BACKGROUND:Earlier studies by our group have demonstrated that a transgenic animal engineered to express Tie2 under the control of the Tie2 promoter produced animals with a scaly skin phenotype that recapitulated many of the hallmarks of atopic dermatitis (AT-Derm). To test the hypothesis that this model of AT-Derm is driven by dysregulated Tie2-signalling, we have bred AT-Derm transgenic (TG) animals with TG-animals engineered to overexpress Angiopoietin-1 or -2, the cognate Tie2 ligands. These two ligands act to antagonize one another in a context-dependent manner. To further evaluate the role of Ang1-driven-Tie2 signalling, we examined the ability of Vasculotide, an Ang1-mimetic, to modulate the AT-Derm phenotype.RESULTS:AT-Derm+Ang2 animals exhibited an accentuated phenotype, whereas AT-Derm+Ang1 presented with a markedly reduced skin disease, similarly VT-treated AT-Derm animals present with a clear decrease in the skin phenotype. Moreover, a decrease in several important inflammatory cytokines and a decrease in the number of eosinophils was noted in VT-treated animals. Bone marrow differentiation in the presence of VT produced fewer CFU-G colonies, further supporting a role for Tie2-signalling in eosinophil development. Importantly, we demonstrate activation of Tie2, the VT-target, in lung tissue from naïve animals treated with increasing amounts of VT.CONCLUSIONS:The AT-Derm phenotype in these animals is driven through dysregulation of Tie2 receptor signalling and is augmented by supplemental Ang2-dependent stimulation. Overexpression of Ang1 or treatment with VT produced a similar amelioration of the phenotype supporting the contention that VT and Ang1 have a similar mechanism of action on the Tie2 receptor and can both counteract the signalling driven by Ang2. Our results also support a possible role for Tie2-signalling in the development of eosinophilic diseases and that activation of Tie2 may directly or indirectly modulate the differentiation of eosinophils, which express Tie2. In summary, these data support the hypothesis that this AT-Derm mouse model is driven by dysregulation of the Tie2 signalling pathway and increased Ang2 levels can aggravate it, whereas it can be reversed by either Ang1-overexpression or VT treatment. Moreover, our data supports the contention that VT acts as an Angiopoietin-1 mimetic and may provide a novel entry point for Tie2-agonist-based therapies for atopic diseases.

VEGF-A (VEGF) drives angiogenesis through activation of downstream effectors to promote endothelial cell proliferation and migration. Although VEGF binds both VEGF receptor 1 (R1) and receptor 2 (R2), its proangiogenic effects are attributed to R2. Secreted protein, acidic, rich in cysteine (SPARC) is a matricellular glycoprotein thought to inhibit angiogenesis by preventing VEGF from activating R1, but not R2. Because R2 rather than R1 mediates proangiogenic activities of VEGF, the role of human SPARC in angiogenesis was reevaluated. We confirm that association of SPARC with VEGF inhibits VEGF-induced HUVEC adherence, motility, and proliferation in vitro and blocks VEGF-induced blood vessel formation ex vivo. SPARC decreases VEGF-induced phosphorylation of R2 and downstream effectors ERK, Akt, and p38 MAPK as shown by Western blot and/or phosphoflow analysis. Surface plasmon resonance indicates that SPARC binds slowly to VEGF (0.865 ± 0.02 × 10(4) M(-1) s(-1)) with a Kd of 150 nM, forming a stable complex that dissociates slowly (1.26 ± 0.003 × 10(-3) s(-1)). Only domain III of SPARC binds VEGF, exhibiting a 15-fold higher affinity than full-length SPARC. These findings support a model whereby SPARC regulates angiogenesis by sequestering VEGF, thus restricting the activation of R2 and the subsequent activation of downstream targets critical for endothelial cell functions.

