Disclosing 3' UTR cis-elements and putative partners involved in gene expression regulation in Leishmania spp.

To identify putative cis-elements involved in gene expression regulation in Leishmania, we previously conducted an in silico investigation to find conserved intercoding sequences (CICS) in the genomes of L. major, L. infantum, and L. braziliensis. Here, the CICS databank was explored to search for sequences that were present in the untranslated regions (UTRs) of groups of genes showing similar expression profiles during in vitro differentiation. Using a selectable marker as a reporter gene, flanked by either an intact 3' UTR or a UTR lacking the conserved element, the regulatory role of a CICS was confirmed. We observed that the pattern of modulation of the mRNA levels was altered in the absence of the CICS. We also identified putative CICS RNA-binding proteins. This study suggests that the publicly available CICS database is a useful tool for identifying regulatory cis-elements for Leishmania genes and suggests the existence of post-transcriptional regulons in Leishmania.