Wnt-5A/B Signaling in Hematopoiesis throughout Life

Wnt signaling is well-known to play major roles in the hematopoietic system, from embryogenesis to aging and disease. In addition to the main β-catenin-dependent pathway, it is now clear that Wnt5a and the structurally related Wnt5b are essential for hematopoiesis, bone marrow colonization and the final steps of hematopoietic stem cell (HSC) maturation via β-catenin-independent signaling. Wnt5a and Wnt5b ligands prevent hematopoietic exhaustion (by maintaining quiescent, long-term HSCs), induce the proliferation of progenitors, and guide myeloid development, in addition to being involved in the development of aging-related alterations. The aim of this review is to summarize the current knowledge on these roles of Wnt5a and Wn5b signaling in the hematopoietic field

Characterization of dual effects induced by antimicrobial peptides: Regulated cell death or membrane disruption

Background: Some reports describe lysis mechanisms by antimicrobial peptides (AMPs), while others describe the activation of regulated cell death. in this study, we compare the cell death-inducing activities of four beta-hairpin AMPs (gomesin, protegrin, tachyplesin and polyphemusin II) along with their linear analogs in the human erythroleukemia K562 cell line to investigate the relationship between their structure and activity.Methods: K562 cells were exposed to AMPs. Morphological and biochemistry alterations were evaluated using light microscopy, confocal microscopy and flow cytometry.Results: Gomesin and protegrin displayed cytotoxic properties that their linear counterparts did not. Tachyplesin and polyphemusin II and also their linear analogs induced cell death. We were able to distinguish two ways in which these AMPs induced cell death. Lower concentrations of AMPs induced controlled cell death mechanisms. Gomesin, tachyplesin and linear-tachyplesin promoted apoptosis that was characterized by annexin labeling, sensitivity to Z-VAD, and caspase-3 activation, but was also inhibited by necrostatin-1. Gomesin and protegrin induced cell death was dependent on intracellular Ca2+ mechanisms and the participation of free radicals was observed in protegrin induced cell death. Polyphemusin II and its linear analog mainly induced necrosis. Conversely, treatment with higher concentrations of AMPs primarily resulted in cell membrane disruption, but with clearly different patterns of action for each AMP tested.Conclusion: Different actions by beta-hairpin AMPs were observed at low concentrations and at higher concentrations despite the structure similarity.General significance: Controlled intracellular mechanism and direct membrane disruption were clearly distinguished helping to understand the real action of AMPs in mammalian cells. (C) 2012 Elsevier B.V. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Universidade Federal de São Paulo, Dept Bioquim, BR-04044020 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biofis, BR-04044020 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Ciencia & Tecnol, BR-12231280 Sao Jose Dos Campos, SP, BrazilUniversidade Federal de São Paulo, Dept Bioquim, BR-04044020 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biofis, BR-04044020 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Ciencia & Tecnol, BR-12231280 Sao Jose Dos Campos, SP, BrazilFAPESP: 2009/54869-2FAPESP: 2011/17584-0Web of Scienc

Divergent effects of Wnt5b on IL-3- and GM-CSF-induced myeloid differentiation

The multiple specialized cell types of the hematopoietic system originate from differentiation of hematopoietic stem cells and progenitors (HSPC), which can generate both lymphoid and myeloid lineages. The myeloid lineage is preferentially maintained during ageing, but the mechanisms that contribute to this process are incompletely understood. Here, we studied the roles of Wnt5a and Wnt5b, ligands that have previously been linked to hematopoietic stem cell ageing and that are abundantly expressed by both hematopoietic progenitors and bone-marrow derived niche cells. Whereas Wnt5a had no major effects on primitive cell differentiation, Wnt5b had profound and divergent effects on cytokine-induced myeloid differentiation. Remarkably, while IL-3-mediated myeloid differentiation was largely repressed by Wnt5b, GM-CSF-induced myeloid differentiation was augmented. Furthermore, in the presence of IL-3, Wnt5b enhanced HSPC self-renewal, whereas in the presence of GM-CSF, Wnt5b accelerated differentiation, leading to progenitor cell exhaustion. Our results highlight discrepancies between IL-3 and GM-CSF, and reveal novel effects of Wnt5b on the hematopoietic system

Sleep deprivation impairs calcium signaling in mouse splenocytes and leads to a decreased immune response

