Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.10.2 (focal adhesion kinase)
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Chronic myeloid leukaemia (CML) is an excellent model for the study of molecular rearrangements caused by a cytogenetic anomaly associated with a disease. The formation of a Philadelphia chromosome by translocation between chromosomes 9 and 22 provokes the breaking and migration of a cellular oncogen (ABL), located in the 9q34 region, towards chromosome 22 and the 22q11 region where the PHL gene is situated. This gene is broken in the bcr area the rearrangements of which are specific to CML. The ABL and PHL genes fragments fuse together, creating a new hybrid gene which is transcribed into an 8.5 kilobase messenger RNA specific to CML. This RNA is translated into a 210 kilodalton protein whose abnormally high tyrosine kinase activity seems to contribute to the development of the disease. Genetic engineering techniques improve our understanding of CML molecular mechanisms and can be very useful to clinicians as they permit the diagnosis of CML in some cases devoid of chromosomal markers, and the detection of a possible relapse in marrow-grafted patients with a much greater sensitivity (one in 100,000 cells) than that of cytogenetics.
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PMID:[Chronic myeloid leukemia: from cytogenetics to molecular biology]. 209 36

The BCR gene (Groffen et al., 1984) plays a critical role in the pathogenesis of human leukemias that involve the Philadelphia chromosome (Ph1) (Rowley, 1973; Nowell & Hungerford, 1960). Cells containing the Ph1 contain a chimeric gene formed from the fusion of BCR (Collins et al., 1987; Lifshitz et al. 1988) and ABL genes that results from the reciprocal translocation of segments of chromosomes 9 and 22 (Shtivelman et al., 1985). The product of this chimera is a 210 kDa protein, termed P210 BCR-ABL, that possesses an activated tyrosine kinase activity (Konopka et al., 1984; Kloetzer et al., 1985). Studies using long-term marrow culture systems and retrovirus-mediated gene transfer have documented that P210 BCR-ABL can stimulate the growth of immature hematopoietic precursor cell types (McLaughlin et al., 1987; Young & Witte, 1984). We have previously reported that P210 BCR-ABL exists in cytoplasmic complexes in association with a 53 kDa protein termed ph-P53 (Maxwell et al., 1987; Li et al. 1988). Similarly, BCR proteins have been found in cytoplasmic complexes containing ph-P53 in cells lacking the Ph1 (Li et al., 1989). These BCR protein complexes possess an associated ser/thr protein kinase activity. In this same study, we found that P210-containing complexes phosphorylate BCR proteins on tyrosine residues in vitro (Li et al., 1989). We now present results which demonstrate that P210 BCR-ABL is tightly associated with P160 BCR and ph-P53 proteins in cytoplasmic complexes from cells containing the Ph1.
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PMID:P210 BCR-ABL is complexed to P160 BCR and ph-P53 proteins in K562 cells. 214 May 98

We studied the cells from three selected patients with Ph-chromosome-negative chronic myeloid leukemia (CML) by Southern blotting, polymerase chain reaction, and in situ hybridization of informative probes to metaphase chromosomes. All three patients had rearrangement of M-BCR sequences in the BCR gene and expression of one or other of the mRNA species characteristic of Ph-positive CML. Leukemic metaphases studied after trypsin-Giemsa banding were indistinguishable from normal. The ABL probe localized both to chromosome 9 and 22 in each case. A probe containing 3' M-BCR sequences localized only to chromosome 22, and not to chromosome 9 as would be expected in Ph-positive CML. Two new probes that recognize different polymorphic regions distal to the ABL gene on chromosome 9 in normal subjects localized exclusively to chromosome 9 in two patients and to both chromosomes 9 and 22 in one patient. These results show that Ph-negative CML with BCR rearrangement is associated with insertion of a variable quantity of chromosome 9 derived material into chromosome 22q11; there is no evidence for reciprocal translocation of material from chromosome 22 to chromosome 9.
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PMID:Interstitial insertion of varying amounts of ABL-containing genetic material into chromosome 22 in Ph-negative CML. 216 19

Leukemic cells from a patient with Ph-negative chronic myeloid leukemia (CML) had a normal karyotype. M-BCR was rearranged and chromosome in situ hybridization showed an ABL insertion between 5' and 3' M-BCR on an apparently normal chromosome 22. The association of 5' BCR and 3' ABL at the 5' junction of the chromosome 9 insert was typical of that found for the BCR-ABL fusion gene in other patients with the standard t(9;22) and CML. With an M-bcr-3' probe, we cloned and characterized a 3' junction fragment. Field inversion gel electrophoresis and chromosome in situ hybridization studies using a probe isolated from genomic DNA 5' of the junction showed that 3' M-BCR was joined to a region of chromosome 9q34 rich in repetitive sequences and lying some distance 3' of ABL. The chromosome 9 insert was at least 329 kilobases long and included 3' ABL and a larger portion of chromosome 9q34. Our results allowed us to exclude transposon- or retroviral-mediated insertion of ABL into chromosome 22. Instead, we favored a two-translocation model in which a second translocation reconstituted a standard t(9;22)(q34;q11) but left the chromosome 9 insert, including 3' ABL, in chromosome 22.
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PMID:Ph-negative chronic myeloid leukemia: molecular analysis of ABL insertion into M-BCR on chromosome 22. 217 2

