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:2.7.10.2 (focal adhesion kinase)
44,029 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We searched for JAK2 exon 12 mutations in patients with JAK2 (V617F)-negative myeloproliferative disorders. Seventeen patients with polycythemia vera (PV), including 15 sporadic cases and 2 familial cases, carried deletions or duplications of exon 12 in circulating granulocytes but not in T lymphocytes. Two of the 8 mutations detected were novel, and the most frequent ones were N542-E543del and E543-D544del. Most patients with PV carrying an exon 12 mutation had isolated erythrocytosis at clinical onset, unlike patients with JAK2 (V617F)-positive PV, most of whom had also elevations in white blood cell and/or platelet counts. Both patients with familial PV carrying an exon 12 mutation had an affected sibling with JAK2 (V617F)-positive PV. Thus, several somatic mutations of JAK2 exon 12 can be found in a myeloproliferative disorder that is mainly characterized by erythrocytosis. Moreover, a genetic predisposition to acquisition of different JAK2 mutations is inherited in families with myeloproliferative disorders.
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PMID:Somatic mutations of JAK2 exon 12 in patients with JAK2 (V617F)-negative myeloproliferative disorders. 1798 12

The diagnosis and management of the BCR-ABL-negative myeloproliferative disorders (MPDs) of polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF) are at an explosive crossroads of scientific investigation and evolving paradigms since the discovery of the tyrosine kinase-activating JAK2V617F mutation in 2005. Additional discovery of relevant molecular lesions (JAK2 exon 12 mutations and c-MplW515L/K) have only further enriched our understanding of MPD pathogenesis. The improved diagnostic certainty these molecular markers provide have resulted in the modification, and simplification, of the World Health Organization (WHO) diagnostic algorithms for MPDs. Despite these scientific advances, however, the initial management of MPDs continues to rely upon a risk-based strategy to minimize the risk of vascular events with control of erythrocytosis, targeted antiplatelet therapy, and risk-based myelosuppressive therapy. No current medical therapy has altered the natural trend of the MPDs to lead to overt severe myelofibrosis or acute leukemia. Investigations into targeted therapies for MPDs are proceeding at a brisk pace with agents aimed at immunomodulation, decreasing marrow stromal reaction to the aberrant clone, DNA hypomethylation, or the inhibition of tyrosine kinases. Specific inhibition of JAK2 itself appears promising by in vitro investigations, and clinical trials with multiple agents are planned to commence enrollment in 2007. The potential impact of JAK2 inhibitors on the manifestations of the MPDs is unclear, but is awaited with great interest.
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PMID:Navigating the evolving paradigms in the diagnosis and treatment of myeloproliferative disorders. 1802 51

JAK2 exon 12 mutations were detected in 4 out of 20 polycythemia vera and idiopathic erythrocytosis V617F-negative patients and were only present in the myeloid lineage. Initial hematologic data of these patients differ from those of V617F-positive patients, but there is no difference in thrombotic development and myelofibrotic transformation.
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PMID:JAK2 exon 12 mutations in polycythemia vera or idiopathic erythrocytosis. 1805 3

Histomorphological evaluation of bone marrow trephines and smears represents the major approach to diagnose the chronic myeloproliferative diseases (CMPD) and the myelodysplastic syndromes (MDS). However, rising insights into molecular pathogenesis of human diseases strengthen the attempt of pathologists to define and to detect underlying defects beyond the microscope. Since discovery of the Philadelphia chromosome in chronic myeloid leukemia as the first specific molecular abnormality ever detected in a human neoplasia the gain of knowledge of molecular pathomechanisms in Philadelphia chromosome negative (Ph-) CMPD was rather sparse. A decisive breakthrough in Ph CMPD was the finding of JAK2 (V617F) derived from a somatic point mutation in the majority of patients with polycythemia vera (P.vera) and half of patients with essential thrombocythemia (ET) and primary myelofibrosis (PMF). It therefore can not be overestimated that detection of JAK2 (V617F) in a suspective myeloproliferation now enables a clearcut discrimination of a true Ph CMPD from a reactive state, e.g. P.vera from reactive erythrocytosis. Interestingly, a basic principle of molecular defects demonstrable in CMPD and related disorders seems to be the involvement of genes with kinase activities. Some of those genes will be discussed in more detail. In primary MDS, karyotyping via classical cytogenetics is the predominant molecular approach to estimate prognosis, e.g. -Y, del(5q) and del(20q) represent favourable anomalies. Indeed, in 5q- syndromes karyotyping enables definite subtyping and allows clinicians and patients to expect a good prognosis. Until now, dozens of molecular abnormalities such as mutations in AML1, FLT3 and Ras as well as epigenetic alterations of genes have been identified to various degrees in MDS subtypes. Some of them seem to be involved in disease initiation ("master event") and others might indicate disease progression. However, even though useful for further dissection of molecular pathomechanisms the majority of aberrations currently does not serve as potent markers in the daily routine. Nevertheless, in CMPD and MDS the importance of molecular analyses for diagnosis, estimation of prognosis, and disease monitoring will further increase in a foreseeable period of time.
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PMID:[Molecular diagnosis of chronic myeloproliferative diseases and myelodysplastic syndromes]. 1831 8

