Abstract P348: Pathophysiological Basis Of A Compound Variant In Calcium And Sarcomere Regulation Causing Cardiac Arrhythmias And Hypertrophic Cardiomyopathy

2021 ◽  
Vol 129 (Suppl_1) ◽  
Author(s):  
Mohit Kumar ◽  
Sholeh Bazrafshan ◽  
Perundurai Dhandapany ◽  
Kobra Haghighi ◽  
Rohit Singh ◽  
...  
Keyword(s):  
Hypertrophic Cardiomyopathy ◽  
Sudden Death ◽  
Cardiac Arrhythmias ◽  
Calcium Binding ◽  
Binding Protein ◽  
Calcium Handling ◽  
Wild Type ◽  
Epinephrine Administration ◽  
Fractional Shortening

Rationale: Hypertrophic cardiomyopathy (HCM) is common inheritable heart disease. HCM is highly associated with arrhythmias and/or sudden death. Studies show that molecular defects in calcium handling impairing the cardiomyocyte contractility is a predominant cause. However, the pathophysiology underlying HCM with arrhythmias is not well understood, hindering the identification of novel therapies. Objective: To investigate the pathophysiological consequences of compound variants, consisting of Histidine Rich Calcium Binding Protein gene ( HRC S96A ) and an intronic 25bp deletion in cardiac myosin binding protein-C ( MYBPC3 Δ25bp ). Methods and Results: Clinical data revealed that co-segregation of HRC S96A and MYBPC3 ΔInt32 results in cardiac arrhythmia, heart failure, and sudden cardiac death in South Asians. To determine the cellular/molecular trigger underlying the pathophysiology of this dual variant, we used humanized, knock-in, heterozygous mouse models, including HRC S81A (equivalent to HRC S96A ) MYBPC3 Δ25bp , HRC S81A / MYBPC3 Δ25bp (double variant, DV), and wild-type controls. Echocardiography revealed a significant decrease in the percentage of ejection fraction and fractional shortening in DV mice, as well as the presence of diastolic dysfunction, at 12 weeks of age, compared to single-variant and wild-type mice. Electrocardiogram tracing of DV mice showed the presence of stress-induced arrhythmias, such as ventricular tachycardia after caffeine and epinephrine administration. Using isolated cardiomyocytes in vitro , Calcium transient experiments indicated a significant decrease in fractional shortening, Ca 2+ transient amplitude, and a higher number of after-contractions in cardiomyocytes from DV mice. DV mouse hearts showed increased phosphorylation of CaMKII and SR Ca 2+ leak by cardiomyocytes. Inclusion of the CaMKII inhibitor KN-93 rescued the increases in SR Ca 2+ leak and in aftercontractions. Conclusion: Impaired Ca 2+ -handling, owing to the HRC S96A variant, aggravates SR Ca 2+ leak and aftercontractions in MYBPC3 Δ25bp cardiomyocytes, subsequently triggering cardiac arrhythmias and sudden death in vivo .

Secreted modular calcium-binding protein 1 binds and activates thrombin to account for platelet hyperreactivity in diabetes

Blood ◽  
2021 ◽  
Vol 137 (12) ◽  
pp. 1641-1651
Author(s):  
Fredy Delgado Lagos ◽  
Amro Elgheznawy ◽  
Anastasia Kyselova ◽  
Dagmar Meyer zu Heringdorf ◽  
Corina Ratiu ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Monoclonal Antibodies ◽  
Platelet Function ◽  
Calcium Binding ◽  
Transforming Growth Factor ◽  
Binding Protein ◽  
Calcium Binding Protein ◽  
Matricellular Protein

Abstract Secreted modular calcium-binding protein 1 (SMOC1) is an osteonectin/SPARC-related matricellular protein, whose expression is regulated by microRNA-223 (miR-223). Given that platelets are rich in miR-223, this study investigated the expression of SMOC1 and its contribution to platelet function. Human and murine platelets expressed SMOC1, whereas platelets from SMOC1+/− mice did not present detectable mature SMOC1 protein. Platelets from SMOC1+/− mice demonstrated attenuated responsiveness to thrombin (platelet neutrophil aggregate formation, aggregation, clot formation, Ca2+ increase, and β3 integrin phosphorylation), whereas responses to other platelet agonists were unaffected. SMOC1 has been implicated in transforming growth factor-β signaling, but no link to this pathway was detected in platelets. Rather, the SMOC1 Kazal domain directly bound thrombin to potentiate its activity in vitro, as well as its actions on isolated platelets. The latter effects were prevented by monoclonal antibodies against SMOC1. Platelets from miR-223–deficient mice expressed high levels of SMOC1 and exhibited hyperreactivity to thrombin that was also reversed by preincubation with monoclonal antibodies against SMOC1. Similarly, SMOC1 levels were markedly upregulated in platelets from individuals with type 2 diabetes, and the SMOC1 antibody abrogated platelet hyperresponsiveness to thrombin. Taken together, we have identified SMOC1 as a novel thrombin-activating protein that makes a significant contribution to the pathophysiological changes in platelet function associated with type 2 diabetes. Thus, strategies that target SMOC1 or its interaction with thrombin may be attractive therapeutic approaches to normalize platelet function in diabetes.

