Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.10.2 (focal adhesion kinase)
 44,029 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

As JAK2 V617F, MPL W515L is a novel acquired mutation that induces constitutive cytokine-independent activation of the JAK-STAT pathway in myeloproliferative disorders (MPD). The discovery of this mutation provides a novel mechanism for activation of signal transduction in hematopoietic malignancies. To investigate its prevalence in Chinese patients with MPD, we introduced allele-specific PCR (AS-PCR) combined with sequence analysis to simultaneously screen MPL W515L and JAK2 V617F mutations in 190 MPD patients. MPL W515L mutation was found to be harbored in only one of 102 patients, who had essential thrombocythemia (ET, 1.0%) and was not detected in patients with polycythemia vera (PV), idiopathic myelofibrosis (IMF), and chronic myelogenous leukemia (CML). Sixty-eight BCR/ABL-negative MPD patients (46.3%) were found harboring JAK2 V617F mutation (PV, 62.5%; ET, 42.1%; IMF 38.1%). Furthermore, MPL W515L and JAK2 V617F mutations were not detected in patients of acute myeloid leukemia, acute lymphoblastic leukemia, myelodysplastic syndromes, and CML. It has been shown that MPL W515L mutations may contribute to the primary molecular pathogenesis of Chinese patients with ET.
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PMID:MPL W515L mutation in Chinese patients with myeloproliferative diseases. 1846 14

Abnormal nuclear megakaryocytic staining for phospho-STAT5 (pSTAT5) correlates with JAK2 V617F mutational status in non-chronic myelogenous leukemia chronic myeloproliferative disorders. However, a proportion of wild-type JAK2 non-chronic myelogenous leukemia chronic myeloproliferative disorders cases also demonstrate this abnormal pSTAT5 expression pattern. We report a patient with a JAK2 V617F-negative myeloproliferative/myelodysplastic syndrome who had abnormal megakaryocytic pSTAT5 expression and a MPL W515L mutation. The patient was a 71-year-old man with anemia and thrombocythemia on laboratory examination. His peripheral blood smear demonstrated occasional dysplastic neutrophils. Bone marrow biopsy revealed hypercellular marrow with features consistent with myeloproliferative/myelodysplastic syndrome. Immunohistochemistry for pSTAT5 showed abnormal nuclear megakaryocyte positivity. Cytogenetic analysis revealed a normal karyotype, fluorescence in situ hybridization for BCR-ABL was negative, and JAK2 genotyping demonstrated wild-type JAK2. However, MPL genotyping showed a MPL W515L mutation. Abnormal nuclear megakaryocytic staining for pSTAT5 expression, previously associated with the JAK2 V617F mutation, is also associated with MPL W515L, likely reflecting activation of the JAK-STAT signaling pathway.
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PMID:Phospho-STAT5 expression pattern with the MPL W515L mutation is similar to that seen in chronic myeloproliferative disorders with JAK2 V617F. 1847 30

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

Essential thrombocythemia (ET) is a chronic myeloproliferative disorder, characterized by increased proliferation of megakaryocytes and elevated platelet count that usually occurs sporadically. We report a family with seven affected individuals in three generations, including one individual with a phenotype resembling polycythemia vera, a related disorder. Megakaryocyte (CFU-MK) colony formation occurred in the absence of added cytokines in cultures of peripheral blood from affected family members. Some reports of familial ET have identified mutations in THPO and MPL, the genes for a cytokine (thrombopoietin, TPO) that regulates platelet production and its receptor (c-MPL), respectively. In this family, the MPL gene was excluded by linkage analysis. Although TPO levels were elevated in most affected family members and evidence for linkage was found between the disease and THPO (theta=0.0, Z(max)=3.0), a THPO mutation was not identified by DNA sequencing. The JAK2 V617F mutation that has been associated with 50% of sporadic cases of ET was identified as a somatic mutation, an acquired defect, in peripheral blood of the two most severely affected family members. These patients also had elevated TPO levels. Further study of familial myeloproliferative diseases will help elucidate the initiating genetic events underlying ET.
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PMID:Familial essential thrombocythemia with spontaneous megakaryocyte colony formation and acquired JAK2 mutations. 1849 61

JAK2 and MPL mutations are recurrent in myeloproliferative neoplasms (MPNs). A JAK2 mutation, primarily JAK2V617F, is almost invariably associated with polycythemia vera (PV). However, JAK2V617F also occurs in the majority of patients with essential thrombocythemia (ET) or primary myelofibrosis (PMF) as well as in a much smaller percentage of those with other MPNs. The mechanism(s) behind this one allele-multiple phenotypes phenomenon has not been fully elucidated. The issue is further confounded by the presence of marked variation in JAK2V617F allele burden among mutation-positive patients. In the current communication, we discuss potential mechanisms for phenotypic diversity among JAK2V617F-positive MPNs as well as review the current literature in regard to genotype-phenotype correlations (that is clinical correlates and prognostic significance) in the context of both the presence or absence of the mutation (ET and PMF) and its allele burden (PV, ET and PMF).
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PMID:Clinical correlates of JAK2V617F presence or allele burden in myeloproliferative neoplasms: a critical reappraisal. 1849 62

