Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0018801 (heart failure)
 72,216 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The molecular pathology of cardiac hypertrophy is multifactorial with transcript regulation of ion channels, ion exchangers and Ca(2+)-handling proteins being speculative. We therefore investigated disease-associated changes in gene expression of various ion channels and their receptors as well as ion exchangers, cytoskeletal proteins and Ca(2+)-handling proteins in normotensive and spontaneously hypertensive (SHR) rats. We also compared experimental findings with results from hypertrophic human hearts, previously published (Borlak, J., and Thum, T., 2003. Hallmarks of ion channel gene expression in end-stage heart failure. FASEB J. 17, 1592-1608). We observed significant (P < 0.05) induction in transcript level of ATP-driven ion exchangers (Atp1A1, NCX-1, SERCA2a), ion channels (L-type Ca(2+)-channel, K(ir)3.4, Na(v)1.5) and RyR-2 in hypertrophic hearts, while gene expression was repressed in diseased human hearts. Further, the genes coding for calreticulin and calmodulin, PMCA 1 and 4 as well as alpha-skeletal actin were significantly (P < 0.05) changed in hypertrophic human heart, but were unchanged in hypertrophic left ventricles of the rat heart. Notably, transcript level of alpha- and beta-MHC, calsequestrin, K(ir)6.1 (in the right ventricle only), phospholamban as well as troponin T were repressed in both diseased human and rat hearts. Our study enabled an identification of disease-associated candidate genes. Their regulation is likely to be the result of an imbalance between pressure load/stretch force and vascular tonus and the observed changes may provide a rational for the rhythm disturbances observed in patients with cardiac hypertrophy.
 ...
PMID:Disease-associated changes in the expression of ion channels, ion receptors, ion exchangers and Ca(2+)-handling proteins in heart hypertrophy. 1612 17

Calstablin2 stabilises the ryanodine receptor (RyR2), preventing aberrant activation of the channels during the resting phase of the cardiac muscle. Loss of this stabilisation may be associated with cardiac arrhythmias, the sudden death occasionally observed in people with structurally normal hearts, as well as the atrial fibrillation in heart failure. Calstabin2-deficient mice have structurally normal hearts but exhibit exercise-induced cardiac ventricular arrhythmias that cause sudden death. In arrhythmias, the calstabin2 stabiliser JTV519 did not prevent arrhythmias in calstabin2-/- mice, but reduced the arrhythmias in calstabin2+/- mice, illustrating the antiarrhythmic potential of stabilising calstablin2. Familial polymorphic ventricular tachycardia in humans has been linked to missense mutants in the hRyR2 gene. In HEK293 cells, these RyR2 mutants showed less binding of 35S-calstabin2 than the wild type, indicating a reduced binding affinity. In human atrial fibrillation and heart failure, where there is excessive disassociation of calstabin2 from the RyR2 receptor in vitro, JTV519 is able to reverse this. In conclusion, calstabin2 is an important new target in sudden cardiac death associated with structurally normal hearts, and in the treatment of atrial fibrillation and heart failure.
 ...
PMID:Stabilisation of calstabin2--a new approach in sudden cardiac death. 1618 51

Phosphodiesterases (PDEs) regulate the local concentration of 3',5' cyclic adenosine monophosphate (cAMP) within cells. cAMP activates the cAMP-dependent protein kinase (PKA). In patients, PDE inhibitors have been linked to heart failure and cardiac arrhythmias, although the mechanisms are not understood. We show that PDE4D gene inactivation in mice results in a progressive cardiomyopathy, accelerated heart failure after myocardial infarction, and cardiac arrhythmias. The phosphodiesterase 4D3 (PDE4D3) was found in the cardiac ryanodine receptor (RyR2)/calcium-release-channel complex (required for excitation-contraction [EC] coupling in heart muscle). PDE4D3 levels in the RyR2 complex were reduced in failing human hearts, contributing to PKA-hyperphosphorylated, "leaky" RyR2 channels that promote cardiac dysfunction and arrhythmias. Cardiac arrhythmias and dysfunction associated with PDE4 inhibition or deficiency were suppressed in mice harboring RyR2 that cannot be PKA phosphorylated. These data suggest that reduced PDE4D activity causes defective RyR2-channel function associated with heart failure and arrhythmias.
 ...
PMID:Phosphodiesterase 4D deficiency in the ryanodine-receptor complex promotes heart failure and arrhythmias. 1621 10

