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Ruggiero C.,Unit of Genomic Approaches to Membrane Traffic | Ruggiero C.,University of Nice Sophia Antipolis | Fragassi G.,Unit of Genomic Approaches to Membrane Traffic | Grossi M.,Unit of Genomic Approaches to Membrane Traffic | And 6 more authors.
Oncotarget | Year: 2015

We recently identified an endomembrane-based signalling cascade that is activated by the KDEL receptor (KDELR) on the Golgi complex. At the Golgi, the KDELRacts as a traffic sensor (presumably via binding to chaperones that leave the ER) and triggers signalling pathways that balance membrane fluxes between ER and Golgi. One such pathway relies on Gq and Src. Here, we examine if KDELR might control other cellular modules through this pathway. Given the central role of Src in extracellular matrix (ECM) degradation, we investigated the impact of the KDELR-Src pathway on the ability of cancer cells to degrade the ECM. We find that activation of the KDELR controls ECM degradation by increasing the number of the degradative structures known as invadopodia. The KDELR induces Src activation at the invadopodia and leads to phosphorylation of the Src substrates cortactin and ASAP1, which are required for basal and KDELR-stimulated ECM degradation. This study furthers our understanding of the regulatory circuitry underlying invadopodia-dependent ECM degradation, a key phase in metastases formation and invasive growth.

Giannotta M.,Unit of Genomic Approaches to Membrane Traffic | Giannotta M.,FIRC Institute of Molecular Oncology Foundation | Ruggiero C.,Unit of Genomic Approaches to Membrane Traffic | Grossi M.,Unit of Genomic Approaches to Membrane Traffic | And 9 more authors.
EMBO Journal | Year: 2012

Membrane trafficking involves large fluxes of cargo and membrane across separate compartments. These fluxes must be regulated by control systems to maintain homoeostasis. While control systems for other key functions such as protein folding or the cell cycle are well known, the mechanisms that control secretory transport are poorly understood. We have previously described a signalling circuit operating at the Golgi complex that regulates intra-Golgi trafficking and is initiated by the KDEL receptor (KDEL-R), a protein previously known to mediate protein recycling from the Golgi to the endoplasmic reticulum (ER). Here, we investigated the KDEL-R signalling mechanism. We show that the KDEL-R is predicted to fold like a G-protein-coupled receptor (GPCR), and that it binds and activates the heterotrimeric signalling G-protein Gαq/11 which, in turn, regulates transport through the Golgi complex. These findings reveal an unexpected GPCR-like mode of action of the KDEL-R and shed light on a core molecular control mechanism of intra-Golgi traffic. ©2012 European Molecular Biology Organization.

Bozza G.,Novartis | Bozza G.,European Medicines Agency | Capitani M.,Unit of Genomic Approaches to Membrane Traffic | Montanari P.,Novartis | And 16 more authors.
PLoS ONE | Year: 2014

Neisseria meningitidis adhesin A (NadA) is a meningococcus surface protein thought to assist in the adhesion of the bacterium to host cells. We have previously shown that NadA also promotes bacterial internalization in a heterologous expression system. Here we have used the soluble recombinant NadA (rNadA) lacking the membrane anchor region to characterize its internalization route in Chang epithelial cells. Added to the culture medium, rNadA internalizes through a PI3K-dependent endocytosis process not mediated by the canonical clathrin or caveolin scaffolds, but instead follows an ARF6-regulated recycling pathway previously described for MHC-I. The intracellular pool of rNadA reaches a steady state level within one hour of incubation and colocalizes in endocytic vesicles with MHC-I and with the extracellularly labeled chaperone Hsp90. Treatment with membrane permeated and impermeable Hsp90 inhibitors 17-AAG and FITC-GA respectively, lead to intracellular accumulation of rNadA, strongly suggesting that the extracellular secreted pool of the chaperone is involved in rNadA intracellular trafficking. A significant number of intracellular vesicles containing rNadA recruit Rab11, a small GTPase associated to recycling endosomes, but do not contain transferrin receptor (TfR). Interestingly, cell treatment with Hsp90 inhibitors, including the membrane-impermeable FITC-GA, abolished Rab11-rNadA colocalization but do not interfere with Rab11-TfR colocalization. Collectively, these results are consistent with a model whereby rNadA internalizes into human epithelial cells hijacking the recycling endosome pathway and recycle back to the surface of the cell via an ARF6-dependent, Rab11 associated and Hsp90-regulated mechanism. The present study addresses for the first time a meningoccoccal adhesin mechanism of endocytosis and suggests a possible entry pathway engaged by N. meningitidis in primary infection of human epithelial cells. © 2014 Bozza et al.

Consoli G.M.L.,CNR Institute of Biomolecular Chemistry | Granata G.,CNR Institute of Biomolecular Chemistry | Fragassi G.,Unit of Genomic Approaches to Membrane Traffic | Grossi M.,Unit of Genomic Approaches to Membrane Traffic | And 2 more authors.
Organic and Biomolecular Chemistry | Year: 2015

A novel fluorescently labeled folate conjugate in which four folic acid units are covalently conjugated with a 7-nitro-benzofurazan fluorophore by means of a calix[4]arene platform was synthesized by using a Cu-catalyzed azide-alkyne cycloaddition reaction (click chemistry). The synthesized construct (FA-C4-NBD) was characterized by mass spectrometry, NMR and fluorescence spectroscopy. Confocal fluorescence microscopy experiments were carried out to evaluate the cell penetration ability of FA-C4-NBD on normal and cancer cells. The cellular uptake of FA-C4-NBD proceeds via folate receptor-mediated endocytosis. FA-C4-NBD is internalized into HeLa cancer cells which express high levels of folate receptors, whereas the uptake into fibroblast NIH3T3 cells which have very low expression levels of folate receptors is negligible. The involvement of the folate receptor was corroborated by competition tests with free folic acid. Co-localization analysis with different organelle markers indicated that FA-C4-NBD is not eliminated by recycling towards the outside of the cell, but accumulates intracellularly in the endo-lysosomal system. This journal is © 2015 The Royal Society of Chemistry.

De Luca A.,Centro Studi sullInvecchiamento | De Luca A.,University of Chieti Pescara | Sanna F.,Centro Studi sullInvecchiamento | Sanna F.,University of Chieti Pescara | And 11 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2010

Breast cancer is one of the most frequent of human malignacies, and it is therefore fundamental to identify the underlying molecular mechanisms leading to cancer transformation. Among other causative agents in the development of breast cancers, an important role for reactive oxygen species (ROS) has emerged. However, most studies on the role of ROS in cancer have not reached specific conclusions, and many issues remain controversial. In the present study, we show that methionine sulfoxide reductase A (MsrA), which is known to protect proteins from oxidation and which acts as a ROS scavenger, is down-regulated in a number of breast cancers. Moreover, levels of MsrA correlate with advanced tumor grade. We therefore investigated the functional role of MsrA in breast cancer cells. Our data show that reduction of MsrA levels results in increased cell proliferation and extracellular matrix degradation, and consequently in a more aggressive cellular phenotype, both in vivo and in vitro. We also show that the underlying molecular mechanisms involve increased ROS levels, resulting in reduction of phosphatase and tensin homolog deleted on chromosome ten protein (PTEN), and activation of the phosphoinositide 3-kinase pathway. In addition, MsrA down-regulation results in up-regulation of VEGF, providing additional support for tumor growth in vivo.

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