Gene Silencing of Porcine MUC13 and ITGB5: Candidate Genes towards Escherichia coli F4ac Adhesion

Abstract

BackgroundIntegrin beta-5 (ITGB5) and mucin 13 (MUC13) genes are highly expressed on the apical surface of intestinal epithelia and are thought to be candidate genes for controlling the expression of the receptor for enterotoxigenic Escherichia coli (ETEC) F4ac. Human MUC13 protein has an expected role in protecting intestinal mucosal surfaces and porcine ITGB5 is a newly identified potential receptor for ETEC F4ac.Methodology/Principal FindingsTo test the hypothesis that ITGB5 and MUC13 both play key roles in protection of the intestinal mucosa against pathogenic bacterium, porcine intestinal epithelial cells (IPEC-J2) were transfected with ITGB5-targeting, MUC13-targeting or negative control small interfering RNA (siRNA), respectively. Firstly, we measured mRNA expression levels of mucin genes (MUC4, MUC20), pro-inflammatory genes (IL8, IL1A, IL6, CXCL2), anti-inflammatory mediator SLPI, and PLAU after RNAi treatments with and without ETEC infection. Secondly, we compared the adhesions of ETEC to the pre- and post-knockdown IPEC-J2 cells of ITGB5 and MUC13, respectively. We found that ITGB5 and MUC13 knockdown both had small but significant effects in attenuating the inflammation induced by ETEC infection, and both increased bacterial adhesion in response to F4ac ETEC exposure.Conclusions/SignificanceOur current study first reported that ITGB5 and MUC13 are important adhesion molecules of mucosal epithelial signaling in response to Escherichia coli in pigs. These data suggest that both ITGB5 and MUC13 play key roles in defending the attachment and adhesion of ETEC to porcine jejunal cells and in maintaining epithelial barrier and immunity function.

Identification of Novel Components Influencing Colonization Factor Antigen I Expression in Enterotoxigenic Escherichia coli

“…The most striking result found here was the strong positive effect of PGM. While other fimbriae, including F5 expressed by porcine ETEC, may adhere to decoy ligands present in mucin [ 42 ], PGM did not inhibit CFA/I mediated MRHA. Of note, the positive effect of PGM was observed despite previous sterilization by autoclaving, indicating that the original structures of the large, complex glycoproteins found in mucin were not critical to the induction of CFA/I surface expression.…”

Transmembrane Mucins: Signaling Receptors at the Intersection of Inflammation and Cancer

“…Probiotic Lactobacillus strains can also upregulate the expression of transmembrane MUC3, and these bacteria induce release of the MUC3 extracellular domain [76]. Transmembrane MUC13 prevents ETEC adhesion in pigs [77] and a MUC13 isoform lacking the glycosylated extracellular domain is associated with an increased susceptibility to ETEC [78]. However, some evidence has been published to suggest that, rather than MUC13, it is a neighboring gene region that is involved in the reported ETEC susceptibility [79].…”

Porcine aminopeptidase N binds to F4+ enterotoxigenic Escherichia coli fimbriae

“…Polymorphisms in intron 7 of the MUC4 gene have been used to classify an important percentage of piglets as susceptible or resistant to F4 ETEC [ 16 , 17 ]. Although Ren et al and Zhou et al both found that susceptibility/resistance toward ETEC F4ac is conferred by the MUC13 gene in pigs, Schroyen et al reported that MUC13 and MUC20 gene expression are not related to ETEC F4ac susceptibility in piglets, and Goetstouwer et al recently confirmed that MUC4 and MUC13 are not completely associated with F4ab/ac ETEC susceptibility [ 10 , 11 , 13 , 18 ].…”

“…Various potential host receptors for F4 fimbriae have been described, including MUC4, MUC13, MUC20, ITGB5, and TFRC [ 10 – 13 ]. The polymorphic Xba I restriction enzyme site in intron 7 of the muc4 gene has been used as a biomarker to classify an important percentage of piglets as susceptible or resistant to F4 + ETEC infections [ 14 – 16 ].…”