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Action anti-leucémique des inhibiteurs de la méthylation de l’ADN et de la déacétylation des histonesLemaire, Maryse 04 1900 (has links)
Les gènes suppresseurs de tumeurs (TSGs) contrôlent la prolifération cellulaire et leur inactivation joue un rôle important dans la leucémogénèse. Deux mécanismes épigénétiques majeurs sont impliqués dans la répression des TSGs: 1- la méthylation de l’ADN et 2- la déacétylation des histones des chromosomes. On les dit épigénétiques car ils n’affectent pas la séquence de l’ADN. Ces phénomènes sont réversibles, faisant donc d’eux des cibles thérapeutiques de choix. Dans le cadre de cette thèse, nous avons évalué le potentiel chimiothérapeutique de différents agents qui visent ces mécanismes épigénétiques et nous les avons administrés seuls et en combinaison dans le but d’améliorer leur efficacité.
La 5-aza-2’-désoxycytidine (5-Aza-CdR) est un inhibiteur de la méthylation de l’ADN qui permet la ré-expression des TSGs. Cet agent s’est avéré efficace contre certaines maladies hématologiques et est d’ailleurs approuvé aux États-Unis dans le traitement du syndrome myélodysplasique depuis 2006. Cependant, le protocole d’administration optimal de cet agent, en termes de doses et de durée, n’est toujours pas établi. Nos recherches suggèrent que le celui-ci devrait être plus intensif que ce que rapporte la littérature.
Les inhibiteurs des déacétylases des histones (HDACi) ont également montré une activité antinéoplasique intéressante. De récentes recherches ont montré que la combinaison d’agents ciblant à la fois la méthylation de l’ADN et la déacétylation des histones produit une réactivation synergique des TSGs, ce à quoi nous nous sommes intéressé. Nous avons observé que la co-administration d’un HDACi avec la 5-Aza-CdR potentialise son action anti-leucémique.
Il est aussi possible d’augmenter l’activité de la 5-Aza-CdR en inhibant sa dégradation par l’enzyme cytidine (CR) désaminase. Nous avons observé que la co-administration du zebularine, un inhibiteur de la CR désaminase, avec la 5-Aza-CdR accroît son efficacité. Le zebularine est aussi un inhibiteur de la méthylation de l’ADN, ce qui pourrait contribuer à la potentialisation de la réponse anti-leucémique observée lors de la co-administration de ces deux agents.
En résumé, il est possible d’augmenter l’efficacité anti-leucémique de la 5-Aza-CdR en : 1- intensifiant son protocole d’administration, en termes de doses et de durée, 2- la combinant avec un HDACi, et 3- diminuant sa dégradation par la CR désaminase. L’utilisation de ces résultats précliniques dans l’élaboration de protocoles cliniques pourrait être bénéfique à beaucoup de patients. / The silencing of tumor suppressor genes (TSG) that normally regulate cells proliferation plays an important role in leukemogenesis. Two major mechanisms are involved in TSG’s silencing: DNA methylation and histones deacetylation. Because those phenomenons are reversible, it makes them interesting therapeutic targets for chemotherapeutic agents. We evaluated the antineoplastic potential of different agents that target those events and we administered them alone or in combination with the goal of improving their efficiency.
5-aza-2’-deoxycytidine (5-Aza-CdR) is a DNA methylation inhibitor that can re-express TSGs that are silenced by methylations. This agent demonstrated its efficacy against hematological malignancies. Therefore, 5-Aza-CdR is used since 2006 in United States of America against myelodysplastic syndrome; but its optimal dose-schedule still needs to be established. Our researches suggest that the dose-schedule of 5-Aza-CdR should be more intensive than what is reported from the literature.
Inhibitors of histones deacetylation (HDACi) also demonstrated some interesting antineoplastic activity. Recently, observations showed that combination of chemotherapeutic agent that targets both DNA methylation and histones deacetylation lead to a synergic reactivation of silenced TSG. This finding allowed us to observe that the co-administration of an HDACi with 5-Aza-CdR improve its antileukemic potential.
