Rebecca B. Katzman

Northwestern University, Evanston, Illinois, United States

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Publications (19)226.53 Total impact

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    ABSTRACT: Mesalamine, 5-aminosalicylic acid (5-ASA), is a potent antioxidant and is known to enhance peroxisome proliferator-activated receptor γ activity in the intestine. Our previous studies suggested reduced Phosphoinositide 3-Kinase (PI3K)/β-catenin signaling as a mechanism for 5-ASA chemoprevention in chronic ulcerative colitis (CUC). We now hypothesize that 5-ASA mediates changes in intestinal epithelial cell (IEC) reactive oxygen species during colitis to affect phosphatase and tensin homolog (PTEN), PI3K, and β-catenin signaling. Here, we examined effects of 5-ASA on oxidant-induced cell signaling pathways in HT-29 cells, IECs from mice, and biopsy tissue from control and CUC patients. Samples were selected to control for inflammation between untreated and 5-ASA-treated CUC patients. Direct evaluation of IEC in H2O2-stimulated whole colonic crypts indicated that 5-ASA reduces reactive oxygen species levels in lower crypt IECs where long-lived progenitor cells reside. Analysis of biopsies from patient samples revealed that 5-ASA increases expression of the antioxidant catalase in CUC patients. Also, 5-ASA increased nuclear peroxisome proliferator-activated receptor γ protein and target gene expression. Data showed 5-ASA-induced peroxisome proliferator-activated receptor γ DNA binding to the PTEN promoter (chromatin immunoprecipitation) and reduced both phosphorylated and oxidized (inactive) PTEN protein levels. Analysis of patient samples revealed 5-ASA that also reduced levels of active phosphorylated Akt in inflamed colitis tissue. Reduced PI3K/Akt signaling and expression of β-catenin target genes in 5-ASA-treated CUC patients additionally suggests enhanced PTEN activity as well. Therefore, 5-ASA reduces CUC-induced reactive oxygen species in colonic progenitor cells and enhances PTEN activity, thus attenuating PI3K/Akt signaling. These data suggest that the antioxidant properties of 5-ASA may be the predominant mechanism for 5-ASA chemoprevention.
    Inflammatory Bowel Diseases 07/2013; 19(10). DOI:10.1097/MIB.0b013e318297d741 · 4.46 Impact Factor
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    ABSTRACT: Chronic ulcerative colitis (CUC) is characterized by increased intestinal epithelial cell (IEC) apoptosis associated with elevated tumor necrosis factor (TNF), inducible nitric oxide synthase (iNOS), and p53. We previously showed that p53 is increased in crypt IECs in human colitis and is needed for IEC apoptosis in chronic dextran sulfate sodium-colitis. Herein, we examined the roles of TNF and iNOS in regulating p53-induced IEC apoptosis in CUC. The IEC TUNEL staining, caspases 3, 8, and 9, and p53 protein levels, induced by anti-CD3 monoclonal antibody (mAb) activation of T cells, were markedly reduced in TNF receptor 1 and 2 gene knockout mice. Induction of IEC apoptosis correlated with increased p53, which was attenuated in iNOS(-/-) mice. IEC p53 levels and apoptosis were reduced in IL-10(-/-) colitic mice treated with neutralizing TNF mAb and the iNOS inhibitor, aminoguanidine, further suggesting that TNF and iNOS are upstream of p53 during colitis-induced IEC apoptosis. IEC apoptosis and p53 levels were assessed in control versus untreated or anti-TNF-treated CUC patients with equivalent levels of inflammation. Data indicated that IEC apoptosis and p53 levels were clearly higher in untreated CUC but markedly reduced in patients treated with anti-TNF mAb. Therefore, TNF-induced iNOS activates a p53-dependent pathway of IEC apoptosis in CUC. The inhibition of IEC apoptosis may be an important mechanism for mucosal healing in anti-TNF-treated CUC patients.
