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PLAGL2 Promotes a Stem Cell Phenotype in Intestinal Epithelial Cells and is Required for a Tumor Phenotype in Colon Cancer Cell Lines
to CRC in a PHB dependent manner. Our results suggest FL3 has potential as therapy for CRC chemoprevention.
spatially distinct, Lgr5-negative stem cell pool that is a subset of Krt19-positive cells. Recent studies have shown that colonic inflammation resulting from DSS-induced colitis leads to loss of distal colonic crypts associated with the rapid loss of Lgr5+ cells. Despite the transient loss of Lgr5+ stem cells, the colonic crypts regenerate and homeostasis is restored. Aims: The goal of this study was to determine whether the Krt19+ colonic stem cell pool is responsible for colonic crypt regeneration during colitis. Methods: To examine whether Lgr5 and/or Krt19 mark normal colonic stem cells that contribute to epithelial regeneration upon colonic injury, we crossed Lgr5-GFP-IRES-CreER or Krt19-BAC-CreER transgenic mice to the ROSA26r-Tdtomato reporter line. Mice were then treated with tamoxifen followed by water (control) or DSS (in the drinking water x 7 days) to induce colitis. Lgr5+ and Krt19+ cells were then studied in the context of normal homeostasis or following colonic injury following DSS injury. Results: Our results demonstrated that Lgr5+ stem cells are sensitive to DSS-induced colonic injury. Similar DSS-induced colitis injury experiments were also carried out using Notch1-CreER and Math1-CreER transgenic mice crossed to ROSA26rTdtomato mice and revealed little to no lineage tracing from absorptive or secretory cells, respectively. In contrast, Krt19 marked long-lived cells above the crypt base were resistant to DSS-induced colonic epithelial injury and gave rise to Lgr5+ cells in the newly regenerated crypts. Moreover, in separate experiments using Lgr5-DTR-GFP;K19-BAC-CreER; ROSA26rTdtomato mice, diphtheria toxin induced ablation of Lgr5+ cells demonstrated that Lgr5+ stem cells are dispensable for colonic epithelial regeneration following DSS-induced colitis. Conclusions: Our data suggest that analogous to the small intestine, a subset of Krt19+ cells in the colon are more resistant to epithelial injury than Lgr5+ stem cells, and these Krt19+ cells retain stem cell activity post colitis.
AGA Abstracts
27 MMP9 FAVORS MICROBIOTA ADHERENCE AND MODULATES ROS LEVELS TO MAINTAIN GENOMIC STABILITY IN COLITIS ASSOCIATED CANCER Lewins Walter, Adani Pujada, Hamed Laroui, Timothy L. Denning, Pallavi Garg Introduction: Chronic inflammation nurtures tumor environment. In the colon this condition is called colitis associated cancer (CAC). CAC is the inflammation-dysplasia driven carcinoma which is significantly different compared to the adenoma-carcinoma driven sporadic colon cancer (CRC). In CAC, chronic inflammation causes accumulation of reactive oxygen species (ROS) resulting in DNA damage fostering the cancer cell growth. Gut microbiota are important in regulating ROS levels, therefore are critical in preserving the genomic stability. Matrix Metalloproteinases (MMPs) are a family of zinc dependent endopeptidases which mediate inflammation, tissue remodeling, and tumorigenesis. MMP9 is the most unique MMP because it is undetectable in healthy tissue but highly upregulated during inflammation and cancer. We have previously shown that MMP9 plays a protective role in CAC which is opposite to its conventional role of mediator in acute inflammation and cancer. Aim: Aim of this study is to understand the mechanism by which MMP9 acts as a tumor suppressor in CAC. Methods: We used C57/B6 transgenic mice which can express MMP9 under villin promoter (TgM9) and their wild type (WT) littermates. CAC was induced by three cycles of dextran sodium sulfate. As a proof of principal model, we used MMP9 small interfering RNA (siRNA) encoded within nanoparticles and gavaged WT mice to inhibit MMP9 in colonic epithelium. Results: QPCR data showed that mRNA levels of total microbiota population was more among TgM9 mice compared to WTs in CAC. QPCR analysis also indicated increased mRNA levels for the phylum Bacteroidetes sp., Akkermansia muciniphila but decreased mRNA levels for the phylum Firmicutes sp. We observed that TgM9 mice had lower levels of ROS compared to WTs in CAC. Our WB data showed significant decrease in protein expressions of γH2AX. Immunostaining indicated increased Muc2 levels among TgM9 mice versus WTs in CAC. Caco2BBE cells overexpressing MMP9 showed increase in EGFR and SP1 protein levels. As a proof of principle model, WT mice treated with MMP9 siRNA loaded nanoparticles showed worsened CAC condition compared to WT mice given scrambled siRNA loaded nanoparticles (control group) as reflected by bodyweight loss and higher clinical score. We also observed that WT mice treated with MMP9 siRNA loaded nanoparticles showed significant increase in protein expression of γH2AX compared to control group. Conclusion: Our study implies two significant clinically relevant outcomes. First, MMP9 promotes the beneficial microbiota population and controls the ROS production, restoring the DNA damage via activation of the EGFR1-SP1-Muc2 pathway and, therefore acts as a tumor suppressor. Second, our proof of principle model contradicts the use of targeted MMP9 inhibitors, specifically in CAC treatment, indicating that MMP9 inhibition can worsen the CAC.