Moreover, it is possible to increase the activity of 5-Aza-CdR by preventing its degradation by cytidine (CR) deaminase. We demonstrated that the co-administration of zebularine, an inhibitor of CR deaminase, with 5-Aza-CdR increases its activity. Zebularine is also an inhibitor of DNA methylation, which may contribute to the enhancement of the antileukemic action of this combination.
In summary, our preclinical data indicate that the antileukemic activity of 5-Aza-CdR can be enhanced by: 1- increasing his dosage, 2- combining it with HDACi, and 3- preventing its inactivation by CR deaminase. The translation of those preclinical observations into clinical protocols may be effective in patients with advanced leukemia.
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Action anti-leucémique des inhibiteurs de la méthylation de l’ADN et de la déacétylation des histonesLemaire, Maryse 04 1900 (has links)
Les gènes suppresseurs de tumeurs (TSGs) contrôlent la prolifération cellulaire et leur inactivation joue un rôle important dans la leucémogénèse. Deux mécanismes épigénétiques majeurs sont impliqués dans la répression des TSGs: 1- la méthylation de l’ADN et 2- la déacétylation des histones des chromosomes. On les dit épigénétiques car ils n’affectent pas la séquence de l’ADN. Ces phénomènes sont réversibles, faisant donc d’eux des cibles thérapeutiques de choix. Dans le cadre de cette thèse, nous avons évalué le potentiel chimiothérapeutique de différents agents qui visent ces mécanismes épigénétiques et nous les avons administrés seuls et en combinaison dans le but d’améliorer leur efficacité.
La 5-aza-2’-désoxycytidine (5-Aza-CdR) est un inhibiteur de la méthylation de l’ADN qui permet la ré-expression des TSGs. Cet agent s’est avéré efficace contre certaines maladies hématologiques et est d’ailleurs approuvé aux États-Unis dans le traitement du syndrome myélodysplasique depuis 2006. Cependant, le protocole d’administration optimal de cet agent, en termes de doses et de durée, n’est toujours pas établi. Nos recherches suggèrent que le celui-ci devrait être plus intensif que ce que rapporte la littérature.
Les inhibiteurs des déacétylases des histones (HDACi) ont également montré une activité antinéoplasique intéressante. De récentes recherches ont montré que la combinaison d’agents ciblant à la fois la méthylation de l’ADN et la déacétylation des histones produit une réactivation synergique des TSGs, ce à quoi nous nous sommes intéressé. Nous avons observé que la co-administration d’un HDACi avec la 5-Aza-CdR potentialise son action anti-leucémique.
Il est aussi possible d’augmenter l’activité de la 5-Aza-CdR en inhibant sa dégradation par l’enzyme cytidine (CR) désaminase. Nous avons observé que la co-administration du zebularine, un inhibiteur de la CR désaminase, avec la 5-Aza-CdR accroît son efficacité. Le zebularine est aussi un inhibiteur de la méthylation de l’ADN, ce qui pourrait contribuer à la potentialisation de la réponse anti-leucémique observée lors de la co-administration de ces deux agents.
En résumé, il est possible d’augmenter l’efficacité anti-leucémique de la 5-Aza-CdR en : 1- intensifiant son protocole d’administration, en termes de doses et de durée, 2- la combinant avec un HDACi, et 3- diminuant sa dégradation par la CR désaminase. L’utilisation de ces résultats précliniques dans l’élaboration de protocoles cliniques pourrait être bénéfique à beaucoup de patients. / The silencing of tumor suppressor genes (TSG) that normally regulate cells proliferation plays an important role in leukemogenesis. Two major mechanisms are involved in TSG’s silencing: DNA methylation and histones deacetylation. Because those phenomenons are reversible, it makes them interesting therapeutic targets for chemotherapeutic agents. We evaluated the antineoplastic potential of different agents that target those events and we administered them alone or in combination with the goal of improving their efficiency.
