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)

Expression of the 93-kd tyrosine kinase encoded by the human c-fes proto-oncogene (also known as FES) is restricted to mature hematopoietic cells of the granulocytic and monocytic lineages, suggestive of a function essential to normal myeloid differentiation. However, recent studies have shown that c-fes can transform fibroblasts if sufficient levels of gene expression are achieved. These findings indicate that strict regulation of the c-fes gene is critical to normal myeloid development, whereas elevated c-fes expression may contribute to malignant transformation. In the present study, we compared the c-fes messenger RNA (mRNA) levels in leukemia blasts from patients with myeloid or lymphoid leukemia with those of peripheral monocytes from a normal donor with the use of a quantitative ribonuclease protection assay. The presence of c-fes mRNA was readily detected in both acute myeloid leukemia (AML) and chronic myeloid leukemia (CML) cells, but c-fes mRNA was present in low levels or was absent in lymphoid leukemia cells. The leukemia cells of two of five AML patients and four of four CML patients expressed more c-fes mRNA than monocytes from a normal donor, with more than a threefold elevation in the cells of one CML patient. No evidence of amplification or rearrangement of the c-fes gene was detectable by Southern blot analysis of myeloid leukemia DNA, suggesting that the variation in c-fes mRNA levels are related to differences in transcriptional activity and/or message stability. These results indicate that elevated c-fes expression is a common feature of myeloid leukemia cells that could potentially contribute to the leukemia phenotype.
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PMID:Elevated expression of the c-fes proto-oncogene in adult human myeloid leukemia cells in the absence of gene amplification. 198 16

A monoclonal antibody from clone T7 raised against total nuclear proteins from the Kc cell line of Drosophila melanogaster (Saumweber, H. Symmons. P. Kabisch, R. Will, H & Bonhoeffer, F, Chromosoma 80 (1980) 253) [1] showed positive immunofluorescent staining on interphase nuclei of HeLa and PTK2 cells. When this antibody was allowed to react with several nuclear protein fractions isolated from HeLa S3 cells, three polypeptides of molecular weights (MW) 44 000, 63 000 and 70 000 were identified as the corresponding antigens, all components of hnRNA containing ribonucleoprotein particles. Sucrose gradient fractionation of such particles after mild RNase treatment and subsequent analysis of the proteins by the immunoblotting method revealed that the 44 000 MW antigen was an integral part of the ribonuclease-resistant complex. The results support the view that hnRNA molecules are associated with certain proteins conserved during evolution which may play structural roles in the ribonucleoprotein organization.
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PMID:Cross-reaction of hnRNP-proteins of HeLa cells with nuclear proteins of Drosophila melanogaster demonstrated by a monoclonal antibody. 681 36

Recently, we and others have cloned cDNAs encoding a second member of the Csk family of inhibitory tyrosine protein kinases, which we have termed Ntk. Intriguingly, the mouse ntk cDNA sequences published by two independent groups differed by the presence or absence of a 136 nucleotide-insert near their 5' ends. In this report, we demonstrate that this 136 nucleotide-sequence likely corresponds to a complete exon in the ntk gene (termed exon 2), and that the two types of cDNAs/transcripts are produced by alternative splicing. Using ribonuclease protection assays, it was also established that brain and lymphoid organs, as well as most hemopoietic cells, predominantly expressed ntk transcripts lacking exon 2. In contrast, selected hemopoietic cell lines, such as the immature myeloid cell lines 32D cl3(G) and WEHI-3B, exclusively possessed exon 2-bearing RNAs. Interestingly, exon 2 introduced a novel in-frame upstream AUG in the ntk transcript, which is in the appropriate context for translation initiation. Evidence was obtained that this AUG is utilized in vivo, and that it extends the amino-terminal sequence of Ntk by 40 amino acids. Indeed, while exon 2-deficient ntk RNAs were translated into a 52 kilodalton (kDa) polypeptide (p52ntk), those bearing exon 2 produced a 56 kDa protein (p56ntk). Furthermore, p56ntk, but not p52ntk, was recognized by an antiserum directed against the novel amino-terminal sequence encoded by exon 2. Additional biochemical characterizations showed that p52ntk and p56ntk were localized to the cytoplasm, and that they partially accumulated in the detergent-insoluble cellular fraction. This last finding suggested that the Ntk proteins can associate with the cytoskeleton. Finally, through linkage analysis of two multilocus crosses, the ntk gene was mapped to Chromosome 10 in the mouse. Taken together, these data showed that ntk, a csk-related tyrosine protein kinase gene, encodes two protein isoforms expressed in distinct cell types. Moreover, they raised the possibility that Ntk may be involved in the regulation of Src-like enzymes in detergent-insoluble cellular compartments.
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PMID:Two distinct protein isoforms are encoded by ntk, a csk-related tyrosine protein kinase gene. 797 Jul 3

