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A Human MicroRNA, miR-122, Promotes Hepatitis C Virus RNA Accumulation through Three Distinct Mechanisms.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	A Human MicroRNA, miR-122, Promotes Hepatitis C Virus RNA Accumulation through Three Distinct Mechanisms./
作者:	Chahal, Jasmin.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2019,
面頁冊數:	183 p.
附註:	Source: Dissertations Abstracts International, Volume: 82-10, Section: B.
Contained By:	Dissertations Abstracts International82-10B.
標題:	MicroRNAs. -
電子資源:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28266881
ISBN:	9798708712264

A Human MicroRNA, miR-122, Promotes Hepatitis C Virus RNA Accumulation through Three Distinct Mechanisms.
Chahal, Jasmin.

A Human MicroRNA, miR-122, Promotes Hepatitis C Virus RNA Accumulation through Three Distinct Mechanisms. - Ann Arbor : ProQuest Dissertations & Theses, 2019 - 183 p.

Source: Dissertations Abstracts International, Volume: 82-10, Section: B.

Thesis (Ph.D.)--McGill University (Canada), 2019.

This item must not be sold to any third party vendors.

Hepatitis C virus (HCV) is a positive-sense single-stranded RNA virus. The 5' untranslated region (UTR) of the HCV genome interacts with a liver-specific microRNA, called miR-122. miR-122 binds to two sites (Site 1 and Site 2) on the 5' UTR of the viral genome and promotes HCV RNA accumulation, although the precise role(s) of miR-122 in the HCV life cycle have remained unclear until recently. Previous studies suggested two main mechanisms of miR-122-mediated viral RNA accumulation: 1) protection from pyrophosphatase and subsequent exoribonuclease activity; and 2) suppression of an alternative secondary structure and promotion of the HCV internal ribosomal entry site (IRES) formation.Herein, we hypothesized that miR-122 binding to HCV genome alters the structure of 5' UTR in a manner that promotes HCV RNA accumulation. Using biophysical analyses and Selective 2' Hydroxyl Acylation analyzed by Primer Extension (SHAPE), we provided a new model of Ago:miR-122 interactions with the HCV genome that suggests that miR-122 plays three roles in the HCV life cycle. Firstly, Ago:miR-122 binds to Site 2 of HCV RNA, suppressing a more energetically favorable secondary structure, termed SLIIalt and promoting formation of the functional SLII structure which makes up part of the viral IRES (SLII-IV). Secondly, another Ago:miR-122 complex is recruited to Site 1, protecting the 5' terminus of the viral genome from cellular pyrophosphatase activity and subsequent exoribonuclease-mediated decay. Finally, in order to accommodate both Ago:miR-122 complexes in such close proximity, the Ago:miR-122 complex at Site 2 weakens its auxiliary base-pairing interactions, but is further stabilized by interacting with SLIIa of the HCV IRES, stabilizing the canonical SLII structure and promoting viral translation.Recent clinical trials using miR-122 inhibitors to treat chronic HCV-infected patients revealed the selection of several resistance associated variants (RAVs) in the 5' terminus of the HCV genome. We hypothesized that these RAVs result in changes to the secondary structure of the HCV genome that promote viral RNA accumulation, even in the absence of miR-122. We demonstrated that the RAVs could be classified into three main classes, with distinct mechanisms of action, all based on changes to the structure of the viral RNA. Specifically, Class I RAVs, including C2GC3U, U4C and G28A are 'riboswitched' and are able to form the functional SLII structure, even in the absence of miR-122. Class II RAVs, including C2GC3U, C3U and U4C result in additional base-pairing interactions at the 5' terminus of the HCV RNA that provide genome stability, independently of miR-122. Finally, the Class III RAV, C37U, alters the structure of the 3' terminus of the negative-strand intermediate, which is predicted to alter positive-strand RNA synthesis, as this region of the genome contains the positive-strand promoter.This research has uncovered the mechanism(s) of action of miR-122 in the HCV life cycle and revealed new paradigms for miRNA function. Moreover, it has revealed three distinct mechanisms of antiviral resistance all based on modifications in RNA structure. We anticipate that this research may be applicable to other important human or veterinary pathogens and will be relevant in the design, development, and evaluation of resistance to miRNA-based therapies more broadly.