MPL (or thrombopoietin receptor, TPO-R) 515 mutations have recently been described in 5-10% of primitive myelofibrosis (PMF) cases as decisive oncogenic events capable of triggering the disease. Here we report additional mutations located in exon 10 of MPL in PMF patients. We investigated whether these new mutations also lead to cell transformation. MPL exon 10 was systematically sequenced in 100 PMF patients. Seven different mutations were found in eight patients. We introduced each MPL mutant in Ba/F3 cells to determine whether they correspond to gain-of-function mutations. Only MPL W515 mutations induced (1) Ba/F3 proliferation independently of growth factors, (2) tumorigenesis in nude mice, (3) spontaneous activation of JAK/STAT, RAS/MAPK and PI3K transduction pathways and (4) increased S phase of cell cycle. Similar to all other myeloproliferative disorder oncogenic events identified to date, these results demonstrate that only the detected MPL W515 mutations trigger spontaneous MPL activation leading to a G(1)/S transition activation. The other mutations are devoid of significant transforming activity but may synergize with JAK2 V617F or other not yet characterized molecular events.
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PMID:New mutations of MPL in primitive myelofibrosis: only the MPL W515 mutations promote a G1/S-phase transition. 1852 23

The Philadelphia chromosome-negative myeloproliferative disorders (MPDs) polycythemia vera (PV), essential thrombocytosis (ET) and primary myelofibrosis (PMF) are characterized by increased proliferation of terminally differentiated myeloid cells. Although these disorders were recognized as clonal hematopoietic stem cell disorders more than 3 decades ago, little was known about the genetic basis for these disorders until 2005 when a single recurrent mutation in the JAK2 tyrosine kinase (JAK2V617F) was identified in >90% of patients with PV and in a significant proportion of patients with ET and PMF. JAK2V617F is a constitutively active tyrosine kinase and has transforming properties in vitro and in vivo, providing validation JAK2V617F is a bona fide oncogene which contributes to MPD pathogenesis. Subsequent studies of JAK2V617F-negative MPDs have identified mutations in JAK2 exon 12 and MPL, and these mutations also result in constitutive activation of JAK2 signaling. In this review, we will discuss the genetics of PV, ET and PMF with regard to known somatic mutations, the role of these mutations in hematopoietic transformation and the therapeutic implications of these findings.
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PMID:JAK2 and MPL mutations in myeloproliferative neoplasms. 1856 40

In polycythemia vera (PV) and essential thrombocythemia (ET) specific JAK2 mutations constitutively activate the JAK-STAT pathway, explaining biologic findings such as endogenous erythroid colony (EECs) growth or PRV-1 RNA overexpression. Since these markers are detected also in JAK2 wild type patients, we hypothesized that, in these cases, the activation of the JAK-STAT pathway could be produced by a deregulation of the suppressor of cytokine signaling (SOCS) protein system. Eighty-one patients with PV and ET (53 adults and 28 children) were investigated for the methylation status of the SOCS-1, SOCS-2 and SOCS-3 CpG islands and for several myeloproliferative markers (including JAK2 and MPL mutations and clonality of hematopoiesis). SOCS-1 or SOCS-3 hypermethylation was identified in 23 patients and was associated with a significant decrease of SOCS-1 or SOCS-3 RNA and protein levels. The gene expression was restored by exposing cells to the demethylating agent 2-deoxyazacytidin. Interestingly, SOCS-1 or SOCS-3 hypermethylation was detected in 6 female patients, proved negative for JAK2 or MPL mutations and exhibiting monoclonal hematopoiesis. In conclusion, SOCS-1 or SOCS-3 hypermethylation can activate the JAK-STAT signaling pathway in alternative or together with JAK2 mutations. These alterations might represent a potential therapeutic target.
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PMID:Epigenetic alteration of SOCS family members is a possible pathogenetic mechanism in JAK2 wild type myeloproliferative diseases. 1862 27

Although it has long been known that the myeloproliferative neoplasms (MPN) polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF) are clonal hematopoietic stem-cell disorders, for many years the genetic basis for these disorders was elusive. A new era in MPN biology began in 2005 with the discovery of a somatic point mutation in JAK2 tyrosine kinase (JAK2V617F), which was identified in a significant proportion of patients with PV, ET and PMF. Based on the hypothesis that JAK-STAT signaling is central to the pathogenesis of JAK2V617F-negative MPN, genomic studies have identified JAK2 exon 12 mutations in JAK2V617F-negative PV and activating mutations in MPL in patients with JAK2V617F-negative ET and PMF. In this review, we will discuss the role of these mutant alleles in the pathogenesis of PV, ET and PMF, the potential therapeutic implications of these discoveries, and the implications of these discoveries for genomic studies of hematopoietic malignancies.
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PMID:JAK2 and MPL mutations in myeloproliferative neoplasms: discovery and science. 1875 26

Oncogenic mutations in JAK2 and MPL genes have recently been identified in myeloproliferative neoplasms (MPNs). In addition to these mutations, cytogenetic aberrations are frequently present at diagnosis but their role in the pathogenesis remains unclear. Two models of MPN pathogenesis have recently emerged based on either a single-hit or a multi-hit concept. The first model proposes that the acquisition of JAK2 mutations is the disease-initiating event, causing both the onset of disease phenotype and establishment of clonal hematopoiesis. The second model postulates the existence of 'pre-JAK2' mutations that establish clonal hematopoiesis before acquisition of JAK2 mutations and onset of disease phenotype. In this review, the two models have been critically evaluated in the context of the latest findings. At present, neither of the two models can be universally applied to all MPN patients due to their genetic heterogeneity. It is likely that the disease pathogenesis in some patients follows the first, and in other patients, the second model. Thus, the somatic mutations in MPN do not seem to be acquired in a predetermined order as seen in other malignancies, but occur randomly. Furthermore, the role of uniparental disomy in MPN and certain aspects of MPN therapy are discussed.
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PMID:Genetic complexity of myeloproliferative neoplasms. 1875 34


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