Inflammation and airway remodeling are features associated with chronic asthmatic lungs. Previous reports have shown the benefits of the angiopoietin-1/Tie2 signaling axis on acute experimentally-induced asthma in mice. However, the more chronic effects as well as the interaction between the inflammatory and vascular components is poorly. Thus, we evaluated the impact of vasculotide, a synthetic Tie2 agonist in a chronic model of asthma. During the chronic allergic response in mice, we show that in addition to endothelial Tie2 receptor expression, there is an increased proportion of dendritic cells and monocytes expressing Tie2. Treatment of experimentally-induced chronic airway inflammation in mice with vasculotide correlated with a skewed CD4+ TH subsets and cytokine profile in the bronchoalveolar lavage of animals. This modified cytokine milieu promoted an altered endothelial cell response characterized by reduced expression of CD62E, CD54 and CD106 on endothelial cells, decreased cellular migration of inflammatory cells to the lung as well as reduced mucus accumulation. Analysis of lung tissues of animals treated with vasculotide revealed a decrease in collagen deposition and thinning of the smooth muscle cell layer in the airways of mice with chronic allergic airway inflammation. Our results demonstrate that vasculotide can impact the inflammatory and remodeling components in chronic asthma through its action on both cells of the immune response and on endothelial cells.

Background: South Asian ethnicity is an independent risk factor for mortality after coronary artery bypass. We tested the hypothesis that this risk results from a greater inflammatory response to cardiopulmonary bypass (CPB).Methods: This was a single-site prospective cohort study. We compared the inflammatory response to CPB in 20 Caucasians and 17 South Asians undergoing isolated coronary artery bypass grafting surgery.Results: Plasma levels of proinflammatory cytokines (interleukin [IL]-6, IL-8, IL-12, interferon gamma, and tumor necrosis factor) and anti-inflammatory mediators (IL-10 and soluble TNF receptor I) were measured. The Toll-like receptor (TLR) signaling pathway was examined in peripheral blood monocytes by flow cytometry, measuring surface expression of TLR2, TLR4, and coreceptor CD14 and activation of downstream messenger molecules (interleukin-1 receptor-associated kinase 4, nuclear factor kappa from B cells (NF-kappa B), c-Jun amino-terminal kinase, p38 mitogen-activated protein kinase, and Protein Kinase B). South Asians had persistently higher plasma levels of IL-6 and exhibited increased TLR signaling through the p38 mitogen-activated protein kinase and Protein Kinase B pathways in inflammatory monocytes after CPB. This increased inflammatory response was paralleled clinically by a higher sequential organ failure assessment score (5.1 +/- 1.4 versus 1.5 +/- 1.6, P = 0.027) and prolonged cardiovascular system failure (23.5% versus 0%) 48 h after CPB.Conclusions: South Asians develop an exacerbated systemic inflammatory response after CPB, which may contribute to the higher morbidity and mortality associated with coronary artery bypass in this population. These patients may benefit from targeted anti-inflammatory therapies designed to mitigate the adverse consequences resulting from this response. (C) 2014 Elsevier Inc. All rights reserved.

The clinical application of hematopoietic progenitor cell-based therapies for the treatment of hematological diseases is hindered by current protocols, which are cumbersome and have limited efficacy to augment the progenitor cell pool. We report that inhibition of T cell protein tyrosine phosphatase (TC-PTP), an enzyme involved in the regulation of cytokine signaling, through gene knockout results in a 9-fold increase in the number of hematopoietic progenitors in murine bone marrow. This effect could be reproduced using a short (48 h) treatment with a pharmacological inhibitor of TC-PTP in murine bone marrow, as well as in human bone marrow peripheral blood and cord blood. We also demonstrate that the ex-vivo use of TC-PTP inhibitor only provides a temporary effect on stem cells and did not alter their capacity to reconstitute all hematopoietic components in vivo. We establish that one of the mechanisms whereby inhibition of TC-PTP mediates its effects involves the IL-18 signaling pathway, leading to increased production of IL-12 and IFN-gamma by progenitor cells. Together, our results reveal a previously unrecognized role for IL-18 in contributing to the augmentation of the stem cell pool, and provide a novel and simple method to rapidly expand progenitor cells from a variety of sources using a pharmacological compound.