The sodium-hydrogen exchanger (NHE) has been implicated in bone resorption by osteoclasts. We have studied expression of NHE-1, an isoform of the NHE, in chicken bone marrow mononuclear phagocyte precursors during differentiation into the osteoclast phenotype in culture. A monoclonal anti-body raised against the carboxy-terminus of NHE-1 detected the presence of a 100 kDa protein (similar to the mammalian form of NHE-1) in the osteoclasts. Laser scanning confocal microscopy revealed association with the alpha(v)beta(3) integrin and focal adhesion kinase (pp(125)FAK) at the basolateral membrane (BLM) of the osteoclast in addition to a more generalized cellular distribution. A fragment of avian NHE-1 cDNA was obtained by polymerase chain reaction cloning, and it was used to characterize expression of NHE-1 transcripts in cultured chicken osteoclast precursors. The avian NHE-1 message was a 3.9 kB band on Northern analysis, which differed from the mammalian message. Retinoic acid (RA) elicited an increase in the steady-state intracellular pH (pH(1)) from 6.87 to 7.10 in the absence of bicarbonate and was inhibited by ethylisopropylamiloride, an inhibitor of Na-H exchange. Using ribonuclease protection assays, we found that NHE-1 transcripts are induced as cells differentiate in vitro and in response to 13-cis-RA. Western blot analysis indicated that protein levels also increased in response to 13-cis-RA. Our results demonstrate expression of NHE-1 in avian osteoclasts with a complex cellular distribution in culture, and NHE-1 expression is induced as cells differentiate into mature osteoclasts in response to 13-cis-RA.
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PMID:Cellular distribution and regulation of NHE-1 isoform of the NA-H exchanger in the avian osteoclast. 883 1

Resistance to hormonal therapy is often a problem in the treatment of breast cancer patients. It has been suggested that resistance could be explained by altered nuclear hormone receptor or coregulator levels or inappropriately increased agonist activity of selective estrogen receptor modulator (SERM). To test these hypotheses, we have established novel MCF-7 cell line-derived in vitro models of anti-estrogen- and progestin-resistant and estrogen-independent breast cancer by long-term culture in the presence of toremifene and medroxyprogesterone acetate (MPA) and in the absence of estradiol, respectively. Using cell growth and multiprobe ribonuclease protection assays, the expression of 5 nuclear hormone receptors and 9 coregulators as well as the alterations in the cell proliferation and target gene transcription in response to hormonal treatments were studied. Progesterone receptor (PR) expression was decreased and silencing mediator for retinoid acid and thyroid hormone receptors (SMRT) and amplified in breast cancer-1 (AIB1) expression increased in anti-estrogen-resistant cells. Estrogen caused PR and ERbeta upregulation in all cell lines, but we did not observe increased agonist activity of anti-estrogen measured by regulation of these estrogen target genes. Basal ERalpha levels and estrogenic growth response were decreased and p300/CBP-associated factor (pCAF) and AIB1 upregulated by estrogen in progestin-resistant cells, but coregulator levels were unchanged. Estrogen-independent cells were still estrogen-responsive and PR, nuclear receptor corepressor (N-CoR) and SMRT expression was increased whereas steroid receptor coactivator-1 (SRC-1a) and CBP-related protein p300 (p300) expression decreased. Their growth was inhibited by toremifene, but estradiol was able to abrogate this effect, which might have interesting clinical implications concerning the use of postmenopausal hormone replacement therapy.
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PMID:Steroid hormone receptors and coregulators in endocrine-resistant and estrogen-independent breast cancer cells. 1615 93

