L’Héparane sulfate (HS) est un polysaccharide linéaire et sulfaté présent à la surface des cellules ou dans le milieu extracellulaire des tissus animaux. Le long des chaines d'HS, des régions présentant une densité de charge négative élevée (domaines S) alternent avec des régions plus faiblement chargées (domaines A). Différents motifs SAS sont ainsi exposés à la surface des cellules et permettent des interactions spécifiques avec de nombreuses protéines comme l’interféron gamma (INF-γ). Cette cytokine interagit avec haute affinité avec les chaines d'HS, ce qui module son activité in vivo (accumulation et localisation tissulaire, clairance sanguine). Pour moduler l’activité de l’INF-γ en inhibant ses interactions avec les chaines d'HS de la surface des cellules, nous avons entrepris la synthèse de mimes de motifs SAS, dans lesquels des fragments synthétiques de domaines S sont liés par un espaceur de longueur modulable. Pour effectuer cette conjugation, nous avons choisi d'utiliser deux types de chimie click la "CuAAC" et la "ligation oxime". Cette stratégie a nécessité de mettre au point des fonctionnalisations orthogonales des extrémités réductrices et non réductrices d'oligosaccharides synthétiques. Nous avons mis au point les réactions sur un disaccharide modèle dérivé du cellobiose, puis les avons transférées à la modification d'un tetrasaccharide synthétique d'HS. Dans ce travail, nous avons optimisé deux réactions clef : une alkylation anomérique dans l’eau et une allylation de fonction alcool dans des conditions neutres / Heparan sulfate (HS) is a linear polysaccharide found in animal tissues at the cell surface or in the extracellular matrix. HS chains display alternating highly negatively charged regions (S) and less charged ones (A). SAS domains with different topologies can thus be exposed at the cell surface with the aim of interacting specifically with different proteins. Gamma interferon (INF-γ) is a cytokine that binds tightly to HS chains. This interaction allows controlling numerous bioactivities of the cytokine (accumulation and location in tissues as well as blood clearance). The discovery of HS fragment able to modulate the activity of IFN-γ could open the way to new innovative therapeutics. To this aim we launched a program aiming at synthesizing mimetic of the SAS motifs found in HS. We devised a strategy allowing linking two synthetic S fragments of HS through a spacer. To this aim we selected two click chemistry reactions: the "CuAAC" triazole formation and "oxime ligation". To implement this strategy, we optimized, on a disaccharide model derived from cellobiose, a methodology allowing the functionalization of the reducing and non-reducing end of synthetic oligosaccharides by to orthogonal reactive functions. Then we extended the methodology to a HS tetrasaccharide fragment. In this work, we optimized two key reactions: an anomeric alkylation in water and a hydroxyl allylation in neutral condition

京都大学 / 0048 / 新制・論文博士 / 博士(医科学) / 乙第12872号 / 論医科博第1号 / 新制||医科||4(附属図書館) / 31590 / (主査)教授 野田 亮, 教授 楠見 明弘, 教授 瀬原 淳子 / 学位規則第4条第2項該当 / Doctor of Medical Science / Kyoto University / DFAM

L'Héparane Sulfate (HS), un polysaccharide linéaire, module les activités biologiques de nombreuses protéines. Afin d'élucider les interactions entre l'HS et les protéines, la synthèse chimique d'HS est un outil précieux, mais elle peut être difficile. Notre équipe a montré que des mélanges combinatoires obtenus par auto-assemblage de différentes combinaisons de dérivés disaccharidiques (lactose et lactose persulfaté) sur surfaces planes d'or peuvent reconnaître spécifiquement certaines protéines se liant à l'HS, telles que les isoformes de la chimiokine CXCL12 ou IFNγ. Avec ces dérivés, nous avons réalisé un auto-assemblage sur des nanoparticules d'or. Mais à cause de la toxicité des nanoparticules d'or, nous avons aussi adapté cette méthode à des nanoparticules lipidiques. En utilisant les conditions qui ont déjà été améliorées pendant la synthèse des dérivés lactose et lactose persulfaté, nous avons préparé deux autres dérivés disaccharidiques plus proches de la structure réelle d'HS. Ces nouveaux dérivés sont utilisés pour réaliser des nanoparticules d'or et nanoparticules lipidiques afin de comparer les propriétés avec les lactose et lactose persulfaté. Les tests d'affinité avec différentes protéines sont en cours de réalisation. / Héparan Sulfate (HS) is a linear polysaccharide that modulates the biological activities of numerous proteins. In order to elucidate the interaction between HS and proteins, the synthesis of HS is an invaluable tool, but the synthesis is sometimes difficult. Our group has demonstrated that the combinatorial mixtures obtained by self-assembly of different combinations of disaccharide derivatives (lactose and persulfated lactose) on gold plan surfaces could recognize specifically some HS binding proteins, such as the isoforms of the chemokine CXCL12 or IFNγ. Because of the toxicity of gold nanoparticles, we have also adapted this method to lipid nanoparticles. Using the conditions that have already improved during the synthesis of lactose and persulfated lactose derivatives, we have synthesized two other disaccharide derivatives, which were closer to the real structure of HS. These new derivatives were used to prepare the gold and lipid nanoparticles at the aim of comparing the properties with lactose and persulfated lactose. The tests of affinities with different proteins are in progress.

