Project description:Paneth cells are a highly specialized population of intestinal epithelial cells located in the crypt adjacent to Lgr5+ stem cells, from which they differentiate through a process that requires downregulation of the Notch pathway. Their ability to store and release antimicrobial peptides protects the host from intestinal pathogens and controls intestinal inflammation. Here we show that PKCλ/ι is required for Paneth cell differentiation at the level of Atoh1 and Gfi1, through the control of EZH2 stability by direct phosphorylation. The selective inactivation of PKCλ/ι in epithelial cells results in the loss of mature Paneth cells, increased apoptosis and inflammation, and enhanced tumorigenesis. Importantly, PKCλ/ι expression in human Paneth cells decreases with progression of Crohn's disease. Kaplan-Meier survival analysis of CRC patients revealed that low PRKCI levels correlated with significantly worse patient survival. Therefore, PKCλ/ι is a negative regulator of intestinal inflammation and cancer through its role in Paneth cell homeostasis.
Project description:The experiment aims to analyze the differences in expressed genes in Paneth cells upon acute intestinal inflammation compared to Paneth cells from non-inflamed control mice
Project description:Cellular binary fate decisions require the progeny to silence genes associated with the alternative fate. The major subsets of alpha:beta T cells have been extensively studied as a model system for fate decisions. While the transcription factor RUNX3 is required for the initiation of Cd4 silencing in CD8 T cell progenitors, it is not required to maintain the silencing of Cd4 and other helper T lineage genes. The other runt domain containing protein, RUNX1, silences Cd4 in an earlier T cell progenitor, but this silencing is reversed whereas the gene silencing after RUNX3 expression is not reverse. Therefore, we hypothesized that RUNX3 and not RUNX1 recruits other factors that maintains the silencing of helper T lineage genes in CD8 T cells. To this end, we performed a proteomics screen of RUNX1 and RUNX3 to determine candidate silencing factors.
Project description:EGFR blockade by the monoclonal antibodies cetuximab or panitumumab causes objective tumor regressions in selected patients with metastatic colorectal cancer (mCRC). However, residual disease reservoirs almost invariably remain even after maximal response to therapy, leading to treatment failure and tumor relapse. Using mCRC patient-derived xenografts (PDXs), we observed that residual cancer cells surviving EGFR inhibition exhibited gene expression patterns reminiscent of a quiescent subpopulation of normal intestinal secretory precursors with Paneth-cell traits. These drug-tolerant cells had reduced expression of EGFR-activating ligands, consistent with lower EGFR dependence, and displayed higher HER2/HER3 pathway activity and persistent PI3K signaling. Mechanistically, cell fate reprogramming towards the Paneth cell-like phenotype was mediated by inactivation of YAP – a master regulator of intestinal epithelium recovery after injury – following cetuximab-induced neutralization of the MAPK cascade. Clinically, tumors from patients in whom cetuximab was not effective were enriched for markers of secretory commitment/Paneth-cell differentiation. In PDX therapeutic experiments, Pan-HER antibodies minimized residual disease burden and induced long-term tumor control after treatment discontinuation. We propose that tolerance to EGFR inhibition in CRC is typified by the adaptive disengagement of an in-built lineage program that jointly drives intestinal regenerative signaling and tumorigenesis. Further, our findings motivate therapeutic strategies to pre-emptively target residual disease before acquisition of irreversible resistance.
Project description:<p>This UH2/UH3 demonstration project entitled "Effects of Crohn's disease risk alleles on enteric microbiota" is focused on characterizing intestinal associated microbiota in patients with ileal Crohn's disease (ileal CD), ulcerative colitis (UC) and control patients without inflammatory bowel diseases (non-IBD). We hypothesize that genetic factors that affect Paneth cell function, contribute to compositional changes in intestinal microbiota. These changes in microbiota may lead to reduction of protective commensal organisms and increased numbers of aggressive organisms that incite intestinal inflammation. This hypothesis is being tested by high throughput 16S rRNA sequence analysis of de-identified ileal and colonic tissues that have been archived at Washington University St. Louis, University of North Carolina, Mount Sinai Hospital and the Cleveland Clinic. Multivariate analysis of the metagenomic data will be conducted with genotyping metadata (highly reproducible CD risk alleles, including NOD2 and ATG16L1) and phenotyping metadata (e.g. age, gender, race, body mass index, medications and smoking.)</p> <p>Shotgun sequencing will be performed on selected fecal specimens linked to ileal tissues to identify additional, or auxiliary, or synergistic pathogenic factors or other functional changes in the microbiome. Because members of this research team have observed that a chronic viral infection is required for the Paneth cell defect in Atg16l1 hypomorphic mice, a major focus of these studies will be towards identifying potential viral triggers for the defective Paneth cell phenotype in individuals harboring the ATG16L1 risk allele. Novel genetic probes for protective and aggressive organisms will be developed by mining bacterial genome and shotgun sequencing data. Genomic sequences will be produced for candidate protective and aggressive strains (e.g. adherent-invasive strains of E. coli) isolated from human intestinal tissues where there is limited existing genome information. Quantitative qPCR assays using the novel as well as established genetic probes will be conducted to test the hypothesis that an imbalance between protective and aggressive organisms is associated with genetic factors that affect Paneth cell function.</p> <p>Our combined expertise in multiple disciplines across multiple institutions, our demonstrated ability to collect a large number of well-phenotyped samples with longitudinal clinical information that will be linked to host response and morphologic studies, and our consortium's capacity for high-throughput sequencing will be used to investigate how alterations in human microbiome relate to CD risk alleles and CD pathogenesis.</p>