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名古屋大学博士学位論文 学位の種類 : 博士(医学)(論文) 学位授与年月日:平成5年10月13日 柴田佳久氏の博士論文として提出された

Ph.D.

Ph.D.

Ph.D.

Thesis (Ph. D.)--University of Oregon, 2003. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 137-145). Also available for download via the World Wide Web; free to University of Oregon users.

Der hochkonservierte Wnt/ß-Catenin-Signaltransduktionsweg spielt eine wichtige Rolle während der Embryonalentwicklung, der Homöostase und der Tumorgenese in Adulten. Die BCL9 Proteine wurden zunächst als Kofaktoren dieses Signalweges identifiziert. Entsprechend agiert BCL9/Legless als essentieller Wnt/ß-Catenin-Kofaktor in Drosophila. Jedoch scheint die Rolle von BCL9 und BCL9-2, der Orthologe von Legless, in Vertebraten komplexer zu sein. Des Weiteren wurden die genauen Funktionen der BCL9 Proteine während der intestinalen Homöostase und Tumorgenese bislang wenig untersucht. Es konnte jedoch bereits gezeigt werden, dass BCL9-2 in intestinalen und Mammakarzinomen verstärkt expremiert wird. Diese Arbeit beschreibt erstmalig den Einfluss und die Funktion von BCL9-2 während der intestinalen Tumorgenese. BCL9-2 beinflusst die Tumorprogression positiv durch Verstärkung des Wnt/ß-Catenin-Signaltransduktionsweg und der Expression von Zielgenen, die Tumorwachstum und -invasion vermitteln. Zudem aktiviert BCL9-2 die Transkription von ß-Catenin-unabhängigen Genen durch einen neuartigen Mechanismus. Im Gegensatz zu BCL9, welches in allen humanen und murinen intestinalen Zelltypen expremiert wurde, beschränkte sich die BCL9-2 Expression auf die Zotten des Darmes. Die Wnt/ß-Catenin-positiven Krypten hingegen zeigten keinerlei BCL9-2-Expression auf, was darauf hinweist, dass BCL9-2 für den Wnt/ß-Catenin-Signalweg bei der intestinalen Homöostase entbehrlich ist. Während jedoch BCL9 Proteinlevel in Kolontumoren, im Vergleich zum normalen Epithel, unverändert blieben, wurde BCL9-2 bereits in frühen Stadien der Tumorgenese und in 90% aller Kolonkarzinome stark expremiert. Darüber hinaus führte transgene Überexpression von BCL9-2 im Darm von K19-BCL9-2;APCMin/+ Mäusen zu einer verstärkten Formation von Adenomen, deren Invasion und einem verringerten Überleben der Versuchstiere. Wie anhand von TOP/FOP Luciferase Reportergen-Versuchen gezeigt werden konnte, korrelierte die Stärke der BCL9-2-Proteinexpression mit der Aktivität des Wnt/ß-Catenin-Signalweges in Kolonkarzinomzellen. Zudem regulierte BCL9-2 die Transkription einiger ß-Catenin-abhängiger und darüber hinaus ß-Catenin-unabhängiger Zielgene, die bei der Tumorentstehung eine wichtige Rolle spielen. Des Weiteren zeigt diese Arbeit, dass in Kolonkarzinomzellen die BCL9-2 abhängige Transkription von CDX1 und CDX2 durch SP1-bindende Elemente über deren proximale Promotoren vermittelt wurde. Mittels Immunpräzipitation konnte zudem eine Interaktion zwischen BCL9-2 und SP1 in Kolonkarzinomzellen bestätigt werden. Zusammenfassend zeigt diese Arbeit, dass BCL9-2-Überexpression in frühen Phasen der intestinalen Tumorgenese die Progression von benignen Tumoren in invasive Karzinome fördert. Diese Eigenschaft wird durch verschiedene Mechanismen vermittelt: Zum einen verstärkt BCL9-2 die Expression einiger Wnt/ß-Catenin-abhängiger Zielgene; zum anderen reguliert BCL9-2 ß-Catenin-unabhängige Gene, die für die Tumorgenese eine wichtige Rolle spielen. Diese Funktion wird vermutlich durch die Bindung an SP1 Transkriptionsfaktoren und damit an die Promotoren von BCL9-2 Zielgenen vermittelt, was zu der verstärkten Expression von Genen führt, die die Tumorprogression und Invasion fördern.

