Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.3.16 (calcineurin)
17,112 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The present study examined the role of calcineurin in insulin-like growth factor (IGF)-1-induced hypertrophy in primary cultures of adult rat ventricular myocytes (ARVM), prepared from the ventricles of 14-16-week-old male Sprague-Dawley rats. The effects of several humoral factors, including phenylephrine, angiotensin II, endothelin-1, IGF-1 and interleukin-6, on the morphology of ARVM were studied. Myocyte surface area was significantly increased by IGF-1 (2,268 +/- 571 to 3,018 +/- 836 microm2, p < 0.01), but not by other humoral factors. This hypertrophic effect of IGF-1 was blocked by genistein (tyrosine kinase inhibitor), PD98059 (MEK inhibitor). These findings suggest that IGF-1 produces ARVM hypertrophy by a tyrosine kinase-MEK mediated pathway as has been reported in neonatal cardiomyocytes. IGF-1-mediated ARVM hypertrophy was also attenuated by cyclosporine A (calcineurin inhibitor), and staurosporine and chelerythrine (protein kinase C inhibitors). IGF-1 markedly increased calcineurin activity (8.7 +/- 1.2 to 98.0 +/- 54.3 pmol x h(-1) mg(-1), p < 0.01), and this activation was completely blocked by pre-treatment with cyclosporine A (8.5 +/- 11.4pmol x h(-1) x mg(-1), p < 0.01) and chelerythrine (2.3 +/- 2.7 pmol x h(-1) mg(-1), p < 0.01). It appears that IGF-1 activates calcineurin by a protein kinase C-dependent pathway. Increased mRNA expression of atrial natriuretic factor by IGF-1 was inhibited by cyclosporine A (p < 0.01). The findings indicate that IGF-1 induces ARVM hypertrophy by protein kinase C and calcineurin-related mechanisms. The fact that elevated calcineurin activity and induced atrial natriuretic factor mRNA expression by IGF-1 were blocked by cyclosporine A further supports the hypothesis that calcineurin is critically involved in IGF-1-induced ARVM hypertrophy.
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PMID:Role of calcineurin in insulin-like growth factor-1-induced hypertrophy of cultured adult rat ventricular myocytes. 1154 82

The transcription factor GATA-4 plays a central role in the regulation of cardiac-muscle gene transcription. The present study demonstrates that endothelin-1 (ET-1) induces GATA-4 activation and phosphorylation. The treatment of HL-1 adult mouse atrial-muscle cells with ET-1 (30 nM) caused a rapid increase in the DNA binding activity of GATA-4 within 3 min. The activation was associated with an upward mobility shift of the GATA-4 band on native PAGE in an electrophoretic- mobility-shift assay. The upward shift of the GATA-4 band also occurred on SDS/PAGE as monitored by immunoblotting. The in vitro treatment of nuclear extracts with lambda-protein phosphatase abolished the upward shift, indicating that GATA-4 was phosphorylated. ET-1 activated the p44/42 mitogen-activated protein kinase (MAPK) and the MAPK kinase (MEK) within 3 min, and PD98059 (a specific inhibitor of MEK) abolished the ET-1-induced GATA-4 phosphorylation. PMA also caused the rapid activation of MAPK and the phosphorylation of GATA-4. In contrast, the activation of MAPK by phenylephrine or H(2)O(2) was weak and did not lead to GATA-4 phosphorylation. Thus ET-1 induces a GATA-4 phosphorylation by activating a MEK-MAPK pathway.
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PMID:Endothelin-1 induces phosphorylation of GATA-4 transcription factor in the HL-1 atrial-muscle cell line. 1158 84

