Spatial expression analysis and target prediction give insight into microRNA function in the model cestode Hymenolepis microstoma.

Tapeworms (class Cestoda) of the genus Hymenolepis are etiological agents of hymenolepiasis, the most prevalent cestode infection in humans, which especially affects children, causing a significant public health impact. Tapeworms have complex life cycles, undergoing morphological and physiological transformations that need precise control of genetic expression. MicroRNAs (miRNAs) are small RNAs that regulate gene expression post transcriptionally, with a prominent role in developmental processes. Previously, we described the microRNA (miRNA) repertoire of Hymenolepis microstoma, a validated laboratory model of the Hymenolepis genus. Here, we aimed to further characterize miRNAs from this parasite, focusing on miR-71, a miRNA previously associated with developmental transitions and potentially involved in cestode infection progression. We identified, for the first time, the predicted miRNA target genes of H. microstoma and H. nana, representing more than 14% of total genes of each parasite. We found that miR-71 was the miRNA with the highest number of predicted target genes, and several of them were related to developmental processes. Here we also characterized, for the first time, the spatial expression of miRNAs in whole H. microstoma specimens. The analysis showed that miR-71 displayed broad expression across tissues, including germinative, nervous, and muscular systems, supporting a central regulatory role. Notably, it was also detected in germinative cells, the only mitotically active population responsible for generating all differentiated cell types. In contrast, the highly conserved miR-1 had a highly restricted expression pattern, predominantly localized in myocytes. This study improves characterization of tapeworm miRNAs and paves the way for future experimental research in cestode biology, providing, as well, a source for identification of novel biomarkers and therapeutic targets for the control of cestodiasis.