5-aza-2’-deoxycytidine (5-Aza-CdR) is a DNA methylation inhibitor that can re-express TSGs that are silenced by methylations. This agent demonstrated its efficacy against hematological malignancies. Therefore, 5-Aza-CdR is used since 2006 in United States of America against myelodysplastic syndrome; but its optimal dose-schedule still needs to be established. Our researches suggest that the dose-schedule of 5-Aza-CdR should be more intensive than what is reported from the literature.
Inhibitors of histones deacetylation (HDACi) also demonstrated some interesting antineoplastic activity. Recently, observations showed that combination of chemotherapeutic agent that targets both DNA methylation and histones deacetylation lead to a synergic reactivation of silenced TSG. This finding allowed us to observe that the co-administration of an HDACi with 5-Aza-CdR improve its antileukemic potential.
Moreover, it is possible to increase the activity of 5-Aza-CdR by preventing its degradation by cytidine (CR) deaminase. We demonstrated that the co-administration of zebularine, an inhibitor of CR deaminase, with 5-Aza-CdR increases its activity. Zebularine is also an inhibitor of DNA methylation, which may contribute to the enhancement of the antileukemic action of this combination.
In summary, our preclinical data indicate that the antileukemic activity of 5-Aza-CdR can be enhanced by: 1- increasing his dosage, 2- combining it with HDACi, and 3- preventing its inactivation by CR deaminase. The translation of those preclinical observations into clinical protocols may be effective in patients with advanced leukemia.
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Mécanismes de réparation de l'ADN et de maintien de la stabilité génomique lors de la diversification des immunoglobulines / DNA repair and maintenance of genome stability during immunoglobulin diversificationGaudot, Léa 25 November 2016 (has links)
L’enzyme Activation-induced cytidine deaminase (AID) initie la diversification des immunoglobulines (Ig) par l’induction de dommages à l’ADN. Alors que les lésions induites aux gènes des Ig sont cruciales pour l’établissement de réponses immunes hautement spécifiques et adaptées, ce même type de lésions provoquées ailleurs dans le génome contribue à la transformation cellulaire et à l’apparition de cancer. Les mécanismes impliqués dans la protection de l’intégrité génomique des cellules B restent à définir. D’une part, nous avons développé une approche de protéomique locus-unique en couplant une technique d’identification de protéine par biotinylation de proximité avec l’outil d’édition du génome CRISPR/Cas9. Cette technique innovante, dont nous avons fait la preuve de principe pour des loci abondants, pourra être utilisée pour identifier le protéome des différentes cibles génomiques d’AID. D’autre part, nous avons caractérisé le rôle de Parp3, Parp9 et Med1, identifiées comme partenaires d’AID, éclairant ainsi les mécanismes qui contrôlent l’activité d’AID et la réparation des lésions induites par AID lors de la diversification des Ig. / Activation-induced cytidine deaminase (AID) initiates immunoglobulin (Ig) diversification by inducing DNA damage. While on-target lesions are crucial for mounting highly specific and adaptive immune responses, off-target lesions contribute to malignant cell transformation. Despite its implications, the events following AID recruitment that enforce genome integrity in B cells remain poorly defined. It is not understood why multiple non-Ig loci bound by AID are not mutated or why AID-induced DNA lesions may lead to mutations or DNA breaks. To address this question, we developed a single-locus proteomic approach coupling proximity-dependent protein identification and genome editing (CRISPR/Cas9) to identify and compare the proteins recruited at individual genomic loci bound by AID. We performed the proof of principle of this innovative tool by identifying the proteome of abundant genomic loci. On the other hand, we functionally characterized Parp3, Parp9 and Med1, identified as AID partners, revealing novel mechanisms that tightly control AID activity and DNA repair during Ig diversification.
