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

Biomed Res Int. 2013:2013:807982. doi: 10.1155/2013/807982. Epub 2012 Dec 24.

Abstract

MT-II, a Lys49PLA2 homologue 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 PLA2s 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 iPLA2, but not P38(MAPK) or cPLA2, signaling pathways are involved in LD formation induced by MT-II. This sPLA2 homologue also induced synthesis of PGE2 that colocalized to LDs. In conclusion, MT-II is able to induce formation of LDs committed to PGE2 formation in a process dependent on C-terminal loop engagement and regulated by distinct protein kinases and iPLA2. LDs may constitute an important inflammatory mechanism triggered by MT-II in macrophages.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bothrops*
  • Catalysis
  • Cell Survival
  • Lipids / chemistry*
  • Lysine / chemistry
  • Macrophages / cytology
  • Macrophages / metabolism*
  • Male
  • Mice
  • Peptides / chemistry
  • Phospholipases A2 / chemistry*
  • Protein Kinases / metabolism
  • Protein Structure, Tertiary
  • Signal Transduction*
  • Snake Venoms / enzymology*

Substances

  • Lipids
  • Peptides
  • Snake Venoms
  • Protein Kinases
  • Phospholipases A2
  • Lysine