La maladie d’Alzheimer (MA), la forme la plus répandue de démence, est caractérisée par une accumulation cérébrale de plaques amyloïdes formées de peptide beta-amyloïde, et d’enchevêtrements neurofibrillaires (NFT) de protéine tau anormalement phosphorylée (P-tau). Depuis plusieurs années, l’évidence d’une implication majeure d’altérations synaptiques dans la pathologie a émergée. De plus, il a été observé dans les cerveaux MA que les héparanes sulfates (HS), normalement extracellulaires, accumulent à l’intérieur des neurones, où ils co-localisent avec tau. Le laboratoire CRRET a mis en évidence que la 3-sulfotransferase 2 (HS3ST2), enzyme prédominante dans le cerveau où elle génère des HS 3-O-sulfatés (3S-HS) de rôle inconnu, est impliquée dans les mécanismes à l’origine de la tauopathie. Puisque la HS3ST2 et les 3S-HS n’ont jamais été caractérisés à la synapse où ils pourraient participer au développement de la tauopathie, les objectifs de ce travail sont : 1) déterminer si la HS3ST2 et les 3S-HS sont présents à la synapse et étudier des possibles rôles physiologiques ; 2) déterminer si les 3S-HS accumulent au niveau intracellulaire dans des cellules neuronales et/ou dans de synaptosomes issus d’un modèle murin de tauopathie ; et 3) examiner si les 3S-HS intracellulaires produits par la HS3ST2 sont impliqués dans le développement ou évolution de la tauopathie au niveau synaptique.Dans ce travail, nous avons montré la présence des 3S-HS et de la HS3ST2 à la synapse de cellules hippocampiques et accumulé des preuves de leur implication dans la stabilité et l’activité synaptique, toutes deux altérées par des peptides se liant aux 3S-HS ont pu bloquer cette activité. Nous avons implémenté et caractérisé le modèle murin de tauopathie rTg4510 et mise en place les cultures primaires de leur neurones hippocampiques. Dans ces cellules, nous avons montré l’accumulation intracellulaire des 3S-HS et une surexpression de la HS3ST2 corrélant avec l’accumulation de P-tau. La digestion enzymatique des HS dans les synaptosomes a résulté dans l’inhibition de la tauopathie.Ce travail révèle pour la première fois un rôle fondamental de la 3-O-sulfatation des chaines d’HS à la synapse, aussi bien dans des conditions physiologiques que pathologiques. Pour la première fois, l’enzyme HS3ST2 est décrite à la synapse. De plus, ce travail donne la preuve d’un lien fort entre l’expression d’HS3ST2, l’accumulation de 3S-HS et la tauopathie au niveau synaptique, ouvrant de nouvelles opportunités pour mieux comprendre la MA. / Alzheimer’s disease (AD), the main form of dementia in the world, is characterized by brain accumulation of amyloid plaques formed of amyloid beta, and neurofibrillary tangles (NFT) made of tau protein in an abnormally hyperphosphorylated form (P-tau). Strong evidences show that synaptic changes are central to the disease process. Moreover, previous observations in AD have shown that heparan sulfates (HS), typically present outside the cell , accumulate inside neurons of AD in where they interact with tau. Recently, the CRRET laboratory demonstrated that the neural 3-O-sulfotransferase 2 (HS3ST2), which generates 3-O-sulfated HS (3S-HS) of still unrevealed physiological roles, is involved in the mechanisms leading to tauopathy. Since it was unknown whether HS3ST2 and 3S-HS are expressed at the synapse and if there they participate to tauopathy development and/or evolution, the objectives of this work were: 1) to determine if HS3ST2 and 3S-HS are present at the synapse and to get insights on their physiological role; 2) to investigate whether 3S-HS accumulate intracellularly in hippocampal cells and/or in synaptosomes from a mice model of tauopathy; and 3) to investigate whether intracellular 3S-HS made by HS3ST2 are involved in tauopathy development and/or evolution at the synaptic level.We described here the presence of 3S-HS and HS3ST2 at the synapse and the role that may play 3S-HS in maintaining synaptic transmission and stability in primary cell culture from mice. These roles are the results of potential multiple implications of 3S-HS in various processes. Secondly, we implement and characterized the rTg4510 mice model of AD-related tauopathy and set primary cultures of hippocampal cells from these mice. In the tauopathic cells, we showed the intracellular accumulation of 3S-HS and HS3ST2 overexpression. Finally, we cleaned P-tau in synaptosomes from the rTg4510 mice aged of 2 months by digesting HS.The present work reveals, for the first time, the presence and a possible fundamental role of HS3ST2 and 3S-HS at the synapse. We give evidences of an interplay between 3S-HS, produced by HS3ST2, and tau and the synaptic level, leading to its abnormal phosphorylation. The results of these work open a new way to understand the phenomenon leading to synaptic impairment in AD patients and could reveal new targets to elaborate protection strategies against the AD pathological lesions.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第18141号 / 医博第3861号 / 新制||医||1002(附属図書館) / 30999 / 京都大学大学院医学研究科医学専攻 / (主査)教授 坂井 義治, 教授 髙田 穣, 教授 武藤 学 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Glycans and glycoconjugates exert myriad important biological functions, extending and diversifying the functionality of protein molecules. Extensive studies have focused on the protein and gene realms; however, due to the lack of means for external amplification and the inherent heterogeneity of glycans and glycoconjugates, their researches have not adequately informed the understanding of critical biological and pathological processes. Researchers in glycoscience have strived to bridge this gap and redefine our understanding of carbohydrate functions. Glycosaminoglycans (GAGs) represent the most highly charged and poly-disperse animal glycans. GAGs exist on the surfaces of most mammalian cells and in the extracellular matrices. They play critical roles in anticoagulation, angiogenesis, inflammation, metastasis, cell proliferation and differentiation. Heparin and heparan sulfate (HS) are the most highly sulfated and structurally diverse GAGs, regulating a variety of cell functions by interacting directly with many growth factors and their receptors. Examples include fibroblast growth factor, bone morphogenetic protein and Wnt. These interactions rely on the unique structural properties of HS/heparin molecules. Extracellular enzymes (Sulfs and heparanase) also alter the fine structure of HS molecules. In order to investigate to the correlation between structure and function for mature HS/heparin chains, we employed mass spectrometry (MS) coupled with liquid chromatography (LC) as a sensitive and robust platform for composition profiling and detailed structural characterization. We developed a novel HPLC-chip based LC-MS platform to enable HS oligosaccharide profiling. In this thesis work, the chip LC-MS platform was improved for effective and informative tandem MS for HS oligosaccharides. We also advanced electron-based ion dissociation methods for more detailed and reliable sequence determination of HS oligosaccharides. These newly developed methods enable the investigation of the HS/heparin structural changes induced by HS extracellular remodeling enzymes, human Sulfs and heparanase. Application of the methods revealed the recognition preferences of these remodeling enzymes at the oligosaccharide level and led to the discovery of a novel peeling reaction induced by the 3-O-sulfation at the reducing end of HS saccharides.