Background: Sleep is a physiological event that directly influences health by affecting the immune system, in which calcium (Ca2+) plays a critical signaling role. We performed live cell measurements of cytosolic Ca2+ mobilization to understand the changes in Ca2+ signaling that occur in splenic immune cells after various periods of sleep deprivation (SD).Methods: Adult male mice were subjected to sleep deprivation by platform technique for different periods (from 12 to 72 h) and Ca2+ intracellular fluctuations were evaluated in splenocytes by confocal microscopy. We also performed spleen cell evaluation by flow cytometry and analyzed intracellular Ca2+ mobilization in endoplasmic reticulum and mitochondria. Additionally. Ca2+ channel gene expression was evaluatedResults: Splenocytes showed a progressive loss of intracellular Ca2+ maintenance from endoplasmic reticulum (ER) stores. Transient Ca2+ buffering by the mitochondria was further compromised. These findings were confirmed by changes in mitochondrial integrity and in the performance of the store operated calcium entry (SOCE) and stromal interaction molecule 1 (STIM1) Ca2+ channels.Conclusions and general significance: These novel data suggest that SD impairs Ca2+ signaling, most likely as a result of ER stress, leading to an insufficient Ca2+ supply for signaling events. Our results support the previously described immunosuppressive effects of sleep loss and provide additional information on the cellular and molecular mechanisms involved in sleep function. (C) 2012 Elsevier B.V. All rights reserved.AFIP (Associacao Fundo de Incentivo a Pesquisa)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Universidade Federal de São Paulo UNIFESP, Dept Psychobiol, São Paulo, BrazilUniversidade Federal de São Paulo UNIFESP, Dept Biosci, Santos, SP, BrazilUniversidade Federal de São Paulo UNIFESP, Dept Biochem, São Paulo, BrazilUniversidade Federal de São Paulo UNIFESP, Dept Psychobiol, São Paulo, BrazilUniversidade Federal de São Paulo UNIFESP, Dept Biosci, Santos, SP, BrazilUniversidade Federal de São Paulo UNIFESP, Dept Biochem, São Paulo, BrazilFAPESP: 05/04366-3FAPESP: CEPID 98/14303-6Web of Scienc

Heparan sulfate mediates trastuzumab effect in breast cancer cells

Background: Trastuzumab is an antibody widely used in the treatment of breast cancer cases that test positive for the human epidermal growth factor receptor 2 (HER2). Many patients, however, become resistant to this antibody, whose resistance has become a major focus in breast cancer research. But despite this interest, there are still no reliable markers that can be used to identify resistant patients. A possible role of several extracellular matrix (ECM) components-heparan sulfate (HS), Syn-1(Syndecan-1) and heparanase (HPSE1)-in light of the influence of ECM alterations on the action of several compounds on the cells and cancer development, was therefore investigated in breast cancer cell resistance to trastuzumab.Methods: the cDNA of the enzyme responsible for cleaving HS chains from proteoglycans, HPSE1, was cloned in the pEGFP-N1 plasmid and transfected into a breast cancer cell lineage. We evaluated cell viability after trastuzumab treatment using different breast cancer cell lines. Trastuzumab and HS interaction was investigated by confocal microscopy and Fluorescence Resonance Energy Transfer (FRET). the profile of sulfated glycosaminoglycans was also investigated by [S-35]-sulfate incorporation. Quantitative RT-PCR and immunofluorescence were used to evaluate HPSE1, HER2 and Syn-1 mRNA expression. HPSE1 enzymatic activity was performed using biotinylated heparan sulfate.Results: Breast cancer cell lines responsive to trastuzumab present higher amounts of HER2, Syn-1 and HS on the cell surface, but lower levels of secreted HS. Trastuzumab and HS interaction was proven by FRET analysis. the addition of anti-HS to the cells or heparin to the culture medium induced resistance to trastuzumab in breast cancer cells previously sensitive to this monoclonal antibody. Breast cancer cells transfected with HPSE1 became resistant to trastuzumab, showing lower levels of HER2, Syn-1 and HS on the cell surface. in addition, HS shedding was increased significantly in these resistant cells.Conclusion: Trastuzumab action is dependent on the availability of heparan sulfate on the surface of breast cancer cells. Furthermore, our data suggest that high levels of heparan sulfate shed to the medium are able to capture trastuzumab, blocking the antibody action mediated by HER2. in addition to HER2 levels, heparan sulfate synthesis and shedding determine breast cancer cell susceptibility to trastuzumab.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Universidade Federal de São Paulo, Dept Biochem, BR-04044020 São Paulo, BrazilFac Med ABC, Dept Biochem, BR-09060650 Santo Andre, SP, BrazilFac Med ABC, Dept Oncol, BR-09060650 Santo Andre, SP, BrazilUniversidade Federal de São Paulo, Dept Biochem, BR-04044020 São Paulo, BrazilWeb of Scienc

