15-Deoxy-Δ12,14-Prostaglandin J2 Negatively Regulates rankl Gene Expression in Activated T Lymphocytes: Role of NF-κB and Early Growth Response Transcription Factors

Abstract

Receptor activator of NF-κB ligand (RANKL) and its receptor RANK are cell surface proteins abundantly expressed in bone and lymphoid tissues, whose interaction triggers different signaling pathways leading to activation and differentiation of osteoclasts, pivotal actors of the normal bone remodeling cycle. Moreover, RANKL may act as an immunomodulator, representing an important dendritic cell survival factor produced by activated T cells. A large body of research has shown that not only does the RANKL/RANK system regulate the physiology of bone development but also plays an important pathological role in bone destruction mediated by inflammatory disorders or bone metastatic tumors. 15-Deoxy-Δ12,14-PGJ2 (15d-PGJ2) is a cyclopentenone-type PG endowed with anti-inflammatory properties and produced by different cells, including those of the immune system. Although 15d-PGJ2 has been studied as a natural ligand of the peroxisome proliferator-activated receptor-γ nuclear receptor, relevant peroxisome proliferator-activated receptor-γ-independent actions mediated by this prostanoid have been described. In this study, we describe the effect of 15d-PGJ2 on the expression of the rankl gene in T lymphocytes. We show that 15d-PGJ2 inhibits rankl mRNA expression, protein, and rankl promoter activity by mechanisms mediated by its chemically reactive cyclopentenone moiety. Our data also indicate that 15d-PGJ2 represses rankl activation by interfering with the expression and/or activity of the transcription factors NF-κB, early growth response-2, and early growth response-3, whose altered balancing and transactivation may contribute for the repression of this gene. These results place rankl as a novel molecular target for the different immunoregulatory activities mediated by 15d-PGJ2. The physiological and pharmacological implications of these observations are discussed.

Inhibition ofTrailGene Expression by Cyclopentenonic Prostaglandin 15-Deoxy-Δ12,14-Prostaglandin J2in T Lymphocytes

“…We have reported recently that 15d-PGJ 2 inhibits fas-l and rankl gene expression in activated T cells (Cippitelli et al, 2003;Fionda et al, 2007).…”

“…Because NF-B is one of the transcription factors strongly inhibited by 15d-PGJ 2 in many cellular types (Rossi et al, 2000;Straus et al, 2000;Piva et al, 2005) including T lymphocytes (Cippitelli et al, 2003;Fionda et al, 2007), we investigated whether it could be involved in the inhibitory action of the prostanoid on trail promoter. In this regard, Twenty-four hours after transfection, cells were left untreated (Ϫ) or were stimulated with 10 ng/ml PMA and 0.5 g/ml ionomycin (P/I) in the absence or presence of 10 M 15d-PGJ 2 .…”

Genotoxic stress modulates the release of exosomes from multiple myeloma cells capable of activating NK cell cytokine production: Role of HSP70/TLR2/NF-kB axis

“…67 Protein concentration of extracts was determined by the BPA method (Pierce, Rockford, IL). The nuclear proteins (4 mg) were incubated with radiolabeled DNA probes in a 20 mL reaction mixture containing 20 mM Tris (pH 7.5), 60 mM KCl, 2 mM EDTA, 0.5 mM dithiothreitol (DTT), 1 mg of poly(dIdC) and 4% ficoll.…”

“…Nucleoprotein complexes were resolved as described previously. 67 Oligonucleotides were purchased by BioFab (Rome, Italy). Complementary strands were annealed and end-labeled as described.…”

“…Complementary strands were annealed and end-labeled as described. 67 Approximately 3£10 4 cpm of labeled DNA was used in a standard electrophoretic mobilityshift assay reaction. The following double-strand oligomers were used as specific labeled probes or cold competitors (sense strand): Octamer-(h-Histone H2b), 5…”