ERdj5-mediated regulation of proliferation and differentiation in colon organoids under inflammatory stress

Background Endoplasmic reticulum (ER) stress is resolved by ER DnaJ domain-containing protein 5 (ERdj5), which functions as a disulfide reductase. In a previous study, we confirmed that ERdj5 was not indispensable for the formation of intestinal epithelial cells in mice. However, studies evaluating the association of ERdj5 and growth factors are limited. In the present study, we observed changes in the proliferation of colon organoids cultured from intestinal crypts obtained from wild-type (WT) and ERdj5 knockout (KO) mice. Methods We cultured colon organoids from WT and ERdj5 KO mice, and we then assessed differentiation- and proliferation-related markers after exposure to various stimuli, such as irradiation and the Toll-like receptor (TLR) 2 ligand Pam3CSK4. Results Over 15 days of organoid culture, ERdj5 KO colon organoids demonstrated a similar increase in leucine-rich repeat-containing G-protein-coupled receptor 5 (Lgr5) expression as WT colon organoids. However, in response to Pam3CSK4-induced stress, the ERdj5 KO organoids exhibited decreased Lgr5 expression and increased C/EBP homologous protein (CHOP) levels. Moreover, after irradiation-induced stress, ERdj5 downregulated epithelial-related genes, including Lgr5, Villin 1, and Prominin 1. Conclusion Inflammation through irradiation or TLR2-induced mild or severe ER stress in both groups, whereas ERdj5 deficiency eventually led to the downregulation of Lgr5. In summary, these findings suggest that colon organoids lack the ability to mount an effective defense against various inflammatory stimuli when there is a deficiency in the ERdj5-related ER stress resolution pathway.