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The role of DNA repair in DNA methylation dynamicsGould, Poppy Aeron January 2018 (has links)
The mammalian epigenome is globally reprogrammed at two stages of development; this involves the erasure and re-establishment of DNA methylation by both passive and active mechanisms, including DNA repair pathways, and occurs concurrently with an increase in developmental potency. In addition to Uhrf1 and the Tet enzymes, the interplay between activation induced cytidine deaminase (AID) and the DNA repair machinery has been implicated in epigenetic reprogramming of various in vivo and in vitro systems including mouse primordial germ cells, zygotes and induced pluripotent stem cells. AID deaminates cytosine to uracil and can also deaminate methylcytosine, whereas the primary role of UNG is to maintain the integrity of the genome through erasure of uracil. In this thesis, I have aimed to investigate the role of DNA repair in demethylation. To do this I have focused on the specific role of AID and UNG in the demethylation of a static system – primed serum ESCs and a dynamic system – serum to 2i (naïve) to epiblast-like ES cells. As the role of both AID and UNG involves genomic uracil, the central theme of my thesis is the impact of accumulation of uracil on DNA methylation levels in the genome. Therefore, my first aim was to develop a quantitative method to detect low levels of genomic uracil in DNA firstly, by mass spectrometry and secondly, by whole genome sequencing. In Chapter Three, I show that the impact of deamination during DNA preparation can be minimised, such that the level of genomic ESC uracil can be accurately determined as around 12,000 uracil per genome and that, as anticipated, Ung null ESCs have almost twice the genomic uracil content of wildtype ESCs. Secondly, I address the main question which is the impact of uracil accumulation on methylation levels. In order to do this, I generate two cell lines: Ung knockout and Aid over expressing, both of which should result in an increase in genomic uracil. I demonstrate that while over expression of Aid stimulates demethylation in static system and in a dynamic demethylating system, the impact of Ung knockout is less clear. In (static) serum ESCs, loss of Ung results in hypomethylation however, in order to transition to 2i (naïve) ESCs, a process which involves demethylation of the genome, it appears the Ung is required as loss of this gene inhibits proper demethylation. As such, I conclude that UNG-mediated DNA repair functions alongside passive demethylation, by reduction of UHRF1 levels, to demethylate 2i ESCs. To probe the mechanism by which accumulation of uracil in the genome alters methylation levels, I investigate the impact of Ung KO and Aid OE on global levels of DNA damage. I show that both cell lines have a greater incidence of double strand breaks compared to a wild type cell line, and accordingly, upregulate their DNA damage response pathway and the expression of certain repair genes. I suggest that increasing genomic levels of uracil causes genomic instability and that DNA demethylation occurs as a consequence of the repair of extensive DNA damage. More broadly, I suggest that ESCs are uniquely poised, due to their heightened DNA damage response, to use uracil as an intermediate of DNA demethylation. Interestingly, I also note that the biological impact on serum ESCs of loss of Ung appears to be an increase in pluripotency.
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Transcriptional regulation of the zebrafish activation-induced cytidine deaminase (AID) genePila, Ea Unknown Date
No description available.
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Etude du système immunitaire d'un amphibien et analyse des effets de l'environnement sur sa réponse humorale / Analysis of the immune system of an amphibian and of the effects of the environment on its humoral responseBascove, Matthieu 17 December 2009 (has links)
During my PhD, I have participated to the characterization of Pleurodeles waltl (urodele amphibian) antibody heavy chains and to the discovery of a new isotype that we named IgP. I have also demonstrated that each antibody heavy chain has its human counterpart. P. waltl IgM are the counterpart of human IgM. IgY are expressed in mucosa and are therefore the physiological counterpart of human IgA. Finally, IgP are predominantly expressed in larvae and are less diverse than IgM. These two characteristics are shared with antibodies produced by mammalian B1 cells. These studies allowed me to approach the effects of a long term spaceflight on the humoral immune response, i.e. the antibody mediated response, which up to now has been poorly studied. The Development and Immunogenetics