We studied two cases of chronic myelogenous leukemia (CML) with unusual variant Philadelphia (Ph) translocation (22;22)(q11;q13). Southern blot analysis showed a chromosomal break in the BCR gene within the 5.8-kilobase (kb) breakpoint cluster region (bcr), between bcr exons 2 and 3 and between bcr exons 3 and 4, respectively. Chimeric bcr-abl mRNA was detected using polymerase chain reaction (PCR) which amplified, according to the respective bcr breakpoints, bcr exon 2-abl exon II and bcr exon 3-abl exon II junction products. These results further support the involvement, even when not cytogenetically detectable, of the 9q34 chromosomal region in all variant Ph translocations and that BCR-ABL gene fusion products are causally involved in the development of Ph positive CML.
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PMID:Chronic myeloid leukemia with unusual variant Ph translocation (22;22)(q11;q13). Two cases with chimeric BCR-ABL transcripts. 220 77

The Philadelphia chromosome (Ph1) is present in 95% of chronic myelogenous leukaemias (CML) and 15% of acute lymphoblastic leukaemias (ALL). This cytogenetic marker is due to a t(9;22) translocation, which causes a rearrangement of the ABL oncogene. In order to better define the relationship between type of genomic rearrangement, variant ABL protein expressed and haematological phenotype, a series of Ph1-positive acute leukaemias, both myeloblastic (AML) and lymphoblastic, and several CML lymphoid blast crises have been analysed at the DNA and protein level. The results confirm the presence of the ABL protein P210 in all cases of CML, ALL and AML positive for rearrangement in the bcr region of chromosome 22, and, surprisingly, in one AML case apparently negative for bcr rearrangement. The ABL protein P190 was found to be present only in cases of ALL negative for bcr rearrangement. Polymerase chain reaction (PCR) analysis of the types of 9/22 junctions present in the mRNA of CML lymphoid blast crises showed no evidence of 'ALL-type' transcripts.
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PMID:ABL proteins in Philadelphia-positive acute leukaemias and chronic myelogenous leukaemia blast crises. 222 47

Chronic myelogenous leukemia (CML) is characterized by the presence of a novel fusion gene comprised of portions of the BCR gene from chromosome (ch) 22 and the ABL gene from ch 9. The present study was designed to identify regulatory DNA regions as determined by DNAase I hypersensitivity to address the question of whether altered chromatin contributes to changes in ABL expression. We identify five hypersensitive (HS) sites within the abnormal BCR/ABL allele in K562 cells in a pattern different from the normal BCR. The pattern of hypersensitivity is modified when the cells undergo hemin induced differentiation. These results indicate that the normal BCR has a chromatin configuration consistent with active transcription and that the BCR/ABL fusion gene chromatin is different. This may be important in the pathogenesis of CML.
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PMID:Chromatin alterations surrounding the BCR/ABL fusion gene in K562 cells. 226 34

A patient who was diagnosed with chronic myeloid leukemia remained in chronic phase for 14 years before progressing into a lymphoid blast crisis in 1983. The acute phase was successfully treated, and the patient has remained in an indolent chronic phase to date. Cytogenetic and molecular analysis during this second chronic phase confirm the presence of the Philadelphia chromosome and its transcribed BCR-ABL mRNA. The breakpoint within M-bcr occurred in the 3' portion of the region and expressed a hybrid joining the b3 exon of BCR to the a2 exon of ABL.
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PMID:Molecular analysis of a CML patient with a long duration of chronic phase before and after lymphoid blast crisis. 235 47

The Philadelphia chromosome is present in more than 95% of chronic myelogenous leukemia patients and in up to 25% of patients with acute lymphocytic leukemia. The major consequence of the aberration is the fusion of the ABL and BCR genes. The position of the breakpoint on chromosome 22 determines which species of the potential three fused mRNAs and proteins will be synthesized. We have used the polymerase chain reaction (PCR) to detect these mRNAs in 53 patients and cell lines and found that around 20% contain simultaneously two BCR-ABL mRNAs, presumably due to a process of alternative splicing. The results also indicate that most patients in lymphocytic blast crisis of CML contain the mRNA in which bcr exon 2 is linked to ABL exon II. Finally, we identified, cloned, and characterized a BCR-related sequence that originated from mRNA.
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PMID:Analysis of BCR-ABL mRNA in chronic myelogenous leukemia patients and identification of a new BCR-related sequence in human DNA. 248 58

The Philadelphia (Ph1) chromosome results in a fusion of portions of the BCR gene from chromosome 22 and the ABL gene from chromosome 9, producing a chimeric BCR-ABL mRNA and protein. In lymphoblastic leukemias, there are two molecular subtypes of the Ph1 chromosome, one with a rearrangement of the breakpoint cluster region (bcr) of the BCR gene, producing the same 8.5-kilobase BCR-ABL fusion mRNA seen in chronic myelogenous leukemia (CML), and the other, without a bcr rearrangement, producing a 7.0-kilobase BCR-ABL fusion mRNA that is seen only in acute lymphoblastic leukemia (ALL). We studied the molecular subtype of the Ph1 chromosome in 11 cases of Ph1-positive ALL, including 2 with a previous diagnosis of CML, using a sensitive method to analyze the mRNA species based on the polymerase chain reaction (PCR). We observed unexpected heterogeneity in BCR-ABL mRNA in this population; in particular, 1 of 6 bcr-rearranged cases and 1 of 5 bcr-unrearranged cases contained none of the known fusion mRNA species, while 1 of the bcr-rearranged cases contained both. This latter case is particularly interesting because it suggests that the acquisition of an additional BCR-ABL fusion species may be a mechanism of disease progression. We conclude that the PCR gives additional information about the Ph1 chromosome gene products that cannot be obtained by genomic analysis, but that it cannot be used as the sole means of detection of this chromosomal abnormality in ALL because of the high incidence of false negative results.
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PMID:Unexpected heterogeneity of BCR-ABL fusion mRNA detected by polymerase chain reaction in Philadelphia chromosome-positive acute lymphoblastic leukemia. 249 81


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