Differential regulatory effects of the N-terminal region in SYK-fusion kinases reveal unique activation-inducible nuclear translocation of ITK-SYK.

ITK-SYK and TEL-SYK (also known as ETV6-SYK) are human tumor-causing chimeric proteins containing the kinase region of SYK, and the membrane-targeting, N-terminal, PH-TH domain-doublet of ITK or the dimerizing SAM-PNT domain of TEL, respectively. ITK-SYK causes peripheral T cell lymphoma, while TEL-SYK was reported in myelodysplastic syndrome. BTK is a kinase highly related to ITK and to further delineate the role of the N-terminus, we generated the corresponding fusion-kinase BTK-SYK.

Specific properties of shRNA-mediated CCR5 downregulation that enhance the inhibition of HIV-1 infection in combination with shRNA targeting HIV-1 rev.

Treatment with RNAi against HIV-1 transcripts efficiently inhibits viral replication but induces selection of escape mutants; therefore, the CCR5 coreceptor was suggested as an additional target. Blocking viral and host transcripts improved the antiviral effect. We have used short hairpin RNA (shRNA) targeting the human CCR5 (shCCR5) or the HIV-1 rev (shRev) transcripts to demonstrate distinctive properties of anti-CCR5 shRNA: shCCR5 induced more sustained protection than shRev; partial reduction in CCR5 expression substantially decreased HIV-1 infection, and shCCR5 performed better than shRev in the mixed shRNA-treated and untreated cultures.

Protein kinase B (AKT) regulates SYK activity and shuttling through 14-3-3 and importin 7.

The Protein kinase B (AKT) regulates a plethora of intracellular signaling proteins to fine-tune signaling of multiple pathways. Here, we found that following B-cell receptor (BCR)-induced tyrosine phosphorylation of the cytoplasmic tyrosine kinase SYK and the adaptor BLNK, the AKT/PKB enzyme strongly induced BLNK (>100-fold) and SYK (>100-fold) serine/threonine phosphorylation (pS/pT). Increased phosphorylation promoted 14-3-3 binding to BLNK (37-fold) and SYK (2.

A murine model of acute myeloid leukemia with Evi1 overexpression and autocrine stimulation by an intracellular form of GM-CSF in DA-3 cells.

The poor treatment response of acute myeloid leukemia (AML) overexpressing high-risk oncogenes such as EVI1, demands specific animal models for new treatment evaluations. Evi1 is a common site of activating integrations in murine leukemia virus (MLV)-induced AML and in retroviral and lentiviral gene-modified HCS. Still, a model of overt AML induced by Evi1 has not been generated.

Dual phosphorylation of Btk by Akt/protein kinase b provides docking for 14-3-3ζ, regulates shuttling, and attenuates both tonic and induced signaling in B cells.

Bruton's tyrosine kinase (Btk) is crucial for B-lymphocyte activation and development. Mutations in the Btk gene cause X-linked agammaglobulinemia (XLA) in humans and X-linked immunodeficiency (Xid) in mice. Using tandem mass spectrometry, 14-3-3ζ was identified as a new binding partner and negative regulator of Btk in both B-cell lines and primary B lymphocytes.

Signaling of the ITK (interleukin 2-inducible T cell kinase)-SYK (spleen tyrosine kinase) fusion kinase is dependent on adapter SLP-76 and on the adapter function of the kinases SYK and ZAP70.

The inducible T cell kinase-spleen tyrosine kinase (ITK-SYK) oncogene consists of the Tec homology-pleckstrin homology domain of ITK and the kinase domain of SYK, and it is believed to be the cause of peripheral T cell lymphoma. We and others have recently demonstrated that this fusion protein is constitutively tyrosine-phosphorylated and is transforming both in vitro and in vivo. To gain a deeper insight into the molecular mechanism(s) underlying its activation and signaling, we mutated a total of eight tyrosines located in the SYK portion of the chimera into either phenylalanine or to the negatively charged glutamic acid.

Regulation of nucleocytoplasmic shuttling of Bruton's tyrosine kinase (Btk) through a novel SH3-dependent interaction with ankyrin repeat domain 54 (ANKRD54).

Bruton's tyrosine kinase (Btk), belonging to the Tec family of tyrosine kinases (TFKs), is essential for B-lymphocyte development. Abrogation of Btk signaling causes human X-linked agammaglobulinemia (XLA) and murine X-linked immunodeficiency (Xid). We employed affinity purification of Flag-tagged Btk, combined with tandem mass spectrometry, to capture and identify novel interacting proteins.

TEC family kinases in health and disease--loss-of-function of BTK and ITK and the gain-of-function fusions ITK-SYK and BTK-SYK.

The TEC family is ancient and constitutes the second largest family of cytoplasmic tyrosine kinases. In 1993, loss-of-function mutations in the BTK gene were reported as the cause of X-linked agammaglobulinemia. Of all the existing 90 tyrosine kinases in humans, Bruton's tyrosine kinase (BTK) is the kinase for which most mutations have been identified.

Phosphatidylinositol-3-kinase-dependent phosphorylation of SLP-76 by the lymphoma-associated ITK-SYK fusion-protein.