scholarly journals Cubitus interruptus Requires DrosophilaCREB-Binding Protein To Activate wingless Expression in theDrosophila Embryo

2000 ◽  
Vol 20 (5) ◽  
pp. 1616-1625 ◽  
Author(s):  
Yang Chen ◽  
R. H. Goodman ◽  
Sarah M. Smolik
Keyword(s):  
Transcriptional Activation ◽  
Target Genes ◽  
Binding Protein ◽  
Point Mutations ◽  
Creb Binding Protein ◽  
Wild Type ◽  
Interaction Domain ◽  
Cubitus Interruptus

ABSTRACT CREB-binding protein (CBP) serves as a transcriptional coactivator in multiple signal transduction pathways. The Drosophilahomologue of CBP, dCBP, interacts with the transcription factors Cubitus interruptus (CI), MAD, and Dorsal (DL) and functions as a coactivator in several signaling pathways during Drosophiladevelopment, including the hedgehog (hh),decapentaplegic (dpp), and Tollpathways. Although dCBP is required for the expression of thehh target genes, wingless (wg) andpatched (ptc) in vivo, and potentiatesci-mediated transcriptional activation in vitro, it is not known that ci absolutely requires dCBP for its activity. We used a yeast genetic screen to identify several ci point mutations that disrupt CI-dCBP interactions. These mutant proteins are unable to transactivate a reporter gene regulated by cibinding sites and have a lower dCBP-stimulated activity than wild-type CI. When expressed exogenously in embryos, the CI point mutants cannot activate endogenous wg expression. Furthermore, a CI mutant protein that lacks the entire dCBP interaction domain functions as a negative competitor for wild-type CI activity, and the expression of dCBP antisense RNAs can suppress CI transactivation in Kc cells. Taken together, our data suggest that dCBP function is necessary forci-mediated transactivation of wg duringDrosophila embryogenesis.

scholarly journals Increased Susceptibility to Isoproterenol-Induced Cardiac Hypertrophy and Impaired Weight Gain in Mice Lacking the Histidine-Rich Calcium-Binding Protein

2006 ◽  
Vol 26 (24) ◽  
pp. 9315-9326 ◽  
Author(s):  
Eric J. Jaehnig ◽  
Analeah B. Heidt ◽  
Stephanie B. Greene ◽  
Ivo Cornelissen ◽  
Brian L. Black
Keyword(s):  
Weight Gain ◽  
Cardiac Hypertrophy ◽  
Knockout Mice ◽  
Calcium Binding ◽  
Calcium Release ◽  
Binding Protein ◽  
Critical Role ◽  
Calcium Binding Protein ◽  
Calcium Handling

ABSTRACT The sarcoplasmic reticulum (SR) plays a critical role in excitation-contraction coupling by regulating the cytoplasmic calcium concentration of striated muscle. The histidine-rich calcium-binding protein (HRCBP) is expressed in the junctional SR, the site of calcium release from the SR. HRCBP is expressed exclusively in muscle tissues and binds calcium with low affinity and high capacity. In addition, HRCBP interacts with triadin, a protein associated with the ryanodine receptor and thought to be involved in calcium release. Its calcium binding properties, localization to the SR, and interaction with triadin suggest that HRCBP is involved in calcium handling by the SR. To determine the function of HRCBP in vivo, we inactivated HRC, the gene encoding HRCBP, in mice. HRC knockout mice exhibited impaired weight gain beginning at 11 months of age, which was marked by reduced skeletal muscle and fat mass, and triadin protein expression was upregulated in the heart of HRC knockout mice. In addition, HRC null mice displayed a significantly exaggerated response to the induction of cardiac hypertrophy by isoproterenol compared to their wild-type littermates. The exaggerated response of HRC knockout mice to the induction of cardiac hypertrophy is consistent with a regulatory role for HRCBP in calcium handling in vivo and suggests that mutations in HRC, in combination with other genetic or environmental factors, might contribute to pathological hypertrophy and heart failure.