Myocardial hypertrophy is an adaptational response of the heart to increased work load, but it is also associated with a high risk of cardiac mortality due to its established role in the development of cardiac failure, one of the leading causes of death in developed countries. Multiple growth factors and various downstream signaling pathways involving, for example, ras, gp-130 (ref. 4), JNK/p38 (refs. 5,6) and calcineurin/NFAT/CaM-kinase have been implicated in the hypertrophic response. However, there is evidence that the initial phase in the development of myocardial hypertrophy involves the formation of cardiac para- and/or autocrine factors like endothelin-1, norepinephrine or angiotensin II (refs. 7,8), the receptors of which are coupled to G-proteins of the Gq/11-, G12/13- and Gi/o-families. Cardiomyocyte-specific transgenic overexpression of alpha1-adrenergic or angiotensin (AT1)-receptors as well as of the Gq alpha-subunit, Galphaq, results in myocardial hypertrophy. These data demonstrate that chronic activation of the Gq/G11-family is sufficient to induce myocardial hypertrophy. In order to test whether Gq/G11 mediate the physiological hypertrophy response to pressure overload, we generated a mouse line lacking both Galphaq and Galpha11 in cardiomyocytes. These mice showed no detectable ventricular hypertrophy in response to pressure-overload induced by aortic constriction. The complete lack of a hypertrophic response proves that the Gq/G11-mediated pathway is essential for cardiac hypertrophy induced by pressure overload and makes this signaling process an interesting target for interventions to prevent myocardial hypertrophy.
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PMID:Absence of pressure overload induced myocardial hypertrophy after conditional inactivation of Galphaq/Galpha11 in cardiomyocytes. 1168 89

Cyclosporine and tacrolimus reduce allograft rejection, improve allograft half-life and patient survival. Ironically, the nephrotoxicity of these agents may adversely affect allograft survival in renal transplant recipients or cause end-stage renal diseases in other solid organ and bone marrow transplant recipients. Acute dose-dependent and chronic non-dose-dependent nephrotoxicity has been reported in both transplant recipients and patients with autoimmune disorders. Preliminary evidence suggests that drug therapeutic monitoring has little value in the diagnosis or management of nephrotoxicity associated with calcineurin inhibitors. Although the exact mechanism of nephrotoxicity is not fully understood, several factors have been implicated in the pathogenesis of immunosuppressive-induced nephrotoxicity. Renal and systemic vasoconstriction, increased release of endothelin-1, decreased production of nitric acid and increased expression of TGF-beta are the major adverse pathophysiologic abnormalities of these agents. Reducing the dose of a calcineurin inhibitor, or using protocols without calcineurin inhibition may ultimately minimize the risk of drug toxicity and improve allograft and patient survival. New experiences with non-nephrotoxic agents and protocols including mycophenolate and sirolimus allow for early calcineurin inhibitor reduction or elimination without increasing the risk of allograft rejection.
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PMID:Nephrotoxicity of immunosuppressive drugs: new insight and preventive strategies. 1180 39

In response to a requirement for increased contractile power in vivo, mammalian cardiac myocytes adapt through a hypertrophic response (cell enlargement in the absence of cell division). This response can be simulated by exposing isolated myocytes in primary culture to alpha-adrenergic agonists or the vasoactive peptide, endothelin-1. The signalling pathways responsible for hypertrophic growth have been actively studied, and it is likely that reversible protein phosphorylation and dephosphorylation are involved. Three signalling pathways show particular potential as regulators of the response, ie protein kinase C (PKC), mitogen-activated protein kinase (MAPK) cascades, and calcineurin. These species are thought to regulate the rate and specificity of gene transcription ultimately through modifying the transactivating activity of nuclear transcription factors. There are three pertinent MAPK cascades, the extracellular signal-regulated kinase (ERK) cascade, the c-Jun N-terminal kinase (JNK or SAPK1) cascade, and the p38-MAPK (SAPK2-5) cascade. PKC participates in the activation of the ERK cascade but does not contribute significantly to the activation of the two remaining cascades. Calcineurin (or protein phosphatase 2B) is activated by increases in [Ca2+i] through the [Ca2+]-sensing protein, calmodulin. In this review, I discuss the evidence for and against the involvement of these signalling proteins in the induction of myocyte hypertrophy and emphasize that the ERK cascade should perhaps feature more widely in the collective consciousness.
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PMID:Signalling pathways in cardiac myocyte hypertrophy. 1181 56