Hydrogen peroxide (H2O2) induces leukemic but not normal hematopoietic cell death in a dose-dependent manner

Over the last few years, studies have suggested that oxidative stress plays a role in the regulation of hematopoietic cell homeostasis. in particular, the effects of hydrogen peroxide (H2O2) range from hematopoietic cell proliferation to cell death, depending on its concentration in the intracellular milieu. in this work, we evaluated the effects of an oxidative environment on normal and leukemic hematopoietic cells by stimulating normal human (umbilical cord blood) and murine (bone marrow) hematopoietic cells, as well as human myeloid leukemic cells (HL-60 lineage), upon H2O2 stimulus. Total cell populations and primitive subsets were evaluated for each cell type. H2O2 stimulus induces HL-60 cell death, whereas the viability of human and murine normal cells was not affected. the effects of H2O2 stimulus on hematopoietic stem/progenitor cell subsets were examined and the normal primitive cells were found to be unaffected; however, the percentage of leukemic stem cells (LSC) increased in response to H2O2, while clonogenic ability of these cells to generate myeloid clones was inhibited. in addition, H2O2 stimulus caused a decrease in the levels of p-AKT in HL-60 cells, which most likely mediates the observed decrease of viability. in summary, we found that at low concentrations, H2O2 preferentially affects both the LSC subset and total HL-60 cells without damage normal cells.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Universidade Federal de São Paulo, Dept Biophys, BR-04062023 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biochem, BR-04062023 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Med, BR-04062023 São Paulo, BrazilIPCTRON Stem Cell Res Inst, BR-04037000 São Paulo, BrazilUniversidade Federal de São Paulo, BR-04039032 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biophys, BR-04062023 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biochem, BR-04062023 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Med, BR-04062023 São Paulo, BrazilUniversidade Federal de São Paulo, BR-04039032 São Paulo, BrazilFAPESP: 2009/52852-5Web of Scienc

Chlorella vulgaris treatment ameliorates the suppressive effects of single and repeated stressors on hematopoiesis

The reports regarding the mutual influence between the central nervous system and the immune system constitute a vast and somewhat controversial body of literature. Stress is known to disturb homeostasis, impairing immunological functions. in this study, we investigated the hematopoietic response of Chlorella vulgaris (CV)-treated mice exposed to single (SST) and repeated stress (RST). We observed a reduction in the numbers of hematopoietic progenitors (HP) in the bone marrow and long-term bone marrow cultures (LTBMC) using flow cytometry and a coinciding decrease in the number of granulocyte-macrophage colonies (CFU-GM) after treatment with both stressors, but SST caused a more profound suppression. We observed a proportional increase in the colony-stimulating activity (CSA) of the serum of animals subjected to SST or RST. in the bone marrow, SST and RST induced a decrease in both mature myeloid and lymphoid populations but did not affect pluripotent hematopoietic progenitors (Lin(-)Sca-1(+)c-kit(+), LSK), and again, a more profound suppression was observed after SST. We further quantified the levels of interleukin-1 alpha (IL-1 alpha) and interleukin-6 (IL-6) and the number of myeloid cells in LTBMC. Both SST and RST reduced the levels of these cytokines to similar degrees. the myeloid population was also reduced in LTBMC, and SST induced a more intense suppression. Importantly, CV treatment prevented the changes produced by SST and RST in all of the parameters evaluated. Together, our results suggest that CV treatment is an effective tool for the prophylaxis of myelosuppression caused by single or repeated stressors. (c) 2012 Elsevier Inc. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Univ Estadual Campinas UNICAMP, Fac Ciencias Med, Dept Farmacol, Campinas, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Biofis, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Farmacol, São Paulo, BrazilUniv São Paulo, Fac Med Vet, Grp Pesquisa Neuroimunomodulacao, BR-05508000 São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Biofis, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Farmacol, São Paulo, BrazilFAPESP: 09/51886-3CNPq: 300764/2010-3Web of Scienc