Comparative characterization of microRNAs of Schistosoma japonicum from SCID mice and BALB/c mice: Clues to the regulation of parasite growth and development

Schistosomiasis, caused by a parasite with a wide range of mammalian hosts, remains one of the most prevailing parasitic diseases in the world. While numerous studies have reported that the growth and reproduction of schistosomes in immunodeficient mice was significantly retarded, the underlying molecular mechanisms have yet to be revealed. In this study, we comparatively analyzed the microRNA expression of Schistosoma japonicum derived from SCID and BALB/c mice on the 35^th day post-infection by high-throughput RNA sequencing as prominent morphological abnormalities had been observed in schistosomes from SCID mice when compared with those from BALB/c mice. The results revealed that more than 72% and 61% of clean reads in the small RNA libraries of female and male schistosomes, respectively, could be mapped to the selected miRs in the miRBase or the sequences of species-specific genomes. Further analysis identified 122 miRNAs using TPM >0.01 as the threshold value, including 75 known and 47 novel miRNAs, 96 of which were commonly expressed across all the four tested schistosome libraries. Comparative analysis of the libraries of schistosomes from SCID and BALB/c mice identified 15 differentially expressed miRNAs (5 up-regulated and 10 down-regulated) among females and 16 among males (9 up-regulated and 7 down-regulated). Integrated analysis of the two sets of differentially expressed miRNAs of female and male worms identified 2 miRNAs (sja-miR-3488 and sja-miR-novel_29) that overlapped between female and male datasets. Prediction of miRNA targets and Gene Ontology (GO) term enrichment analysis of the predicted target genes revealed that these genes were involved in some important biological processes, such as nucleic acid metabolic process, macromolecule modification, and cellular aromatic compound metabolic process. The predicted target genes were further matched to the differentially expressed genes in male and female schistosomes from the above two hosts, obtaining 7 genes that may be responsible for regulating the growth, development and sex maturation of schistosomes. Taken together, this study provides the first identification of differentially expressed miRNAs in schistosomes from SCID and BALB/c mice. These miRNAs and their predicted target mRNAs are probably involved in the regulation of development, growth, and maturation of schistosomes. Therefore, this study expands our understanding of schistosome development regulation and host-parasite relationship, and also provides a valuable set of potential anti-schistosomal targets for prevention and control of schistosomiasis.

The effects of nested miRNAs and their host genes on immune defense against Bacillus thuringiensis infection in Caenorhabditis elegans

microRNAs (miRNAs) are small non-coding RNA-molecules that influence translation by binding to the target gene mRNA. Many miRNAs are found in nested arrangements within larger protein-coding host genes. miRNAs and host genes in a nested arrangement are often transcribed simultaneously, which may indicate that both have similar functions. miRNAs have been implicated in regulating defense responses against pathogen infection in C. elegans and in mammals. Here, we asked if miRNAs in nested arrangements and their host genes are involved in the C. elegans response against infection with Bacillus thuringiensis (Bt). We performed miRNA sequencing and subsequently focused on four nested miRNA-host gene arrangements for a functional genetic analysis. We identified mir-58.1 and mir-2 as negative regulators of C. elegans resistance to Bt infection. However, we did not find any miRNA/host gene pair in which both contribute to defense against Bt.

Profiling of miRNAs in Mouse Peritoneal Macrophages Responding to Echinococcus multilocularis Infection

Alveolar echinococcosis (AE) is a zoonotic helminthic disease caused by infection with the larval of Echinococcus multilocularis in human and animals. Here, we compared miRNA profiles of the peritoneal macrophages of E. multilocularis-infected and un-infected female BALB/c mice using high-throughput sequencing. A total of 87 known miRNAs were differentially expressed (fold change ≥ 2, p < 0.05) in peritoneal macrophages in mice 30- and 90-day post infection compared with ones in un-infected mice. An increase of mmu-miR-155-5p expression was observed in peritoneal macrophages in E. multilocularis-infected mice. Compared with the control group, the production of nitric oxide (NO) was increased in peritoneal macrophages transfected with mmu-miR-155-5p mimics at 12 h after transfection (p < 0.001). Two key genes (CD14 and NF-κB) in the LPS/TLR4 signaling pathway were also markedly altered in mmu-miR-155-5p mimics transfected cells (p < 0.05). Moreover, mmu-miR-155-5p mimics suppressed IL6 mRNA expression and promoted IL12a and IL12b mRNA expression. Luciferase assays showed that mmu-miR-155-5p was able to bind to the 3′ UTR of the IKBKE gene and decreased luciferase activity. Finally, we found the expression of IKBKE was significantly downregulated in both macrophages transfected with mmu-miR-155-5p and macrophages isolated from E. multilocularis-infected mice. These results demonstrate an immunoregulatory effect of mmu-miR-155 on macrophages, suggesting a role in regulation of host immune responses against E. multilocularis infection.