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Descartes, France

Nunes A.F.,University of Porto | Liz M.A.,University of Porto | Franquinho F.,University of Porto | Teixeira L.,University of Porto | And 5 more authors.
FEBS Journal | Year: 2010

To better understand the role of neuropeptide Y (NPY) in bone homeostasis, as its function in the regulation of bone mass is unclear, we assessed its expression in this tissue. By immunohistochemistry, we demonstrated, both at embryonic stages and in the adult, that NPY is synthesized by osteoblasts, osteocytes, and chondrocytes. Moreover, peptidylglycine α-amidating monooxygenase, the enzyme responsible for NPY activation by amidation, was also expressed in these cell types. Using transthyretin (TTR) KO mice as a model of augmented NPY levels, we showed that this strain has increased NPY content in the bone, further validating the expression of this neuropeptide by bone cells. Moreover, the higher amidated neuropeptide levels in TTR KO mice were related to increased bone mineral density and trabecular volume. Additionally, RT-PCR analysis established that NPY is not only expressed in MC3T3-E1 osteoblastic cells and bone marrow stromal cells (BMSCs), but is also detectable by RIA in BMSCs undergoing osteoblastic differentiation. In agreement with our in vivo observations, in vitro, TTR KO BMSCs differentiated in osteoblasts had increased NPY levels and exhibited enhanced competence in undergoing osteoblastic differentiation. In summary, this work contributes to a better understanding of the role of NPY in the regulation of bone formation by showing that this neuropeptide is expressed in bone cells and that increased amidated neuropeptide content is related to increased bone mass. © 2009 FEBS. Source


Bonnet M.-E.,Polyplus-transfection | Gossart J.-B.,Polyplus-transfection | Benoit E.,Polyplus-transfection | Messmer M.,IBMC | And 8 more authors.
Journal of Controlled Release | Year: 2013

RNA interference allows the design of new inhibitors that target deregulated pathways in cancer. However systemic delivery of siRNA for the treatment of solid tumors still remains an issue. In our study, in order to suppress the progression of lung cancer metastasis in mice, we developed sticky siRNA (ssiRNA) to inhibit survivin and cyclin B1, two candidates involved in cell survival and proliferation. We exploited the linear polyethylenimine (PEI) as potent non-viral carrier to efficiently deliver our inhibitors. As a proof of concept, we have chosen a very aggressive mammary adenocarcinoma model (TSA-Luc cells), which forms lung metastases upon systemic cell injection. We confirmed in vitro, that the ssiRNAs delivered with PEI are not only able to inhibit our target genes at the mRNA and protein levels, but are also able to block the cell cycle and cell proliferation through a mechanism of RNA interference. More importantly, we showed in vivo by luciferase dosage, bioimaging and tissue section, an inhibition of lung tumor metastases after systemic delivery of cyclin B1 and survivin ssiRNA complexed with PEI. Alternating treatment with cisplatin and ssiRNA/PEI showed an additive effect between the two anticancer drugs on lung tumor inhibition leading to a significant increase in animal survival. Moreover a promising window between activity (IC50) and toxic-ity (LD50), essential for therapeutic application, was observed. Our data show that systemic delivery of ssiRNA/PEI complexes targeting the cell cycle is a valuable strategy for the treatment of lung tumor metastasis and that it can be combined with chemotherapy. © 2013 Elsevier B.V. All rights reserved. Source


Kedinger V.,Polyplus-transfection | Meulle A.,Polyplus-transfection | Zounib O.,Polyplus-transfection | Bonnet M.-E.,Polyplus-transfection | And 7 more authors.
BMC Cancer | Year: 2013