Congestive heart failure is one of the major issues for cardiologists. Since cardiac hypertrophy deteriorates into heart failure, it is important to elucidate the mechanisms of cardiac hypertrophy. Hemodynamic overload, namely mechanical stress, is a major cause for cardiac hypertrophy. Mechanical stress induces various hypertrophic responses such as activation of phosphorylation cascades of many protein kinases, expression of specific genes and an increase in protein synthesis. During this process, secretion and production of vasoactive peptides such as angiotensin II and endothelin-1, are increased and play critical roles in the induction of these hypertrophic responses. Recently, a Ca2+ dependent protein kinase, CaMK, and a Ca2+ dependent protein phosphatase, calcineurin, have attracted great attention as critical molecules that induce cardiac hypertrophy. In this review, we described the mechanisms by which mechanical stress induces cardiac hypertrophy, especially focusing on the role of calcineurin in the development of cardiac hypertrophy.
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PMID:Molecular and cellular mechanisms of mechanical stress-induced cardiac hypertrophy. 1200 44

In the canine ventricular myocardium, endothelin-1 and the muscarinic agonist carbachol scarcely affect the basal force of contraction but do induce a pronounced negative inotropic effect in the presence of beta-adrenoceptor agonists. Experiments were performed to examine whether the protein phosphatase inhibitor cantharidin inhibits the negative inotropic effect induced by endothelin-1 and carbachol in isolated canine ventricular trabeculae. In the presence of 100 nM norepinephrine, endothelin-1 (10 nM) and carbachol (30 nM) decreased the norepinephrine-induced positive inotropic effect to about 40% of the norepinephrine-induced maximal response. Cantharidin at 10 microM affected neither the basal force of contraction nor the positive inotropic effect of 100 nM norepinephrine, but it did attenuate markedly the negative inotropic effect of endothelin-1. By contrast, the negative inotropic effect of carbachol was not affected by 10 microM cantharidin. At 30 microM, cantharidin induced a positive inotropic effect and enhanced the positive inotropic effect of norepinephrine by approximately 60%. Cantharidin (30 microM) markedly attenuated the negative inotropic effect of 30 nM carbachol and partially decreased the negative inotropic effect of 100 nM carbachol. The present results indicate that the activation of phosphatase that is susceptible to cantharidin is involved in both the endothelin-1-induced and the carbachol-induced negative inotropic effect. The observation that the negative inotropic effect of endothelin-1 is inhibited by cantharidin at 10 microM and that cantharidin does not affect the negative inotropic effect of carbachol supports the view that the extent of the contribution of phosphatase activation may be higher in the endothelin-1-induced negative inotropic effect than in the carbachol-induced negative inotropic effect.
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PMID:Inhibitory action of the phosphatase inhibitor cantharidin on the endothelin-1-induced and the carbachol-induced negative inotropic effect in the canine ventricular myocardium. 1268 4

A subset of cyclin-dependent protein kinases--Cdk7, Cdk8, and Cdk9--participates directly, in complex ways, with the fundamental machinery for gene transcription, as elements of general transcription factors whose substrate is the C-terminal domain (CTD) of RNA polymerase II. Here, we review recent data implicating the CTD kinase Cdk9 as a critical determinant of cardiac hypertrophy, in vitro and in vivo. Diverse trophic signals that increase cardiac mass all activated Cdk9 (work load, the small G-protein Gaq, and the calcium-dependent phosphatase calcineurin in mouse myocardium; endothelin-1, a hypertrophic agonist, in cultured cardiomyocytes). Little or no change occurred in levels of the kinase or its activator, cyclin T. Instead, in all four hypertrophic models, Cdk9 activation involves the dissociation of 7SK small nuclear RNA (snRNA), an endogenous inhibitor. In culture, dominant-negative Cdk9 blocked ET-1-induced hypertrophy, whereas an anti-sense "knockdown" of 7SK snRNA provoked spontaneous cell growth. In trans-genie mice, concordant with these results, activation of Cdk9 activity via cardiac-specific overexpression of cyclin Tl suffices to provoke hypertrophy. Together, these findings implicate Cdk9 activity as a pivotal regulator of pathophysiological heart growth. Because hypertrophy, in turn, is a cardinal risk factor for developing cardiac pump failure, these results support the logic of examining Cdk9 as a potential drug target in heart disease.
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PMID:Cyclins that don't cycle--cyclin T/cyclin-dependent kinase-9 determines cardiac muscle cell size. 1269 56