Explaining the uniqueness of the acquired somatic JAK2 V617F mutation, which is present in more than 95% of polycythemia vera patients, has been a challenge. The V617F mutation in the pseudokinase domain of JAK2 renders the unmutated kinase domain constitutively active. We have performed random mutagenesis at position 617 of JAK2 and tested each of the 20 possible amino acids for ability to induce constitutive signaling in Ba/F3 cells expressing the erythropoietin receptor. Four JAK2 mutants, V617W, V617M, V617I, and V617L, were able to induce cytokine independence and constitutive downstream signaling. Only V617W induced a level of constitutive activation comparable with V617F. Also, only V617W stabilized tyrosine-phosphorylated suppressor of cytokine signaling 3 (SOCS3), a mechanism by which JAK2 V617F overcomes inhibition by SOCS3. The V617W mutant induced a myeloproliferative disease in mice, mainly characterized by erythrocytosis and megakaryocytic proliferation. Although JAK2 V617W would predictably be pathogenic in humans, the substitution of the Val codon, GTC, by TTG, the codon for Trp, would require three base pair changes, and thus it is unlikely to occur. We discuss how the predicted conformations of the activated JAK2 mutants can lead to better screening assays for novel small molecule inhibitors.
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PMID:Substitution of pseudokinase domain residue Val-617 by large non-polar amino acids causes activation of JAK2. 1832 42

Erythropoietin (Epo) induces erythrocytosis by suppressing erythroid progenitor cell apoptosis through the Janus-activated kinase-signal transducers and activators of transcription (JAK-STAT) pathway. Since apoptosis contributes to cisplatin (CP)-induced nephrotoxicity and Epo receptors (EpoR) are expressed in the kidney, we examined the role of antiapoptosis in recombinant human erythropoietin (rHuEpo)-mediated renal protection. In human renal proximal tubular epithelial (RPTE) cells in culture, rHuEpo, but not inactive rHuEpo (I-rHuEpo), the receptor-binding sites of which are mutated, caused a significant reduction in CP-induced apoptosis at > or = 100 U/ml. rHuEpo, but not I-rHuEpo, increased STAT5 and Akt/PKB phosphorylation, demonstrating functional EpoR expression on RPTE cells. Furthermore, the JAK2 inhibitor tyrphostin AG-490 attenuated rHuEpo protection, suggesting a role of the JAK-STAT pathway in rHuEpo-mediated antiapoptosis. In rats, intravenous administration of 5,000 U/kg rHuEpo, but not an equivalent peptide mass of I-rHuEpo, before a single 5.5 mg/kg iv injection of CP, significantly increased hematocrit (Hct) and reduced the CP-induced increase in serum creatinine. Serum creatinine on day 4 was 3.4 +/- 0.3, 1.9 +/- 0.3, and 3.5 +/- 0.4 mg/dl in the CP, CP + rHuEpo, and CP + I-rHuEpo groups, respectively. Similarly, darbepoietin-alpha (DA), a hyperglycosylated analog of rHuEpo with prolonged in vivo activity when injected at 25 microg/kg iv before CP, significantly increased Hct and reduced serum creatinine. Renal clearance studies based on glomerular filtration rate and renal blood flow confirmed the significant renal protection by DA against CP. Tubular apoptosis and necrosis were significantly reduced in the kidneys of the CP + DA vs. the CP + saline group. Moreover, the equalization of Hct by venesection did not abrogate the DA-mediated renal protection. Administration of DA 48 h after CP injection also conferred significant renal protection. Thus our experiments confirm a role for erythropoiesis-stimulating proteins, including the new analog DA, in limiting CP-induced nephrotoxicity and suggest that antiapoptosis via the Epo-EpoR interaction is an important mechanism for renal protection.
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PMID:Antiapoptotic properties of erythropoiesis-stimulating proteins in models of cisplatin-induced acute kidney injury. 1838 71

Familial chronic myeloproliferative disorders are defined when in the same pedigree at least two relatives have a chronic myeloproliferative disorder (CMD) as polycythemia vera (PV), essential thrombocythemia (ET) or primary myelofibrosis (PMF). This condition should be distinguished from inherited disorders with Mendelian transmission and single haematopoietic lineage proliferation, named hereditary erythrocytosis and thrombocytosis. The recently discovered mutations in patients with CMD (V617F and exon 12 of JAK2 gene, MPL gene), and those identified in hereditary erythrocytosis and in hereditary thrombocytosis have improved our ability to discriminate these conditions. In familial CMD, the JAK2 mutations are acquired and occur as secondary genetic events. As both mutations of the JAK2 gene have been reported in the same pedigree, a genetic predisposition to the acquisition of the JAK2 mutations is supposed to be inherited. The prevalence of familial cases within CMD is at least 7.6%. The inheritance pattern of familial CMD is consistent with an autosomal dominant trait with decreased penetrance. The clinical presentation at diagnosis of patients with familial CMD does not differ from that of patients with sporadic CMD. In addition, patients with familial CMD develop the same type of complications (thrombosis and haemorrhage) and disease evolution (post-PV myelofibrosis, post-ET myelofibrosis and leukaemia) observed in patients with sporadic CMD. The 10-year survival is 83% for patients with familial PV, 100% for those with familial ET, and 30% for those with familial PMF. The aim of this review is to focus the state of the art of familial CMD and to offer an overview of inherited conditions causing erythrocytosis and thrombocytosis.
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PMID:Familial chronic myeloproliferative disorders: the state of the art. 1848 77

