Identification of AP-1-inducing factors of Schistosoma mansoni-egg secreted proteins

Questions Schistosomiasis is one of the most common parasitic infections of humans worldwide. The eggs of S. mansoni induce chronic granulomatous lesions in the liver and bowel of infected mammals. We have demonstrated that the protooncogene c-Jun is permanently induced in perigranolomatous hepatocytes and enterocytes by egg secreted proteins during S. mansoni infection. The current study aims to identify the AP-1-inducing S. mansoni-egg-secreted protein.

Methods We developed an AP-1 reporter gene assay by using the pGL4.44[luc2P]AP1 vector (Promega). Protein fractions of soluble egg antigens (SEA) were separated by molecular mass using liquid chromatography. The distribution of individual egg secreted factors were analyzed by western blotting in these fractions. SW620 cells were stimulated with the fractions and induction of the AP-1 specific promotor was analyzed by reporter gene assay.

Results While IPSE-containing SEA fractions induced a moderate activation of the AP-1 promotor, AP-1-promotor activity peaked with Omega-1 containing fractions. Enhanced phosphorylation of c-Jun in the cell lysates of IPSE and Omega-1-treated cells was demonstrated by western blotting.

Conclusion The results suggest that IPSE and Omega-1 are the most important proteins of S. mansoni egg antigens, which are involved in the activation of the AP-1 promotor. Further mechanistic studies using IPSE and Omega-1 enriched or depleted SEA may verify our current conclusions.

Publication History

Article published online:
23 January 2024