Yeung Sau-Man. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 139-172). / Abstracts in English and Chinese. / Title page --- p.i / Acknowledgements --- p.ii / Table of Content --- p.iv / List of Figures --- p.viii / List of Graphs --- p.x / List of Tables --- p.xi / Abbreviations --- p.xiv / Abstract --- p.xv / Chinese Abstract --- p.xvii / Chapter Chapter 1 --- General Introduction --- p.1 / Chapter 1.1 --- Diabetes Mellitus --- p.2 / Chapter 1.1.1 --- Type 1 diabetes mellitus --- p.3 / Chapter 1.1.2 --- Type 2 diabetes mellitus --- p.5 / Chapter 1.1.3 --- Maturity onset diabetes of the young (MODY) --- p.6 / Chapter 1.1.4 --- Gestational diabetes --- p.7 / Chapter 1.2 --- Effect of Diabetes on Pregnancy --- p.9 / Chapter 1.3 --- Suggested Causes of Diabetic Embryopathy --- p.10 / Chapter 1.3.1 --- Glucose --- p.10 / Chapter 1.3.2 --- Ketone bodies --- p.11 / Chapter 1.3.3 --- Somatomedin inhibitors --- p.12 / Chapter 1.3.4 --- TNF-α --- p.12 / Chapter 1.3.5 --- Oxidative stress --- p.13 / Chapter 1.4 --- Animal Model of Diabetes --- p.15 / Chapter 1.4.1 --- Chemically-induced --- p.15 / Chapter 1.4.2 --- Mutants --- p.17 / Chapter 1.5 --- Gene-teratogen Interaction under Diabetic Pregnancy --- p.19 / Chapter 1.6 --- Strategy of the Thesis --- p.21 / Chapter Chapter 2 --- General Materials and Methods --- p.24 / Chapter 2.1 --- Mouse Maintenance and Mating Method --- p.25 / Chapter 2.2 --- Induction of Diabetes --- p.25 / Chapter 2.3 --- Preparation of All-trans Retinoic Acid --- p.26 / Chapter 2.4 --- Dissection of Embryos --- p.26 / Chapter 2.5 --- DNA Extraction from Yolk Sac for Genotyping --- p.27 / Chapter 2.6 --- Genotyping of Embryos --- p.28 / Chapter 2.7 --- Preparation of RNA Probes for In Situ Hybridization --- p.29 / Chapter 2.7.1 --- Mini-scale preparation of plasmid DNA --- p.29 / Chapter 2.7.2 --- Linearization of plasmid DNA --- p.30 / Chapter 2.7.3 --- In vitro transcription --- p.31 / Chapter 2.8 --- Whole Mount In Situ Hybridization --- p.33 / Chapter 2.8.1 --- Fixation and dehydration of embryos --- p.33 / Chapter 2.8.2 --- Hybridization --- p.33 / Chapter 2.8.3 --- Post-hybridization wash --- p.34 / Chapter 2.8.4 --- Antibody wash and color development --- p.35 / Chapter 2.8.5 --- Embryo powder preparation --- p.36 / Chapter 2.8.6 --- Pre-absorption of antibody --- p.35 / Chapter 2.9 --- Whole Mount TUNEL Staining --- p.36 / Chapter Chapter 3 --- "Maternal Diabetes, Sp2H and RA Interaction" --- p.39 / Chapter 3.1 --- Introduction --- p.40 / Chapter 3.1.1 --- Neural tube defects --- p.41 / Chapter 3.1.2 --- Retinoic acid as environmental factor --- p.41 / Chapter 3.1.3 --- Sp2H as genetic factor --- p.44 / Chapter 3.1.4 --- Experimental design of this chapter --- p.46 / Chapter 3.2 --- Material and Methods --- p.47 / Chapter 3.2.1 --- Sp2H mice --- p.47 / Chapter 3.2.2 --- Mating and RA injection protocol --- p.47 / Chapter 3.2.3 --- Dissection of fetuses and analysis of neural tube development --- p.48 / Chapter 3.3 --- Results --- p.49 / Chapter 3.3.1 --- Maternal diabetes alone --- p.50 / Chapter 3.3.2 --- Sp2H mutation alone --- p.51 / Chapter 3.3.3 --- RA alone --- p.52 / Chapter 3.3.4 --- Maternal diabetes and RA interaction --- p.53 / Chapter 3.3.5 --- Sp2H mutation and RA interaction --- p.55 / Chapter 3.3.6 --- Sp2H mutation and maternal diabetes interaction --- p.57 / Chapter 3.3.7 --- "Maternal diabetes, Sp2H mutation and RA