A5000460366- Cardiac electrophysiology and arrhythmias
- Cardiac Ischemia and Reperfusion
- Ion channel regulation and function
- Cardiomyopathy and Myosin Studies
- Ion Transport and Channel Regulation
- Receptor Mechanisms and Signaling
- Signaling Pathways in Disease
- Protein Kinase Regulation and GTPase Signaling
- Cardiac Arrest and Resuscitation
- Fuel Cells and Related Materials
- Cardiac Fibrosis and Remodeling
- Cardiovascular Effects of Exercise
- Histone Deacetylase Inhibitors Research
- Nitric Oxide and Endothelin Effects
- Renin-Angiotensin System Studies
- Cardiovascular Function and Risk Factors
- Heart Failure Treatment and Management
- Anesthesia and Neurotoxicity Research
- Cardiac Imaging and Diagnostics
- Peptidase Inhibition and Analysis
- Melanoma and MAPK Pathways
- Viral Infections and Immunology Research
- Hormonal Regulation and Hypertension
- Mitochondrial Function and Pathology
- Adipose Tissue and Metabolism
St Thomas' Hospital
2011-2024
King's College London
2013-2024
British Heart Foundation
2013-2024
Manchester Metropolitan University
2016
Institute of Molecular Biology and Biophysics
2014
University of Cincinnati Medical Center
2011
Loyola University Chicago
2008-2011
University of California, Davis
2011
University of California, San Diego
2011
Cincinnati Children's Hospital Medical Center
2011
Cardiac hypertrophy and heart failure (HF) are associated with reactivation of fetal cardiac genes, class II histone deacetylases (HDACs) (eg, HDAC5) have been strongly implicated in this process. We shown previously that inositol trisphosphate, Ca2+/calmodulin-dependent protein kinase (CaMKII), (PK)D involved HDAC5 phosphorylation nuclear export normal adult ventricular myocytes also CaMKIIdelta trisphosphate receptors upregulated HF. Here we tested whether, our rabbit HF model,...
Rationale: Cardiac myosin-binding protein-C (cMyBP-C) phosphorylation at Ser-273, Ser-282, and Ser-302 regulates myocardial contractility. In vitro in vivo experiments suggest the nonequivalence of these sites potential importance Ser-282 modulating protein's overall function. Objective: To determine whether complete cMyBP-C is dependent on to define its role We hypothesized that cardiac function during β-adrenergic stimulation. Methods Results: Using recombinant human C1-M-C2 peptides...
Hypertrophic cardiomyopathy (HCM) is frequently caused by mutations in MYBPC3 encoding cardiac myosin-binding protein C (cMyBP-C). The mechanisms leading from gene to the HCM phenotype remain incompletely understood, partially because current mouse models of do not faithfully reflect human situation and early hypertrophy confounds interpretation functional alterations. goal this study was evaluate whether myofilament Ca(2+) sensitization diastolic dysfunction are associated or precede...
Protein kinase D (PKD) is a serine whose myocardial substrates are unknown. Yeast 2-hybrid screening of human cardiac library, using the PKD catalytic domain as bait, identified troponin I (cTnI), myosin-binding protein C (cMyBP-C), and telethonin PKD-interacting proteins. In vitro phosphorylation assays revealed PKD-mediated cTnI, cMyBP-C, telethonin, well myomesin. Peptide mass fingerprint analysis cTnI by liquid chromatography-coupled spectrometry indicated peptide containing Ser22 Ser23,...
The inactivation of glycogen synthase kinase-3beta (GSK-3beta) is proposed as the event integrating protective pathways initiated by preconditioning and other interventions. GSK-3 thought to decrease probability opening mitochondrial permeability transition pore. aim this study was verify role using a targeted mouse line lacking critical N-terminal serine within GSK-3beta (Ser9) highly homologous GSK-3alpha (Ser21), which when phosphorylated results in kinase inactivation. Postconditioning...
Sarcolemmal Na(+)/H(+) exchanger (NHE) activity is mediated by NHE isoform 1 (NHE1), which subject to regulation protein kinases. Our objectives were determine whether NHE1 phosphorylated kinase B (PKB), identify any pertinent phosphorylation site(s), and delineate the functional consequences of such phosphorylation. Active PKBalpha in vitro a glutathione S-transferase (GST)-NHE1 fusion comprising amino acids 516 815 carboxyl-terminal regulatory domain. PKBalpha-mediated GST-NHE1 proteins...
Protein kinase D (PKD), a serine/threonine with emerging cardiovascular functions, phosphorylates cardiac troponin I (cTnI) at Ser<sup>22</sup>/Ser<sup>23</sup>, reduces myofilament Ca<sup>2+</sup> sensitivity, and accelerates cross-bridge cycle kinetics. Whether PKD regulates function entirely through cTnI phosphorylation Ser<sup>22</sup>/Ser<sup>23</sup> remains to be established. To determine the role of in PKD-mediated regulation function, we used transgenic mice that express which are...