Lymphangiogenesis is a highly regulated process that involves the reprogramming of venous endothelial cells into early lymphatic endothelial cells. This reprogramming not only displays a polarized expression pattern from the cardinal vein, but also demonstrates vascular specificity; early lymphatics only develop from the cardinal vein and not the related dorsal aorta. In our transgenic model of lymphangiogenesis, we demonstrate that Prox1 overexpression has the ability to reprogram venous endothelium but not early arterial endothelial cells in vivo, in spite of the fact that Prox1 expression is forced onto both vascular beds. Our observations suggest that this specificity during embryogenesis may be due to cell-cell interactions between the developing arterial endothelial cells and smooth muscle cells. These conclusions have far reaching implications on how we understand the vascular specificity of lymphangiogenesis.

The clinical application of hematopoietic progenitor cell-based therapies for the treatment of hematological diseases is hindered by current protocols, which are cumbersome and have limited efficacy to augment the progenitor cell pool. We report that inhibition of T-cell protein tyrosine phosphatase (TC-PTP), an enzyme involved in the regulation of cytokine signaling, through gene knockout results in a ninefold increase in the number of hematopoietic progenitors in murine bone marrow (BM). This effect could be reproduced using a short (48 hours) treatment with a pharmacological inhibitor of TC-PTP in murine BM, as well as in human BM, peripheral blood, and cord blood. We also demonstrate that the ex vivo use of TC-PTP inhibitor only provides a temporary effect on stem cells and did not alter their capacity to reconstitute all hematopoietic components in vivo. We establish that one of the mechanisms whereby inhibition of TC-PTP mediates its effects involves the interleukin-18 (IL-18) signaling pathway, leading to increased production of IL-12 and interferon-gamma by progenitor cells. Together, our results reveal a previously unrecognized role for IL-18 in contributing to the augmentation of the stem cell pool and provide a novel and simple method to rapidly expand progenitor cells from a variety of sources using a pharmacological compound.

South Asian ethnicity is an independent risk factor for mortality after coronary artery bypass grafting (CABG) surgery, which could result from an unrestrained inflammatory response to cardiopulmonary bypass (CPB). This study compared the inflammatory response to CPB in Caucasians and South Asians undergoing CABG surgery. A prospective study of 37 patients (20 Caucasians, 17 South Asians) undergoing CABG surgery with CPB was conducted. Serum levels of pro-inflammatory (IL-1β, IL 6, IL-8, IL-10, IL-12p70, IL-18, IFNγ, TNFα) and anti-inflammatory (IL-1RII, sTNFRI) cytokines were measured. The TLR4 signaling pathway was examined by flow cytometry in each patient, by measuring the serum level of endogenous (HSP60) and exogenous (LPS) TLR4 ligands; surface expression of TLR4 and co-receptor molecules (CD14, sCD14); and activation of downstream messenger molecules (IRAK4, NF-κB, JNK, p38 MAPK, AKT) in monocytes. South Asians had persistently higher serum levels of IL-6 and IL-8, which was associated with increased signaling through TLR4 in inflammatory monocytes following CPB. This increased inflammatory response was associated clinically with a higher Sequential Organ Failure Assessment score (5.1 ± 1.4 v. 1.5 ± 1.6, P = 0.027) and prolonged cardiovascular system failure (23.5% v. 0%) 48 h post CPB. This study demonstrates that increased systemic inflammation induced by CPB in South Asians may explain the higher mortality associated with CABG surgery in this population, and suggests that anti-inflammatory therapies could potentially be used to mitigate the adverse consequences resulting from this response.