Thirty-six unrelated cases with erythrocytosis of unknown origin were investigated. Exons 5-8 of the erythropoietin receptor gene (EPOR), the von Hippel-Lindau gene, and the prolyl hydroxylase domain protein 2 gene (PHD2) were screened by direct DNA sequencing. The Janus kinase 2 mutation, JAK2 (Val617Phe), was screened by allele specific PCR. In this study, three new mutations of EPOR causing deletions in exon 8 were found: the first led directly to a stop codon [g.5957_5958delTT (p.Phe424X)], the second to a stop codon after one residue [g.5828_5829delCC (p.Pro381GlnfsX1)] and the third to a stop codon following a frameshift sequence of 23 residues [g.5971delC (p.Leu429TrpfsX23)]. One patient had a previously reported EPOR mutation [g.6146A>G (p.Asn487Ser)] and another, a silent one (g.5799G>A). All were heterozygotes. In addition, 2 patients were positive for JAK2 (Val617Phe), and 2 reported elsewhere, were mutated in the PHD2 gene [c.606delG (p.Met202IlefsX71).
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PMID:A study of 36 unrelated cases with pure erythrocytosis revealed three new mutations in the erythropoietin receptor gene. 1849 94

A single mutation 1849G>T in the JAK2 gene (V617F) has recently been described in classical myeloproliferative disorders (MPD). To investigate the incidence and clinical significance of the JAK2 mutation, we performed allele-specific polymerase chain reaction (PCR) and enzyme-based assessment in 11 idiopathic erythrocytosis (IE) and 15 polycythemia vera (PV) patients. Aberrant bands indicating the V617F mutation were detected in only one of 11 patients with IE, whereas all of the 15 patients with PV showed the JAK2 mutation. Sequence analysis was subsequently performed in the IE patient showing aberrant bands on allele-specific PCR, and a nucleotide change corresponding to the V617F mutation was detected in four of 29 clones tested. This patient might have progressed to PV according to the new WHO diagnostic criteria proposed in 2007, since a gradual increase in platelet counts was observed 4 years after the time of diagnosis. A further longitudinal study monitoring V617F positive-cells will clarify the process of progression from IE to PV in such a patient.
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PMID:JAK2 V617F mutation is rare in idiopathic erythrocytosis: a difference from polycythemia vera. 1852 46

Several sensitive methods for the detection of JAK2 V617F mutation have been published recently, most of them based on Real Time polymerase chain reaction (PCR). However, only some of them have performed studies of diagnostic validity. This study compares three methods based on Real Time PCR to detect JAK2 V617F mutation: two based on hybridization probes (HP) and peptide nucleic acid probe (PNA) and a third employing allele specific oligonucleotide primers for JAK2 V617F quantification. One hundred forty-nine healthy subjects, 61 essential thrombocythemia (ET), 32 polycythemia vera (PV), 38 secondary thrombocytoses, and 35 secondary erythrocytoses were included. Validity test study for JAK2 617 HP PCR in PV Sensitivity (Se) was 88% and in Specificity (Sp), 100%. In ET, Se was 57% and Sp, 100%. For JAK2 617 PNA PCR in PV, Se was 94% and Sp, 97.8%. In ET, Se was 70% and Sp, 95.7%. In JAK2 V671F allelo-specific-oligonucleotide (ASO) quantitative PCR (qPCR), cutoff point of 1% was established by receiving operating characteristic (ROC) curves. In PV, Se was 93.8% and Sp, 98.5%. In ET, Se was 80% and Sp, 95.9%. Two percent of the healthy subjects were positive by JAK2 617 PNA PCR and 2% by JAK2 617 ASO qPCR. JAK2 V617F mutation was detected in healthy subjects by cloning and sequencing. JAK2 617 HP is an adequate test in differential diagnosis for both erythrocytosis and thrombocytosis. When JAK2 V617F allele burden is low, JAK2 617 ASO qPCR should be performed. Simultaneous determination of JAK2 V617F and PRV-1 overexpression does not improve the diagnostic value of JAK2 V617F tests in MPD.
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PMID:Validity test study of JAK2 V617F and allele burden quantification in the diagnosis of myeloproliferative diseases. 1857 65


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