team, JE 2537, has immunized adult P. waltl during their five month stay onboard the Mir space station and showed that heavy chain variable domains of specific IgM are encoded by genes belonging to the VHII and VHVI families. However, these families are used in different proportions in animals immunized onboard Mir by comparison to animals immunized on Earth. To better understand this difference, I have determined how these animals use their individual VHII and VHVI genes. My work revealed that only one VHII gene and four VHVI genes (A, B, C and D) are used by immunized animals. I observed an increase in the expression of IgM heavy chain mRNAs encoded by the VHII, VHVI.C and VHVI.D genes and a strong decrease in the expression of IgM heavy chain mRNAs encoded by the VHVI.A and VHVI.B genes in spaceflight animals, demonstrating that this environment affects the humoral response. These observations may be due to a change in B-cell selection under spaceflight conditions. Furthermore, I described for the first time the effects of spaceflight on somatic hypermutations. I isolated and characterized the P. waltl mRNA coding for the main effector of these mutations: the activation-induced cytidine deaminase (AID). I demonstrated that this protein is present and conserved in P. waltl. Then, I described somatic hypermutations in P. waltl. I mapped somatic hypermutations, studied their distribution and calculated their frequency in animals immunized on Earth and in animals immunized onboard the Mir space station. This work revealed a strong depression of somatic hypermutations in animals immunized onboard Mir. This observation does not result from a change in AID transcription. We believe that this may be the consequence of a lower B lymphocyte survival under spaceflight conditions. / Durant ma thèse, j'ai participé à la caractérisation des isotypes de chaînes lourdes d'anticorps chez le pleurodèle (Pleurodeles waltl, amphibien urodèle) et à la mise en évidence d'un nouvel isotype d'anticorps : les IgP. J'ai également montré que chaque chaîne lourde a son équivalent humain. Les IgM du pleurodèle sont l'équivalent des IgM humaines. Les IgY sont exprimées principalement au niveau des muqueuses tout comme les IgA humaines. Enfin, les IgP sont observées majoritairement chez les larves et ont une diversité plus faible que les IgM. Ces deux caractéristiques sont partagées avec les anticorps produits par les cellules B1. Ces travaux m'ont ensuite permis d'aborder l'impact d'un séjour de longue durée dans l'espace sur la réponse immunitaire humorale, c'est-à-dire la réponse médiée par les anticorps qui, jusqu'à présent, a été très peu étudiée. L'équipe Développement et Immunogénétique, JE 2537, a immunisé des pleurodèles lors d'un séjour de 5 mois à bord de la station spatiale Mir et a montré que les chaînes lourdes d'IgM produites en réponse à la stimulation antigénique sont fabriquées à partir de gènes des familles VHII et VHVI. Cependant ces familles sont utilisées dans des proportions différentes chez les animaux immunisés dans Mir. Mes travaux ont permis d'approfondir ces résultats par une étude des gènes VHII et VHVI utilisés dans ces chaînes lourdes. J'ai ainsi montré qu'un seul gène VHII et quatre gènes VHVI (A, B, C et D) sont utilisés par les animaux immunisés. Les gènes VHII, VHVI.C et VHVI.D sont plus exprimés chez les animaux immunisés dans Mir alors que l'expression des gènes VHVI.A et VHVI.B est fortement diminuée chez ces mêmes animaux. Ces résultats démontrent clairement que le séjour dans Mir a affecté la réponse immunitaire humorale de ces animaux. Ces observations pourraient résulter d'un changement de la distribution et de sélection des lymphocytes B dans l'espace. Par ailleurs, j'ai décrit pour la première fois les effets d'un séjour dans l'espace sur les hypermutations somatiques. Avant d'étudier ce phénomène, j'ai isolé et caractérisé chez le pleurodèle l'ARNm codant l'effecteur indispensable pour ces mutations : la protéine AID (activation-induced cytidine deaminase). J'ai ainsi montré que cette protéine est bien présente et conservée dans cette espèce. J'ai ensuite mis en évidence et caractérisé pour la première fois le phénomène des hypermutations somatiques chez le pleurodèle. Pour cela, j'ai étudié les profils des mutations observées, cartographié ces dernières et calculé leur fréquence. Ces différents critères ont été comparés entre les animaux immunisés sur Terre et les animaux immunisés à bord de la station Mir. Ainsi, j'ai pu montrer que la fréquence des hypermutations somatiques est diminuée chez les pleurodèles immunisés dans Mir. Cette diminution n'est pas due à un changement de la transcription d'AID mais pourrait être due à une diminution de la survie des lymphocytes B dans l'espace.