ISBN: 9798708712264Subjects--Topical Terms:

2147037
MicroRNAs.
Subjects--Index Terms:

Human microRNA

A Human MicroRNA, miR-122, Promotes Hepatitis C Virus RNA Accumulation through Three Distinct Mechanisms.
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100 1 $a Chahal, Jasmin. $3 3562786
245 1 0 $a A Human MicroRNA, miR-122, Promotes Hepatitis C Virus RNA Accumulation through Three Distinct Mechanisms.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2019
300 $a 183 p.
500 $a Source: Dissertations Abstracts International, Volume: 82-10, Section: B.
500 $a Advisor: Sagan, Selena.
502 $a Thesis (Ph.D.)--McGill University (Canada), 2019.
506 $a This item must not be sold to any third party vendors.
520 $a Hepatitis C virus (HCV) is a positive-sense single-stranded RNA virus. The 5' untranslated region (UTR) of the HCV genome interacts with a liver-specific microRNA, called miR-122. miR-122 binds to two sites (Site 1 and Site 2) on the 5' UTR of the viral genome and promotes HCV RNA accumulation, although the precise role(s) of miR-122 in the HCV life cycle have remained unclear until recently. Previous studies suggested two main mechanisms of miR-122-mediated viral RNA accumulation: 1) protection from pyrophosphatase and subsequent exoribonuclease activity; and 2) suppression of an alternative secondary structure and promotion of the HCV internal ribosomal entry site (IRES) formation.Herein, we hypothesized that miR-122 binding to HCV genome alters the structure of 5' UTR in a manner that promotes HCV RNA accumulation. Using biophysical analyses and Selective 2' Hydroxyl Acylation analyzed by Primer Extension (SHAPE), we provided a new model of Ago:miR-122 interactions with the HCV genome that suggests that miR-122 plays three roles in the HCV life cycle. Firstly, Ago:miR-122 binds to Site 2 of HCV RNA, suppressing a more energetically favorable secondary structure, termed SLIIalt and promoting formation of the functional SLII structure which makes up part of the viral IRES (SLII-IV). Secondly, another Ago:miR-122 complex is recruited to Site 1, protecting the 5' terminus of the viral genome from cellular pyrophosphatase activity and subsequent exoribonuclease-mediated decay. Finally, in order to accommodate both Ago:miR-122 complexes in such close proximity, the Ago:miR-122 complex at Site 2 weakens its auxiliary base-pairing interactions, but is further stabilized by interacting with SLIIa of the HCV IRES, stabilizing the canonical SLII structure and promoting viral translation.Recent clinical trials using miR-122 inhibitors to treat chronic HCV-infected patients revealed the selection of several resistance associated variants (RAVs) in the 5' terminus of the HCV genome. We hypothesized that these RAVs result in changes to the secondary structure of the HCV genome that promote viral RNA accumulation, even in the absence of miR-122. We demonstrated that the RAVs could be classified into three main classes, with distinct mechanisms of action, all based on changes to the structure of the viral RNA. Specifically, Class I RAVs, including C2GC3U, U4C and G28A are 'riboswitched' and are able to form the functional SLII structure, even in the absence of miR-122. Class II RAVs, including C2GC3U, C3U and U4C result in additional base-pairing interactions at the 5' terminus of the HCV RNA that provide genome stability, independently of miR-122. Finally, the Class III RAV, C37U, alters the structure of the 3' terminus of the negative-strand intermediate, which is predicted to alter positive-strand RNA synthesis, as this region of the genome contains the positive-strand promoter.This research has uncovered the mechanism(s) of action of miR-122 in the HCV life cycle and revealed new paradigms for miRNA function. Moreover, it has revealed three distinct mechanisms of antiviral resistance all based on modifications in RNA structure. We anticipate that this research may be applicable to other important human or veterinary pathogens and will be relevant in the design, development, and evaluation of resistance to miRNA-based therapies more broadly.
