Several potential anti-RA agents have been discovered from this model

degranulation within the asthmatic BSM layer. We have previously demonstrated that, in severe asthmatic BSM, the Butein increased FCS-induced BSM cell proliferation is related to an altered calcium signaling through an abnormal extra-cellular calcium entry. Subsequently, Mahn et al. demonstrated that, the expression of the sarco/endoplasmic reticulum calcium pump is decreased in the BSM from moderate asthmatics. Moreover, knocking down SERCA2 increased non asthmatic BSM cell proliferation. These two studies strongly argue in favor of a direct relationship between calcium response and BSM cell proliferation induced by FCS. In the present study, both PAR2-dependent calcium response and cell proliferation were increased in asthmatic BSM cells. However, whereas PAR-2 over-expression reproduced the increased calcium response to SLIGKV-NH2 in non asthmatic BSM cells, it failed to increase BSM cell proliferation. These results suggest that, the sole overexpression of a receptor coupled to calcium signaling is not enough to increase BSM cell proliferation. This lack of proliferative effect of PAR-2 over-expression was not due to a difference in either the EC50 of SLIGKV-NH2 or the level of PAR-2 expression. Indeed, we paid a special attention to optimize the experimental conditions, in order to obtain a similar PAR-2 expression level in non asthmatic BSM cells following lentiviral transduction to 6 PAR-2 Function in Asthmatic Smooth Muscle Cells pathways. The phosphorylation of ERK appears to be involved since the increased amount of phospho-ERK was restricted to asthmatic BSM cells and, its inhibition by PD98059 inhibited PAR-2 dependent asthmatic BSM cell proliferation. In contrast, the role of p38 could not be demonstrated since, increased amount of phospho-p38 was observed in both asthmatic and non asthmatic BSM cells and, its inhibition by SB203580 did not decrease PAR-2 dependent asthmatic BSM cell proliferation. The current results also point out a striking difference between, asthmatic BSM cells with higher basal levels of PAR-2 and, lentiviral-induced PAR-2 over-expression in non asthmatic BSM cells. Indeed, we have previously demonstrated that, in severe asthmatic BSM, the increased FCS-induced cell proliferation is related to an increased mitochondrial biogenesis, which was not found in non asthmatic BSM cells with lentiviral-induced PAR-2 over-expression. In conclusion, asthmatic BSM cells are characterized by an increased expression of functional PAR-2, the prolonged PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19648918 stimulation of which may contribute to many pathophysiological patterns present in asthma such as bronchial hyperresponsiveness and BSM remodeling. However, the higher basal levels of PAR-2 account for the increased calcium response but are not sufficient to explain increased BSM cell proliferation, which needs the additional up-regulation of ERK phosphorylation. Blocking BSM PAR-2 and/or its transduction pathways could be interesting and promising targets for therapeutic intervention in asthma. RIG-I is an intracellular detector of 59 triphosphate RNA that activates a signaling pathway leading to the production of type I interferon and initiation of the antiviral state. The three dimensional structures of RIG-I from several species provide a molecular model for RIG-I activation. The pathway starts upon sensing of viral RNA by the RIG-I helicase and regulatory domains, which undergo a conformational change, acting as a molecular camshaft that uses energy from ATP hydrolysis