30 NEUROD1-EXPRESSING MATURE ENTEROENDOCRINE CELLS CONTRIBUTE TO BASAL AND PATHOLOGICAL STEM CELL DYNAMICS IN THE SMALL INTESTINE Yoshitatsu Sei, Jianying Feng, Xilin Zhao, Sajung Yun, Ayla O. White, Deborah E. Citrin, Stephen Wank Background: The intestinal epithelium is continuously regenerated at a rapid rate from actively cycling Lgr5-expressing intestinal stem cells (ISCs) that reside at the crypt base. However, upon loss of Lgr5+ISCs during inflammation or radiation-induced injury, restoration of the epithelium is mediated by reserve ISCs. Recent lineage tracing studies suggest that secretory cell precursors and enteroendocrine cell (EEC) lineage have reserve ISC potential. However, the role of mature EECs in stem cell dynamics remains unclear. Aim: To investigate ISC properties of mature post-Ngn3 EECs by genetic lineage tracing of NeuroD1expressing EECs in stem cell dynamics in the small intestine under normal conditions and following radiation-induced injury. Methods: In-vivo and ex-vivo lineage tracing of EECderived cells was performed using NeuroD1-CreERT2; Rosa26-tdTomato (NeuroD1-Tom) mice and their organoids established from isolated primary crypts following tamoxifen (TAM) induction. Small intestinal sections were assessed for EECs using Chromogranin A (ChgA) IHC. Results: NeuroD1-derived cells analyzed in crypts at day 1, 2 and 5 after TAM induction showed that the majority of NeuroD1-derived cells were ChgA+ mature EECs and most frequently located at +4 position and above p10 within the crypts. Analysis at day 14 after TAM identified long-lived NeuroD1-derived ChgA+ mature EECs that reside predominantly at +4 position over 14 days in 6.7% of the crypts examined. Whole-mount intestines showed migration streams of NeuroD1-derived differentiated epithelial cells, observed as ribbon-like streaks, indicating that NeuroD1-derived cells revert to ISCs to generate intestinal epithelium. Over time, there was an exponential increase in numbers of ribbons up to approximately 8 weeks (≈ 70 ribbons) in the small intestine after a single dose of TAM. NeuroD1-derived migration streams were also observed in ex-vivo organoids established from isolated crypts of NeuroD1-Tom mice. Finally, the effect of radiation-induced injury on NeuroD1-derived clonal expansion was examined in mice given abdominal irradiation (14 Gy) 2 days after a single TAM administration. Whole-mount intestines 7 weeks after TAM induction showed multiple patches of NeuroD1-derived ribbons, that originated from 10-25 tomato+ crypts in the irradiated mice, suggesting a major role of NeuroD1-expressing EECs in the intestinal epithelial repair process. Conclusion: The present study suggests that NeuroD1-expressing mature post-Ngn3 EECs contribute to basal and pathological stem cell dynamics in the small intestine. Further investigation of this role may provide novel insights into the stem cell dynamics of the intestinal epithelium as well as the tumorigenesis of EEC derived tumors.
