveal any gastro-intestinal problems. According to questionnaires, it appeared that patients with diabetes type 2 had 3 or more gastrointestinal disorders, 72 % had bloating, 16% constipation and 12% diarrhea. Patients with prediabetes had 3 and more intestinal disorders: 56 % had bloating, 23% constipation and 21 % diarrhea. Despite, multiple studies supporting the importance of gut microbiota in pathophysiology of T2DM, the field is in early stage. Currently, we have reached a point in our understanding that some probiotics and related molecular mechanisms may be involved in glucose metabolism related to T2DM. We should work towards precision/personalized medicine selecting anti-diabetics and probiotics for a given patient to treat patients successfully.

scholarly journals Array-Based Resequencing Assay for Mutations Causing Hypertrophic Cardiomyopathy

2008 ◽  
Vol 54 (4) ◽  
pp. 682-687 ◽  
Author(s):  
Stephan Waldmüller ◽  
Melanie Müller ◽  
Kirsten Rackebrandt ◽  
Priska Binner ◽  
Sven Poths ◽  
...  
Keyword(s):  
Hypertrophic Cardiomyopathy ◽  
Large Scale ◽  
Troponin T ◽  
Phenotypic Diversity ◽  
Myosin Binding Protein ◽  
Myosin Binding Protein C ◽  
Heterozygous Variant ◽  
High Workload ◽  
Long Range Pcr

Abstract Background: Dissecting the complex genetic basis of hypertrophic cardiomyopathy (HCM) may be key to both better understanding and optimally managing this most prevalent genetic cardiovascular disease. An array-based resequencing (ABR) assay was developed to facilitate genetic testing in HCM. Methods: An Affymetrix resequencing array and a single long-range PCR protocol were developed to cover the 3 most commonly affected genes in HCM, MYH7 (myosin, heavy chain 7, cardiac muscle, beta), MYBPC3 (myosin binding protein C, cardiac), and TNNT2 [troponin T type 2 (cardiac)]. Results: The assay detected the underlying point mutation in 23 of 24 reference samples and provided pointers toward identifying a G insertion and a 3-bp deletion. The comparability of array-based assay results to conventional capillary sequencing was ≥99.9%. Both techniques detected 1 heterozygous variant that was missed by the other method. Conclusions: The data provide evidence that ABR can substantially reduce the high workload previously associated with a genetic test for HCM. Therefore, the HCM array could facilitate large-scale studies aimed at broadening the understanding of the genetic and phenotypic diversity of HCM and related cardiomyopathies.

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