Regulation of mRNA decay by Pumilio in Drosophila melanogaster

During early embryogenesis in all animals, development is driven by maternally loaded mRNAs synthesized in the female parent during oogenesis. These maternally synthesized mRNAs are regulated by post-transcriptional mechanisms, including mRNA localization, degradation and translational activation and repression. Many of these processes rely on RNA-binding proteins to initially recognize and bind specific mRNAs and then, subsequently, recruit the appropriate post-transcriptional machinery. Eventually the products encoded by the zygotic genome regulate embryo development. My thesis focuses on an RNA-binding protein called Pumilio and its role in regulating the degradation of maternal mRNAs in Drosophila melanogaster embryos. Pumilio protein and pumilio mRNA are both maternally loaded and deficiencies in pumilio are maternal-effect lethal. While homologs of Pumilio had been implicated in mediating mRNA degradation, the global role of Pumilio itself had been unclear, with contradictory results from embryos and whole flies with a conditional pumilio mutant genotype. I first produced transgenic flies expressing a tandem affinity tagged Pumilio transgene. Then, by pulling down tagged Pumilio followed by next-generation sequencing of co-purifying RNAs, I found that the Pumilio protein associates with ~200 mRNAs in early embryos. Using a null pumilio allele combination, I found that Pumilio regulates the decay of a set of mRNAs in a manner that, in part, appears to be dependent on zygotically encoded factors. I observed that many of the mRNAs whose stability is affected in pumilio mutant embryos are amongst those physically associated with Pumilio protein in early embryos and validated my findings using reporter transgenes. My data show that Pumilio is a regulator of maternal transcript degradation in D. melanogaster.

Department dc:contributor.department

Molecular and Medical Genetics

Year dc:date.issued

2013

Author dc:creator

• Kekis, Mariana

Advisors dc:contributor.advisor

• Hughes, Timothy
• Lipshitz, Howard

• post-transcriptional regulation
• maternal mRNA decay

Statement dc:rights

• Attribution-ShareAlike 2.5 Canada

Licence dc:rights.uri

• http://creativecommons.org/licenses/by-sa/2.5/ca/

Language dc:language.iso

en_ca

Handle dc:identifier.uri

http://hdl.handle.net/1807/70091

OAI identifier oai:identifier

oai:utoronto.scholaris.ca:1807/70091