28 PLAGL2 PROMOTES A STEM CELL PHENOTYPE IN INTESTINAL EPITHELIAL CELLS AND IS REQUIRED FOR A TUMOR PHENOTYPE IN COLON CANCER CELL LINES Ashlee M. Strubberg, Tingting Zhao, Blair Madison The highly conserved Let-7 microRNAs (miRNAs) are one of the most abundantly expressed miRNA families in adult mammalian tissues, including the intestine, where we have previously shown that Let-7 miRNAs are critical for inhibiting cellular proliferation, promoting differentiation and repressing carcinogenesis. Ablation of Let-7 through tissue-specific expression of Lin-28 Homolog B (Lin28b) in mouse models resulted in an enhancement of stem cell fate and the development of intestinal adenocarcinomas concomitant with reduced survival. Additionally, depletion of Let-7 resulted in elevated expression of a novel Let-7 target we describe here, Pleiomorphic Adenoma Gene-Like 2 (PLAGL2). PLAGL2 is a zinc finger transcription factor that has been reported to inhibit differentiation of neural stem cells and glioma, but its specific role in the intestine has not yet been fully elucidated. We find that PLAGL2 is overexpressed in a majority of human colorectal cancers (CRCs) and is a predictor of poor outcomes, consistent with our following findings that PLAGL2 promotes intestinal epithelial cell (IEC) transformation. With regard to transformation potential, the overexpression PLAGL2, but not other Let-7 targets, in rat IEC6 cells enhanced soft-agar colony formation. Conversely, mutation of PLAGL2 in a human colon adenocarcinoma cell line, DLD1, resulted in a significant decrease in proliferation and migration. Regarding effects on normal IECs, PLAGL2 overexpression in murine enteroids induced expression of the intestinal stem cell marker, achaete-scute family bHLH transcription factor 2 (ASCL2), which has been reported to specify the stem cell fate in intestinal crypts via the activation of a stem cell signature through cooperation with Wnt signaling. Consistent with this, PLAGL2 overexpression in murine enteroids triggered the formation of large cyst-like structures (typically indicative of hyperactive Wnt signaling and a stem cell phenotype) and enhanced colony forming potential of stem cells. Together, these data suggest that PLAGL2 promotes a stem cell phenotype and drives tumorigenesis in the intestine, potentially through the transcriptional activation of ASCL2.
31 THE ERBB3 RECEPTOR TYROSINE KINASE RESTRICTS INTESTINAL PANETH CELL NUMBERS THROUGH PI 3-KINASE SIGNALING Dana Almohazey, Jonathan J. Hsieh, Ken S. Lau, Mark R. Frey BACKGROUND: Paneth cells (PC) support intestinal stem cells (ISC) with growth factors and participate in innate immunity by releasing antimicrobial peptides, including lysozyme and defensins. PC loss and dysfunction are associated with disorders such as Crohn's disease and necrotizing enterocolitis. The specific pathways regulating PC development and function are not fully understood, though some evidence suggests that intracellular signaling downstream of receptor tyrosine kinases may affect the balance of secretory lineages, including PCs. Here, we tested the role of the neuregulin (NRG) receptor ErbB3 in control of PC differentiation and the ISC niche. METHODS: Ileal tissues from ErbB3flox/flox (functionally wild type) and ErbB3flox/flox;Villin-Cre (E3KOIE; intestinal epithelium specific deletion) mice were characterized by immunofluorescence, qPCR, and disaggregation/cytometry time-offlight analyses. In vitro, ErbB3 was activated with NRG1β (10 ng/ml, 24 h exposure) or downstream signaling was inhibited (PI 3-kinase/Akt with LY294002; MEK/ERK with U0126) in matrigel-embedded ileal enteroids and human HT-29 colorectal adenocarcinoma cells; RNA and protein were extracted and analyzed by qPCR. RESULTS: Intestinal epithelial ErbB3 knockout caused precocious appearance of PCs as early as postnatal day 7, and substantially increased the number of mature PCs (9.9 vs. 5.6% of epithelial cells, p=0.008) and levels of Lyz (67.5% increase, p<0.0001) in adult mouse ileum. ErbB3 loss had no effect on other secretory lineages (goblet, tuft, or enteroendocrine), but increased the expression of the ISC marker Lgr5 (by 46.7%, p=0.012). E3KOIE intestines had elevated levels of the
29 THE ROLE OF KERATIN-19 POSITIVE CELLS IN COLONIC REGENERATION POST COLITIS Elena N. Fazio, Roy Nattiv, David Castillo-Azofeifa, Julia Schanin, Ysbrand Nusse, Ophir D. Kein, Samuel Asfaha Background: The intestinal and colonic epithelia are rapidly renewed every 3 to 5 days. In the intestine, at least two principal stem cell pools, comprised of rapidly cycling crypt based columnar (CBC) Lgr5+ cells and slower cycling Bmi1-expressing cells located above the crypt base, have been described. In the colon, however, we have recently identified an additional,
AGA Abstracts