Background Flavaglines are a family of natural products from the genus Aglaia that exhibit anti-cancer activity in vitro and in vivo and inhibit translation initiation. They have been shown to modulate the activity of eIF4A, the DEAD-box RNA helicase subunit of the eukaryotic initiation factor (eIF) 4F complex, a complex that stimulates ribosome recruitment during translation initiation. One flavagline, silvestrol, is capable of modulating chemosensitivity in a mechanism-based mouse model. Methodology/Principal Findings Among a number of flavagline family members tested herein, we find that silvestrol is the more potent translation inhibitor among these. We find that silvestrol impairs the ribosome recruitment step of translation initiation by affecting the composition of the eukaryotic initiation factor (eIF) 4F complex. We show that silvestrol exhibits significant anticancer activity in human breast and prostate cancer xenograft models, and that this is associated with increased apoptosis, decreased proliferation, and inhibition of angiogenesis. We demonstrate that targeting translation by silvestrol results in preferential inhibition of weakly initiating mRNAs. Conclusions/Significance Our results indicate that silvestrol is a potent anti-cancer compound in vivo that exerts its activity by affecting survival pathways as well as angiogenesis. We propose that silvestrol mediates its effects by preferentially inhibiting translation of malignancy-related mRNAs. Silvestrol appears to be well tolerated in animals.

The immune system requires for its proper ontogeny, differentiation, and maintenance the function of several tyrosine kinases and adapters that create and modify tyrosine phosphorylation sites. Tyrosine phosphorylation is a crucial protein modification in immune cell signaling and can be reversed by protein tyrosine phosphatases (PTPs). Much progress has been made in identifying and understanding PTP function in the immune system. In this review, we present one of these proteins, named T-cell PTPs (TC-PTP) (gene name PTPN2), a classical, non-receptor PTP that is ubiquitously expressed with particularly high expression in hematopoietic tissues. TC-PTP is remarkable not only by the fact that it appears to influence most, if not all, cells involved in the development of the immune system, from stem cells to differentiated lineages, but also recent findings have positioned it at the core of several human diseases from autoimmune disease to cancer.

The control of tyrosine phosphorylation depends on the fine balance between kinase and phosphatase activities. Protein tyrosine phosphatase 1B (PTP-1B) and T cell protein tyrosine phosphatase (TC-PTP) are 2 closely related phosphatases known to control cytokine signaling. We studied the functional redundancy of PTP-1B and TC-PTP by deleting 1 or both copies of these genes by interbreeding TC-PTP and PTP-1B parental lines. Our results indicate that the double mutant (tcptp(-/-)ptp1b(-/-)) is lethal at day E9.5-10.5 of embryonic development with constitutive phosphorylation of Stat1. Mice heterozygous for TC-PTP on a PTP-1B-deficient background (tcptp(+/-)ptp1b(-/-)) developed signs of inflammation. Macrophages from these animals were highly sensitive to IFN-gamma, as demonstrated by increased Stat1 phosphorylation and nitric oxide production. In addition, splenic T cells demonstrated increased IFN-gamma secretion capacity. Mice with deletions of single copies of TC-PTP and PTP-1B (tcptp(+/-)ptp1b(+/-)) exhibited normal development, confirming that these genes are not interchangeable. Together, these data indicate a nonredundant role for PTP-1B and TC-PTP in the regulation of IFN signaling.

Adult bone marrow contains stem cells capable of reconstituting the vascular system. The ordered progression of stem cells and more differentiated endothelial precursor cells through successive developmental stages is tightly controlled. The specialized microenvironment of the bone marrow as well as cell-autonomous processes directs the renewal and differentiation of stem cells into endothelial cells. Tyrosine phosphorylation of receptors, adaptors, and structural proteins is one mechanism whereby endothelial cell development is regulated, which involves the opposing action of protein tyrosine kinases and phosphatases. The present review focuses on the role of four nontransmembrane protein tyrosine phosphatases (TC-PTP, PTP1B, SHP-1, and SHP-2) in the self-renewal, differentiation, mobilization, and homing of endothelial progenitor cells, as well as their ability to incorporate into nascent blood vessels. Endothelial progenitor cells are known to promote vasculogenesis, accelerating restoration of blood flow to ischemic tissues, and improve cardiac function after infarct. The use of protein tyrosine phosphatase inhibitors to modulate the development and function of endothelial progenitor cells as a potential novel therapy for peripheral vascular and coronary artery disease in humans is discussed.

