LMTK3 confers chemo-resistance in breast cancer

Lemur tyrosine kinase 3 (LMTK3) is an oncogenic kinase that is involved in different types of cancer (breast, lung, gastric, colorectal) and biological processes including proliferation, invasion, migration, chromatin remodeling as well as innate and acquired endocrine resistance. However, the role of LMTK3 in response to cytotoxic chemotherapy has not been investigated thus far. Using both 2D and 3D tissue culture models, we found that overexpression of LMTK3 decreased the sensitivity of breast cancer cell lines to cytotoxic (doxorubicin) treatment. In a mouse model we showed that ectopic overexpression of LMTK3 decreases the efficacy of doxorubicin in reducing tumor growth. Interestingly, breast cancer cells overexpressing LMTK3 delayed the generation of double strand breaks (DSBs) after exposure to doxorubicin, as measured by the formation of γH2AX foci. This effect was at least partly mediated by decreased activity of ataxia-telangiectasia mutated kinase (ATM) as indicated by its reduced phosphorylation levels. In addition, our RNA-seq analyses showed that doxorubicin differentially regulated the expression of over 700 genes depending on LMTK3 protein expression levels. Furthermore, these genes were found to promote DNA repair, cell viability and tumorigenesis processes / pathways in LMTK3-overexpressing MCF7 cells. In human cancers, immunohistochemistry staining of LMTK3 in pre- and postchemotherapy breast tumor pairs from four separate clinical cohorts revealed a significant increase of LMTK3 following both doxorubicin and docetaxel based chemotherapy. In aggregate, our findings show for the first time a contribution of LMTK3 in cytotoxic drug resistance in breast cancer

The B-Cell Specific Transcription Factor, Oct-2, Promotes Epstein-Barr Virus Latency by Inhibiting the Viral Immediate-Early Protein, BZLF1

The Epstein-Barr virus (EBV) latent-lytic switch is mediated by the BZLF1 immediate-early protein. EBV is normally latent in memory B cells, but cellular factors which promote viral latency specifically in B cells have not been identified. In this report, we demonstrate that the B-cell specific transcription factor, Oct-2, inhibits the function of the viral immediate-early protein, BZLF1, and prevents lytic viral reactivation. Co-transfected Oct-2 reduces the ability of BZLF1 to activate lytic gene expression in two different latently infected nasopharyngeal carcinoma cell lines. Furthermore, Oct-2 inhibits BZLF1 activation of lytic EBV promoters in reporter gene assays, and attenuates BZLF1 binding to lytic viral promoters in vivo. Oct-2 interacts directly with BZLF1, and this interaction requires the DNA-binding/dimerization domain of BZLF1 and the POU domain of Oct-2. An Oct-2 mutant (Δ262–302) deficient for interaction with BZLF1 is unable to inhibit BZLF1-mediated lytic reactivation. However, an Oct-2 mutant defective for DNA-binding (Q221A) retains the ability to inhibit BZLF1 transcriptional effects and DNA-binding. Importantly, shRNA-mediated knockdown of endogenous Oct-2 expression in several EBV-positive Burkitt lymphoma and lymphoblastoid cell lines increases the level of lytic EBV gene expression, while decreasing EBNA1 expression. Moreover, treatments which induce EBV lytic reactivation, such as anti-IgG cross-linking and chemical inducers, also decrease the level of Oct-2 protein expression at the transcriptional level. We conclude that Oct-2 potentiates establishment of EBV latency in B cells

Debranching of brachiocephalic trunk of DeBakey Type-I AoD followed by emergency TEVAR for subsequent aorto-esophageal fistula”- report of a case

10.13140/RG.2.1.3117.768424th Annual Congress Association of Thoracic and Cardiovascular Surgeons of Asia (ATCSA 2014

N-Acetylcysteine's Renoprotective Effect in Cardiac Surgery: A Systematic Review and Meta-Analysis

10.5761/atcs.oa.21-00132ANNALS OF THORACIC AND CARDIOVASCULAR SURGERY282138-14

Usp12 stabilizes the T-cell receptor complex at the cell surface during signaling

Posttranslational modifications are central to the spatial and temporal regulation of protein function. Among others, phosphorylation and ubiquitylation are known to regulate proximal T-cell receptor (TCR) signaling. Here we used a systematic and unbiased approach to uncover deubiquitylating enzymes (DUBs) that participate during TCR signaling in primary mouse T lymphocytes. Using a C-terminally modified vinyl methyl ester variant of ubiquitin (HA-Ub-VME), we captured DUBs that are differentially recruited to the cytosol on TCR activation. We identified ubiquitin-specific peptidase (Usp) 12 and Usp46, which had not been previously described in this pathway. Stimulation with anti-CD3 resulted in phosphorylation and time-dependent translocation of Usp12 from the nucleus to the cytosol. Usp12(-/-) Jurkat cells displayed defective NFκB, NFAT, and MAPK activities owing to attenuated surface expression of TCR, which were rescued on reconstitution of wild type Usp12. Proximity-based labeling with BirA-Usp12 revealed several TCR adaptor proteins acting as interactors in stimulated cells, of which LAT and Trat1 displayed reduced expression in Usp12(-/-) cells. We demonstrate that Usp12 deubiquitylates and prevents lysosomal degradation of LAT and Trat1 to maintain the proximal TCR complex for the duration of signaling. Our approach benefits from the use of activity-based probes in primary cells without any previous genome modification, and underscores the importance of ubiquitin-mediated regulation to refine signaling cascade

Cell surface alpha 2,3-linked sialic acid facilitates Zika virus internalization

10.1080/22221751.2019.1590130EMERGING MICROBES & INFECTIONS81426-43

No Evidence That Soluble TACI Induces Signalling via Membrane-Expressed BAFF and APRIL in Myeloid Cells.