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spatially distinct, Lgr5-negative stem cell pool that is a subset of Krt19-positive cells. Recent studies have shown that colonic inflammation resulting from DSS-induced colitis leads to loss of distal colonic crypts associated with the rapid loss of Lgr5+ cells. Despite the transient loss of Lgr5+ stem cells, the colonic crypts regenerate and homeostasis is restored. Aims: The goal of this study was to determine whether the Krt19+ colonic stem cell pool is responsible for colonic crypt regeneration during colitis. Methods: To examine whether Lgr5 and/or Krt19 mark normal colonic stem cells that contribute to epithelial regeneration upon colonic injury, we crossed Lgr5-GFP-IRES-CreER or Krt19-BAC-CreER transgenic mice to the ROSA26r-Tdtomato reporter line. Mice were then treated with tamoxifen followed by water (control) or DSS (in the drinking water x 7 days) to induce colitis. Lgr5+ and Krt19+ cells were then studied in the context of normal homeostasis or following colonic injury following DSS injury. Results: Our results demonstrated that Lgr5+ stem cells are sensitive to DSS-induced colonic injury. Similar DSS-induced colitis injury experiments were also carried out using Notch1-CreER and Math1-CreER transgenic mice crossed to ROSA26rTdtomato mice and revealed little to no lineage tracing from absorptive or secretory cells, respectively. In contrast, Krt19 marked long-lived cells above the crypt base were resistant to DSS-induced colonic epithelial injury and gave rise to Lgr5+ cells in the newly regenerated crypts. Moreover, in separate experiments using Lgr5-DTR-GFP;K19-BAC-CreER; ROSA26rTdtomato mice, diphtheria toxin induced ablation of Lgr5+ cells demonstrated that Lgr5+ stem cells are dispensable for colonic epithelial regeneration following DSS-induced colitis. Conclusions: Our data suggest that analogous to the small intestine, a subset of Krt19+ cells in the colon are more resistant to epithelial injury than Lgr5+ stem cells, and these Krt19+ cells retain stem cell activity post colitis.
AGA Abstracts
27 MMP9 FAVORS MICROBIOTA ADHERENCE AND MODULATES ROS LEVELS TO MAINTAIN GENOMIC STABILITY IN COLITIS ASSOCIATED CANCER Lewins Walter, Adani Pujada, Hamed Laroui, Timothy L. Denning, Pallavi Garg Introduction: Chronic inflammation nurtures tumor environment. In the colon this condition is called colitis associated cancer (CAC). CAC is the inflammation-dysplasia driven carcinoma which is significantly different compared to the adenoma-carcinoma driven sporadic colon cancer (CRC). In CAC, chronic inflammation causes accumulation of reactive oxygen species (ROS) resulting in DNA damage fostering the cancer cell growth. Gut microbiota are important in regulating ROS levels, therefore are critical in preserving the genomic stability. Matrix Metalloproteinases (MMPs) are a family of zinc dependent endopeptidases which mediate inflammation, tissue remodeling, and tumorigenesis. MMP9 is the most unique MMP because it is undetectable in healthy tissue but highly upregulated during inflammation and cancer. We have previously shown that MMP9 plays a protective role in CAC which is opposite to its conventional role of mediator in acute inflammation and cancer. Aim: Aim of this study is to understand the mechanism by which MMP9 acts as a tumor suppressor in CAC. Methods: We used C57/B6 transgenic mice which can express MMP9 under villin promoter (TgM9) and their wild type (WT) littermates. CAC was induced by three cycles of dextran sodium sulfate. As a proof of principal model, we used MMP9 small interfering RNA (siRNA) encoded within nanoparticles and gavaged WT mice to inhibit MMP9 in colonic epithelium. Results: QPCR data showed that mRNA levels of total microbiota population was more among TgM9 mice compared to WTs in CAC. QPCR analysis also indicated increased mRNA levels for the phylum Bacteroidetes sp., Akkermansia muciniphila but decreased mRNA levels for the phylum Firmicutes sp. We observed that TgM9 mice had lower levels of ROS compared to WTs in CAC. Our WB data showed significant decrease in protein expressions of γH2AX. Immunostaining indicated increased Muc2 levels among TgM9 mice versus WTs in CAC. Caco2BBE cells overexpressing MMP9 showed increase in EGFR and SP1 protein levels. As a proof of principle model, WT mice treated with MMP9 siRNA loaded nanoparticles showed worsened CAC condition compared to WT mice given scrambled siRNA loaded nanoparticles (control group) as reflected by bodyweight loss and higher clinical score. We also observed that WT mice treated with MMP9 siRNA loaded nanoparticles showed significant increase in protein expression of γH2AX compared to control group. Conclusion: Our study implies two significant clinically relevant outcomes. First, MMP9 promotes the beneficial microbiota population and controls the ROS production, restoring the DNA damage via activation of the EGFR1-SP1-Muc2 pathway and, therefore acts as a tumor suppressor. Second, our proof of principle model contradicts the use of targeted MMP9 inhibitors, specifically in CAC treatment, indicating that MMP9 inhibition can worsen the CAC.
