Biomedical subjects

Annalisa Mancini

Publications and source records attributed to Annalisa Mancini.

7 recordsLinked to original sources

PubMed2005

[M(R-dmet)2] bis(1,2-dithiolenes): a promising new class intermediate between [M(dmit)2] and [M(R,R'-timdt)2] (M = Ni, Pd, Pt).

We report the first examples of metal dithiolenes belonging to the class [M(R-dmet)(2)] [R-dmet = formally monoreduced N-substituted thiazolidine-2,4,5-trithione; R = Et, M = Ni (1), Pd (2), Pt (3)]. A comparative spectroscopic, electrochemical, and density functional theory theoretical investigation indicates that [M(R-dmet)(2)] complexes show features intermediate between those of the dithiolenes belonging to the previously reported classes [M(R,R'-timdt)(2)] and [M(dmit)(2)] (R,R'-timdt = formally monoreduced N,N'-disubstituted imidazolidine-2,4,5-trithione; dmit = 2-thioxo-1,3-dithiole-4,5-dithiolato). UV-vis-near-IR spectroscopy and cyclic voltammetry/differential pulsed voltammetry measurements performed on 1 and 3 proved that the new dithiolenes are stable as neutral, monoanionic, and bianionic species and feature a near-IR electrochromic absorption falling at about 1000 and 1250 nm for neutral and monoanionic species, respectively.

Journal Article↗

PubMed2005

The SH2-domian-containing inositol 5-phosphatase (SHIP)-2 binds to c-Met directly via tyrosine residue 1356 and involves hepatocyte growth factor (HGF)-induced lamellipodium formation, cell scattering and cell spreading.

Recently, evidence has been accumulating that inositol and phosphatidylinositol polyphosphate play important roles in a variety of signal transduction systems including membrane traffic, actin cytoskeleton rearrangement and cell motility. In this paper, we show for the first time that the SH2-domain-containing inositol 5-phosphatase (SHIP)-2 binds directly to the hepatocyte growth factor (HGF/SF) receptor, c-Met, via phosphotyrosine 1356. HGF induces the breakdown of cell junctions and the dispersion of colonies of epithelial cells including MDCK cells. Whereas only few lamellipodia are observed in MDCK cells 2 min after stimulation with HGF, both SHIP-2- and SHIP-1-overexpressing cells form large, broad lamellipodia. The number of lamellipodia is 2-4-fold greater than that of mock-transfected MDCK cells in the same time period and SHIP is found to colocalize with actin at the leading edge. Furthermore, overexpression of a catalytic inactive mutant of SHIP-2 suppresses HGF-potentiated cell scattering and cell spreading, although these mutant-expressing cells form enhanced number of lamellipodia 2 min after HGF stimulation. Interestingly, cells expressing a mutant lacking the proline-rich domain of SHIP-2 at the C-terminal form few lamellipodia, but still spread and scatter upon stimulation with HGF at a reduced rate. These data suggest that phosphatase activity is required for HGF-mediated cell spreading and scattering but not for alteration of lamellipodium formation, while the proline-rich region influences lamellipodium formation. Furthermore, treatment with 10 microM of phosphatidylinositol 3 (PI3) kinase inhibitor, LY294002, abrogates HGF-induced cell scattering of SHIP-2-overexpressing cells but not parental HEK293 cells, suggesting that a balance between PI3 kinase and SHIP is important for cell motility.

Animals↗

PubMed2004

The M-CSF receptor substrate and interacting protein FMIP is governed in its subcellular localization by protein kinase C-mediated phosphorylation, and thereby potentiates M-CSF-mediated differentiation.

Macrophage colony-stimulating factor (M-CSF or CSF-1) and its cognate receptor, the tyrosine kinase c-fms, are essential for monocyte and macrophage development. We have recently identified an Fms-interacting protein (FMIP) that binds transiently to the cytoplasmic domain of activated Fms molecules and is phosphorylated on tyrosine by Fms tyrosine kinase. FMIP is a substrate not only for Fms but also for protein kinase C (PKC). Mutagenesis reveals that this occurs on serines 5 and 6. Adjacent to these sites is a nuclear localization signal (NLS). We show that this NLS is essential for the predominantly nuclear localization of FMIP. Generation of phosphomimetic substitutions on serine residues 5 and 6 confirms that PKC-mediated phosphorylation on this site leads to translocation of FMIP to the cytosol. Furthermore, the mutant FMIP (FMIPSS5,6AA) was detected abundantly in the nucleus even in the presence of activated PKCalpha. Wild-type FMIP and FMIPSS5,6AA inhibited M-CSF-mediated survival signaling, while FMIPSS5,6EE-expressing cells survived and differentiated into macrophages more efficiently than wild-type cells in the presence of M-CSF or TPA. We conclude M-CSF-mediated activation of PKCalpha can potentiate FMIP action to initiate survival/differentiation signaling.