    American Journal Of Pathology 08/2012; 181(4):1306-15. DOI:10.1016/j.ajpath.2012.06.016 · 4.59 Impact Factor
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    ABSTRACT: Endoscopic therapies for Barrett's esophagus (BE) associated dysplasia, particularly radiofrequency ablation (RFA), are popular alternatives to surgery. The effect of such therapies on dysplastic stem/progenitor cells (SPC) is unknown. Recent studies suggest that AKT phosphorylation of β-Catenin occurs in SPCs and may be a marker of activated SPCs. We evaluate the effect of RFA in restoring AKT-mediated β-Catenin signaling in regenerative epithelium. Biopsies were taken from squamous, non-dysplastic BE, dysplastic BE and esophageal adenocarcinoma (EAC). Also, post-RFA, biopsies of endoscopically normal appearing neosquamous epithelium were taken at 3, 6, and 12 months after successful RFA. Immunohistochemistry and Western blot analysis was performed for Pβ-Catenin(552) (Akt-mediated phosphorylation of β-Catenin), Ki-67 and p53. There was no difference in Pβ-Catenin552 in squamous, GERD, small bowel and non-dysplastic BE. There was a fivefold increase in Pβ-Catenin(552) in dysplasia and EAC compared to non-dysplastic BE (P < 0.05). Also, there was a persistent threefold increase in Pβ-Catenin(552) in neosquamous epithelium 3 months after RFA compared to native squamous epithelium (P < 0.05) that correlated with increased Ki-67. Six months after RFA, Pβ-Catenin(552) and Ki-67 are similar to native squamous epithelium. Enhanced AKT-mediated β-Catenin activation is seen in BE-associated carcinogenesis. Three months after RFA, squamous epithelial growth from SPC populations exhibited increased levels of Pβ-Catenin(552). This epithelial response becomes quiescent at 6 months after RFA. These data suggest that elevated Pβ-Catenin(552) after RFA denotes a repair response in the neosquamous epithelium 3 months post-RFA.
    Digestive Diseases and Sciences 09/2011; 57(2):294-302. DOI:10.1007/s10620-011-1899-0 · 2.61 Impact Factor
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    ABSTRACT: Background & AimsInflammatory bowel disease (IBD) is associated with increased apoptosis of intestinal epithelial cells (IECs). Mutations in the tumor suppressor p53 appear during early stages of progression from colitis to cancer. We investigated the role of p53 and its target, p53-upregulated modulator of apoptosis (PUMA), in inflammation-induced apoptosis of IECs.Methods Apoptosis was induced in mouse models of mucosal inflammation. Responses of IECs to acute, T-cell activation were assessed in wild-type, p53−/−, Bid−/−, Bim−/−, Bax3−/−, Bak−/−, PUMA−/−, and Noxa−/− mice. Responses of IECs to acute and chronic colitis were measured in mice following 1 or 3 cycles of dextran sulfate sodium (DSS), respectively. Apoptosis was assessed by TUNEL staining and measuring activity of caspases 3 and 9; levels of p53 and PUMA were assessed in colon tissue from patients with and without ulcerative colitis.ResultsApoptosis of IECs occurred in the lower crypts of colitic tissue from humans and mice. Colitis induction with anti-CD3 or 3 cycles of DSS increased apoptosis and protein levels of p53 and PUMA in colonic crypt IECs. In p53−/− and PUMA−/− mice, apoptosis of IECs was significantly reduced but inflammation was not. Levels of p53 and PUMA were increased in inflamed mucosal tissues of mice with colitis and in patients with UC, compared with controls. Induction of PUMA in IECs of p53−/− mice indicated that PUMA-mediated apoptosis was independent of p53.Conclusions In mice and humans, colon inflammation induces apoptosis of IECs via p53-dependent and -independent mechanisms; PUMA also activates an intrinsic apoptosis pathway associated with colitis.