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Structural Mechanism of Substrate Specificity In Human Cytidine Deaminase Family APOBEC3sHou, Shurong 28 April 2020 (has links)
APOBEC3s (A3s) are a family of human cytidine deaminases that play important roles in both innate immunity and cancer. A3s protect host cells against retroviruses and retrotransposons by deaminating cytosine to uracil on foreign pathogenic genomes. However, when mis-regulated, A3s can cause heterogeneities in host genome and thus promote cancer and the development of therapeutic resistance. The family consists of seven members with either one (A3A, A3C and A3H) or two zinc-binding domains (A3B, A3D, A3D and A3G). Despite overall similarity, A3 proteins have distinct deamination activity and substrate specificity. Over the past years, several crystal and NMR structures of apo A3s and DNA/RNA-bound A3s have been determined. These structures have suggested the importance of the loops around the active site for nucleotide specificity and binding. However, the structural mechanism underlying A3 activity and substrate specificity requires further examination.
Using a combination of computational molecular modeling and parallel molecular dynamics (pMD) simulations followed by experimental verifications, I investigated the roles of active site residues and surrounding loops in determining the substrate specificity and RNA versus DNA binding among A3s. Starting with A3B, I revealed the structural basis and gatekeeper residue for DNA binding. I also identified a unique auto-inhibited conformation in A3B that restricts access to the active site and may underlie lower catalytic activity compared to the highly similar A3A. Besides, I investigated the structural mechanism of substrate specificity and ssDNA binding conformation in A3s. I found an interdependence between substrate conformation and specificity. Specifically, the linear DNA conformation helps accommodate CC dinucleotide motif while the U-shaped conformation prefers TC. I also identified the molecular mechanisms of substrate sequence specificity at -1’ and -2’ positions. Characterization of substrate binding to A3A revealed that intra-DNA interactions may be responsible for the specificity in A3A. Finally, I investigated the structural mechanism for exclusion of RNA from A3G catalytic activity using similar methods.
Overall, the comprehensive analysis of A3s in this thesis shed light into the structural mechanism of substrate specificity and broaden the understanding of molecular interactions underlying the biological function of these enzymes. These results have implications for designing specific A3 inhibitors as well as base editing systems for gene therapy.
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Molekulární podstata etiologie toxického působení fluoropyrimidinů se zaměřením na palmární-plantární erythrodysesthesii a použití potenciálních antidot / Molecular basis of fluoropyrimidine toxic effect etiology with focus on palmar-plantar erythrodysesthesia and potential antidote useHartinger, Jan January 2017 (has links)
(thesis): Palmar-plantar erythrodysesthesia (PPE) frequently accompanies the therapy with a continuous 5-FU infusion or peroral capecitabine (5-FU prodrug). In the most severe cases this adverse effect leads to discontinuation of a needful therapy. Local 10 % uridine ointment is used to prevent and treat the said adverse event. Nevertheless, this method is not generally accepted as an effective one because it has never been proved in a randomized controlled clinical trial. Most probably, a direct effect of a cytostatic compound on the skin of hands and foots causes PPE. The toxicity of 5-FU is mediated primarily by its incorporation into RNA and by thymidylate synthase (TS) inhibition and subsequent DNA synthesis disruption. The importance of particular 5-FU toxicity mechanisms varies in different cell types. For choosing the best PPE local antidote it is necessary to find out which molecular mechanism applies in keratinocytes. We have chosen pyrimidine nucleosides as the most suitable compounds for the local PPE therapy because the uridine ointment is already being used in several oncology centers in the Central Europe. In order to find out the 5-FU toxicity mechanism, we further tested the effect of calciumfolinate (CF) which strengthens the TS inhibition by 5-FU. We studied also uracil and...