Recurrent chromosomal translocations have long been implicated in various types of lymphomas and other malignancies. Novel recurrent t(5;9)(q33;q22) has been recently discovered in un-specified peripheral T-cell lymphoma. To elucidate the role of this translocation, the corresponding fusion construct encoding the N-terminal portion of the ITK kinase and the C-terminal catalytic region of the SYK kinase was generated.

NF-kappaB regulates the transcription of protein tyrosine kinase Tec.

The tyrosine kinase expressed in hepatocellular carcinoma (Tec) is a non-receptor protein tyrosine kinase (PTK) that is expressed in hematopoietic cells, such as B and T lymphocytes, myeloid lineage cells and neutrophils. Mutations in the human Btk gene cause X-linked agammaglobulinemia (XLA), but the corresponding mutation in mice results in a much milder defect. However, the combined inactivation of Btk and Tec genes in mice cause a severe phenotype resembling XLA.

Proteasome inhibitors block HIV-1 replication by affecting both cellular and viral targets.

HIV-1 has proved to be notoriously difficult to tackle despite the availability of more than 20 clinically approved drugs. The majority of these drugs, however, target viral genes and their continued use will select for drug-resistant strains. Since NF-kappaB signaling is critical for viral replication, we wanted to investigate the effect of proteasome inhibitors on viral gene expression.

Bruton's tyrosine kinase (Btk): function, regulation, and transformation with special emphasis on the PH domain.

Bruton's agammaglobulinemia tyrosine kinase (Btk) is a cytoplasmic tyrosine kinase important in B-lymphocyte development, differentiation, and signaling. Btk is a member of the Tec family of kinases. Mutations in the Btk gene lead to X-linked agammaglobulinemia (XLA) in humans and X-linked immunodeficiency (Xid) in mice.

Proteasome-dependent autoregulation of Bruton tyrosine kinase (Btk) promoter via NF-kappaB.

Bruton tyrosine kinase (Btk) is critical for B-cell development. Btk regulates a plethora of signaling proteins, among them nuclear factor-[kappa]B (NF-kappaB). Activation of NF-kappaB is a hallmark of B cells, and NF-kappaB signaling is severely compromised in Btk deficiency.

Sequence-specific inhibition of RNA polymerase III-dependent transcription using Zorro locked nucleic acid (LNA).

Background: RNA polymerase III (pol III)-dependent transcripts are involved in many fundamental activities in a cell, such as splicing and protein synthesis. They also regulate cell growth and influence tumor formation. During recent years vector-based systems for expression of short hairpin (sh) RNA under the control of a pol III promoter have been developed as gene-based medicines.

Zorro locked nucleic acid induces sequence-specific gene silencing.

Locked nucleic acids (LNAs) are synthetic analogs of nucleic acids that contain a bridging methylene carbon between the 2' and 4' positions of the ribose ring. In this study, we generated a novel sequence-specific antigene molecule "Zorro LNA", which simultaneously binds to both strands, and that induced effective and specific strand invasion into DNA duplexes and potent inhibition of gene transcription, also in a cellular context. By comparing the Zorro LNA with linear LNA as well as an optimized bisPNA (peptide nucleic acid) oligonucleotide directed against the same target sites, respectively, we found that the Zorro LNA construct was unique in its ability to arrest gene transcription in mammalian cells.

Regulation of Bruton tyrosine kinase by the peptidylprolyl isomerase Pin1.

Bruton tyrosine kinase (Btk) is expressed in B-lymphocytes. Mutations in Btk cause X-linked agammaglobulinemia in humans. However, the mechanism of activation and signaling of this enzyme has not been fully investigated.

Inducible H1 promoter-driven lentiviral siRNA expression by Stuffer reporter deletion.

Introduction of 19-23-bp small interfering RNA (siRNA) into mammalian cells has become a standard procedure to downregulate mRNA with high efficacy. siRNAs can be introduced into cells either as synthetic duplexes or as hairpin structures produced by Pol III promoter-driven vectors. Pol III promoter-expressed small hairpin RNAs (shRNAs) offer a great possibility for the production of endogenous siRNA, which can be used for stable siRNA production in vivo.

Bruton's tyrosine kinase: cell biology, sequence conservation, mutation spectrum, siRNA modifications, and expression profiling.

Bruton's tyrosine kinase (Btk) is encoded by the gene that when mutated causes the primary immunodeficiency disease X-linked agammaglobulinemia (XLA) in humans and X-linked immunodeficiency (Xid) in mice. Btk is a member of the Tec family of protein tyrosine kinases (PTKs) and plays a vital, but diverse, modulatory role in many cellular processes. Mutations affecting Btk block B-lymphocyte development.

Functional interaction of caveolin-1 with Bruton's tyrosine kinase and Bmx.

Bruton's tyrosine kinase (Btk), a member of the Tec family of protein-tyrosine kinases, has been shown to be crucial for B cell development, differentiation, and signaling. Mutations in the Btk gene lead to X-linked agammaglobulinemia in humans and X-linked immunodeficiency in mice. Using a co-transfection approach, we present evidence here that Btk interacts physically with caveolin-1, a 22-kDa integral membrane protein, which is the principal structural and regulatory component of caveolae membranes.