Helmut Grasberger, Bryan E. Essien, Juanita L. Merchant, Rachael D. Romain, Alexander Yang, David J. Law, Mohamad El Zaatari, Michael M. Hayes, Arthur Tessier, Natalia A. Veniaminova, and Milena Saqui–Salces
Background & Aims ZBP-89 (also ZNF148 or Zfp148) is a butyrate-inducible zinc finger transcription factor that binds to GC-rich DNA elements. Deletion of the N-terminal domain is sufficient to increase mucosal susceptibility to chemical injury and inflammation. We investigated whether conditional deletion of ZBP-89 from the intestinal and colonic epithelium of mice increases their susceptibility to pathogens such as Salmonella typhimurium . Methods We generated mice with a conditional null allele of Zfp148 (ZBP-89 FL/FL ) using homologous recombination to flank Zfp148 with LoxP sites (ZBP-89 FL/FL ), and then bred the resulting mice with those that express VillinCre. We used microarray analysis to compare gene expression patterns in colonic mucosa between ZBP-89 ΔInt and C57BL/6 wild-type mice (controls). Mice were gavaged with 2 isogenic strains of S typhimurium after administration of streptomycin. Results Microarray analysis revealed that the colonic mucosa of ZBP-89 ΔInt mice had reduced levels of tryptophan hydroxylase 1 (Tph1) messenger RNA, encoding the rate-limiting enzyme in enterochromaffin cell serotonin (5-hydroxytryptamine [5HT]) biosynthesis. DNA affinity precipitation demonstrated direct binding of ZBP-89 to the mouse Tph1 promoter, which was required for its basal and butyrate-inducible expression. ZBP-89 ΔInt mice did not increase mucosal levels of 5HT in response to S typhimurium infection, and succumbed to the infection 2 days before control mice. The ΔhilA isogenic mutant of S typhimurium lacks this butyrate-regulated locus and stimulated, rather than suppressed, expression of Tph1 approximately 50-fold in control, but not ZBP-89 ΔInt , mice, correlating with fecal levels of butyrate. Conclusions ZBP-89 is required for butyrate-induced expression of the Tph1 gene and subsequent production of 5HT in response to bacterial infection in mice. Reductions in epithelial ZBP-89 increase susceptibility to colitis and sepsis after infection with S typhimurium , partly because of reduced induction of 5HT production in response to butyrate and decreased secretion of antimicrobial peptides.