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Probing the Structural Topology of HIV-1 Virion Infectivity Factor (VIF): A DissertationAuclair, Jared R. 14 December 2007 (has links)
Human Immunodeficiency Virus Type 1 (HIV-1), the virus that causes Acquired Immunodeficiency Syndrome (AIDS), attacks the immune system leaving patients susceptible to opportunistic infections that eventually cause death. Highly Active Antiretroviral Therapy, HAART, is the current drug strategy used to combat HIV. It is a combination therapy that includes HIV-1 Reverse Transcriptase and HIV-1 Protease inhibitors. Drug resistant strains arise that evade current HAART treatments; therefore novel drugs are needed.
HIV-1 regulatory proteins such as Tat, Rev, Nef, Vpr, Vpu, and Vif are attractive new drug targets. Of particular interest is the HIV-1 Vif protein and its cellular binding partner APOBEC3G. In the absence of HIV-1 Vif, APOBEC3G, a cytidine deaminase, is able to mutate the viral cDNA and render the virus noninfectious. HIV-1 Vif binds to APOBEC3G and targets it for proteosomal degradation through an interaction with a Cullin-RING ligase complex. Blocking the HIV-1 Vif APOBEC3G interaction would allow APOBEC3G to perform its antiviral function.
An attractive strategy to target the HIV-1 Vif APOBEC3G interaction would be a structure-based one. To apply structure-based drug design approaches to HIV-1 Vif and APOBEC3G, I attempted to collect high resolution structural data on HIV-1 Vif and APOBEC3G. My attempts were unsuccessful because the milligram quantities of soluble protein required were not obtained.
Therefore, in Chapter III I used chemical cross-linking and mass spectrometry to probe the structural topology of HIV-1 Vif obtaining low resolution structural data. Chemical cross-linking formed HIV-1 Vif multimers including dimers, trimers, and tetramers. Analysis of the cross-linked monomer revealed that HIV-1 Vif’s N-terminal domain is a well-folded, compact, globular domain, where as the C-teriminal domain is predicted to be disordered. In addition, disorder prediction programs predicted the C-terminal domain of HIV-1 Vif to be disordered. Upon oligomerization the C-terminal domain undergoes a disorder-to-order transition that not only facilitates oligomerization but may facilitate other protein-protein interactions. In addition, HIV-1 Vif oligomerization bring Lys34 and Glu134 in close proximity to each other likely creating one molecular surface forming a “hot spot” of biological activity.
In Chapter IV I confirmed my low resolution structural data via peptide competition experiments where I identified peptides that can be used as scaffolds for future drug design. HIV-1 Vif oligomerization is concentration dependent. The HIV-1 Vif peptides Vif(29-43) and Vif(125-139) were able to disrupt HIV-1 Vif oligomerization, which confirms the low resolution structural data. HIV-1 Vif peptides Vif(25-39) and Vif(29-43) reduced the amount of APOBEC3G immobilized on the Protein A beads, reduced the amount of HIV-1 Vif interacting with APOBEC3G, or degraded APOBEC3G itself. These peptides could be used as scaffolds to design novel drugs that disrupt the function of HIV-1 Vif and or APOBEC3G.
Therefore, low resolution structural data and peptide competition experiments were successful in identifying structurally important domains in HIV-1 Vif. They also provided insight into a possible mechanism for HIV-1 Vif function where a disorder-to-order transition facilitates HIV-1 Vif’s ability to interact with a diverse set of macromolecules. These data advance our structural understanding of HIV-1 Vif and they will facilitate future highresolution studies and novel drug designs.
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Chronic Lung Injury by Constitutive Expression of Activation-Induced Cytidine Deaminase Leads to Focal Mucous Cell Metaplasia and Cancer / AIDの恒常的発現による慢性肺障害が引き起こす巣状粘液細胞化生と肺癌Kitamura, Jiro 25 May 2015 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第19177号 / 医博第4019号 / 新制||医||1010(附属図書館) / 32169 / 京都大学大学院医学研究科医学専攻 / (主査)教授 武藤 学, 教授 武田 俊一, 教授 小川 誠司 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM
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