30 NEUROD1-EXPRESSING MATURE ENTEROENDOCRINE CELLS CONTRIBUTE TO BASAL AND PATHOLOGICAL STEM CELL DYNAMICS IN THE SMALL INTESTINE Yoshitatsu Sei, Jianying Feng, Xilin Zhao, Sajung Yun, Ayla O. White, Deborah E. Citrin, Stephen Wank Background: The intestinal epithelium is continuously regenerated at a rapid rate from actively cycling Lgr5-expressing intestinal stem cells (ISCs) that reside at the crypt base. However, upon loss of Lgr5+ISCs during inflammation or radiation-induced injury, restoration of the epithelium is mediated by reserve ISCs. Recent lineage tracing studies suggest that secretory cell precursors and enteroendocrine cell (EEC) lineage have reserve ISC potential. However, the role of mature EECs in stem cell dynamics remains unclear. Aim: To investigate ISC properties of mature post-Ngn3 EECs by genetic lineage tracing of NeuroD1expressing EECs in stem cell dynamics in the small intestine under normal conditions and following radiation-induced injury. Methods: In-vivo and ex-vivo lineage tracing of EECderived cells was performed using NeuroD1-CreERT2; Rosa26-tdTomato (NeuroD1-Tom) mice and their organoids established from isolated primary crypts following tamoxifen (TAM) induction. Small intestinal sections were assessed for EECs using Chromogranin A (ChgA) IHC. Results: NeuroD1-derived cells analyzed in crypts at day 1, 2 and 5 after TAM induction showed that the majority of NeuroD1-derived cells were ChgA+ mature EECs and most frequently located at +4 position and above p10 within the crypts. Analysis at day 14 after TAM identified long-lived NeuroD1-derived ChgA+ mature EECs that reside predominantly at +4 position over 14 days in 6.7% of the crypts examined. Whole-mount intestines showed migration streams of NeuroD1-derived differentiated epithelial cells, observed as ribbon-like streaks, indicating that NeuroD1-derived cells revert to ISCs to generate intestinal epithelium. Over time, there was an exponential increase in numbers of ribbons up to approximately 8 weeks (≈ 70 ribbons) in the small intestine after a single dose of TAM. NeuroD1-derived migration streams were also observed in ex-vivo organoids established from isolated crypts of NeuroD1-Tom mice. Finally, the effect of radiation-induced injury on NeuroD1-derived clonal expansion was examined in mice given abdominal irradiation (14 Gy) 2 days after a single TAM administration. Whole-mount intestines 7 weeks after TAM induction showed multiple patches of NeuroD1-derived ribbons, that originated from 10-25 tomato+ crypts in the irradiated mice, suggesting a major role of NeuroD1-expressing EECs in the intestinal epithelial repair process. Conclusion: The present study suggests that NeuroD1-expressing mature post-Ngn3 EECs contribute to basal and pathological stem cell dynamics in the small intestine. Further investigation of this role may provide novel insights into the stem cell dynamics of the intestinal epithelium as well as the tumorigenesis of EEC derived tumors.