The protein tyrosine phosphatase PEST (PTP-PEST) is involved in the regulation of the actin cytoskeleton. Despite the emerging functions attributed to both PTPs and the actin cytoskeleton in apoptosis, the involvement of PTP-PEST in apoptotic cell death remains to be established. Using several cell-based assays, we showed that PTP-PEST participates in the regulation of apoptosis. As apoptosis progressed, a pool of PTP-PEST localized to the edge of retracting lamellipodia. Expression of PTP-PEST also sensitized cells to receptor-mediated apoptosis. Concertedly, specific degradation of PTP-PEST was observed during apoptosis. Pharmacological inhibitors, immunodepletion experiments, and in vitro cleavage assays identified caspase-3 as the primary regulator of PTP-PEST processing during apoptosis. Caspase-3 specifically cleaved PTP-PEST at the (549)DSPD motif and generated fragments, some of which displayed increased catalytic activity. Moreover, caspase-3 regulated PTP-PEST interactions with paxillin, leupaxin, Shc, and PSTPIP. PTP-PEST acted as a scaffolding molecule connecting PSTPIP to additional partners: paxillin, Shc, Csk, and activation of caspase-3 correlated with the modulation of the PTP-PEST adaptor function. In addition, cleavage of PTP-PEST facilitated cellular detachment during apoptosis. Together, our data demonstrate that PTP-PEST actively contributes to the cellular apoptotic response and reveal the importance of caspases as regulators of PTPs in apoptosis.

L'invention concerne un procede d'augmentation de l'expansion de cellules souches et d'isolement de cellules souches. Le procede d'expansion des cellules souches comprend l'incubation des cellules avec un agent inhibant la proteine tyrosine phosphatase des lymphocytes T (TC-PTP).

The CSLSR is a nationally registered non-profit organization created by life science students for fellow student researchers. We are dedicated to bringing together young student researchers at the undergraduate, graduate, postgraduate and professional levels to share upcoming scientific/health research and discoveries, and allow for furthering the knowledge amongst these future academics, clinicians, clinician-scientists and industry professionals in the life science fields. During the conference, we were honoured to welcome renowned scientist keynote speakers from both academia and industry. For a synopsis of the conference, and for more information on our upcoming events and student opportunities, please visit our website at www.cslsr.ca. On behalf of the executive and chapter representatives of the CSLSR, I would like to thank the Canadian Institutes of Health Research (CIHR)'s Institute of Infection and Immunity and Merck-Frosst for their support of this year's conference. We gratefully acknowledge McGill University for their support in our hosting of this year's conference at their institution. I would also like to personally congratulate the student oral and poster presentation award winners: Finally, we would like to thank all attendees, speakers, affiliates and sponsors from across the country for making this conference a great success. We look forward to seeing you in 2008. Heats shock cognate protein 70 accumulates in the nucleolus of HeLa cells during heat stress recovery. Influence of oral and subcutaneous bisphenol-A on intrauterine implantation of fertilized ova in inseminated female mice Lipid metabolism in peroxisomes, endoplasmic reticulum and lipid bodies controls chronological aging in yeast Breast cancer cells inhibit osteoblast differentiation. potlights on the DNA repair system in late spermatogenesis: stage-specific DNA fragmentation and activation of H2AX Characterization of CD11d leukocyte integrin surface expression I. Moheshwarnath and M. Bisaillon Probing into the GTP specificity of an mRNA capping enzyme Interleukin 33 (IL-33) in severe asthma and modulation of its expression in airway smooth muscle cell (ASMC) Biological activity of cross-linked intravenous immunoglobulins (IVIg) on human B cells Apoptosis in epithelial fetal lung cells exposed to stretching as a result of positive ventilation Caspase substrates screening by diagonal gel approach and study on caspase-1 substrates on glycolytic pathway Megakaryocytic cells expressing a peptide derived from a protein regulating the actin cytoskeleton, MTPG-24, exhibit an increased cell size ADAM12 effects on Dupuytren's Disease cell morphology and cytoplasmic beta catenin accumulation require Type I IGF receptor tyrosine kinase activity