DmCatD, a cathepsin D-like peptidase of the hematophagous insect vector Dipetalogaster maxima (Hemiptera: Reduviidae): Bioinformatic analysis and internalization pathway in developing oocytes.

RAMOS FO; SETTEMBRINI BP; LEYRIA J; LIGABUE-BRAUN; CANAVOSO LE; FRUTTERO LL; CARLINI, C.R.

Orlando

Congreso; XXV International Congress of Entomology; 2016

Entomological Society of America

In insects, vitellogenesis is a central event of reproduction that elicits the uptake of yolk protein precursors (YPPs) by developing oocytes. Employing Dipetalogaster maxima, a Chagas disease vector, we demonstrated that a cathepsin D-like peptidase,DmCatD, is synthesized by the fat body and the ovary as a YPP. DmCatD plays a central role in early vitellin proteolysis during follicular atresia, nevertheless, the mechanism involved in its internalization by the oocytes has not been established. The aim of this work was to characterize in silico the partial DmCatD sequence as well as to analyze the biochemical events involved in its accumulation in the ovarian tissue. Approximately 73% of the DmCatD sequence was obtained by PCR. CBS and ScanProsite servers predicted putative N-glycosylation, phosphorylation, Nmyristoylation and signal peptidecleavage sites. The structural modeling, carried out with the Phyre 2 portal, evidenced an expected folding for the enzyme and a conserved active site architecture. The evolutionary history was inferred using the maximumlikelihood method and the obtained phylogeny followed the expected grouping for a species tree. Assays employing hemolymph of vitellogenic females demonstrated that DmCatD co-immunoprecipitated with lipophorin, the main insect lipoprotein. Partial colocalization between lipophorin and DmCatD in the oocyte membrane facing the perioocytic space was detected by immunofluorescence. Taken into account that lipophorin is taken up by the oocytes through specific receptors, our results suggest that such a lipoprotein may act as a carrier for DmCatD, facilitating its internalization by the oocytes. (Supported by PICT 2013-0626).