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:2.7.10.1 (ERK)
95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The aim of the study was the estimation of the right ventricular function in patients with hypertrophic cardiomyopathy (HC). 20 patients, 14 men and 6 women of age 23-50 with echocardiography diagnosed hypertrophic cardiomyopathy were examined. Equilibrium gated radionuclide angiography was performed in all patients. Right and left ventricle ejection fraction (EF), 1/3 first ejection fraction (1/3EF), maximal and average rate of emptying (MER, AER), time to peak emptying (TTPE), 1/3 first filling fraction (1/3FF), maximal and average rate of filling (MFR, AFR), time to peak filling (TTPF) and MFR/MER ratio were calculated. Analysing function of right ventricle in patients with HC impaired diastolic function was observed. MFR was 1.44 +/- 0.54EDV/s,AFR-0.95 +/- 0.24EDV/s, 1/3 FF-0.49 +/- 0.09. Positive correlation between right and left ventricle MFR was found (r = 0.62; p < 0.01). Mean value of RVEF was 40.8 +/- 7%, 1/3EF-17.5 +/- 5%, MER-1.88 +/- 0.4EDV/s, AER-1.59 +/- 0.4EDV/s. Decreased ejection fractions of the right ventricle in patients with the thickest interventricular septum were observed. Mean value of the time to peak emptying was short (x = 68.6 ms). Regional ejection fractions from septum region of RV were decreased. It was the result of the abnormal function of the interventricular septum in patients with hypertrophic cardiomyopathy. Indexes of RV function in the two groups of patients were also analysed: with and without left ventricular outflow tract obstruction. Mean value of RV systolic and diastolic function indexes were similar in two groups of patients. In conclusion, impairment of the right ventricle diastolic function in patients with hypertrophic cardiomyopathy is predominated. The more diastolic function of the RV deteriorates the worse diastolic function of the left ventricle remains in patients with HC.
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PMID:[Evaluation of right ventricular function in patients with hypertrophic cardiomyopathy]. 875 24

We investigated ACE gene polymorphism in 80 patients with hypertrophic cardiomyopathy (HCM) and in 88 of their unaffected siblings and children. Genotypes were identified by polymerase chain reaction with oligonucleotide in intron 16 of the ACE gene. The D allele frequency was higher among patients with solitary HCM than among those with familial HCM. We also determined the expression of beta-adrenergic receptor kinase (beta ARK) mRNA in the heart in patients with congestive heart failure. beta ARK mRNA expression in failing heart was significantly increased compared with that in normal heart. These molecular biological methods such as investigation of ACE gene polymorphism and beta ARK mRNA expression are sufficient for detecting cardiac disease.
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PMID:[Evaluation of cardiac function by biochemical and molecular biological techniques]. 959 26

Noonan syndrome is characterized by short stature, facial dysmorphia and a wide spectrum of congenital heart defects. Mutations of PTPN11, KRAS and SOS1 in the RAS-MAPK pathway cause approximately 60% of cases of Noonan syndrome. However, the gene(s) responsible for the remainder are unknown. We have identified five different mutations in RAF1 in ten individuals with Noonan syndrome; those with any of four mutations causing changes in the CR2 domain of RAF1 had hypertrophic cardiomyopathy (HCM), whereas affected individuals with mutations leading to changes in the CR3 domain did not. Cells transfected with constructs containing Noonan syndrome-associated RAF1 mutations showed increased in vitro kinase and ERK activation, and zebrafish embryos with morpholino knockdown of raf1 demonstrated the need for raf1 for the development of normal myocardial structure and function. Thus, our findings implicate RAF1 gain-of-function mutations as a causative agent of a human developmental disorder, representing a new genetic mechanism for the activation of the MAPK pathway.
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PMID:Germline gain-of-function mutations in RAF1 cause Noonan syndrome. 1760 82

Noonan and LEOPARD syndromes are developmental disorders with overlapping features, including cardiac abnormalities, short stature and facial dysmorphia. Increased RAS signaling owing to PTPN11, SOS1 and KRAS mutations causes approximately 60% of Noonan syndrome cases, and PTPN11 mutations cause 90% of LEOPARD syndrome cases. Here, we report that 18 of 231 individuals with Noonan syndrome without known mutations (corresponding to 3% of all affected individuals) and two of six individuals with LEOPARD syndrome without PTPN11 mutations have missense mutations in RAF1, which encodes a serine-threonine kinase that activates MEK1 and MEK2. Most mutations altered a motif flanking Ser259, a residue critical for autoinhibition of RAF1 through 14-3-3 binding. Of 19 subjects with a RAF1 mutation in two hotspots, 18 (or 95%) showed hypertrophic cardiomyopathy (HCM), compared with the 18% prevalence of HCM among individuals with Noonan syndrome in general. Ectopically expressed RAF1 mutants from the two HCM hotspots had increased kinase activity and enhanced ERK activation, whereas non-HCM-associated mutants were kinase impaired. Our findings further implicate increased RAS signaling in pathological cardiomyocyte hypertrophy.
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PMID:Gain-of-function RAF1 mutations cause Noonan and LEOPARD syndromes with hypertrophic cardiomyopathy. 1760 83