Thrombin can activate the plasma membrane Na + -H exchanger in a variety of noncardiac cells. We have studied (1) effect thrombin on activity sarcolemmal freshly isolated quiescent ventricular myocytes from adult rat heart and (2) signaling mechanism(s) underlying any effect. Reverse-transcription polymerase chain reaction analysis revealed receptor mRNA expression myocyte-enriched cell preparation. As an index activity, acid efflux rates ( J H s) were determined single (n=4 to 11 per group)...
Protein kinase D (PKD) is a serine/threonine with emerging myocardial functions; in skinned adult rat ventricular myocytes (ARVMs), recombinant PKD catalytic domain phosphorylates cardiac troponin I at Ser22/Ser23 and reduces myofilament Ca(2+) sensitivity. We used adenoviral gene transfer to determine the effects of full-length on protein phosphorylation, sarcomere shortening [Ca(2+)](i) transients intact ARVMs. In transduced express wild-type PKD, heterologously expressed enzyme was...
Myofilament proteins are responsible for cardiac contraction. The myofilament subproteome, however, has not been comprehensively analyzed thus far. In the present study, cardiomyocytes were isolated from rodent hearts and stimulated with endothelin-1 isoproterenol, potent inducers of protein phosphorylation. Subsequently, "skinned," subproteome was using a high mass accuracy ion trap tandem spectrometer (LTQ Orbitrap XL) equipped electron transfer dissociation. As expected, small number...
Hypertrophic cardiomyopathy (HCM) is characterized by left ventricular hypertrophy, increased stiffness and impaired diastolic filling. We investigated to what extent myocardial functional defects can be explained alterations in the passive active properties of human cardiac myofibrils. Skinned myocytes were prepared from patients with obstructive HCM (two MYBPC3 mutations, one a MYH7 mutation, three no mutation either gene) four donors. Passive stiffness, viscous properties, titin isoform...
Abstract —Activation of the sarcolemmal Na + -H exchanger (NHE) has been implicated as a mechanism inotropic, arrhythmogenic, antiacidotic, and hypertrophic effects α 1 -adrenoceptor (AR) stimulation. Although such regulation NHE activity shown to be selectively mediated through 1A -AR subtype, distal signaling mechanisms remain poorly defined. We investigated roles various kinase pathways in -AR–mediated stimulation adult rat ventricular myocytes. As an index activity, trans -sarcolemmal...
Activity of the Na+/H+ exchanger (NHE) isoform 1 (NHE1) is increased by intracellular acidosis through interaction H+ with an allosteric modifier site in transport domain. Additional regulation achieved via kinase-mediated modulation NHE1 regulatory To determine if stimulates activity solely mechanism, we subjected cultured neonatal rat ventricular myocytes (NRVM) native expression to (pHi approximately 6.6) for up 6 min transient exposure NH4Cl and its washout presence NHE inhibition (by...
Increased sarcolemmal Na(+)/H(+) exchanger activity has been implicated as a mediator of the cardiac actions angiotensin II. We studied receptor subtypes and signaling pathways involved in regulation by II adult rat ventricular myocytes. Cells were loaded with pH-sensitive fluoroprobe carboxy-seminaphthorhodafluor-1, acid efflux rates estimated during recovery from intracellular acidosis used to quantify activity. Sarcolemmal was not affected alone but increased plus PD123319 (AT(2)...
Activation of sarcolemmal Na+/H+ exchange has been proposed as a causal factor in reperfusion arrhythmogenesis. To test this hypothesis, we determined the antiarrhythmic efficacy two structurally distinct but equipotent Na+H+ inhibitors, 5-(N-ethyl-N-isopropyl)amiloride (EIPA) and novel drug, 3-methylsulfonyl-4-piperidinobenzoyl guanidine (HOE-694), isolated rat hearts (n = 12/group) subjected to independent dual coronary perfusion. After 15 min aerobic perfusion both beds, flow left bed...
It has been proposed that the activity of cardiac sarcolemmal Na+/Ca2+ exchanger may be greatest in developing animals before sarcoplasmic reticulum (SR) reaches functional maturity. Experiments were performed rabbits, which have a sparse SR at birth, and newborn guinea pigs, exhibit more extensive SR. Whole cell voltage clamp techniques used to characterize Ni(2+)-sensitive exchange current single freshly isolated myocytes. was measured from holding potential -40 mV by using slow-ramp...
Background Despite evidence that pharmacological inhibition of the Na + /H exchanger (NHE) is cardioprotective, activation NHE has been proposed as a protective mechanism ischemic preconditioning (PC). Methods and Results In isolated rat ventricular myocytes (n=8 to 11 per group) loaded with fluorescent pH indicator C-SNARF-1, we showed HOE-642 (HOE) was potent inhibitor sarcolemmal (80% at 1 μmol/L); such readily reversible by washout drug. We confirmed μmol/L HOE produces significant...
G(q) protein-coupled receptor stimulation increases sarcolemmal Na(+)/H(+) exchanger (NHE1) activity in cardiac myocytes by an ERK/RSK-dependent mechanism, most likely via RSK-mediated phosphorylation of the NHE1 regulatory domain. Adenosine A(1) inhibits this response through a G(i) protein-mediated pathway, but distal inhibitory signaling mechanisms are unknown. In cultured adult rat ventricular (ARVM), agonist cyclopentyladenosine (CPA) inhibited increase induced alpha(1)-adrenoreceptor...