The cardiac isoform of the ryanodine receptor (RyR2) from dog binds predominantly a 12.6-kDa isoform of the FK506-binding protein (FKBP12.6), whereas RyR2 from other species binds both FKBP12.6 and the closely related isoform FKBP12. The role played by FKBP12.6 in modulating calcium release by RyR2 is unclear at present. We have used cryoelectron microscopy and three-dimensional (3D) reconstruction techniques to determine the binding position of FKBP12.6 on the surface of canine RyR2. Buffer conditions that should favor the "open" state of RyR2 were used. Quantitative comparison of 3D reconstructions of RyR2 in the presence and absence of FKBP12.6 reveals that FKBP12.6 binds along the sides of the square-shaped cytoplasmic region of the receptor, adjacent to domain 9, which forms part of the four clamp (corner-forming) structures. The location of the FKBP12.6 binding site on "open" RyR2 appears similar, but slightly displaced (by 1-2 nm) from that found previously for FKBP12 binding to the skeletal muscle ryanodine receptor that was in the buffer that favors the "closed" state. The conformation of RyR2 containing bound FKBP12.6 differs considerably from that depleted of FKBP12.6, particularly in the transmembrane region and in the clamp structures. The x-ray structure of FKBP12.6 was docked into the region of the 3D reconstruction that is attributable to bound FKBP12.6, to show the relative orientations of amino acid residues (Gln-31, Asn-32, Phe-59) that have been implicated as being critical in interactions with RyR2. A thorough understanding of the structural basis of RyR2-FKBP12.6 interaction should aid in understanding the roles that have been proposed for FKBP12.6 in heart failure and in certain forms of sudden cardiac death.
 ...
PMID:Three-dimensional visualization of FKBP12.6 binding to an open conformation of cardiac ryanodine receptor. 1621 74

Abnormal release of Ca from sarcoplasmic reticulum (SR) via the cardiac ryanodine receptor (RyR2) may contribute to contractile dysfunction and arrhythmogenesis in heart failure (HF). We previously demonstrated decreased Ca transient amplitude and SR Ca load associated with increased Na/Ca exchanger expression and enhanced diastolic SR Ca leak in an arrhythmogenic rabbit model of nonischemic HF. Here we assessed expression and phosphorylation status of key Ca handling proteins and measured SR Ca leak in control and HF rabbit myocytes. With HF, expression of RyR2 and FK-506 binding protein 12.6 (FKBP12.6) were reduced, whereas inositol trisphosphate receptor (type 2) and Ca/calmodulin-dependent protein kinase II (CaMKII) expression were increased 50% to 100%. The RyR2 complex included more CaMKII (which was more activated) but less calmodulin, FKBP12.6, and phosphatases 1 and 2A. The RyR2 was more highly phosphorylated by both protein kinase A (PKA) and CaMKII. Total phospholamban phosphorylation was unaltered, although it was reduced at the PKA site and increased at the CaMKII site. SR Ca leak in intact HF myocytes (which is higher than in control) was reduced by inhibition of CaMKII but was unaltered by PKA inhibition. CaMKII inhibition also increased SR Ca content in HF myocytes. Our results suggest that CaMKII-dependent phosphorylation of RyR2 is involved in enhanced SR diastolic Ca leak and reduced SR Ca load in HF, and may thus contribute to arrhythmias and contractile dysfunction in HF.
 ...
PMID:Ca2+/calmodulin-dependent protein kinase modulates cardiac ryanodine receptor phosphorylation and sarcoplasmic reticulum Ca2+ leak in heart failure. 1633 92

The Ca(2+) antagonists nifedipine has been used for more than three decades to treat hypertension, but its effects on the transcriptional regulation of cardiac genes are basically unknown. We therefore studied expression of genes coding for ion channels, ion transporters and associated partners as well as Ca(2+)-binding proteins in ventricular tissue of normotensive and spontaneously hypertensive (SH) rats after repeated intraperitoneally (i.p.) dosing of nifedipine. Notably, we observed significant (P < 0.05) repression in transcript levels of most of the genes investigated, including cardiac Na(+), K(+), Ca(2+)-channels (L-type Ca(2+)-channel, K(ir)3.4, K(ir)6.1, Na(v)1.5), ATP-driven ion exchangers (Na(+)-K(+)-ATPase, NCX-1, PMCA 2 and 4, SERCA 2a and 2b) and their associated partners (phospholamban, RyR-2) as well as cytoskeletal proteins (alpha and beta-MHC, alpha cardiac and alpha skeletal actin, troponin T and I). Repression in transcript levels was, however, only seen in ventricular tissue of hypertensive animals. This points to fundamental differences in the mode of action of nifedipine in diseased and healthy animals. Indeed, this preponderance of repressed genes will promote disturbed ion homeostasis to result in contractile dysfunction. It is of considerable importance that repressed gene expression was also seen in end-stage human heart failure. We propose repression of cardiac-specific gene expression as a hallmark of nifedipine treatment in hypertrophic hearts.
 ...
PMID:Nifedipine represses ion channels, transporters and Ca(2+)-binding proteins in hearts of spontaneously hypertensive rats. 1634 76

Periodic changes in calcium (Ca(2+)) concentration in cardiomyocytes are essential for cardiac contraction and relaxation, and the intracellular Ca(2+)concentration is integrally regulated by proteins associated with the sarcoplasmic reticulum (SR), an extensive intracellular membrane system. The activity of the cardiac ryanodine receptor (RyR2) and the sarco/endoplasmic reticulum Ca(2+) ATPase 2a (SERCA2a) are known to be under fine-tuning by their intrinsic regulatory domains and associated SR proteins. A growing body of evidence, including studies using genetically engineered mouse models, has shown that Ca(2+)cycling and Ca(2+)-dependent signaling pathways play a pivotal role in heart failure. The improvement of the SR function has ameliorated effects on cardiac pump function and it has potential therapeutic value for heart failure.
 ...
PMID:[Sarcoplasmic reticulum function and heart failure: a novel therapeutic target for heart failure]. 1639 49

