mRNA Import into Yeast Nuclei is Controlled by Components of Cytoplasmic P-bodies

Persistent Link:
http://hdl.handle.net/10150/194343
Title:
mRNA Import into Yeast Nuclei is Controlled by Components of Cytoplasmic P-bodies
Author:
Pilkington, Guy Robert
Issue Date:
2008
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
In eukaryotes, the regulation of mRNA translation and decay provides a mechanism which can be finely tuned to control gene expression. This ability to control the life cycle of an mRNA begins with the control of mRNA export from the nucleus and extends to the processes which regulate the degradation of the message. In my work, summarized below, I describe how some of the proteins involved in cytoplasmic decay regulate many aspects of the control of mRNA and also describe a novel regulatory mechanism involving the relocation of cytoplasmic mRNA back into the nucleus of the cell.Firstly, I have identified that the protein Pat1, which has been shown to be critical for translational repression and activation of decapping, consists of essentially 3 major domains. By means of a deletional functional analysis, I show that two of these domains are the primary functional domains responsible for all of the currently ascribed function of Pat1. One domain promotes translational repression and P-body assembly, while the second domain promotes mRNA decapping after assembly of the mRNA into a P-body mRNP. Along with the first evidence that Pat1 binds to RNA, we also determine numerous domain-specific interactions with mRNA decapping factors.In eukaryotic cells mRNAs are produced in the nucleus followed by what is thought to be unidirectional export to the cytoplasm. In the cytosol, mRNAs either associate with ribosomes for translation or can be found in cytoplasmic RNP granules, termed P-bodies, when they are translationally repressed. I have now demonstrated that yeast mRNAs can be re-imported into the nucleus. Import of mRNAs into the nucleus is in competition with translation and increased in strains lacking specific components of cytoplasmic processing bodies, which also exhibit nuclear-cytoplasmic shuttling. This indicates that one function of cytoplasmic granules is to limit the import of cytoplasmic mRNAs back into the nucleus. These results demonstrate a novel pathway for mRNA import into the nucleus and suggest distinct pathways of mRNA export of nascent mRNAs and imported mRNAs.
Type:
text; Electronic Dissertation
Keywords:
mRNA; regulation; P-body; Pat1; nuclei; import
Degree Name:
PhD
Degree Level:
doctoral
Degree Program:
Molecular & Cellular Biology; Graduate College
Degree Grantor:
University of Arizona
Committee Chair:
Parker, Roy R.

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titlemRNA Import into Yeast Nuclei is Controlled by Components of Cytoplasmic P-bodiesen_US
dc.creatorPilkington, Guy Roberten_US
dc.contributor.authorPilkington, Guy Roberten_US
dc.date.issued2008en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractIn eukaryotes, the regulation of mRNA translation and decay provides a mechanism which can be finely tuned to control gene expression. This ability to control the life cycle of an mRNA begins with the control of mRNA export from the nucleus and extends to the processes which regulate the degradation of the message. In my work, summarized below, I describe how some of the proteins involved in cytoplasmic decay regulate many aspects of the control of mRNA and also describe a novel regulatory mechanism involving the relocation of cytoplasmic mRNA back into the nucleus of the cell.Firstly, I have identified that the protein Pat1, which has been shown to be critical for translational repression and activation of decapping, consists of essentially 3 major domains. By means of a deletional functional analysis, I show that two of these domains are the primary functional domains responsible for all of the currently ascribed function of Pat1. One domain promotes translational repression and P-body assembly, while the second domain promotes mRNA decapping after assembly of the mRNA into a P-body mRNP. Along with the first evidence that Pat1 binds to RNA, we also determine numerous domain-specific interactions with mRNA decapping factors.In eukaryotic cells mRNAs are produced in the nucleus followed by what is thought to be unidirectional export to the cytoplasm. In the cytosol, mRNAs either associate with ribosomes for translation or can be found in cytoplasmic RNP granules, termed P-bodies, when they are translationally repressed. I have now demonstrated that yeast mRNAs can be re-imported into the nucleus. Import of mRNAs into the nucleus is in competition with translation and increased in strains lacking specific components of cytoplasmic processing bodies, which also exhibit nuclear-cytoplasmic shuttling. This indicates that one function of cytoplasmic granules is to limit the import of cytoplasmic mRNAs back into the nucleus. These results demonstrate a novel pathway for mRNA import into the nucleus and suggest distinct pathways of mRNA export of nascent mRNAs and imported mRNAs.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectmRNAen_US
dc.subjectregulationen_US
dc.subjectP-bodyen_US
dc.subjectPat1en_US
dc.subjectnucleien_US
dc.subjectimporten_US
thesis.degree.namePhDen_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineMolecular & Cellular Biologyen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.chairParker, Roy R.en_US
dc.contributor.committeememberParker, Roy R.en_US
dc.contributor.committeememberWeinert, Teden_US
dc.contributor.committeememberBosco, Giovannien_US
dc.contributor.committeememberAhmad, Nafeesen_US
dc.identifier.proquest2681en_US
dc.identifier.oclc659749686en_US
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