Familial hypertrophic cardiomyopathy (FHC) is an autosomal dominant disease characterized by left ventricular hypertrophy (LVH) predominantly affecting the interventricular septum. Cardiac myosin-binding protein C (cMyBP-C) mutations are common causes of FHC. Gene expression profiling was performed in left ventricles of 9-week-old wild-type mice, heterozygous cMyBP-C KO mice displaying asymmetric septal hypertrophy, and homozygous mice developing eccentric LVH. Knocking out one or two cMyBP-C genes leads primarily to gene expression changes indicating an increased energy demand, activation of the JNK and p38 parts of the MAPK pathway and deactivation of the ERK part, and induction of apoptosis. Altered gene expression for processes related to cardiac structure, contractile proteins, and protein turnover was also identified. Many of the changes were more pronounced in the homozygous KO mice. These alterations point to physiological and pathological adaptations in the prehypertrophic heterozygous KO mice and the hypertrophic homozygous mice.
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PMID:Altered myocardial gene expression reveals possible maladaptive processes in heterozygous and homozygous cardiac myosin-binding protein C knockout mice. 1806 Jul 37

Noonan syndrome (NS) is the most common nonchromosomal genetic disorder associated with cardiovascular malformations. The most prominent cardiac defects in NS are pulmonary valve stenosis and hypertrophic cardiomyopathy. Gain-of-function mutations in the protein tyrosine phosphatase Shp2 have been identified in 50% of NS families. We created a NS mouse model with selective overexpression of mutant Shp2 (Q79R-Shp2) in the developing endocardial cushions. In our model, Cre recombinase driven by the Tie2 promoter irreversibly activates transgenic Q79R-Shp2 expression in the endothelial-derived cell lineage. Q79R-Shp2 expression resulted in embryonic lethality by embryonic day 14.5. Importantly, mutant embryos showed significantly enlarged endocardial cushions in the atrioventricular canal and in the outflow tract. In contrast, overexpression of wild-type Shp2 protein at comparable levels did not enhance endocardial cushion growth or alter the morphology of the mature adult valves. Expression of Q79R-Shp2 was accompanied by increased ERK1/2 activation in a subset of cells within the cushion mesenchyme, suggesting that hyperactivation of this signaling pathway may play a pathogenic role. To test this hypothesis in vivo, Q79R-Shp2-expressing mice were crossed with mice carrying either a homozygous ERK1 or a heterozygous ERK2 deletion. Deletion of ERK1 completely rescued the endocardial cushion phenotype, whereas ERK2 protein reduction did not affect endocardial cushion size. Constitutive hyperactivation of ERK1/2 signaling alone with a transgenic approach resulted in a phenocopy of the valvular phenotype. The data demonstrate both necessity and sufficiency of increased ERK activation downstream of Shp2 in mediating abnormal valve development in a NS mouse model.
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PMID:Role of ERK1/2 signaling in congenital valve malformations in Noonan syndrome. 1901 99

Accumulating data suggest a link between alterations/deficiencies in cytoskeletal proteins and the progression of cardiomyopathy and heart failure, although the molecular basis for this link remains unclear. Cypher/ZASP is a cytoskeletal protein localized in the sarcomeric Z-line. Mutations in its encoding gene have been identified in patients with isolated non-compaction of the left ventricular myocardium, dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy. To explore the role of Cypher in myocardium and to better understand molecular mechanisms by which mutations in cypher cause cardiomyopathy, we utilized a conditional approach to knockout Cypher, specially in either developing or adult myocardium. Cardiac-specific Cypher knockout (CKO) mice developed a severe form of DCM with disrupted cardiomyocyte ultrastructure and decreased cardiac function, which eventually led to death before 23 weeks of age. A similar phenotype was observed in inducible cardiac-specific CKO mice in which Cypher was specifically ablated in adult myocardium. In both cardiac-specific CKO models, ERK and Stat3 signaling pathways were augmented. Finally, we demonstrate the specific binding of Cypher's PDZ domain to the C-terminal region of both calsarcin-1 and myotilin within the Z-line. In conclusion, our studies suggest that (i) Cypher plays a pivotal role in maintaining adult cardiac structure and cardiac function through protein-protein interactions with other Z-line proteins, (ii) myocardial ablation of Cypher results in DCM with premature death and (iii) specific signaling pathways participate in Cypher mutant-mediated dysfunction of the heart, and may in concert facilitate the progression to heart failure.
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PMID:Cardiac-specific ablation of Cypher leads to a severe form of dilated cardiomyopathy with premature death. 1902 70

