dc.contributor.advisor | Lührmann, Reinhard Prof. Dr. | de |
dc.contributor.author | Andrei, Maria Alexandra | de |
dc.date.accessioned | 2013-01-22T15:43:54Z | de |
dc.date.available | 2013-01-30T23:51:00Z | de |
dc.date.issued | 2008-04-23 | de |
dc.identifier.uri | http://hdl.handle.net/11858/00-1735-0000-000D-F14A-E | de |
dc.identifier.uri | http://dx.doi.org/10.53846/goediss-3440 | |
dc.format.mimetype | application/pdf | de |
dc.language.iso | eng | de |
dc.rights.uri | http://creativecommons.org/licenses/by-nc-nd/3.0/ | de |
dc.title | Characterization of cytoplasmic bodies involved in 5' to 3' mRNA degradation in human cells | de |
dc.type | doctoralThesis | de |
dc.title.translated | Charakterisierung von zytoplasmatischen Körper die an den 5' zu 3' mRNA Abbau in humanen Zellen beteiligt sind | de |
dc.contributor.referee | Einsle, Oliver J. P. Dr. | de |
dc.date.examination | 2007-05-04 | de |
dc.subject.dnb | 570 Biowissenschaften, Biologie | de |
dc.subject.gok | WF 000 | de |
dc.subject.gok | WF 200 | de |
dc.subject.gok | WH 000 | de |
dc.subject.gok | WHA 000 | de |
dc.subject.gok | WHC 000 | de |
dc.description.abstracteng | In the context of gene expression
regulation, discontinuing translation of mRNAs occurs by
evolutionarily conserved mechanisms whose executors have been
described to be associated with various types of cytoplasmic mRNA
granules. Processing (P) bodies are such granules where mRNA
co-localizes with effectors of the 5' to 3' mRNA degradation, RNA
interference and Nonsense Mediated Decay pathways.
In this manuscript we demonstrate that the m7G cap-binding protein
eIF4E and one of its interaction partners, eIF4E-Transporter, are
also components of mammalian P bodies. We further show, by FRET,
that they form a molecular complex with each other in P bodies in
vivo. Additionally, eIF4E interacts with the translational
repressor rck/p54. In contrast, other translation initiation
factors such as eIF4G or components of the translation machinery
were not detected in these cytoplasmic foci, ruling out the
possibility that P bodies are sites where active translation can
occur. It was possible to show that eIF4E requires that it is bound
to the m7G cap of the mRNA and interact with eIF4E-T in order to be
targeted to the P bodies. Altogether, eIF4E-T prevents the
formation of a translationally active mRNP by interacting with
eIF4E and thus plays a role in remodeling events that render mRNAs
available for degradation. No particular sequence within eIF4E-T
was found sufficient for its localization to the P bodies, but only
the full-length eIF4E-T molecule could assemble inside these
bodies. Using RNAi-mediated knockdowns we observed that a subset of
P body factors, including eIF4E-T, LSm1, rck/p54, and Ccr4 are
required for the accumulation of each other and of eIF4E in P
bodies. Furthermore, cycloheximide treatment of cells lead to
disassembly of the entire structure, indicating that the
accumulation of LSm1, eIF4E, eIF4E-T, and rck/p54 in P bodies also
requires that an mRNA flux be available. These results suggest that
these factors are targeted to P bodies as part of a larger mRNP
complex and that they are essential for P body formation and
function in mRNA processing. A block in the decay of the mRNA body
upon depletion of the decapping enzyme Dcp2 or the exoribonuclease
Xrn1, leads to an increase in the size and number of P bodies. A
distinct hierarchy of remodeling steps and sequence of events can
be inferred towards formation of the P bodies whereas early acting
factors are represented by the deadenylase Ccr4, LSm1, eIF4E-T and
rck/p54 and late joining factors include Dcp2 and Xrn1.
Mass spectrometric analyses helped to identify a novel RNA-binding
protein residing in the P bodies, which has preference for
Cytosine-rich elements and hints to a mechanism implying
sequence-specific silencing of mRNAs inside the P bodies. | de |
dc.contributor.coReferee | Doenecke, Detlef Prof. Dr. | de |
dc.contributor.thirdReferee | Kessel, Michael Prof. Dr. | de |
dc.subject.topic | Mathematics and Natural Science | de |
dc.subject.ger | Processing bodies | de |
dc.subject.ger | eIF4E | de |
dc.subject.ger | eIF4E-T | de |
dc.subject.ger | PCBP1 | de |
dc.subject.ger | mRNA Abbau | de |
dc.subject.ger | RNAi | de |
dc.subject.eng | Processing bodies | de |
dc.subject.eng | eIF4E | de |
dc.subject.eng | eIF4E-T | de |
dc.subject.eng | PCBP1 | de |
dc.subject.eng | mRNA degradation | de |
dc.subject.eng | RNAi | de |
dc.subject.bk | 42.13 | de |
dc.subject.bk | 42.15 | de |
dc.subject.bk | 42.03 | de |
dc.subject.bk | 35.70 | de |
dc.identifier.urn | urn:nbn:de:gbv:7-webdoc-1765-8 | de |
dc.identifier.purl | webdoc-1765 | de |
dc.identifier.ppn | 588951587 | de |