520 $a Le virus de l'hepatite C (VHC) est un virus a ARN simple brin a polarite positive (sens). L'extremite 5' non-codante (UTR) du genome du VHC interagit avec un microARN specifique du foie, appele miR-122. Le miR-122 se lie a deux sites (Site 1 et Site 2) sur la region 5' UTR du genome viral et favorise l'accumulation de l'ARN du VHC. Cependant, le(s) role(s) precis du miR-122 dans le cycle de vie du VHC sont demeures mal definis jusqu'a recemment. Des etudes ont suggere deux mecanismes principaux pour l'accumulation de l'ARN viral mediee par le miR-122: 1) la protection contre les pyrophosphatases et une activite exonuclease subsequente; et 2) la suppression d'une structure ARN secondaire alternative et la promotion de la formation du site d'entree interne des ribosomes (IRES) du VHC.Ici, nous avons emis l'hypothese que la liaison du miR-122 au genome du VHC modifie la structure de la region 5' UTR d'une maniere qui favorise l'accumulation de l'ARN du VHC. A l'aide d'analyses biophysiques et de la technique d'acylation selective d'hydroxyle en 2' analysees par extension d'amorce (SHAPE), nous avons propose un nouveau modele d'interactions Ago:miR-122 avec le genome du VHC qui suggere que le miR-122 joue trois roles dans le cycle de vie du VHC. Premierement, Ago:miR-122 se lie au site 2 de l'ARN du VHC, supprimant une structure secondaire plus favorable sur le plan energetique, appelee SLIIalt et favorisant la formation de la structure fonctionnelle SLII qui fait partie de l'IRES viral (SLII-IV). Deuxiemement, un autre complexe Ago:miR-122 est recrute sur le site 1, protegeant l'extremite 5' du genome viral contre l'activite de la pyrophosphatase cellulaire et la degradation subsequente induite par les exoribonucleases. Enfin, afin d'accueillir les deux complexes Ago:miR-122 a une telle proximite, le complexe Ago:miR-122 du site 2 affaiblit ses interactions auxiliaires de couplage de bases, mais est encore stabilise en interagissant avec la SLIIa de l'IRES, ce qui stabilise la structure canonique SLII et favorise la traduction du genome viral.Des essais cliniques recents utilisant des inhibiteurs de miR-122 pour traiter des patients chroniquement infectes par le VHC ont revele la selection de plusieurs variants associees a la resistance (RAV) a l'extremite 5' du genome du VHC. Nous avons emis l'hypothese que ces RAV entrainent des changements dans la structure secondaire du genome du VHC qui favorisent l'accumulation d'ARN viral, meme en l'absence de miR-122. Nous avons demontre que les RAV pouvaient etre classes en trois classes principales, avec des mecanismes d'action distincts, tous bases sur des changements dans la structure de l'ARN viral. Plus precisement, les RAV de classe I, y compris les C2GC3U, U4C et G28A, sont « riboswitched » et sont capables de former la structure SLII fonctionnelle, meme en l'absence de miR-122. Les RAV de classe II, y compris C2GC3U, C3U et U4C, entrainent des interactions d'appariement de bases supplementaires a l'extremite 5' de l'ARN du VHC qui assurent la stabilite du genome, meme en l'absence de miR-122. Enfin, le RAV de classe III, C37U, modifie la structure de l'extremite 3' de l'intermediaire a polarite negative (antisens), qui devrait modifier la synthese d'ARN a polarite positive, car cette region du genome contient le promoteur a brin positif.Cette etude a demontre des mecanismes d'action du miR-122 dans le cycle de vie du VHC et a revele de nouveaux paradigmes pour la fonction des microARNs. De plus, nous avons identifie trois mecanismes distincts de resistance antivirale, tous bases sur des modifications de la structure de l'ARN. Nous prevoyons que cette recherche peut etre applicable a d'autres pathogenes humains ou animaux importants et sera pertinente dans la conception, le developpement et l'evaluation de la resistance aux therapies a base de microARN.
590 $a School code: 0781.
650 4 $a MicroRNAs. $3 2147037
650 4 $a Viruses. $3 571474
650 4 $a Genomes. $3 592593
650 4 $a Hepatitis C. $3 834557
650 4 $a Biosynthesis. $3 516407
650 4 $a Copyright clearance. $3 3562787
653 $a Human microRNA
653 $a miR-122
653 $a Hepatitis C virus RNA accumulation
690 $a 0982
690 $a 0410
710 2 $a McGill University (Canada). $3 1018122
773 0 $t Dissertations Abstracts International $g 82-10B.
790 $a 0781
791 $a Ph.D.
792 $a 2019
793 $a English
856 4 0 $u https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28266881