Abstract 5567: Caveolae/caveolin-1 Are Crucial For IL-1β-induced Proangiogenic Processes In Endothelial Cells Mediated Via TRAF6, p38-MAPK, MK2 And Hsp27
Interleukin-1β (IL-1β) is a major inducer of pro-inflammatory processes but also possesses potent pro-angiogenic properties, both entities known to be important in the pathogenesis of cardiovascular disease. Whereas IL-1β-induced pro-inflammatory signaling pathways are well characterized, little is known about the signaling pathways mediating its pro-angiogenic properties. Therefore, the present study investigated the underlying signaling pathways mediating the IL-1β-induced pro-angiogenic processes in endothelial cells (EC). IL-1β (10 ng/ml) significantly promoted tube formation (matrigel, +300%, n=5, p<0.05) and migration (scratch assay, +300%, n=5, p<0.05) of EC which was associated with a marked activation of p38-MAPK, MK2 and Hsp27 (westernblot: phospho-p38,-MK2,-Hsp27). Silencing of TRAF6 by lentiviral-shRNA in EC dramatically reduced the IL-1β-induced pro-angiogenic and migratory capacity of EC (−90%, n=5, p<0.05) which was accompanied by a markedly reduced IL-1β-induced activation of p38-MAPK, MK2 and Hsp27. In line, inhibition of p38-MAPK (SB203580) and MK-2 (siRNA) mimicked the impaired IL-1β-dependent tube formation and migration observed in EC after TRAF6-silencing (-90%, n=5, p<0.01). Similarly to TRAF6-silencing, disruption of caveolae by methyl-β-cyclodextrin (MCD) and filipin markedly reduced the IL-1β-dependent activation of p38-MAPK, MK-2 and Hsp27 and almost blunted the IL-1β-induced tube formation (−95%, n=5, p<0.01) and migratory capacity of EC (−85%, n=4, p<0.01). Furthermore, IL-1β-induced translocation of TRAF6 to the caveolin-1 enriched membrane fraction was prevented by treatment of EC with MCD and filipin. In line, silencing of caveolin-1 (siRNA) in EC prevented the IL-1β-induced translocation of TRAF6 to the caveolin-1 enriched membrane fraction and potently inhibited IL-1β-dependent tube formation and migration of EC (−90%, n=5, p<0.01). Caveolae/caveolin-1 are crucial for IL-1β-induced proangiogenic processes in EC mediated via TRAF6, p38-MAPK, MK2 and Hsp27. This IL-1β-dependent pro-angiogenic signaling modul might represent an attractive target to intervene into angiogenesis-dependent cardiovascular processes and diseases.