    Gastroenterology 05/2011; 141(3):1036-1045. DOI:10.1053/j.gastro.2011.05.032 · 16.72 Impact Factor
  • Gastroenterology 01/2011; 140(5). DOI:10.1016/S0016-5085(11)62598-5 · 16.72 Impact Factor
  • Gastroenterology 01/2011; 140(5). DOI:10.1016/S0016-5085(11)61949-5 · 16.72 Impact Factor
  • Gastroenterology 01/2011; 140(5). DOI:10.1016/S0016-5085(11)62650-4 · 16.72 Impact Factor
  • Jeffrey Z. Ko · Rebecca B. Katzman · Terrence A. Barrett
    Gastroenterology 01/2011; 140(5). DOI:10.1016/S0016-5085(11)61552-7 · 16.72 Impact Factor
  • Gastroenterology 05/2010; 138(5). DOI:10.1016/S0016-5085(10)61847-1 · 16.72 Impact Factor
  • Gastroenterology 05/2010; 138(5). DOI:10.1016/S0016-5085(10)61183-3 · 16.72 Impact Factor
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    ABSTRACT: In inflammatory bowel disease (IBD), aberrant activation of innate and adaptive immune responses enhances mucosal permeability through mechanisms not completely understood. To examine the role of epithelial nuclear factor (NF-kappaB) in IBD-induced enhanced permeability, epithelial-specific IkappaBalpha mutant (NF-kappaB super repressor) transgenic (TG) mice were generated. NF-kB activation was inhibited in TG mice, relative to wild-type mice, following T cell-mediated immune cell activation using an anti-CD3 monoclonal antibody. Furthermore, epithelial NF-kappaB super repressor protein inhibited diarrhea and blocked changes in transepithelial resistance and transmucosal flux of alexa350 (0.35 kDa) and dextran3000 (3 kDa). In vivo perfusion loop studies in TG mice revealed reversed net water secretion and reduced lumenal flux of different molecular probes (bovine serum albumin, alexa350, and dextran3000). Cell-imaging and immunoblotting of low-density, detergent-insoluble membrane fractions confirmed that tight junction proteins (occludin, claudin-1 and zona occludens-1) are internalized through an NF-kappaB-dependent pathway. Taken together, these data suggest that IBD-associated diarrhea results from NF-kappaB-mediated tight junction protein internalization and increased paracellular permeability. Thus, reduction of epithelial NF-kappaB activation in IBD may repair defects in epithelial barrier function, reduce diarrhea, and limit protein (eg, serum albumin) losses. Epithelial NF-kappaB activation induced by mucosal T cells, therefore, actively plays a role in opening paracellular spaces to promote transmucosal fluid effux into the intestinal lumen.
    American Journal Of Pathology 12/2009; 176(1):158-67. DOI:10.2353/ajpath.2010.090548 · 4.59 Impact Factor
  • Gastroenterology 05/2009; 136(5). DOI:10.1016/S0016-5085(09)60049-4 · 16.72 Impact Factor
  • Elizabeth Managlia · Rebecca B. Katzman · Terrence A. Barret
    Gastroenterology 05/2009; 136(5). DOI:10.1016/S0016-5085(09)62563-4 · 16.72 Impact Factor
  • Gastroenterology 05/2009; 136(5). DOI:10.1016/S0016-5085(09)61084-2 · 16.72 Impact Factor
  • Gastroenterology 05/2009; 136(5). DOI:10.1016/S0016-5085(09)60355-3 · 16.72 Impact Factor
  • Gastroenterology 05/2009; 136(5). DOI:10.1016/S0016-5085(09)63227-3 · 16.72 Impact Factor
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    Rebecca B Katzman · Mark Seeger · Kathleen Rundell
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    ABSTRACT: Three simian virus 40 (SV40) reporter viruses were constructed in this study. One expresses the green fluorescent protein (GFP) as a fusion protein with the first exon of large-T (LT) antigen and is useful for live-cell imaging. A second reporter virus has a FLAG epitope tag at the C-terminus of large-T antigen (vC-LT(FLAG)), and a third has the FLAG tag at the N-terminus of LT (vN-LT(FLAG)). The vC-LT(FLAG) construct grows to titers near those of wild-type (WT) virus and functions well as a reporter virus for SV40 infection. The vN-LT(FLAG) construct, while viable, has a defect in the production and spread of infectious particles. All three viruses are useful in detecting superinfecting virus in cells in which nuclear LT is already present, such as persistently infected human mesothelial cells.
