RESUMO
During its life cycle, the malarial parasite Plasmodium goes through different asexual stages in human blood, and asexualand sexual stage in mosquito. Expression of stage-specific proteins is important for successful completion of its life cycleand requires tight gene regulation. In case of Plasmodium, due to relative paucity of the transcription factors, it is postulatedthat post-transcriptional regulation plays an important role in stage-specific gene expression. Although miRNA-mediatedgene regulation has been well-established to function in post-transcriptional regulation in many eukaryotes, existence ofsuch a phenomenon or the presence of miRNA-associated factors in Plasmodium remains unclear. A number of miRNAsare shown to be imported into Plasmodium falciparum from erythrocytes and role of these miRNAs is not understood. Herewe show that human Argonaute 2 (hAgo2) a component of the miRISC complex is imported by P. falciparum. In theparasite hAgo2 exists as in a complex with specific human miRNAs like let-7a and miR15a which can potentially target thePlasmodium genes Rad54 and Lipid/sterol:H? symporter respectively. We show that hAgo2 associates with Rad54, Lipid/sterol:H? symporter and other P. falciparum transcripts. These results highlight the existence of a mechanism by whichmalarial parasite imports hAgo2-miRNA complex from the host cells to regulate its gene expression.