Rac1 modification by an electrophilic 15-deoxy Δ12,14-prostaglandin J2 analog

Abstract

Vascular endothelial cells (ECs) are important for maintaining vascular homeostasis. Dysfunction of ECs contributes to cardiovascular diseases, including atherosclerosis, and can impair the healing process during vascular injury. An important mediator of EC response to stress is the GTPase Rac1. Rac1 responds to extracellular signals and is involved in cytoskeletal rearrangement, reactive oxygen species generation and cell cycle progression. Rac1 interacts with effector proteins to elicit EC spreading and formation of cell-to-cell junctions. Rac1 activity has recently been shown to be modulated by glutathiolation or S-nitrosation via an active site cysteine residue. However, it is not known whether other redox signaling compounds can modulate Rac1 activity. An important redox signaling mediator is the electrophilic lipid, 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2). This compound is a downstream product of cyclooxygenase and forms covalent adducts with specific cysteine residues, and induces cellular signaling in a pleiotropic manner. In this study, we demonstrate that a biotin-tagged analog of 15d-PGJ2 (bt-15d-PGJ2) forms an adduct with Rac1 in vitro at the C157 residue, and an additional adduct was detected on the tryptic peptide associated with C178. Rac1 modification in addition to modulation of Rac1 activity by bt-15d-PGJ2 was observed in cultured ECs. In addition, decreased EC migration and cell spreading were observed in response to the electrophile. These results demonstrate for the first time that Rac1 is a target for 15d-PGJ2 in ECs, and suggest that Rac1 modification by electrophiles such as 15d-PGJ2 may alter redox signaling and EC function.

Pleiotropic effects of 4-hydroxynonenal on oxidative burst and phagocytosis in neutrophils

“…4 ). Interestingly, modification of Rac1 by other lipid electrophiles has previously been reported [62] .…”

Spatial perspectives in the redox code—Mass spectrometric proteomics studies of moonlighting proteins

“…The fragment network includes transport between the nucleus, cytosol and plasma membrane, nuclear phosphorylation of SET, cytoplasmic interaction of SET‐RAC1 and plasma membrane interaction of SET‐RAC1‐PP2A. It may include redox modification of RAC1 with prostaglandin at the plasma membrane (Wall et al, ). Since SET, RAC1, and PP2A all have other activities, the evaluation of the functional importance of this fragment requires its quantitative encapsulation in a more extensive network.…”

15-Deoxy-Δ12,14-Prostaglandin J2 Modifies Components of the Proteasome and Inhibits Inflammatory Responses in Human Endothelial Cells

“…First, 15d-PGJ 2 is a ligand for peroxisome proliferator-activated receptor gamma (PPAR-γ), a member of the nuclear receptor superfamily and a transcription factor with pleiotropic effects on adipocyte differentiation, glucose homeostasis, lipid metabolism, cell growth, and inflammation (29, 32). Second, 15d-PGJ 2 also exerts effects by covalently modifying proteins through the reactive α,β-unsaturated carbonyl group located in the cyclopentenone ring, a structural feature unique to J series prostaglandins (Figure 1A) (9–15). In earlier studies, we used biotin-15d-PGJ 2 to capture a wide range of protein candidates in EC (27).…”

“…15d-PGJ 2 was also identified as a potent ligand of the nuclear receptor, PPAR-γ (6–8). There is evidence that at least some of these anti-inflammatory effects are mediated through the covalent modification of cellular proteins, via its reactive α,β-unsaturated carbonyl group (9–15), which in turn modifies their biological functions (14). …”