No description available.

The primary aim of this text is to gain insight on how cellular activation by a insulin-like growth factor (IGF-I), in the presence of insulin-like growth factor binding protein-3 (IGFBP-3), is influenced by heparan sulfate proteoglycans (HSPG). Initial research will be presented, assumptions and hypotheses that were included in the development of mathematical models will be discussed, and the future enhancements of the models will be explored. There are many potential scenarios for how each component might influence the others. Mathematical modeling techniques will highlight the contributions made by numerous extracellular parameters on IGF-I cell surface binding. Tentative assumptions can be applied to modeling techniques and predictions may aid in the direction of future experiments. Experimentally, it was found that IGFBP-3 inhibited IGF-I Bovine Aortic Endothelial (BAE) cell surface binding while p9 HS slightly increased IGF-I BAE cell surface binding. IGFBP-3 has a higher binding affinity for IGF-I (3 x 10-9 M) than p9 HS has for IGF-I (1.5 x 10-8 M) as determined with cell-free binding assays. The presence of p9 HS countered the inhibiting effect of IGFBP-3 on IGF-I BAE cell surface binding. Although preliminary experiments with labeled p9 HS and IGFBP-3 indicated little to no cell surface binding, later experiments indicated that both IGFBP-3 and p9 HS do bind to the BAE cell surface. Pre-incubation of BAE cells with either IGFBP-3 or p9 HS resulted in an increase of IGF-I BAE cell surface binding . There was a more substantial increase of IGF-I surface binding when cells were pre-incubated with IGFBP- 3 than p9 HS. There was a larger increase of IGF-I BAE cell surface binding when cells were pre-incubated with p9 HS than when p9 HS and IGF-I were added simultaneously. This suggests that IGFBP-3 and p9 HS surface binding plays key role in IGF-I surface binding, however, p9 HS surface binding does not alter IGF-I surface binding as much as IGFBP-3 surface binding seems to. Experimental work helps further the understanding of IGF-I cellular activation as regulated by IGFBP-3 and p9 HS. Developing mathematical models allows the researcher to focus on individual elements in a complex systems and gain insight on how the real system will respond to individual changes. Discrepancies between the model results and the experimental data presented indicate that soluble receptor inhibition is not sufficient to account for experimental results. The alliance of engineering analysis and molecular biology helps to clarify significant principles relevant to the conveyance of growth factors into tissue. Awareness of the effects of individual parameters in the delivery system, made possible with mathematical models, will provide guidance and save time in the design of future therapeutics involving growth factors. / Master of Science

