Acyl-CoA esters have many functions in cells, such as energy source, substrate in metabolism and cell signaling. However, these lipids are toxic when present in high concentrations, causing membrane damage. To avoid these toxic effects, the acyl-CoA-binding protein (ACBP), a highly conserved 10 kDa intracellular protein, binds straight-chain long acyl-CoA esters with very high affinity. Moreover, ACBP protects acyl-CoA esters from hydrolysis, thus functioning as a reserve of acyl-CoA esters by regulating their availability for a variety of metabolic purposes. In insects, the gut epithelium cells absorb free fatty acids, and convert them to their CoA derivates prior to the synthesis of complex lipids, such as diacylglycerol (DG), that will then be secreted to export to hemolymphatic lipophorin. ACBP must have a role in the acyl-coA transport to this process.
     ACBP gene has been sequenced from a Rhodnius prolixus midgut cDNA library. BLAST analysis showed that it has great similarity with other ACBP. Bioinformatics analysis predicted molecular mass of 10 kDa, theoretical pI of 5.5, six putative phosphorylation sites, none glycosilation site and a secondary structure with four helices. ACBP gene expression was detected in the anterior midgut, posterior midgut, fat body, ovary and flight muscle by RT-PCR. Expression analysis of ACBP gene in the midgut by real-time PCR showed an increase in expression after blood meal, and it was maximal from the first day to the fourth day after feeding and then decreased to the unfed levels in the seventh day. Insects fed only with Tyrode buffer also showed an increase of ACBP expression, suggesting that ACBP expression is possibly regulated by factors induced by crop extension. Injection of Rosiglitazone, a PPAR gamma agonist, induced a small increase (26%) in ACBP gene expression, suggesting a possible role of PPAR in regulation of ACBP gene expression. This study intends to investigate the role of ACBP in intracellular lipid transport in Rhodnius prolixus midgut.
     Supported by CNPq, PIBIC/UFRJ and Faperj