Myeloid cells express the TNF family ligands BAFF/BLyS and APRIL, which exert their effects on B cells at different stages of differentiation via the receptors BAFFR, TACI (Transmembrane Activator and CAML-Interactor) and/or BCMA (B Cell Maturation Antigen). BAFF and APRIL are proteins expressed at the cell membrane, with both extracellular and intracellular domains. Therefore, receptor/ligand engagement may also result in signals in ligand-expressing cells via so-called "reverse signalling". In order to understand how TACI-Fc (atacicept) technically may mediate immune stimulation instead of suppression, we investigated its potential to activate reverse signalling through BAFF and APRIL. BAFFR-Fc and TACI-Fc, but not Fn14-Fc, reproducibly stimulated the ERK and other signalling pathways in bone marrow-derived mouse macrophages. However, these effects were independent of BAFF or APRIL since the same activation profile was observed with BAFF- or APRIL-deficient cells. Instead, cell activation correlated with the presence of high molecular mass forms of BAFFR-Fc and TACI-Fc and was strongly impaired in macrophages deficient for Fc receptor gamma chain. Moreover, a TACI-Fc defective for Fc receptor binding elicited no detectable signal. Although these results do not formally rule out the existence of BAFF or APRIL reverse signalling (via pathways not tested in this study), they provide no evidence in support of reverse signalling and point to the importance of using appropriate specificity controls when working with Fc receptor-expressing myeloid cells

Tyrosine kinase Flt3/Flt3-ligand signaling in the modulation of immune responses in experimental arthritis

Rheumatoid arthritis (RA) is an autoimmune, chronic systemic inflammatory disorder that primarily affects flexible joints resulting in severe joint destruction and disability if left untreated. Today, advances in treatment have significantly improved the outcome for patients, although the pathogenesis of RA remains relatively unknown. Signaling through the tyrosine kinase receptor fms-like tyrosine kinase 3 (Flt3) has been suggested to play a part in the RA pathogenesis. Flt3 is primarily expressed on hematopoietic stem cells and lymphoid progenitors in the bone marrow and has an important role in early B-cell development and formation of dendritic cells (DC). Furthermore, the ligand for Flt3 (Flt3L) serves as a regulator of regulatory T-cell (Treg) homeostasis and has been suggested to support differentiation of bone-resorbing osteoclasts. This thesis aimed to investigate the effect of Flt3/Flt3L signaling on the immune system during development of arthritis using an experimental animal model of human RA. Our study shows that Flt3 signaling supports formation of DCs and Treg cells during arthritis development. Treg expansion associated with Flt3L treatment resulted in a reduced production of inflammatory cytokines, reduced levels of antigen-specific antibodies and reduced bone destruction. On the contrary, lack of Flt3L was associated with reduced Treg formation resulting in loss of control over T-cell proliferation, and bone destruction during arthritis. Flt3L was found to positively influence the transcription of the osteoclast-regulating factor IRF8, and could by this mechanism influence osteoclast formation. Impaired signaling through Flt3 resulted in low IRF8 expression, accumulation of osteoclasts in the arthritic joint and an increased loss of femoral trabecular bone. Conversely, Flt3L treatment was associated with increased IRF8 expression, reduced osteoclast formation and restoration of trabecular bone formation in mice lacking Flt3L (Flt3LKO). Finally, we could identify a previously unacknowledged role for Flt3 in peripheral B-cell responses. We demonstrated that Flt3 was re-expressed on activated B-cells following LPS stimulation in vitro and on a population of germinal center B-cells in vivo. By using Flt3LKO mice we could identify an important role for Flt3L in class switch recombination (CSR) to IgG1. B-cells from Flt3LKO mice were found have reduced activation of Stat6 after IL-4 stimulation, resulting in impaired initiation of CSR to IgG1 and highly reduced formation of IgG1+ B-cells and IgG1 production. In summary this thesis shows that Flt3L has an important function in regulating DC and Treg homeostasis and function during arthritis. Furthermore, Flt3L has a regulatory role on osteoclast development and on trabecular bone formation. Finally, signaling through the Flt3 receptor on activated B-cells has an important role in the CSR process and deficiency of Flt3L leads to a skewed antibody response towards the more potent IgG subclasses IgG2b and IgG2c. Together, these results suggest that Flt3L might play a protective role during arthritis by reduction of bone destruction, induction of regulatory T-cells and regulation of antibody effector functions. The conclusion of this thesis is that signaling through the tyrosine kinase Flt3 plays an important role in modulating immune responses during experimental arthritis