Animals↗

PubMed2004

c-Cbl binds to tyrosine-phosphorylated neurotrophin receptor p75 and induces its ubiquitination.

The p75 neurotrophin receptor (p75NTR) has dual functions in cell survival and cell death but its intracellular signalling pathways are not understood. Here we describe that in rat brain and in pervanadate-stimulated PCNA and HEK293 cells p75NTR is phosphorylated at a single tyrosine residue within the cytosolic C-terminus. Phosphorylated tyrosine 308 constitutes a binding site for the ubiquitin ligase c-Cbl. This interaction is a prerequisite for ubiquitination of p75NTR. Our data suggest a c-Cbl-dependent ubiquitination of p75NTR involved in the regulation of p75NTR signalling.

Amino Acid Sequence↗

PubMed2003

First example of an infinite polybromide 2D-network.

The reaction of the neutral dithiolene [Pd(Et2timdt)2] (Et2timdt = formally monoreduced diethylimidazolidine-2,4,5-trithione) with an excess of Br2 yielded few crystals of [1(Et) x 2Br](2+)(Br-)2(Br2)3 as a by-product (1(Et) = 4,5,9,10-tetrathiocino-[1,2-b:5,6-b']-1,3,6,8-tetraethyl-diimidazolyl-2,7-dithione); X-ray diffraction analysis showed that this compound represents the first example of a polybromide 2D-network templated by [1(Et) x 2Br](+2) dications, and featuring all the Br-Br distances shorter than those found in solid state bromine.

Journal Article↗

PubMed2002

The SH2-containing inositol 5-phosphatase (SHIP)-1 is implicated in the control of cell-cell junction and induces dissociation and dispersion of MDCK cells.

Hepatocyte growth factor (HGF) induces the breakdown of cell junction and the dispersion of colonies of epithelial cells, providing a model system for the investigation of the molecular mechanisms of one of the important aspects of tumorogenesis. We have previously reported that the SH2-domain-containing inositol 5'phosphatase (SHIP)-1 binds to c-Met, and potentiated HGF-mediated branching tubulogenesis. In this study, we describe the establishment of MDCK cell lines which express MycHis-tagged SHIP-1 at different levels. Expression of SHIP-1 in MDCK cells at a high level resulted in cell morphology characteristic of an epithelial-mesenchymal like transition; cells lost cortical actin, developed actin stress fibers and gained spontaneous motility without treatment of HGF. When the level of MycHis-tagged SHIP-expression was relatively low, transfectants partially lost cortical actin and phalloidin stained puncta appeared at cell-cell junctions even in the absence of HGF. The treatment of MAP kinase inhibitor, PD98059, did not influence SHIP-1 mediated alteration of adherens-junction of MDCK cells, while, phosphatidylinositol 3 (PI 3)- kinase inhibitor, LY294002, drastically reduced SHIP-1 mediated phenotype. Furthermore, expression of a mutant SHIP-1 lacking catalytic activity in MDCK cells did not alter the cortical actin distribution and HGF-mediated MAP and Akt kinase-phosphorylation, but suppressed HGF induced cell dispersion, suggesting that phosphatase activity is important for cytoskeleton rearrangement and cell dispersion.

Adherens Junctions↗

PubMed2002

c-Cbl associates directly with the C-terminal tail of the receptor for the macrophage colony-stimulating factor, c-Fms, and down-modulates this receptor but not the viral oncogene v-Fms.

The receptor for the macrophage colony-stimulating factor (CSF-1, also termed M-CSF), the tyrosine kinase c-Fms, was originally determined to be the oncogene product of the McDonough strain of feline sarcoma virus, v-Fms. The structural difference between c-Fms and v-Fms amounts to only five point mutations in the extracellular domain, two mutations in the cytoplasmic domain, and the replacement of 50 amino acids by 14 unrelated amino acids at the C-terminal tail. Here, we have identified c-Cbl as the direct binding partner for c-Fms. c-Cbl binds to phosphotyrosine residue 977 at the C-terminal end of feline c-Fms, which is absent in v-Fms. The replacement of the C-terminal end of v-Fms by the corresponding part of c-Fms (vc-Fms) restored the binding potential. As a result, vc-Fms reduced the transforming potency of v-Fms. The overexpression of Cbl did not influence the v-Fms-transformed phenotype, although c-Cbl forms a complex with v-Fms indirectly. In contrast, the expression of Cbl drastically reduced the vc-Fms-transformed phenotype and the activation of Erk and enhanced Fms ubiquitination via phosphotyrosine residue 977. Furthermore, the replacement of tyrosine 977 into phenylalanine in feline c-Fms and vc-Fms reduced the Cbl-dependent ubiquitination. These data suggest that an indirect association of c-Cbl via multimeric complex induced a different signaling pathway from the pathway induced by c-Cbl direct interaction.

3T3 Cells↗