28 PLAGL2 PROMOTES A STEM CELL PHENOTYPE IN INTESTINAL EPITHELIAL CELLS AND IS REQUIRED FOR A TUMOR PHENOTYPE IN COLON CANCER CELL LINES Ashlee M. Strubberg, Tingting Zhao, Blair Madison The highly conserved Let-7 microRNAs (miRNAs) are one of the most abundantly expressed miRNA families in adult mammalian tissues, including the intestine, where we have previously shown that Let-7 miRNAs are critical for inhibiting cellular proliferation, promoting differentiation and repressing carcinogenesis. Ablation of Let-7 through tissue-specific expression of Lin-28 Homolog B (Lin28b) in mouse models resulted in an enhancement of stem cell fate and the development of intestinal adenocarcinomas concomitant with reduced survival. Additionally, depletion of Let-7 resulted in elevated expression of a novel Let-7 target we describe here, Pleiomorphic Adenoma Gene-Like 2 (PLAGL2). PLAGL2 is a zinc finger transcription factor that has been reported to inhibit differentiation of neural stem cells and glioma, but its specific role in the intestine has not yet been fully elucidated. We find that PLAGL2 is overexpressed in a majority of human colorectal cancers (CRCs) and is a predictor of poor outcomes, consistent with our following findings that PLAGL2 promotes intestinal epithelial cell (IEC) transformation. With regard to transformation potential, the overexpression PLAGL2, but not other Let-7 targets, in rat IEC6 cells enhanced soft-agar colony formation. Conversely, mutation of PLAGL2 in a human colon adenocarcinoma cell line, DLD1, resulted in a significant decrease in proliferation and migration. Regarding effects on normal IECs, PLAGL2 overexpression in murine enteroids induced expression of the intestinal stem cell marker, achaete-scute family bHLH transcription factor 2 (ASCL2), which has been reported to specify the stem cell fate in intestinal crypts via the activation of a stem cell signature through cooperation with Wnt signaling. Consistent with this, PLAGL2 overexpression in murine enteroids triggered the formation of large cyst-like structures (typically indicative of hyperactive Wnt signaling and a stem cell phenotype) and enhanced colony forming potential of stem cells. Together, these data suggest that PLAGL2 promotes a stem cell phenotype and drives tumorigenesis in the intestine, potentially through the transcriptional activation of ASCL2.
31 THE ERBB3 RECEPTOR TYROSINE KINASE RESTRICTS INTESTINAL PANETH CELL NUMBERS THROUGH PI 3-KINASE SIGNALING Dana Almohazey, Jonathan J. Hsieh, Ken S. Lau, Mark R. Frey BACKGROUND: Paneth cells (PC) support intestinal stem cells (ISC) with growth factors and participate in innate immunity by releasing antimicrobial peptides, including lysozyme and defensins. PC loss and dysfunction are associated with disorders such as Crohn's disease and necrotizing enterocolitis. The specific pathways regulating PC development and function are not fully understood, though some evidence suggests that intracellular signaling downstream of receptor tyrosine kinases may affect the balance of secretory lineages, including PCs. Here, we tested the role of the neuregulin (NRG) receptor ErbB3 in control of PC differentiation and the ISC niche. METHODS: Ileal tissues from ErbB3flox/flox (functionally wild type) and ErbB3flox/flox;Villin-Cre (E3KOIE; intestinal epithelium specific deletion) mice were characterized by immunofluorescence, qPCR, and disaggregation/cytometry time-offlight analyses. In vitro, ErbB3 was activated with NRG1β (10 ng/ml, 24 h exposure) or downstream signaling was inhibited (PI 3-kinase/Akt with LY294002; MEK/ERK with U0126) in matrigel-embedded ileal enteroids and human HT-29 colorectal adenocarcinoma cells; RNA and protein were extracted and analyzed by qPCR. RESULTS: Intestinal epithelial ErbB3 knockout caused precocious appearance of PCs as early as postnatal day 7, and substantially increased the number of mature PCs (9.9 vs. 5.6% of epithelial cells, p=0.008) and levels of Lyz (67.5% increase, p<0.0001) in adult mouse ileum. ErbB3 loss had no effect on other secretory lineages (goblet, tuft, or enteroendocrine), but increased the expression of the ISC marker Lgr5 (by 46.7%, p=0.012). E3KOIE intestines had elevated levels of the
29 THE ROLE OF KERATIN-19 POSITIVE CELLS IN COLONIC REGENERATION POST COLITIS Elena N. Fazio, Roy Nattiv, David Castillo-Azofeifa, Julia Schanin, Ysbrand Nusse, Ophir D. Kein, Samuel Asfaha Background: The intestinal and colonic epithelia are rapidly renewed every 3 to 5 days. In the intestine, at least two principal stem cell pools, comprised of rapidly cycling crypt based columnar (CBC) Lgr5+ cells and slower cycling Bmi1-expressing cells located above the crypt base, have been described. In the colon, however, we have recently identified an additional,
AGA Abstracts
S-12