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-89FL/FL) using homologous recombination to flank Zfp148 with LoxP sites (ZBP89(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(Delta Int) 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(Delta Int) 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 butyrateinducible expression. ZBP-89(Delta Int) 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 Delta hilA 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(Delta Int), 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.