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)

The biological basis for the pleiotropic activity of extracellular human immunodeficiency virus (HIV)-1 Tat protein on lymphoid T cell survival is not well understood. We have here demonstrated that the addition in culture of 0.1-10 nM Tat protein to 36-h serum-starved lymphoblastoid Jurkat T cells rapidly stimulates the catalytic activity of phosphatidylinositol 3-kinase (PI 3-K). The peak of activation was observed 30 min after Tat addition. Extracellular Tat also stimulated the catalytic activity of the Akt/PKB kinase, a major target of PI 3-K lipid products. Pretreatment of serum-starved Jurkat cells with 100 nM wortmannin (WT) or 10 microM LY294002, two unrelated pharmacological inhibitors of PI 3-K, markedly suppressed the catalytic activity of both PI 3-K and Akt/PKB in Jurkat cells. Moreover, at low concentrations (0.1-1 nM), extracellular Tat showed a small but reproducible protection of Jurkat cells from apoptosis induced by serum deprivation (p < 0.05), while the combination of Tat plus 100 nM WT significantly (p < 0.05) increased the percentage of apoptosis with respect to cells left untreated or treated with Tat alone. Taken together, these data suggest that the anti-apoptotic activity of low concentrations of Tat protein on Jurkat cells is mediated by a PI 3-kinase/Akt pathway.
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PMID:Extracellular HIV-1 Tat protein activates phosphatidylinositol 3- and Akt/PKB kinases in CD4+ T lymphoblastoid Jurkat cells. 939 3

Isolation and sequencing of a genomic clone encoding the mouse gene for the relaxin-like factor (RLF), which is endogenously expressed to a high level exclusively in Leydig cells, indicated that similar sequences were also present at the 3' end of the mouse JAK3 gene, a gene expressed predominantly in lymphoid tissues. More extensive Southern blot, polymerase chain reaction and sequencing analyses showed that the published mouse sequence for exon 23 of the JAK3 gene in fact comprises two exons, 23A and 23B, separated by an additional novel intron of 2.2 kb, and that within this intron the promoter and exon 1 of the mouse RLF gene are encoded. The two overlapping transcripts appear to use different polyadenylation signals in the common 3' untranslated region of exon 23B. Transient transfection of different RLF promoter reporter constructs into Leydig, Sertoli, granulosa and kidney cell lines indicate that as little as 0.7 kb of the region upstream of exon 1 of the RLF gene, and within the novel intron 22 of the JAK3 gene, is sufficient to account for cell-specific expression of the RLF gene. This promoter region is specifically hypomethylated in Leydig cells compared to non-expressing tissues.
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PMID:The mouse relaxin-like factor gene and its promoter are located within the 3' region of the JAK3 genomic sequence. 942 31

The hallmark of chronic myeloid leukemia (CML) is the chimeric tyrosine kinase oncogene bcr-abl. Since expression of bcr-abl mRNA frequently increases with disease progression and a duplication of the Philadelphia chromosome (harbouring the bcr-abl hybrid locus) represents the most frequent karyotypic abnormality in acute phase CML, we hypothesized that the level of BCR-ABL protein may affect the disease phenotype. Therefore, the biological effects of high and low levels of BCR-ABL expression were compared in growth factor-dependent and -independent myeloid and lymphoid cell lines. Our results demonstrated that low levels of BCR - ABL were sufficient to render these cell lines growth factor independent and tumorigenic, but higher levels were mandatory for additional protection against apoptotic stimuli. The provision of growth factor or an activated ras oncogene did not afford the same degree of protection as high levels of BCR-ABL and there were qualitative differences between the survival signals mediated by BCR-ABL and Bcl-2. These results have enabled us to establish a dose-dependent hierarchy of BCR-ABL induced biological effects, thus distinguishing the activation of pathways mediating protection from cytokine withdrawal from those protecting against other apoptotic stimuli.
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PMID:BCR-ABL activates pathways mediating cytokine independence and protection against apoptosis in murine hematopoietic cells in a dose-dependent manner. 946 59

Chronic myeloid leukaemia (CML) develops when two genes, BCR on chromosome 22 and ABL on chromosome 9, recombine to form a hybrid BCR-ABL gene with leukaemogenic properties. The mechanism which underlies this recombination is unknown, but additional chromosome sites may be involved to form complex BCR-ABL rearrangements. The majority of breakpoints in BCR occur within a 5 kb major breakpoint cluster region, M-Bcr. Here, we show that the 3' part of M-Bcr recombined within, or immediately adjacent to, Alu elements at the additional sites in all five complex BCR-ABL rearrangements that have been examined so far. This is a new finding which suggests that Alu sequences have an affinity for the BCR-ABL recombination process in complex rearrangements, and provides additional evidence for the association of these elements with somatic rearrangements which cause human leukaemia. We further show that sequence motifs similar to IgH switch pentamers and consensus binding sites of the lymphoid-associated Translin protein are present on one or more participating strands at 3'M-Bcr recombination sites. Motifs similar to Translin-binding sites were also identified within the Alu consensus. Expressed sequences mapped close to the breakpoint sites on other chromosomes in three of the five cases examined.
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PMID:The BCR gene recombines preferentially with Alu elements in complex BCR-ABL translocations of chronic myeloid leukaemia. 953 79