The correct patterning of embryos requires the exchange of information between cells. This is in part achieved by the proper distribution of signaling molecules, many of which exert their function by establishing gradients of concentration. Because of this property they were named "morphogens", or "form giving" substances. Among these, proteins belonging to the Hedgehog (Hh) family have received much attention, owing to their unusual double lipid modification and their involvement in human disease, causing congenital birth defects and cancer. Great efforts have been made in order to elucidate the mechanisms by which Hh molecules are propagated in the embryo. However, no conclusive evidence exists to date to which structures these molecules localize and how they, despite their membrane association, establish a gradient of concentration. Therefore, I decided to study the distribution of the vertebrate Hh homolog, Sonic Hedgehog (Shh) in developing zebrafish embryos. By fluorescently tagging Shh proteins, I found that these localize to discrete punctate structures at the membranes of expressing cells. These were often regions from which filopodial protrusions emanated from the cells. Puctate deposits of Shh were also located outside of expressing cells. In dividing cells, Shh accumulated at the cleavage plane. Furthermore, by making use of confocal microscopy and time lapse analysis, I visualized Shh proteins moving in filopodial extensions present between cells. This suggests a novel mechanism of Shh distribution, which relies on the direct contact of cells by filopodia for the exchange of signaling proteins. In a second part of my thesis, I characterized genes implicated in regulating Shh protein distribution and signaling function. I cloned three zebrafish genes belonging to the Ext1 (exostosin) family of glycosyltransferases required for the synthesis of Heparan Sulfate Proteoglycans and established a tentative link of these genes to somitic Hh signaling. In addition, I characterized the developmental expression and function of zebrafish Rab23, a small GTPase, which acts as a negative regulator of the Shh signaling pathway. Performing knock-down experiments of zebrafish Rab23, I found that Rab23 functions in left-right axis specification, a process previously shown to depend on proper Shh signaling.

The correct patterning of embryos requires the exchange of information between cells. This is in part achieved by the proper distribution of signaling molecules, many of which exert their function by establishing gradients of concentration. Because of this property they were named "morphogens", or "form giving" substances. Among these, proteins belonging to the Hedgehog (Hh) family have received much attention, owing to their unusual double lipid modification and their involvement in human disease, causing congenital birth defects and cancer. Great efforts have been made in order to elucidate the mechanisms by which Hh molecules are propagated in the embryo. However, no conclusive evidence exists to date to which structures these molecules localize and how they, despite their membrane association, establish a gradient of concentration. Therefore, I decided to study the distribution of the vertebrate Hh homolog, Sonic Hedgehog (Shh) in developing zebrafish embryos. By fluorescently tagging Shh proteins, I found that these localize to discrete punctate structures at the membranes of expressing cells. These were often regions from which filopodial protrusions emanated from the cells. Puctate deposits of Shh were also located outside of expressing cells. In dividing cells, Shh accumulated at the cleavage plane. Furthermore, by making use of confocal microscopy and time lapse analysis, I visualized Shh proteins moving in filopodial extensions present between cells. This suggests a novel mechanism of Shh distribution, which relies on the direct contact of cells by filopodia for the exchange of signaling proteins. In a second part of my thesis, I characterized genes implicated in regulating Shh protein distribution and signaling function. I cloned three zebrafish genes belonging to the Ext1 (exostosin) family of glycosyltransferases required for the synthesis of Heparan Sulfate Proteoglycans and established a tentative link of these genes to somitic Hh signaling. In addition, I characterized the developmental expression and function of zebrafish Rab23, a small GTPase, which acts as a negative regulator of the Shh signaling pathway. Performing knock-down experiments of zebrafish Rab23, I found that Rab23 functions in left-right axis specification, a process previously shown to depend on proper Shh signaling.