Dicer is an essential ribonuclease involved in the biogenesis of miRNAs. Previous studies have reported downregulation of Dicer in multiple cancers including hepatocellular carcinoma. To identify signaling pathways that are altered upon Dicer depletion, we carried out quantitative phosphotyrosine profiling of liver tissue from Dicer knockout mice. We employed antibody-based enrichment of phosphotyrosine containing peptides coupled with SILAC spike-in approach for quantitation. High resolution mass spectrometry-based analysis identified 349 phosphotyrosine peptides corresponding to 306 unique phosphosites of which 75 were hyperphosphorylated and 78 were hypophosphorylated. Several receptor tyrosine kinases including MET, PDGF receptor alpha, Insulin-like growth factor 1 and Insulin receptor as well as non-receptor tyrosine kinases such as Src family kinases were found to be hyperphosphorylated upon depletion of Dicer. In addition, signaling molecules such as IRS-2 and STAT3 were hyperphosphorylated. Activation of these signaling pathways has been implicated previously in various types of cancers. Interestingly, we observed hypophosphorylation of molecules including focal adhesion kinase and paxillin. Our study profiles the perturbed signaling pathways in response to dysregulated miRNAs resulting from depletion of Dicer. Our findings warrant further studies to investigate oncogenic effects of downregulation of Dicer in cancers.
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PMID:Ablation of Dicer leads to widespread perturbation of signaling pathways. 2603 4

The DNA damage response network stimulates microRNA (miRNA) biogenesis to coordinate repair, cell cycle checkpoints, and apoptosis. The multistep process of miRNA biogenesis involves the cleavage of primary miRNAs by the microprocessor complex composed of the ribonuclease Drosha and the RNA binding protein DGCR8. We found that the tyrosine kinase ABL phosphorylated DGCR8, a modification that was required for the induction of a subset of miRNAs after DNA damage. Focusing on the miR-34 family, ABL stimulated the production of miR-34c, but not miR-34a, through Drosha/DGCR8-dependent processing of primary miR-34c (pri-miR-34c). This miRNA-selective effect of ABL required the sequences flanking the precursor miR-34c (pre-miR-34c) stem-loop. In pri-miRNA processing, DGCR8 binds the pre-miR stem-loop and recruits Drosha to the miRNA. RNA cross-linking assays showed that DGCR8 and Drosha interacted with pri-miR-34c, but we found an inverse correlation between ABL-stimulated processing and DGCR8 association with pri-miR-34c. When coexpressed in HEK293T cells, ABL phosphorylated DGCR8 at Tyr(267). Ectopic expression of a Y267F-DGCR8 mutant reduced the recruitment of Drosha to pri-miR-34c and prevented ABL or Drosha from stimulating the processing of pri-miR-34c. In mice engineered to express a nuclear import-defective mutant of ABL, miR-34c, but not miR-34a, expression was reduced in the kidney, and apoptosis of the renal epithelial cells was impaired in response to cisplatin. These results reveal a new pathway in the DNA damage response wherein ABL-dependent tyrosine phosphorylation of DGCR8 stimulates the processing of selective primary miRNAs.
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PMID:The kinase ABL phosphorylates the microprocessor subunit DGCR8 to stimulate primary microRNA processing in response to DNA damage. 2612 15

