Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026986 (myelodysplastic syndrome)
 14,926 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Neurofibromatosis 1 gene (NF1) is a tumor suppressor gene and the product of which down-regulates Nras protein by its GTPase activating protein-related domain (NF1-GRD). Although the incidence of NF1 mutation was reported to be rare in the chronic phase of myelodysplastic syndrome (MDS), there have been no previous reports on its configuration in patients showing the disease progression. We examined NF1 in 50 patients with MDS including 9 who had progressed to more advanced stages and 16 to acute leukemia. Six patients had an Nras mutation. We carried out allele specific restriction analysis (ASRA) to detect a mutation at the first nucleotide A of codon 1423 (AAG), a mutational hot spot. We also employed a polymerase chain reaction mediated single strand conformation polymorphism (PCR-SSCP) method to confirm the result of ASRA and to detect a point mutation in other sequences of FLR exon. In consequence, ASRA disclosed wild type configuration and PCR-SSCP showed no aberrant band in any sample examined whether the samples harboured an Nras mutation or not. We conclude that NF1 mutation does not play a crucial role in the development and the progression of MDS.
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PMID:Neurofibromatosis 1 gene (NF1) mutation is a rare genetic event in myelodysplastic syndrome regardless of the disease progression. 759 22

RAS genes have been implicated in several different malignancies. The mechanism of activation in most cases has been due to point mutations at critical domains responsible for guanine nucleotide binding. These changes alter the conformation of the protein resulting in insensitivity of the protein to the GTPase activating protein which normally hydrolyses the active p21RAS GTP-bound form to the inactive GDP-bound form. RAS genes have potent effects on the differentiation and proliferation program of cells. The mechanism induced depends on the context in which RAS is found as well as its mutational status and indeed which RAS gene family member is involved. RAS mutations have been described early in the disease process in haematologically normal individuals at risk of mutations induced by either occupational hazard exposure, such as benzene, or of secondary disease after chemotherapy for a previous malignancy. It also been associated with disease progression from myelodysplasia (MDS) to acute myelogenous leukaemia (AML), but it has also been described to be lost upon disease progression, thus showing that RAS mutations are unlikely to be initiating events or at least not required for maintenance of disease. As RAS appears to be involved in primary and secondary myeloid leukaemias, it is a good candidate for gene targeted therapeutic intervention. Studies to target RAS either directly or indirectly by interfering in the RAS pathway are underway. Clinical trials with a peptide RAS vaccine are also ongoing in solid tumours. This report seeks to review the evidence for RAS involvement as oncogenes, focusing on MDS, the reasons as to why the hot spots of codons 12/13 and 61 are particularly potent in activating the transformation potential of RAS and the different approaches being undertaken to translate laboratory findings into therapeutic reality.
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PMID:RAS and the myelodysplastic syndromes. 940 80

Recent progress in the understanding of signal transduction and gene regulation in hematopoietic cells has shown that many intracellular signalling pathways are modulated by low molecular weight guanine nucleotide (GTP)-binding proteins (LMWGs). LMWGs act as molecular switches for regulating a wide range of signal-transduction pathways in virtually all cells. In hematopoietic cells, LMWGs have been shown to participate in essential functions such as growth control, differentiation, cytoskeletal organization, cytokine and chemoattractant-induced signalling events, reduced nicotinamide adenine dinucleotide phosphate oxidase activity, intracellular vesicle transport and secretion. In human leukemias, myelodysplastic syndromes and myeloproliferative disorders, Ras activation occurs by point mutations, overexpression or by alteration of NF-1 Ras-GTPase activating protein (GAP). These are postinitiation events in leukemia but may modulate growth-factor-dependent and independent leukemic growth. Two animal models of mutated N-ras expression resulting in myelodysplastic and myeloproliferative features are discussed. The role of Ras in organ development is discussed in the context of transgenic knockout mice. More LMWG functions will certainly be identified as we gain a better understanding of regulatory pathways modulating myeloid signal transduction. This review will summarize our current understanding of this rapidly advancing area of research.
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PMID:The role of ras and other low molecular weight guanine nucleotide (GTP)-binding proteins during hematopoietic cell differentiation. 1121 20

Rasa3 is a GTPase activating protein of the GAP1 family which targets Ras and Rap1. Ubiquitous Rasa3 catalytic inactivation in mouse results in early embryonic lethality. Here, we show that Rasa3 catalytic inactivation in mouse hematopoietic cells results in a lethal syndrome characterized by severe defects during megakaryopoiesis, thrombocytopenia and a predisposition to develop preleukemia. The main objective of this study was to define the cellular and the molecular mechanisms of terminal megakaryopoiesis alterations. We found that Rasa3 catalytic inactivation altered megakaryocyte development, adherence, migration, actin cytoskeleton organization and differentiation into proplatelet forming megakaryocytes. These megakaryocyte alterations were associated with an increased active Rap1 level and a constitutive integrin activation. Thus, these mice presented a severe thrombocytopenia, bleeding and anemia associated with an increased percentage of megakaryocytes in the bone marrow, bone marrow fibrosis, extramedular hematopoiesis, splenomegaly and premature death. Altogether, our results indicate that Rasa3 catalytic activity controls Rap1 activation and integrin signaling during megakaryocyte differentiation in mouse.
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PMID:Rasa3 controls megakaryocyte Rap1 activation, integrin signaling and differentiation into proplatelet. 2496 84