interaction" --- p.59 / Chapter 3.4 --- Discussion --- p.62 / Chapter 3.4.1 --- Maternal diabetes alone does not cause neural tube defects --- p.62 / Chapter 3.4.2 --- RA induces neural tube defects --- p.63 / Chapter 3.4.3 --- Interaction of maternal diabetes with RA in increasing the susceptibility to neural tube defects --- p.64 / Chapter 3.4.4 --- Embryos with Sp2H allele show increased susceptibility to neural tube defects when triggered by maternal diabetes and RA --- p.67 / Chapter Chapter 4 --- Molecular and Cellular Bases of Interaction --- p.71 / Chapter 4.1 --- Introduction --- p.72 / Chapter 4.1.1 --- Mechanism of diabetic embryopathy --- p.72 / Chapter 4.1.2 --- Mechanism of Sp2H mutation in development of neural tube defects --- p.74 / Chapter 4.1.3 --- Mechanism of RA teratogenicity --- p.75 / Chapter 4.1.4 --- "Possible common pathways shared by maternal diabetes, RA and Sp2H mutation" --- p.76 / Chapter 4.1.5 --- Experimental design of this chapter --- p.78 / Chapter 4.2 --- Materials and Methods --- p.80 / Chapter 4.2.1 --- Sample collection for studying Pax3 expression in Sp2H/+ And +/+ embryos in response to maternal diabetes or RA by whole mount in situ hybridization --- p.80 / Chapter 4.2.2 --- "Sample collection for studying the level of apoptosis in response to the interaction of maternal diabetes, Sp2H mutation and RA by whole mount TUNEL staining" --- p.82 / Chapter 4.3 --- Results --- p.86 / Chapter 4.3.1 --- Expression levels of Pax3 mRNA detected by whole mount in situ hybridization / Chapter 4.3.1.1 --- Expression of Pax3 in Sp2H/+/- and +/+ embryos --- p.86 / Chapter 4.3.1.2 --- Effect of maternal diabetes on Pax3 expression in Sp2H/+ and +/+ embryos --- p.87 / Chapter 4.3.1.3 --- Effect of RA on Pax3 expression in Sp2H /+ and +/+ embryos --- p.88 / Chapter 4.3.2 --- Level of apoptosis detected by whole mount TUNEL --- p.89 / Chapter 4.3.2.1 --- Effect of Sp2H allele on apoptosis --- p.94 / Chapter 4.3.2.2 --- Effect of maternal diabetes on apoptosis in Sp2H/+ and +/+ embryos --- p.95 / Chapter 4.3.2.3 --- Effect of RA on apoptosis in Sp2H/+ and +/+ embryos --- p.96 / Chapter 4.3.2.4 --- Effect of maternal diabetes and RA on apoptosis in Sp2H/+ and +/+ embryos --- p.97 / Chapter 4.4 --- Discussion --- p.99 / Chapter 4.4.1 --- Underexpression of Pax3 and increases in apoptosis under maternal diabetes --- p.99 / Chapter 4.4.2 --- "RA does not down regulate Pαx3, but increases apoptosis" --- p.102 / Chapter 4.4.3 --- Interaction of maternal diabetes and RA in increasing apoptosis --- p.104 / Chapter Chapter 5 --- "Maternal Diabetes, NOD and RA Interaction" --- p.108 / Chapter 5.1 --- Introduction --- p.109 / Chapter 5.1.1 --- Diabetic embryopathy in NOD mice --- p.109 / Chapter 5.1.2 --- Experimental design of this chapter --- p.110 / Chapter 5.2 --- Materials and Methods --- p.112 / Chapter 5.2.1 --- NOD mice --- p.112 / Chapter 5.2.2 --- Mating and RA Injection Protocol --- p.112 / Chapter 5.2.3 --- Sample Collection for the Study of Pax3 Expression --- p.113 / Chapter 5.3 --- Results --- p.115 / Chapter 5.3.1 --- Maternal diabetic alone --- p.116 / Chapter 5.3.2 --- NOD mutation alone --- p.117 / Chapter 5.3.3 --- RA alone --- p.118 / Chapter 5.3.4 --- Maternal diabetes and RA interaction --- p.119 / Chapter 5.3.5 --- NOD mutation and RA interaction --- p.121 / Chapter 5.3.6 --- NOD mutation and maternal diabetes interaction --- p.123 / Chapter 5.3.7 --- "Maternal diabetes, NOD mutation and RA interaction" --- p.125 / Chapter 5.3.8 --- Expression of Pax3 in embryos with different copies of NOD alleles --- p.128 / Chapter 5.4 --- Discussion --- p.130 / Chapter 5.4.1 --- Maternal diabetes interacts with NOD mutation to increase susceptibility to neural tube defects --- p.130 / Chapter 5.4.2 --- Interaction of maternal diabetes with NOD mutation is greatly exacerbated when exposed to RA --- p.131 / Chapter 5.4.3 --- Pax3 is not involved in the interaction --- p.133 / Chapter Chapter 6 --- Conclusion and Future Perspectives --- p.134 / References --- p.139 / Figures / Graphs

Diabetic pregnancy is associated with increased risk of congenital malformations. Previous studies have shown that maternal diabetes can interact with the vitamin A metabolite, all-trans retinoic acid (RA), in increasing embryonic susceptibility to caudal regression and neural tube defects. The aim of this thesis is to investigate the cellular and molecular mechanisms that underlie this interaction. / First hypothesis. RA concentration in the embryo is tightly regulated by the synthesizing enzyme retinaldehyde dehydrogenase type II (RALDH2), and the degrading enzyme CYP26. Alteration in expression levels of these enzymes under maternal diabetes may affect the availability of RA and thus its teratogenicity. / In conclusion, results of this thesis provide insight into the mechanism of how maternal diabetes interacts with RA in enhancing embryonic susceptibility to congenital malformations. This is also the first report to show that maternal diabetes alters RA homeostasis. (Abstract shortened by UMI.) / Second hypothesis. The transfer of RA to the nucleus for molecular action is regulated by cytoplasmic cellular retinoic acid binding proteins CRABP-I and CRABP-II. Alteration in expression levels of these binding proteins under maternal diabetes may affect the amount of RA reaching the nucleus and thus its teratogenicity. / Third hypothesis. The action of RA is mediated via different nuclear retinoic acid receptors (RAR) and retinoid X receptors (RXR). Alteration in expression levels of these receptors under maternal diabetes may affect the efficacy of RA signal transduction and thus its teratogenicity. / Three hypotheses are proposed to explain the underlying mechanism of increased embryonic susceptibility to RA teratogenicity under maternal diabetes: / To investigate these hypotheses, expression levels of various genes in different groups were compared. Result show that there are no significant differences in mRNA expression levels of CRABP-I, CRABP-II, RARgamma, RARgamma and RXRalpha between embryos of diabetic and non-diabetic mice with or without RA treatment. In contrast, expression levels of Raldh2 and CYP26 are significantly reduced in embryos of diabetic mothers, and in embryos of non-diabetic mice cultured in vitro in hyperglycemic conditions. Moreover, embryos of diabetic mice show significantly reduced response to RA-induced up-regulation of CYP26. These findings suggest that the rate of degradation of RA is slower in embryos of diabetic mice and thus the teratogenic effect of RA is enhanced. / Leung Bo Wah. / "July 2005." / Adviser: Alisa S. W. Shum. / Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 3779. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 158-198). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.