Ribonuclease L (RNase-L) is an endoribonuclease well known for its roles in innate immunity. Recently it has been shown to regulate several cellular functions by modulating the levels of specific mRNAs. In this study, we investigated whether RNase-L may regulate adipocyte functions. We showed that knockdown of RNase-L reduced 3T3-L1 adipocyte differentiation and lipid accumulation. After mRNA profiling, we found that upregulation of Pref-1 mRNA, an inhibitory regulator of adipogenesis, could explain the reduced adipocyte differentiation with RNase-L downregulation. The signaling molecules downstream to Pref-1, including focal adhesion kinase, extracellular signal-regulated kinases and SRY-box 9, were activated by RNase-L suppression. The presence of Pref-1 mRNA was detected in the mRNP complexes precipitated by anti-RNase-L antibody. Moreover, the Pref-1 mRNA decay rate was raised by elevated RNase-L ribonuclease activity. Finally, in stable cell clones with RNase-L silencing, suppression of Pref-1 mRNA by specific siRNA partially recovered the adipocyte differentiation phenotype. Consistent with our findings, meta-analysis of 45 public array datasets from seven independent studies showed a significant negative relationship between RNase-L and Pref-1 mRNA levels in mouse adipose tissues. Higher RNase-L and lower Pref-1 mRNAs were found in the adipose tissues of high-fat diet mice compared to those of ND mice. In line with this, our animal data also showed that the adipose tissues of obese rats contained higher RNase-L and lower Pref-1 expression in comparison to that of lean rats. This study demonstrated that Pref-1 mRNA is a novel substrate of RNase-L. RNase-L is involved in adipocyte differentiation through destabilizing Pref-1 mRNA, thus offering a new link among RNA metabolism, innate immunity and adipogenesis in obesity progression.
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PMID:A link between adipogenesis and innate immunity: RNase-L promotes 3T3-L1 adipogenesis by destabilizing Pref-1 mRNA. 2783 65

Oncoprotein staphylococcal nuclease and tudor domain containing 1 (SND1) regulates gene expression at a posttranscriptional level in multiple cancers, including hepatocellular carcinoma (HCC). Staphylococcal nuclease (SN) domains of SND1 function as a ribonuclease (RNase), and the tudor domain facilitates protein-oligonucleotide interaction. In the present study, we aimed to identify RNA interactome of SND1 to obtain enhanced insights into gene regulation by SND1. RNA interactome was identified by immunoprecipitation (IP) of RNA using anti-SND1 antibody from human HCC cells followed by RNA immunoprecipitation sequencing (RIP-Seq). Among RNA species that showed more than 10-fold enrichment over the control, we focused on the tumor suppressor protein tyrosine phosphatase nonreceptor type 23 (PTPN23) because its regulation by SND1 and its role in HCC are not known. PTPN23 levels were down-regulated in human HCC cells versus normal hepatocytes and in human HCC tissues versus normal adjacent liver, as revealed by immunohistochemistry. In human HCC cells, knocking down SND1 increased and overexpression of SND1 decreased PTPN23 protein. RNA binding and degradation assays revealed that SND1 binds to and degrades the 3'-untranslated region (UTR) of PTPN23 messenger RNA (mRNA). Tetracycline-inducible PTPN23 overexpression in human HCC cells resulted in significant inhibition in proliferation, migration, and invasion and in vivo tumorigenesis. PTPN23 induction caused inhibition in activation of tyrosine-protein kinase Met (c-Met), epidermal growth factor receptor (EGFR), Src, and focal adhesion kinase (FAK), suggesting that, as a putative phosphatase, PTPN23 inhibits activation of these oncogenic kinases. Conclusion: PTPN23 is a novel target of SND1, and our findings identify PTPN23 as a unique tumor suppressor for HCC. PTPN23 might function as a homeostatic regulator of multiple kinases, restraining their activation.
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PMID:Posttranscriptional Inhibition of Protein Tyrosine Phosphatase Nonreceptor Type 23 by Staphylococcal Nuclease and Tudor Domain Containing 1: Implications for Hepatocellular Carcinoma. 3149 46

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