RSUME as a potential target to modulate inflammatory responses

JIMENA DRUKER; JUAN GEREZ; ALBERTO CARBIA-NAGASHIMA; SUSANA SILBERSTEIN; MARCELO PAEZ PEREDA; GUNTER STALLA; FLORIAN HOLSBOER; EDUARDO ARZT

Buenos Aires, Argentina

Congreso; III Iberoamerican Congress of NeuroImmunomodulation; 2009

Intoduction: The ubiquitin-proteasome and sumoylation systems regulate the activity of main mediators involved in the inflammatory processes. Sumoylation, a post-translational modification, regulates NFkB as well asglucocorticoid receptor (GR) activity. RSUME, a new small RWD-containing protein, has a central role in the regulation of sumoylation by enhancing SUMO conjugation. In this work, we analyzed the action of RSUME on GR transcriptional activity. Methodology: Transient transfections were made with TK-GREx2-LUC, AP-1-LUC and NFkB-LUC reporter vectors, CMV-hGR with or without RSUME expression vector. Afterwards LUC activity was measured in cells extracts. In vivo sumoylation and co-immunoprecipitation assays were analyzed by Western blot. Results: we observed: i) a physical interaction of RSUME and GR, ii) RSUME enhances GR sumoylation and this increase is not observed with the Y61A/P62A RSUME mutant, indicating that this effect depends on RSUME s RWD domain, and iii) Overexpression of RSUME enhances GR transcriptional activity. Additionally, RSUME potentiates GR transrepression activity on AP-1 response elements but has no effect on GR-mediated NFkB transrepression. Conclusions:based on the fact that RSUME inhibits NFkB by enhancing IkB sumoylation (Cell 131(2):309-323.2007) and modifies GR transactivation and transrepression activity, the impact of RSUME on inflammatory responsesmay be relevant for immune-neuroendocrine networks.