Novel nitrated lipid mediators as ligands of FABPs

MARÍA LAMAS; FRANCISCO J. SCHOPFER; BETINA CÓRSICO; GISELA R. FRANCHINI; ANA M. FERREIRA

La Plata

Congreso; 8th International Conference on Lipid Binding Proteins; 2013

The nitroalkenes (NO2-FA, from nitro fatty acids) are lipid mediators belonging to a family of nitrated derivatives of polyunsaturated fatty acids, which has interesting biological properties. NO2-FA has shown antiinflammatory effects and the ability to control lipid metabolism, through the regulation of different transcription factors. One of their targets is a family of nuclear receptors known as PPAR, which not only regulates the cellular lipid metabolism, by mediating lipid transport and storage, but also controls anti-inflammatory responses. We have confirmed that NO2-FA activates PPARγ, by determining their capacity to increase the expression of a PPAR reporter gen, CD36, in THP-1 monocyte cells. Although NO2-FA are produced endogenously in inflammatory contexts, the molecular mechanisms associated with PPAR activation by NO2-FA are unknown; FABPs may be involved considering NO2-FA lipid nature, and the interactions between FABPs and PPAR already described. As a first step to aboard this hypothesis we studied if FABPs are capable of binding these nitrated products, since nitration could affect the naturally binding capacity of these proteins. We specifically studied the interaction of two FABPs isoforms, the liver (LFABP) and the intestine (IFABP) one, by competition experiments. Briefly we measured the displacement of bound ANS to an FABP by nitro oleic acid (OANO2)monitoring the decrease of fluorescence intensity with increasing OANO2 concentration. The dissociation constant for OANO2 was calculated, and compared with that of the precursor fatty acid. Results showed that the nitration did not affect the recognition of the OANO2 by the IFABP. Similar experiments are currently being carried out with other NO2-FA such as conjugated nitro linoleic acid (CLANO2) and nitro arachidonic acid (AANO2). Overall these studies will help to elucidate whether NO2-FA are ligands of FABPs, suggesting a role of these proteins in the molecular mechanisms of NO2-FA signaling.