Interleukin-2 (IL-2) is recognized as a T cell growth factor. We have previously reported that human carcinoma cell lines are inhibited in growth by exogenous IL-2, which binds to the IL-2 receptor beta (IL-2Rbeta) chain ubiquitously expressed on the surface of tumor cells. A possibility was considered that IL-2Rbeta on carcinomas responsible for negative signaling was different from that expressed on hematopoietic cells. To investigate this possibility, mRNA for the IL-2Rbeta chain was amplified and compared in carcinoma and lymphoid cells. Using RT-PCR with pairs of sense-antisense oligonucleotide primers specific for the various regions of extracellular, transmembrane and intracellular domains of the IL-2Rbeta chain, we amplified mRNA obtained from three human carcinoma cell lines and human lymphoid cells as controls. The identity of the amplicons was confirmed by Southern analysis with the 32P-labeled cDNA probe coding for the entire span of the IL-2Rbeta chain. In addition, genomic DNA obtained from the tumor cell lines was sequenced to examine the possibility that a mutation is present in the gene coding for the intracellular IL-2Rbeta chain domain. No mutations or deletions were detected. The message for all three domains of the beta chain was identical in tumor cells and in normal lymphoid cells used as controls. Also, by Western blot and northern analyses no differences between IL-2Rbeta chain in tumors vs that expressed in lymphoid cells were demonstrable. The IL-2Rgamma chain, which participates in IL-2/IL-2R signaling pathway, was expressed in tumor cells. Expression of JAK1 transcripts in these cells was comparable to that in lymphocytes. However, RT-PCR analysis identified differences in expression of JAK3 splice variants (B and M) in tumor cells. These differences may be responsible for altered downstream signaling by IL-2. Overall, our data indicate that the same IL-2/IL-2R pathway is operative in human carcinomas and in normal epithelial or lymphoid cells.
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PMID:Molecular analysis of the IL-2 receptor beta chain gene expressed in human tumor cells. 954 32

We have identified a novel cytoplasmic protein, leupaxin, that is preferentially expressed in hematopoietic cells and is most homologous to the focal adhesion protein, paxillin. Leupaxin possesses two types of protein interaction domains. There are four carboxyl-terminal LIM domains in leupaxin that share 70% amino acid identity and 80% similarity with those in paxillin. Paxillin LIM domains mediate localization to focal contacts. In the amino-terminal region of leupaxin there are three short stretches of approximately 13 amino acids that share 70-90% similarity with paxillin LD motifs. Paxillin LD motifs have been implicated in focal adhesion kinase (FAK) and vinculin binding resulting in the localization of FAK to focal adhesions. Leupaxin is expressed in cell types, such as macrophage, that lack FAK. We demonstrate here that leupaxin associates with a second FAK family member, PYK2. As leupaxin and PYK2 are both preferentially expressed in leukocytes they may therefore form a cell type-specific signaling complex. We also demonstrate that leupaxin is a substrate for a tyrosine kinase in lymphoid cells and thus may function in and be regulated by tyrosine kinase activity. Leupaxin is thus a phosphotyrosine protein with LD and LIM binding motifs most homologous to paxillin that may assemble and regulate PYK2 signaling complexes in leukocytes.
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PMID:Leupaxin is a novel LIM domain protein that forms a complex with PYK2. 956 92

HEF1, p130(Cas), and Efs/Sin constitute a family of multidomain docking proteins that have been implicated in coordinating the regulation of cell adhesion. Each of these proteins contains an SH3 domain, conferring association with focal adhesion kinase; a domain rich in SH2-binding sites, phosphorylated by or associating with a number of oncoproteins, including Abl, Crk, Fyn, and others; and a highly conserved carboxy-terminal domain. In this report, we show that the HEF1 protein is processed in a complex manner, with transfection of a single cDNA resulting in the generation of at least four protein species, p115(HEF1), p105(HEF1), p65(HEF1), and p55(HEF1). We show that p115(HEF1) and p105(HEF1) are different phosphorylation states of the full-length HEF1. p55(HEF1), however, encompasses only the amino-terminal end of the HEF1 coding sequence and arises via cleavage of full-length HEF1 at a caspase consensus site. We find that HEF1 proteins are abundantly expressed in epithelial cells derived from breast and lung tissue in addition to the lymphoid cells in which they have been predominantly studied to date. In MCF-7 cells, we find that expression of the endogenous HEF1 proteins is cell cycle regulated, with p105(HEF1) and p115(HEF1) being rapidly upregulated upon induction of cell growth, whereas p55(HEF1) is produced specifically at mitosis. While p105(HEF1) and p115(HEF1) are predominantly cytoplasmic and localize to focal adhesions, p55(HEF1) unexpectedly is shown to associate with the mitotic spindle. In support of a role at the spindle, two-hybrid library screening with HEF1 identifies the human homolog of the G2/M spindle-regulatory protein Dim1p as a specific interactor with a region of HEF1 encompassed in p55(HEF1). In sum, these data suggest that HEF1 may directly connect morphological control-related signals with cell cycle regulation and thus play a role in pathways leading to the progression of cancer.
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PMID:Cell cycle-regulated processing of HEF1 to multiple protein forms differentially targeted to multiple subcellular compartments. 958 94