O4-03-06: Calcium binding protein Secretagogin expression in wild type and transgenic tau (P301L) mice

2009 ◽  
Vol 5 (4S_Part_5) ◽  
pp. P155-P155
Author(s):  
Johannes Attems ◽  
Magdalena Grosinger-Quass ◽  
Roger Nitsch ◽  
Magdalena Maj ◽  
Ludwig Wagner ◽  
...  
Keyword(s):  
Calcium Binding ◽  
Binding Protein ◽  
Calcium Binding Protein ◽  
Wild Type

scholarly journals Calcium Binding Protein S100A16 Expedites Proliferation, Invasion and EMT Process in Gastric Cancer

2021 ◽  
Author(s):  
Xiaoying You ◽  
Min Li ◽  
Hongwei Cai ◽  
Wenwen Zhang ◽  
Ye Hong ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Molecular Mechanism ◽  
Calcium Binding ◽  
Malignant Tumors ◽  
Binding Protein ◽  
Calcium Binding Protein ◽  
Tumor Formation ◽  
Mesenchymal Transition

Abstract Background: Gastric cancer (GC) is one of the most common malignant tumors of the digestive system, which has been the second cause of cancer-related deaths worldwide. The distant metastasis is one of the main reasons for the high recurrence and mortality rate of GC patients. Hence, it is necessary to investigate the molecular mechanism underlying gastric carcinogenesis and progression, especially the key genes and signaling pathways that promote GC cells proliferation, invasion, and metastasis. Methods: Using bioinformatics and clinicopathological analysis, in vivo tumor formation assays, mass spectrometry and so on, we characterized the role and molecular mechanism of S100 Calcium Binding Protein A16 (S100A16) in promoting GC tumor growth, migration, invasion and epithelial-to-mesenchymal transition (EMT), and investigated how Zonula Occludens-2 (ZO-2) inhibition mediates S100A16-induced metastasis and progression in GC.Results: We analyzed S100A16 expression with the GEPIA database and the UALCAN cancer database, and the prognostic analysis was performed using 100 clinical GC samples. We found that S100A16 is significantly upregulated in GC tissues and closely correlated with poor prognosis in GC patients. Functional studies reveal that S100A16 overexpression triggers GC cells proliferation and migration both in vivo and in vitro; by contrast, S100A16 knockdown restricts the speed of GC cells growth and mobility. Proteomic analysis results reveal a large S100A16 interactome, which includes ZO-2, a master regulator of cell-to-cell tight junctions. Mechanistic assay results indicate that excessive S100A16 instigates GC cell invasion, migration and EMT via ZO-2 inhibition, which arose from S100A16-mediated ZO-2 ubiquitination and degradation. Conclusions: Our results not only reveal that S100A16 is a promising candidate biomarker in GC early diagnosis and prediction of metastasis, but also establish the therapeutic importance of targeting S100A16 in order to prevent ZO-2 loss and suppress GC metastasis and progression.

scholarly journals The multiubiquitin-chain-binding protein Mcb1 is a component of the 26S proteasome in Saccharomyces cerevisiae and plays a nonessential, substrate-specific role in protein turnover.

1996 ◽  
Vol 16 (11) ◽  
pp. 6020-6028 ◽  
Author(s):  
S van Nocker ◽  
S Sadis ◽  
D M Rubin ◽  
M Glickman ◽  
H Fu ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Binding Protein ◽  
Degradation Pathway ◽  
26S Proteasome ◽  
Wild Type ◽  
Cell Extracts ◽  
Steady State Levels ◽  
Type Rate ◽  
Beta Galactosidase

The 26S proteasome is an essential proteolytic complex that is responsible for degrading proteins conjugated with ubiquitin. It has been proposed that the recognition of substrates by the 26S proteasome is mediated by a multiubiquitin-chain-binding protein that has previously been characterized in both plants and animals. In this study, we identified a Saccharomyces cerevisiae homolog of this protein, designated Mcb1. Mcb1 copurified with the 26S proteasome in both conventional and nickel chelate chromatography. In addition, a significant fraction of Mcb1 in cell extracts was present in a low-molecular-mass form free of the 26S complex. Recombinant Mcb1 protein bound multiubiquitin chains in vitro and, like its plant and animal counterparts, exhibited a binding preference for longer chains. Surprisingly, (delta)mcb1 deletion mutants were viable, grew at near-wild-type rates, degraded the bulk of short-lived proteins normally, and were not sensitive to UV radiation or heat stress. These data indicate that Mcb1 is not an essential component of the ubiquitin-proteasome pathway in S.cerevisiae. However, the (delta)mcb1 mutant exhibited a modest sensitivity to amino acid analogs and had increased steady-state levels of ubiquitin-protein conjugates. Whereas the N-end rule substrate, Arg-beta-galactosidase, was degraded at the wild-type rate in the (delta)mcb1 strain, the ubiquitin fusion degradation pathway substrate, ubiquitin-Pro-beta-galactosidase, was markedly stabilized. Collectively, these data suggest that Mcb1 is not the sole factor involved in ubiquitin recognition by the 26S proteasome and that Mcb1 may interact with only a subset of ubiquitinated substrates.

