Modification and Activation of Ras Proteins by Electrophilic Prostanoids with Different Structure are Site-Selective

Abstract

Cyclopentenone prostanoids (cyP) arise as important modulators of inflammation and cell proliferation. Although their physiological significance has not been fully elucidated, their potent biological effects have spurred their study as leads for the development of therapeutic agents. A key determinant of cyP action is their ability to bind to thiol groups in proteins or in glutathione through Michael addition. Even though several protein targets for cyP addition have been identified, little is known about the structural determinants from the protein or the cyP that drive this modification. The results herein presented provide the first evidence that cyP with different structures target distinct thiol sites in a protein molecule, namely, H-Ras. Whereas 15-deoxy-Delta12,14-prostaglandin J2 (15d-PGJ2) and Delta12-PGJ2 preferentially target the C-terminal region containing cysteines 181 and 184, PGA1 and 8-iso-PGA1 bind mainly to cysteine 118, located in the GTP-binding motif. The biological counterparts of this specificity are the site-selective modification and activation of H-Ras in cells and the differential interaction of cyP with H, N, and K-Ras proteins. Cysteine 184 is unique to H-Ras, whereas cysteine 118 is present in the three Ras homologues. Consistent with this, PGA1 binds to and activates H-, N-, and K-Ras, thus differing from the preferential interaction of 15d-PGJ2 with H-Ras. These results put forward the possibility of influencing the selectivity of cyP-protein addition by modifying cyP structure. Furthermore, they may open new avenues for the development of cyP-based drugs.

Evidence for the importance of OxPAPC interaction with cysteines in regulating endothelial cell function

“…The similarity of structure in these two molecules suggested that they might have similar interactions with cell proteins. Previous studies have shown similar effects of 15dPGJ 2 to OxPAPC in several pathways ( 7,9,12,14,15,(22)(23)(24)(25)(26)(27). We now demonstrate that OxPNB and 15dPGJ 2 bind to the same cysteines in H-Ras (C181 and C184) and that 15dPGJ 2 can inhibit the binding of OxPNB to H-Ras.…”

“…study of the role played by specifi c cysteines in Ras activation (12)(13)(14)(15). The current study examines the mechanism by which OxPNB interacts with H-Ras.…”

Identification of Aldo-Keto Reductase AKR1B10 as a Selective Target for Modification and Inhibition by Prostaglandin A1: Implications for Antitumoral Activity

“…This property is essential for cyPG biological actions (4), including PPAR activation (5) and inhibition of NF-kB and AP-1 transcription factors (1,6). A-and J-series cyPG were initially observed to share several protein targets and biological actions (7)(8)(9). However, recent studies have shown that cyPG with different structures may target selective subsets of cellular proteins (10), and even different residues within the same protein.…”

“…However, recent studies have shown that cyPG with different structures may target selective subsets of cellular proteins (10), and even different residues within the same protein. Ras proteins and histone deacetylases constitute examples of this intra-and intermolecular selectivity (9,11). Identification of the factors involved in the selectivity of protein modification by different cyPG, as well as of the selectively modified targets, could unveil potential opportunities for drug discovery.…”

Mammalian Son of Sevenless Guanine Nucleotide Exchange Factors: Old Concepts and New Perspectives

“…Signaling molecules such as nitric oxide (NO) or the cyclopentenone prostaglandins (CyPG) PGA 1 and 15d-PGJ 2 have been reported to trigger cellular Ras activation in a process including direct modification of specific cysteine residues of the C-terminal Ras region. [96][97][98][99] In the current paradigm, upon RTK or GPCR activation, Sos proteins are recruited to the plasma membrane via formation of a complex with Grb2 adaptor proteins. 5,[57][58][59] However, a still unanswered question is the mechanism of the possible participation of Sos in the process of CyPG-mediated Ras activation.…”