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A Bioinformatics Pipeline for Investigating Molecular Evolution and Gene Expression using RNA-seq
Published on: May 28, 2021
Exportin-5 orthologues are functionally divergent among species
Satoshi Shibata1, Mitsuho Sasaki, Takashi Miki
1Department of Cell Biology and Neuroscience, Graduate School of Medicine, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
Nucleic Acids Research
|September 12, 2006
Summary
Exportin-5 proteins have diverse roles across species. Drosophila exportin-5 exports both microRNA precursors and tRNAs, unlike its human counterpart which only exports microRNA precursors.
Area of Science:
- Molecular Biology
- Genetics
- Cell Biology
Background:
- Exportin-5 is a key nuclear export factor for small noncoding RNAs, including microRNA precursors, in mammals.
- It belongs to the importin-beta protein family, crucial for nucleocytoplasmic transport.
Purpose of the Study:
- To investigate the functional divergence of exportin-5 orthologues across different species.
- To elucidate the specific roles of exportin-5 in RNA export in yeast, fruit flies, and humans.
Main Methods:
- Comparative analysis of exportin-5 orthologues from human, fruit fly (Drosophila), and yeast (S. cerevisiae).
- RNA binding assays to determine substrate specificity (double-stranded RNA, pre-miRNA, tRNA).
- Gene knockdown experiments in cultured cells to assess the in vivo function of exportin-5.
Main Results:
- Yeast exportin-5 (Msn5p) binds double-stranded RNAs, preferring shorter RNAs over pre-miRNAs.
- Drosophila exportin-5 binds pre-miRNAs and shows a high affinity for tRNAs.
- Knockdown of Drosophila exportin-5 reduced both tRNA and miRNA levels, while human exportin-5 knockdown affected only miRNA levels.
Conclusions:
- Double-stranded RNA binding is an conserved ancestral function of exportin-5 orthologues.
- Drosophila exportin-5 has a dual role in exporting both pre-miRNAs and tRNAs, compensating for the absence of exportin-t.
- Functional diversification of exportin-5 has occurred across species, leading to specialized roles in RNA export pathways.
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