Defective regulation of the cardiac ryanodine receptor (RyR2)/calcium release channel, required for excitation-contraction coupling in the heart, has been linked to cardiac arrhythmias and heart failure. For example, diastolic calcium "leak" via RyR2 channels in the sarcoplasmic reticulum has been identified as an important factor contributing to impaired contractility in heart failure and ventricular arrhythmias that cause sudden cardiac death. In patients with heart failure, chronic activation of the "fight or flight" stress response leads to protein kinase A (PKA) hyperphosphorylation of RyR2 at Ser-2808. PKA phosphorylation of RyR2 Ser-2808 reduces the binding affinity of the channel-stabilizing subunit calstabin2, resulting in leaky RyR2 channels. We developed RyR2-S2808A mice to determine whether Ser-2808 is the functional PKA phosphorylation site on RyR2. Furthermore, mice in which the RyR2 channel cannot be PKA phosphorylated were relatively protected against the development of heart failure after myocardial infarction. Taken together, these data show that PKA phosphorylation of Ser-2808 on the RyR2 channel appears to be a critical mediator of progressive cardiac dysfunction after myocardial infarction.
 ...
PMID:Ryanodine receptor/calcium release channel PKA phosphorylation: a critical mediator of heart failure progression. 1675 87

The ryanodine receptor (RyR)/calcium-release channel on the sarcoplasmic reticulum mediates intracellular calcium release required for striated muscle contraction. RyR2, the predominant isoform in cardiac myocytes, comprises a macromolecular complex that includes calstabin2 (FKBP12.6). Calstabin2, an 11.8-kDa cis-trans peptidyl-prolyl isomerase (apparent molecular mass 12.6 kDa), stabilizes the closed state of the RyR2 channel, but the mechanism by which it achieves this regulation is not fully understood. Protein kinase A (PKA) phosphorylation of RyR2 decreases the affinity of calstabin2 for the RyR2 channel complex. In the present study we identified key aspartic acid residues on calstabin2 that are involved in binding to RyR2 and likely play a role in PKA phosphorylation-induced dissociation of calstabin2 from RyR2. We show that a mutant calstabin2 in which a key negatively charged residue (Asp-37) has been neutralized binds to a mutant RyR2 channel that mimics constitutively PKA-phosphorylated RyR2 (RyR2-S2808D). Furthermore, using wild-type and genetically altered murine models of heart failure induced by myocardial infarction, we show that manipulating the stoichiometry between calstabin2 and RyR2 can restore normal cardiac function in vivo.
 ...
PMID:Analysis of calstabin2 (FKBP12.6)-ryanodine receptor interactions: rescue of heart failure by calstabin2 in mice. 1648 13

We have recently shown that RyR2 (cardiac ryanodine receptor) is phosphorylated by PKA (protein kinase A/cAMP-dependent protein kinase) at two major sites, Ser-2030 and Ser-2808. In the present study, we examined the properties and physiological relevance of phosphorylation of these two sites. Using site- and phospho-specific antibodies, we demonstrated that Ser-2030 of both recombinant and native RyR2 from a number of species was phosphorylated by PKA, indicating that Ser-2030 is a highly conserved PKA site. Furthermore, we found that the phosphorylation of Ser-2030 responded to isoproterenol (isoprenaline) stimulation in rat cardiac myocytes in a concentration- and time-dependent manner, whereas Ser-2808 was already substantially phosphorylated before beta-adrenergic stimulation, and the extent of the increase in Ser-2808 phosphorylation after beta-adrenergic stimulation was much less than that for Ser-2030. Interestingly, the isoproterenol-induced phosphorylation of Ser-2030, but not of Ser-2808, was markedly inhibited by PKI, a specific inhibitor of PKA. The basal phosphorylation of Ser-2808 was also insensitive to PKA inhibition. Moreover, Ser-2808, but not Ser-2030, was stoichiometrically phosphorylated by PKG (protein kinase G). In addition, we found no significant phosphorylation of RyR2 at the Ser-2030 PKA site in failing rat hearts. Importantly, isoproterenol stimulation markedly increased the phosphorylation of Ser-2030, but not of Ser-2808, in failing rat hearts. Taken together, these observations indicate that Ser-2030, but not Ser-2808, is the major PKA phosphorylation site in RyR2 responding to PKA activation upon beta-adrenergic stimulation in both normal and failing hearts, and that RyR2 is not hyperphosphorylated by PKA in heart failure. Our results also suggest that phosphorylation of RyR2 at Ser-2030 may be an important event associated with altered Ca2+ handling and cardiac arrhythmia that is commonly observed in heart failure upon beta-adrenergic stimulation.
 ...
PMID:Ser-2030, but not Ser-2808, is the major phosphorylation site in cardiac ryanodine receptors responding to protein kinase A activation upon beta-adrenergic stimulation in normal and failing hearts. 1662 81


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>