Exosome-delivered miR-153 from Trichinella spiralis promotes apoptosis of intestinal epithelial cells by downregulating Bcl2

Abstract

Abstract Trichinellosis, a helminthic zoonosis, exhibits a cosmopolitan distribution and is a public health concern. In our previous studies, we reported that the exosomes secreted by Trichinella spiralis larvae (TsExos) largely affected cell life activities. The miRNAs, as exosome-delivered cargoes, affect the life activities of the host by targeting genes. The present study aimed to elucidate the mechanisms by which miRNAs interacted with intestinal epithelial cells. First, we constructed a miRNA library of TsExos; then, based on high-throughput miRNA sequencing results, miR-153 and its predicted target genes, namely Agap2, Bcl2 and Pten, were selected for follow-up studies. The dual-luciferase reporter assays revealed that miR-153 directly targeted Bcl2 and Pten. Further, real time qPCR and the Western blotting revealed that only Bcl2 was downregulated by TsExos-delivered miR-153 in porcine intestinal epithelial cells (IPEC-J2). Bcl2, an important antiapoptotic protein, plays an essential role in cell apoptosis as a common intersection molecule of various signal transduction pathways. Therefore, we hypothesized that miR-153 derived from TsExos causes cell apoptosis by targeting Bcl2. The results suggested that miR-153 could induce apoptosis, reduce mitochondrial membrane potential, affect cell proliferation, and cause damage and substantial oxidative stress. Furthermore, miR-153 co-incubated with IPEC-J2 cells stimulated the accumulation of the proapoptotic proteins Bax and Bad, which belong to the Bcl2 family proteins and apoptosis-implementing proteins Caspase9 and Caspase3. Moreover, we confirmed that miR-153 could promote apoptosis by regulating the MAPK and p53 signaling pathways involved in apoptosis. Taken together, exosome-mediated miR-153 delivery secreted by T. spiralis could induce the occurrence of apoptosis and affected the MAPK and p53 signaling pathways by downregulating Bcl2 in IPEC-J2 cells. Our study highlights the mechanisms underlying the invasion of T. spiralis larva.