Background: Melanoma represents one of the most aggressive and therapeutically challenging malignancies as it often gives rise to metastases and develops resistance to classical chemotherapeutic agents. Although diverse therapies have been generated, no major improvement of the patient prognosis has been noticed. One promising alternative to the conventional therapeutic approaches currently available is the inactivation of proteins essential for survival and/or progression of melanomas by means of RNA interference. Survivin and cyclin B1, both involved in cell survival and proliferation and frequently deregulated in human cancers, are good candidate target genes for siRNA mediated therapeutics.Methods: We used our newly developed sticky siRNA-based technology delivered with linear polyethyleneimine (PEI) to inhibit the expression of survivin and cyclin B1 both in vitro and in vivo, and addressed the effect of this inhibition on B16-F10 murine melanoma tumor development.Results: We confirm that survivin and cyclin B1 downregulation through a RNA interference mechanism induces a blockage of the cell cycle as well as impaired proliferation of B16-F10 cells in vitro. Most importantly, PEI-mediated systemic delivery of sticky siRNAs against survivin and cyclin B1 efficiently blocks growth of established subcutaneaous B16-F10 tumors as well as formation and dissemination of melanoma lung metastases. In addition, we highlight that inhibition of survivin expression increases the effect of doxorubicin on lung B16-F10 metastasis growth inhibition.Conclusion: PEI-mediated delivery of sticky siRNAs targeting genes involved in tumor progression such as survivin and cyclin B1, either alone or in combination with chemotherapeutic drugs, represents a promising strategy for melanoma treatment. © 2013 Kedinger et al.; licensee BioMed Central Ltd. Source


Mannarino S.C.,Federal University of Rio de Janeiro | Vilela L.F.,Federal University of Rio de Janeiro | Brasil A.A.,Federal University of Rio de Janeiro | Aranha J.N.,Federal University of Rio de Janeiro | And 6 more authors.
Yeast | Year: 2011

It has been shown that the activation of cytosolic superoxide dismutase (Sod1) in Saccharomyces cerevisiae is only dependent on Ccs1, which is responsible for insertion of copper into the enzyme catalytic center, and that glutathione (GSH) is not necessary for this process. In this work, we addressed an important role of GSH in Sod1 activation by a Ccs1-dependent mechanism during oxidative stress and its role in yeast lifespan. Exponential cells of Saccharomyces cerevisiae, treated or not with 0.5 mM menadione for 1 h, were used for evaluation of the effect of a mild oxidative stress pre-treatment on chronological lifespan. The results showed that menadione induced a lifespan extension in the wild-type (WT) strain but this adaptive response was repressed in gsh1 and in sod1 strains. Interestingly, menadione treatment increased SOD1 and CCS1 gene expression in both WT and gsh1 strains. However, while these strains showed the same Sod1 activity before treatment, only the WT presented an increase of Sod1 activity after menadione exposure. Glutathionylation seems to be essential for Sod1 activation since no increase in activity was observed after menadione treatment in grx1 and grx2 null mutants. Our results suggest that GSH and glutathionylation are fundamental to protect Sod1 sulfhydryl residues under mild oxidative stress, enabling Sod1 activation and lifespan extension. © 2010 John Wiley & Sons, Ltd. Source


Moreira H.T.,University of Porto | Silva I.M.,University of Porto | Sousa M.,IBMC | Sampaio P.,IBMC | Cunha J.P.S.,University of Porto
Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS | Year: 2015

The communication between two neurons is established by endogenous chemical particles aggregated in vesicles that move along the axons. It is known that an abnormal transport of these vesicles is correlated with neurodegenerative diseases. The quantification of the dynamics of vesicles movement can therefore be a window to study early detection of such diseases. Nevertheless, most of the studies in the literature rely on manual tracking techniques. In this paper we present a novel methodology for quantifying neurotransmitter vesicle dynamics by using a combination of image tracking and classification algorithms. We use confocal microscopy videos of living neurons to detect and classify vesicles using support vector machine (SVM), while motion is extracted via global nearest neighbor (GNN) tracking approach. Results of the classification algorithm are presented and compared to a ground truth dataset defined by experts. Sensitivity of 90% and specificity of 97% were obtained at a much lower computational cost than an established method from the literature (0.24s/frame vs. 125s/frame). These preliminary results suggest the great potential of the method and tool we have been developing for single particle movement dynamics measure in living cells. © 2015 IEEE. Source

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