A Lys49 phospholipase A2, isolated from Bothrops asper snake venom, induces lipid droplet formation in macrophages which depends on distinct signaling pathways and the C-terminal region

Abstract

MT-II, a Lys49PLAhomologue devoid of catalytic activity from B. asper venom, stimulates inflammatory events in macrophages. We investigated the ability of MT-II to induce formation of lipid droplets (LDs), key elements of inflammatory responses, in isolated macrophages and participation of protein kinases and intracellular PLA in this effect. Influence of MT-II on PLIN2 recruitment and expression was assessed, and the effects of some synthetic peptides on LD formation were further evaluated. At noncytotoxic concentrations, MT-II directly activated macrophages to form LDs. This effect was reproduced by a synthetic peptide corresponding to the C-terminal sequence 115-129 of MT-II, evidencing the critical role of C-terminus for MT-II-induced effect. Moreover, MT-II induced expression and recruitment of PLIN2. Pharmacological interventions with specific inhibitors showed that PKC, PI3K, ERK1/2, and iPLA but not P38MAPK or cPLA signaling pathways are involved in LD formation induced by MT-II. This sPLAhomologue also induced synthesis of PGEthat colocalized to LDs. In conclusion, MT-II is able to induce formation of LDs committed to PGEformation in a process dependent on C-terminal loop engagement and regulated by distinct protein kinases and iPLA LDs may constitute an important inflammatory mechanism triggered by MT-II in macrophages. © 2013 Karina Cristina Giannotti et al.