Acute lymphocytic leukemia (ALL) is considered a clonal disease restricted to the lymphoid compartment. The Philadelphia chromosome (Ph) is found in a subset of ALL with poor prognosis. Here we present the largest series of Ph+ ALL analyzed for involvement of the myeloid compartment. For the first time at a single cell level the presence of Ph in lineages other than lymphoid is demonstrated. Granulocytes from nine patients diagnosed with BCR-ABL + ALL (eight Ph+, one Ph-) were purified using two layer density gradient separation. They were further identified by the morphology of DAPI-stained nuclei and studied for the presence of the Ph by fluorescence in situ hybridization (FISH) using a BCR-ABL dual-color probe. Ph was demonstrated in 30 to 93% of granulocytes in all patients. FISH identified major and minor BCR gene breakpoints (M-bcr and m-bcr). In one patient, with CD19+/34+/33-/2-/3-/7-/10- lymphoblasts, involvement of B cells (CD19+), T cells (CD3+), myeloid (CD13+), erythroid (glycophorin A+) cells was found by FISH following fluorescence-activated cell sorting (FACS). The diagnosis of ALL as opposed to lymphoblastic transformation of CML was established based on clinical and laboratory data including Western blot results demonstrating the presence of p190/m-bcr in five of the nine cases studied. Results suggest that Ph+ ALL originates from a pluripotent stem cell.
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PMID:Multilineage involvement of Philadelphia chromosome positive acute lymphoblastic leukemia. 959 63

The cytoplasmic protein tyrosine kinase Syk has two amino-terminal SH2 domains that engage phosphorylated immunoreceptor tyrosine-based activation motifs in the signaling subunits of immunoreceptors. Syk, in conjunction with Src family kinases, has been implicated in immunoreceptor signaling in both lymphoid and myeloid cells. We have investigated the role of Syk in Fcgamma receptor (FcgammaR)-dependent and -independent responses in bone marrow-derived macrophages and neutrophils by using mouse radiation chimeras reconstituted with fetal liver cells from Syk-/- embryos. Chimeric mice developed an abdominal hemorrhage starting 2 to 3 months after transplantation that was ultimately lethal. Syk-deficient neutrophils derived from the bone marrow were incapable of generating reactive oxygen intermediates in response to FcgammaR engagement but responded normally to tetradecanoyl phorbol acetate stimulation. Syk-deficient macrophages were defective in phagocytosis induced by FcgammaR but showed normal phagocytosis in response to complement. The tyrosine phosphorylation of multiple cellular polypeptides, including the FcgammaR gamma chain, as well as Erk2 activation, was compromised in Syk-/- macrophages after FcgammaR stimulation. In contrast, the induction of nitric oxide synthase in macrophages stimulated with lipopolysaccharide and gamma interferon was not dependent on Syk. Surprisingly, Syk-deficient macrophages were impaired in the ability to survive or proliferate on plastic petri dishes. Taken together, these results suggest that Syk has specific physiological roles in signaling from FcgammaRs in neutrophils and macrophages and raise the possibility that in vivo, Syk is involved in signaling events other than those mediated by immunoreceptors.
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PMID:The Syk protein tyrosine kinase is essential for Fcgamma receptor signaling in macrophages and neutrophils. 963 5

Exposure of B-lineage lymphoid cells to ionizing radiation induces an elevation of c-jun proto-oncogene mRNA levels. This signal is abrogated by protein-tyrosine kinase (PTK) inhibitors, indicating that activation of an as yet unidentified PTK is mandatory for radiation-induced c-jun expression. Here, we provide experimental evidence that the cytoplasmic tyrosine kinases BTK, SYK, and LYN are not required for this signal. Lymphoma B-cells rendered deficient for LYN, SYK, or both by targeted gene disruption showed increased c-jun expression levels after radiation exposure, but the magnitude of the stimulation was lower than in wild-type cells. Thus, these PTKs may participate in the generation of an optimal signal. Notably, an inhibitor of JAK-3 (Janus family kinase-3) abrogated radiation-induced c-jun activation, prompting the hypothesis that a chicken homologue of JAK-3 may play a key role in initiation of the radiation-induced c-jun signal in B-lineage lymphoid cells.
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PMID:Role of tyrosine kinases in induction of the c-jun proto-oncogene in irradiated B-lineage lymphoid cells. 965 74


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