Noonan syndrome (NS) and related disorders are autosomal dominant disorders characterized by heart defects, facial dysmorphism, ectodermal abnormalities, and mental retardation. The dysregulation of the RAS/MAPK pathway appears to be a common molecular pathogenesis of these disorders: mutations in PTPN11, KRAS, and SOS1 have been identified in patients with NS, those in KRAS, BRAF, MAP2K1, and MAP2K2 in patients with CFC syndrome, and those in HRAS mutations in Costello syndrome patients. Recently, mutations in RAF1 have been also identified in patients with NS and two patients with LEOPARD (multiple lentigines, electrocardiographic conduction abnormalities, ocular hypertelorism, pulmonary stenosis, abnormal genitalia, retardation of growth, and sensorineural deafness) syndrome. In the current study, we identified eight RAF1 mutations in 18 of 119 patients with NS and related conditions without mutations in known genes. We summarized clinical manifestations in patients with RAF1 mutations as well as those in NS patients withPTPN11, SOS1, or KRAS mutations previously reported. Hypertrophic cardiomyopathy and short stature were found to be more frequently observed in patients with RAF1 mutations. Mutations in RAF1 were clustered in the conserved region 2 (CR2) domain, which carries an inhibitory phosphorylation site (serine at position 259; S259). Functional studies revealed that the RAF1 mutants located in the CR2 domain resulted in the decreased phosphorylation of S259, and that mutant RAF1 then dissociated from 14-3-3, leading to a partial ERK activation. Our results suggest that the dephosphorylation of S259 is the primary pathogenic mechanism in the activation of RAF1 mutants located in the CR2 domain as well as of downstream ERK.
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PMID:Molecular and clinical analysis of RAF1 in Noonan syndrome and related disorders: dephosphorylation of serine 259 as the essential mechanism for mutant activation. 2005 57

Hypertrophic cardiomyopathy (HCM) is a leading cause of sudden death in children and young adults. Abnormalities in several signaling pathways are implicated in the pathogenesis of HCM, but the role of the RAS-RAF-MEK-ERK MAPK pathway has been controversial. Noonan syndrome (NS) is one of several autosomal-dominant conditions known as RASopathies, which are caused by mutations in different components of this pathway. Germline mutations in RAF1 (which encodes the serine-threonine kinase RAF1) account for approximately 3%-5% of cases of NS. Unlike other NS alleles, RAF1 mutations that confer increased kinase activity are highly associated with HCM. To explore the pathogenesis of such mutations, we generated knockin mice expressing the NS-associated Raf1(L613V) mutation. Like NS patients, mice heterozygous for this mutation (referred to herein as L613V/+ mice) had short stature, craniofacial dysmorphia, and hematologic abnormalities. Valvuloseptal development was normal, but L613V/+ mice exhibited eccentric cardiac hypertrophy and aberrant cardiac fetal gene expression, and decompensated following pressure overload. Agonist-evoked MEK-ERK activation was enhanced in multiple cell types, and postnatal MEK inhibition normalized the growth, facial, and cardiac defects in L613V/+ mice. These data show that different NS genes have intrinsically distinct pathological effects, demonstrate that enhanced MEK-ERK activity is critical for causing HCM and other RAF1-mutant NS phenotypes, and suggest a mutation-specific approach to the treatment of RASopathies.
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PMID:MEK-ERK pathway modulation ameliorates disease phenotypes in a mouse model of Noonan syndrome associated with the Raf1(L613V) mutation. 2133 40

Donohue syndrome (DS) is a rare autosomal recessive condition caused by mutations in the gene encoding the insulin receptor. It is characterised by severe metabolic and endocrine derangement, prenatal and postnatal linear growth impairment, soft tissue overgrowth, and poor development of adipose tissue and muscle. Causes of death, which is often within the first year of life, include intercurrent infection and, in some cases, heart failure. Management is currently based on case reports and very small case series only, and no formal guidelines or recommendations exist. We describe a preterm infant who had typical features of DS but who later developed hypertrophic cardiomyopathy with heart failure leading to death at 10 weeks old. Molecular genetic analysis revealed compound heterozygosity for the previously reported p.Arg890X nonsense mutation and the novel p.Tyr818Cys missense mutation in the INSR gene. Tyrosine 818 falls in an exquisitely conserved residue of the alphabeta fibronectin domain of the insulin receptor, whose structure and function are much less well understood than other parts of the receptor. We discuss management options for DS, including the therapeutic dilemma around whether recombinant human insulin-like growth factor 1, one of the few available treatments for the syndrome, may exacerbate hypertrophic cardiomyopathy and cardiac failure.
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PMID:A novel mutation of the insulin receptor gene in a preterm infant with Donohue syndrome and heart failure. 2276 70


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