Probiotics are defined as live microorganisms that confer beneficial effects to health when administered in a sufficient amount. In previous studies about the beneficial effects of probiotic bacteria to health, particularly in the fields of intestinal mucosa defence responses, specific probiotics, in a strain-dependent manner, show some potential to reinforce the integrity of intestinal epithelium and/or regulate some immune components. However, the mechanisms involved in the interactions between probiotics or bioactive components of probiotics with the intestinal epithelium are still not yet clearly defined or systematically studied. Among all possible routes of modulation by probiotics of intestinal epithelial cell–mediated defence responses, modulations of mucin and trefoil factor expression as well as the cytokine profiles are important components of the innate and adaptive mucosal immune responses of the intestinal epithelial cells and are considered to play important role in the intestinal defence responses against pathogenic bacteria. This thesis examined and characterized the in vitro modulation effects by metabolic products of two commonly studied probiotics bacterial strains, Lactobacillus rhamnosus GG (LGG) and Escherichia coli Nissle 1917 (EcN), on the intestinal epithelial cell-mediated defence responses. It was found that the metabolic products of EcN decreased the transcriptional levels of secretory mucins MUC5AC, MUC5B and MUC2 while LGG metabolic products only down-regulated that of MUC5AC. In partial agreement with the reduction of mucin gene expression levels, intracellular MUC5B and MUC2 mucin expression was reduced by EcN metabolic products and MUC5AC and MUC2 by the metabolic products of LGG. In contrast, the extracellular MUC5AC and MUC2 mucin expression tended to increase upon the effects of both LGG and EcN metabolic products, which might result from accumulative effects of the modulation on extracellular mucin secretion during the time of treatment or the differential responsiveness of cellular mucin gene and protein expression upon stimulation. The expression of trefoil factor 3 in both gene and protein levels upon the effects of EcN metabolic products while those of LGG enhanced the transcriptional but not protein level. As for the modulation of cytokine profiles, LGG metabolic products mainly influence the secretion of anti-inflammatory cytokines such as IL-4, IL-5 and IL-10 in a moderate manner while EcN metabolic products exerted broad pro-inflammatory potential to the intestinal epithelial cells by inducing the secretion of pro-inflammatory cytokines such as IL-8, MCP-1, TGF-α, TNF-α and GM-CSF, which indicated that the metabolic products of LGG and EcN might initiate differential signaling pathway to influence the intestinal epithelial adaptive immune responses. To conclude, the present research provides evidence to substantiate that LGG and EcN display differential modulation mechanisms of the intestinal epithelial cell-mediated defence responses that involve intestinal-cell mediated mucin and trefoil factor secretion as well as pro- and anti-inflammatory cytokine expression. / published_or_final_version / Biological Sciences / Master / Master of Philosophy

Cell-based insulin therapies can potentially improve glycemic regulation in insulin dependent diabetes patients and thus help reduce secondary complications. The long-term goal of our work is to engineer autologous insulin-secreting intestinal endocrine cells as a non-beta cell approach to alleviate donor cell shortage and immune rejection issues associated with islet transplantation. These cells have been chosen for their endogenous similarity to beta cells, but generating cell constructs with sufficient insulin secretion for therapeutic effect has proven challenging. Previous work in our lab showed that a tissue engineered pancreatic substitute (TEPS) based on an engineered insulin-secreting L cell line, GLUTag-INS, was insufficient in affecting blood glucose levels in streptozotocin-induced diabetic mice, but promising since human insulin was detected in the blood. The objective of this project was therefore to fabricate an improved TEPS based on GLUTag-INS cells and evaluate its suitability as a standalone diabetes therapy. To achieve this objective, the following specific aims were (1) to investigate gene incorporation as a strategy to enhance recombinant insulin secretion from GLUTag-INS cells; (2) to develop and characterize a TEPS in vitro based on a microcapsule system containing improved GLUTag-INS cells with bioluminescence monitoring capability; and (3) to assess therapeutic efficacy of the graft in a diabetic, immune-competent mouse model and use bioluminescence monitoring to elucidate in vivo transplant behavior. This thesis therefore reports on the progression of studies from the genetic and molecular levels for improved insulin secretion per-cell, to the tissue level for enhanced secretion per-graft, and lastly to the preclinical level for therapeutic assessment in a diabetic mouse model.

A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine. / Purpose: Infants born with Heterotaxy Syndrome (HS) often have intestinal malrotation in addition to severe congenital heart disease (CHD). Given the catastrophic risk of midgut volvulus, where the vascular supply to the gut is cut off causing necrotic bowel and possible future short‐gut syndrome following surgery, an elective Ladd procedure is recommended at the first diagnosis of malrotation. In patients with severe CHD, however, the risk of complications from prophylactic surgery is high, especially in infancy prior to stable cardiac palliation. This study sought to determine whether deferring a Ladd procedure during the first six months of life in infants with CHD is safe by focusing on the incidence of volvulus in the HS population, morbidity of volvulus and morbidity of an elective Ladd procedure. Methods: Medical records of patients with HS and intestinal malrotation at Phoenix Children’s Hospital from 2006‐2011 were reviewed. Stage of heart surgery, severity of heart disease, diagnosis of intestinal malrotation, and timing of Ladd procedure if applicable were recorded. Results: 31 patients with HS and intestinal malrotation were identified. Of the 31, 9 had a Ladd procedure prior to six months of age, 2 for volvulus and the other 7 either electively or for less severe GI symptoms that were not suggestive of volvulus. The other 22 did not have a Ladd procedure prior to six months of age. There was one death (1/22) from a non‐gastrointestinal cause in a patient who had not undergone a Ladd procedure. There were no deaths in the 9 patients who underwent a Ladd procedure (0/9). Conclusions: Given the low overall incidence of volvulus in HS, and with continued vigilance for obstructive symptoms, this study suggests that delaying the Ladd procedure in asymptomatic patients with HS and CHD and intestinal malrotation is safe. Watchful waiting may reduce the incidence of cardiac complications during the Ladd procedure by allowing for stabilizing cardiac surgical palliation prior to elective abdominal surgery.