M G Malabarba

Publications (5)47.81 Total impact

• Article: A repertoire library that allows the selection of synthetic SH2s with altered binding specificities.

  M G Malabarba, E Milia, M Faretta, R Zamponi, P G Pelicci, P P Di Fiore
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  ABSTRACT: Tyrosine phosphorylation is one of the major mechanisms involved in the intracellular propagation of external signals. Strategies aimed at interfering with this process might allow the control of several cellular phenotypes. SH2 domains mediate protein-protein interactions by recognizing phosphotyrosine (pY) residues in the context of specific phosphopeptides. We created an SH2-scaffolded repertoire library by randomly mutagenizing five critical amino acid positions in the specificity-determining region of the PLCgamma C-terminal SH2 domain. Synthetic SH2 domains were selected from the library using biotinylated phosphopeptides derived from a natural PLCgamma-SH2 ligand as well as unrelated SH2 ligands. The isolated SH2s displayed high binding affinity constants for the selecting peptides and were capable of interacting with the corresponding proteins.
  Oncogene 09/2001; 20(37):5186-94. · 6.37 Impact Factor
• Article: The Eps8 protein coordinates EGF receptor signalling through Rac and trafficking through Rab5.

  L Lanzetti, V Rybin, M G Malabarba, S Christoforidis, G Scita, M Zerial, P P Di Fiore
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  ABSTRACT: How epidermal growth factor receptor (EGFR) signalling is linked to EGFR trafficking is largely unknown. Signalling and trafficking involve small GTPases of the Rho and Rab families, respectively. But it remains unknown whether the signalling relying on these two classes of GTPases is integrated, and, if it is, what molecular machinery is involved. Here we report that the protein Eps8 connects these signalling pathways. Eps8 is a substrate of the EGFR, which is held in a complex with Sos1 by the adaptor protein E3bl (ref. 2), thereby mediating activation of Rac. Through its src homology-3 domain, Eps8 interacts with RN-tre. We show that RN-tre is a Rab5 GTPase-activating protein, whose activity is regulated by the EGFR. By entering in a complex with Eps8, RN-tre acts on Rab5 and inhibits internalization of the EGFR. Furthermore, RN-tre diverts Eps8 from its Rac-activating function, resulting in the attenuation of Rac signalling. Thus, depending on its state of association with E3b1 or RN-tre, Eps8 participates in both EGFR signalling through Rac, and trafficking through Rab5.
  Nature 12/2000; 408(6810):374-7. · 36.28 Impact Factor
• Article: Effects of pidotimod on macrophage functions in methylprednisolone-treated mice.

  D Taramelli, M G Malabarba, N Basilico, G Sala, R Mattina, C Cocuzza
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  ABSTRACT: CD-1 mice were treated with methylprednisolone (mPDN) 2-5 mg/kg s.c., for 11 or 6 days, in order to achieve an immunosuppressed state. For the same length of time a group of mice also received pidotimod ((R)-3-[(S)-(5-oxo-2-pyrrolidinyl) carbonyl]-thiazolidine-4-carboxylic acid. PGT/1A, CAS 121808-62-6) i.p. at 100 or 10 mg/kg. At the end of treatment, peritoneal macrophages (MO) were recovered, purified by adherence to plastic and activated in vitro with different stimuli. After 24 h of incubation, the supernatants were collected and assayed for the presence of tumor necrosis factor-alpha (TNF-alpha) and nitrite (NO2-), which is the stable derivative of nitric oxide (NO) in acqueous solution. It is well known that TNF-alpha and NO represent two out of many molecules secreted by activated MO which are essential for killing microorganisms and for natural response to infections. It was observed that MO from mPDN-treated mice were unable to produce sufficient levels of both TNF-alpha and NO when stimulated in vitro with lipopolysaccharide, IFN-gamma or conidia from an opportunistic fungus, Aspergillus fumigatus, confirming that corticosteroids are able to inhibit the antimicrobial activity of MO. However, MO from mice received mPDN plus pidotimod fully recovered the capacity to produce TNF-alpha and NO in response to the same stimuli. Optimal dose of pidotimod was 100 mg/kg. In addition, pidotimod was also able to reconstitute the cellularity of the peritoneum and of the spleens of mice immunodepressed by mPDN.(ABSTRACT TRUNCATED AT 250 WORDS)
  Arzneimittel-Forschung 01/1995; 44(12A):1425-30. · 0.72 Impact Factor
• Article: In vitro activity of pharmacological compounds carried by lipidic microparticles.

  D Taramelli, M G Malabarba, P Rossi, C Granucci, M Ghione
  Pharmacological Research 10/1992; 26 Suppl 2:126-7. · 4.44 Impact Factor
• Article: Production of cytokines by alveolar and peritoneal macrophages stimulated by Aspergillus fumigatus conidia or hyphae.

  D Taramelli, M G Malabarba, G Sala, N Basilico, G Cocuzza
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  ABSTRACT: Aspergillus fumigatus is an opportunistic pathogen responsible for severe, invasive infections in neutropenic hosts. Lung clearance of A. fumigatus conidia seems to be mediated by phagocytic cells and oxygen radicals. It is not known if cytokines or nitrogen radicals are also involved. We tested for the production of TNF alpha, IL-1 and nitric oxide (NO) after stimulation of mouse macrophages with the fungus. We found that both cytokines, but not NO, were produced in a dose-dependent manner during the first 24 h of culture. Except for a faster kinetic, no appreciable differences were seen between alveolar and peritoneal macrophages. Furthermore, both hyphae and conidia, either alive or killed, were capable of inducing cytokines production. However, among different Aspergillus spp. only A. fumigatus and A. flavus seemed to induce significant amount of TNF alpha and IL-1, whereas A. terreus and A. niger were less effective. In no case could we detect production of NO. Finally, macrophages from dexamethasone-treated mice failed to produce cytokines in response to A. fumigatus conidia. These results indicate that in normal hosts inflammatory cytokines contribute to the natural response against Aspergillus infections and suggest that the impairment of cytokine production, in immunodepressed patients, may favour the growth and spread of the fungus.
  Journal of medical and veterinary mycology: bi-monthly publication of the International Society for Human and Animal Mycology 34(1):49-56.