Immunosuppressive drugs common in clinical transplantation are known to have untoward effects on the vascular system. The effects of some drugs, notably cyclosporin A (CyA), have been studied on the vascular system, while those of others have not. In the vascular system, endothelial cells are the predominant cell type exposed to intravascular concentrations of immunosuppressive drugs. We therefore studied the effects of drugs common in clinical transplantation on endothelial cells in a capillary tube assay. The endothelial cells in the capillary tubes are morphologically more similar to those in the microvasculature than endothelial cells in monolayers. We studied the kinetics and extent of capillary tube formation and prostacyclin (PGI2) and endothelin-1 (ET-1) release from the in vitro capillaries to determine the morphological and biochemical effects of five immunosuppressive agents on endothelial function. We found a significant difference in the morphological and biochemical effects of the two common calcineurin inhibitors, CyA and tacrolimus (FK506) on capillary morphology in vitro. The former had a pronounced injurious effect on the morphology of the in vitro capillaries, while the latter did not. CyA also significantly increased ET-1 release by the capillaries, but FK506 did not. Mycophenolate mofetil (MMF) was the only other agent that had a moderately injurious effect on the morphology of the in vitro capillaries. Sirolimus (rapamycin) and dexamethasone, similar to FK506, had no effect on the capillary morphology. All these agents, except dexamethasone, increased PGI2 release. Our data suggest that CyA adversely affects the morphology of the microvasculature and that this is mediated, at least partly, by an increased ET-1 release by endothelial cells exposed to CyA. These findings describe a novel effect of CyA and MMF on endothelial cells that could be relevant to understanding the mechanisms of immunosuppressive drug-mediated endothelial injury in clinical transplantation.
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PMID:Morphological and biochemical effects of immunosuppressive drugs in a capillary tube assay for endothelial dysfunction. 1279 61

Cardiac transplantation is the definitive treatment for eligible patients with end-stage cardiac failure. Techniques have evolved to reduce surgical mortality to under 5%. Immediate and subsequent long-term survival is more dependent on acute and chronic rejection and the complications of immunosuppressive therapy. Ten-year survival is greater than 50%.The success of transplantation over the last 20 years has been largely due to the advances in immunosuppression. The most notable and dramatic milestone was the introduction of cyclosporine in the early 1980s, which resulted in a significant improvement in allograft and patient survival. Cyclosporine is a peptide that inhibits the immune system by suppressing T-helper cell activation via inhibition of calcineurin, a critical intracellular enzyme. Tacrolimus has a similar (but not identical) mechanism of action, and was introduced in the 1990s. Drugs such as cyclosporine and tacrolimus, generically referred to as calcineurin inhibitors, have become the cornerstones of immunosuppressive protocols. As a group, calcineurin inhibitors have adverse effects, including neurotoxicity, hypertension, and nephrotoxicity, which complicate their use. Early renal insufficiency manifests as postoperative oliguria (<50 mL/h urine output) or rising serum creatinine levels. There are a variety of postulated causes for calcineurin inhibitor-associated early renal insufficiency including direct calcineurin inhibitor-mediated renal arteriolar vasoconstriction, increased levels of endothelin-1 (a potent vasoconstrictor), as well as decreased nitric oxide production and alterations in the kidney's ability to adjust to changes in serum tonicity. Once early renal insufficiency occurs, no single treatment has been shown to be effective. Approaches discussed in this paper include reduction in calcineurin inhibitor dosages, as well as various drugs to promote increased renal perfusion such as misoprostol and dopamine. In addition, the paper emphasizes the importance of ruling out other causes of renal insufficiency in the early postoperative period, including volume depletion, depressed cardiac output, and mechanical obstruction to urine flow. Given that there is no highly efficacious treatment for this syndrome, ways to avoid its occurrence are desirable. One paper is referenced that suggests that avoidance of rapid changes in tacrolimus level during the first three days of therapy is associated with a low occurrence of early renal insufficiency.
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PMID:Calcineurin inhibitor-associated early renal insufficiency in cardiac transplant recipients: risk factors and strategies for prevention and treatment. 1496 63


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