ZBP-89 regulates expression of tryptophan hydroxylase i and mucosal defense against salmonella typhimurium in mice

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.