    Journal of Virological Methods 07/2008; 150(1-2):7-13. DOI:10.1016/j.jviromet.2008.02.013 · 1.78 Impact Factor
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    Kelly M Fahrbach · Rebecca B Katzman · Kathleen Rundell
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    ABSTRACT: Viral DNA is maintained episomally in SV40 infected mesothelial cells and virus is produced at low but steady rates. High copy numbers of the viral DNA are maintained in a WT infection where both early antigens are expressed. In the absence of ST, cells are immortal but non-transformed and the infected cells maintain only a few copies of episomal viral DNA. We show that ST expression is necessary for the maintenance of high copy numbers of viral DNA and that the PP2A binding ability of ST plays a role in genome maintenance. Interestingly, an siRNA to the virus late region downregulates virus copy number and virus production but does not prevent the anchorage-independent growth of these cells. Furthermore, addition of virus neutralizing antibody to culture media also decreases copy numbers of viral DNA in WT-infected cells, suggesting that virus production and re-infection of cells may play a role in maintaining the persistent infection.
    Virology 02/2008; 370(2):255-63. DOI:10.1016/j.virol.2007.09.008 · 3.32 Impact Factor
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    ABSTRACT: Members of the evolutionarily conserved Mastermind (MAM) protein family, including the three related mammalian Mastermind-like (MAML) proteins MAML1-3, function as crucial coactivators of Notch-mediated transcriptional activation. Given the recent evidence of cross-talk between the p53 and Notch signal transduction pathways, we have investigated whether MAML1 may also be a transcriptional coactivator of p53. Indeed, we show here that MAML1 is able to interact with p53. We show that MAML1-p53 interaction involves the N-terminal region of MAML1 and the DNA-binding domain of p53, and we use a chromatin immunoprecipitation assay to show that MAML1 is part of the activator complex that binds to native p53-response elements within the promoter of the p53 target genes. Overexpression of wild-type MAML1 as well as a mutant, defective in Notch signaling, enhanced the p53-dependent gene induction in mammalian cells, whereas MAML1 knockdown reduced the p53-dependent gene expression. MAML1 increases the half-life of p53 protein and enhances its phosphorylation/acetylation upon DNA damage of cells. Finally, RNA interference-mediated knockdown of the single Caenorhabditis elegans MAML homolog, Lag-3, led to substantial abrogation of p53-mediated germ-cell apoptotic response to DNA damage and markedly reduced the expression of Ced-13 and Egl-1, downstream pro-apoptotic targets of the C. elegans p53 homolog Cep-1. Thus, we present evidence for a novel coactivator function of MAML1 for p53, independent of its function as a coactivator of Notch signaling pathway.
    Journal of Biological Chemistry 05/2007; 282(16):11969-81. DOI:10.1074/jbc.M608974200 · 4.57 Impact Factor

Publication Stats

129 Citations
226.53 Total Impact Points


  • 2008–2013
    • Northwestern University
      • • Division of Gastroenterology and Hepatology
      • • Department of Microbiology-Immunology
      Evanston, Illinois, United States
  • 2012
    • University of Illinois at Chicago
      Chicago, Illinois, United States
  • 2009
    • University of Chicago
      • Department of Pathology
      Chicago, Illinois, United States