scholarly journals Contractility parameters of human β-cardiac myosin with the hypertrophic cardiomyopathy mutation R403Q show loss of motor function

2015 ◽  
Vol 1 (9) ◽  
pp. e1500511 ◽  
Author(s):  
Suman Nag ◽  
Ruth F. Sommese ◽  
Zoltan Ujfalusi ◽  
Ariana Combs ◽  
Stephen Langer ◽  
...  
Keyword(s):  
Hypertrophic Cardiomyopathy ◽  
Actin Filaments ◽  
Duty Ratio ◽  
Cardiac Myosin ◽  
Wild Type ◽  
Genes Encoding ◽  
New Methodologies ◽  
Unloaded Velocity

Hypertrophic cardiomyopathy (HCM) is the most frequently occurring inherited cardiovascular disease. It is caused by mutations in genes encoding the force-generating machinery of the cardiac sarcomere, including human β-cardiac myosin. We present a detailed characterization of the most debated HCM-causing mutation in human β-cardiac myosin, R403Q. Despite numerous studies, most performed with nonhuman or noncardiac myosin, there is no consensus about the mechanism of action of this mutation on the function of the enzyme. We use recombinant human β-cardiac myosin and new methodologies to characterize in vitro contractility parameters of the R403Q myosin compared to wild type. We extend our studies beyond pure actin filaments to include the interaction of myosin with regulated actin filaments containing tropomyosin and troponin. We find that, with pure actin, the intrinsic force generated by R403Q is ~15% lower than that generated by wild type. The unloaded velocity is, however, ~10% higher for R403Q myosin, resulting in a load-dependent velocity curve that has the characteristics of lower contractility at higher external loads compared to wild type. With regulated actin filaments, there is no increase in the unloaded velocity and the contractility of the R403Q myosin is lower than that of wild type at all loads. Unlike that with pure actin, the actin-activated adenosine triphosphatase activity for R403Q myosin with Ca2+-regulated actin filaments is ~30% lower than that for wild type, predicting a lower unloaded duty ratio of the motor. Overall, the contractility parameters studied fit with a loss of human β-cardiac myosin contractility as a result of the R403Q mutation.

scholarly journals The Calcium-Binding Protein EFhd2 Modulates Synapse Formation In Vitro and Is Linked to Human Dementia

2014 ◽  
Vol 73 (12) ◽  
pp. 1166-1182 ◽  
Author(s):  
Eva Borger ◽  
Abigail Herrmann ◽  
David A. Mann ◽  
Tara Spires-Jones ◽  
Frank Gunn-Moore
Keyword(s):  
Calcium Binding ◽  
Synapse Formation ◽  
Binding Protein ◽  
Calcium Binding Protein

scholarly journals Purification and characterization of the 27,000 Da calcium-binding protein of bovine brain

1987 ◽  
Vol 244 (2) ◽  
pp. 401-408 ◽  
Author(s):  
M Tokuda ◽  
N C Khanna ◽  
D M Waisman
Keyword(s):  
Calcium Binding ◽  
Binding Protein ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sedimentation Coefficient ◽  
Bovine Brain ◽  
Stokes Radius ◽  
Acidic Nature ◽  
Bovine Pancreas

A Ca2+-binding protein named CAB-27 was purified from bovine brain 100,000 g supernatant. The protein has a molecular mass of 27,000 Da as determined by SDS/polyacrylamide-gel electrophoresis and 35,500 Da by sedimentation-coefficient and Stokes-radius analysis. The protein contains about 26% Glx and Asx and 13% basic residues. The acidic nature of the molecule is confirmed by its pI of 4.80. In the presence of 3 mM-MgCl2 and 150 mM-KCl, CAB-27 binds 2.0 mol of Ca2+/mol of protein, with an apparent Kd of 0.2 microM. Ca2+-binding is unaffected by prior incubation of the protein at 80 degrees C for 2 min. Brain contains about 130 mg of CAB-27/kg. Immunoblotting identified CAB-27 in several bovine tissues; it appears to be particularly rich in brain and kidney. In addition, CAB-27 is identified as an inhibitor of bovine pancreas phospholipase A2 in vitro. The inhibitory activity of CAB-27 was 20-fold less potent than lipocortin. On the basis of the Ca2+-binding properties, intracellular concentration and tissue distribution of this protein, we suggest that CAB-27 may be an important intracellular Ca2+ receptor.

Sign in / Sign up

Export Citation Format

Share Document