I. Study of the importance of the modifications of endosomal GTPases in health and disease.
Lipidic modifications of small GTPases by isoprenylation and palmitoylation at cysteine residues close to their C-termini play a key role in their subcellular localization and activity. We have shown that the isoprenylation and palmitoylation motif of the GTPase RhoB elicits the lysosomal localization and degradation of chimeric proteins bearing this sequence in cells from diverse species. We are exploring the mechanisms and applications of this phenomenon. In addition, palmitoylation cysteines mediate the redox regulation of these proteins since they are also targets of oxidative modifications or addition of electrophilic compounds, the structure of which determines the subcellular platform from where these GTPases signal.
From Commun Integr Biol 8:5, e1078041
II. Study of the modification of proteins of pathophysiological/pharmacological interest by lipid electrophiles.
Prostaglandins with cyclopentenone structure (cyPG) are electrophilic eicosanoids that display antiinflammatory and antiproliferative effects. cyPG form adducts with proteins with a selectivity depending on structural features of both the protein and the cyPG. We have identified numerous protein targets of cyPG, including enzymes of the aldo-keto-reductase (AKR) family and glutathione-transferases, which are involved in carcinogenesis and chemoresistance. Treatment of tumor cells with PGA1 inhibits these enzymes and reduces tumorigenic potential and resistance against the antitumoral drug doxorubicin. These findings could open novel standpoints for the development of new chemotherapeutic compounds.Moreover, AKR1B1 is involved in the development of diabetic complications. We have identified several PG that can inhibit this enzyme in ex vivo models of diabetes, thus broadening the perspectives for potential pharmacological agents. Finally, the study of targets of electrophilic lipids has unveiled novel mechanisms of redox signalling and pinpointed protein residues of previously unknown role that have turned out to be essential for protein function, as in the case of the single cysteine residue of the cytoskeletal protein vimentin, which constitutes a redox sensing switch and is involved in zinc binding.
III. Interactions between protein modification by electrophilic lipids, redox and drugs.
We are interested in the study of protein modification by drugs. This provides information on the mechanisms of drug action and of adverse effects. In particular, drug-protein adduct formation is considered a key process for development of drug allergy. In this context we have recently identified protein targets for haptenation by amoxicillin both in serum and in cells. Moreover we have obtained the first evidence for the presence of haptenated proteins in exosomes that can be secreted from drug-exposed cells and taken up by target cells. Characterization of these adducts may help improve diagnostic and therapeutic procedures for drug hypersensitivity reactions. Notably, certain proteins may be targets for modification by several agents and constitute points of interaction which integrate signals from inflammatory and redox signaling, as well as pharmacological treatments. These interactions may influence the outcome of pathophysiological processes.