Drosha protein levels are translationally regulated during Xenopus oocyte maturation.
MicroRNAs (miRNAs) are ∼21-nucleotide-long, single-stranded noncoding RNAs that regulate gene expression. Biogenesis of miRNAs is mediated by the two RNase III-like enzymes, Drosha and Dicer. Here we study miRNA biogenesis during maturation of Xenopus oocytes to eggs using microinjection of pri-miRNAs. We show that processing of exogenous and endogenous primary miRNAs (pri-miRNAs) is strongly enhanced upon maturation of oocytes to eggs. Overexpression of cloned Xenopus Drosha in oocytes, however, boosts pri-miRNA processing dramatically, indicating that Drosha is a rate-limiting factor in Xenopus oocytes. This developmental regulation of Drosha is controlled by poly(A) length addition to the Drosha mRNA, which boosts translation upon transition from oocytes to eggs. Processing of pri-miRNAs by Drosha and Dicer has been shown to be affected by adenosine-to-inosine deamination-type RNA editing. Using activated Xenopus eggs for microinjection experiments, we demonstrate that RNA editing can reduce pri-miRNA processing in vivo. This processing block is determined by the structural but not sequence changes introduced by RNA editing.
Department of Chromosome Biology, Max F. Perutz Laboratories, University of Vienna, A-1030 Vienna, Austria.
Dominik
D
Muggenhumer
Department of Chromosome Biology, Max F. Perutz Laboratories, University of Vienna, A-1030 Vienna, Austria.
Cornelia
C
Vesely
Department of Chromosome Biology, Max F. Perutz Laboratories, University of Vienna, A-1030 Vienna, Austria.
Simon
S
Nimpf
Institute of Biochemistry, College of Life Sciences, Zhejiang University (Zijingang Campus), Hangzhou, Zhejiang ZJ310058, China.
Nan
N
Tian
Institute of Biochemistry, College of Life Sciences, Zhejiang University (Zijingang Campus), Hangzhou, Zhejiang ZJ310058, China.
Jin
J
Yongfeng
Department of Chromosome Biology, Max F. Perutz Laboratories, University of Vienna, A-1030 Vienna, Austria Michael.Jantsch@univie.ac.at.
Michael F
MF
Jantsch
D000818:Animals; D001483:Base Sequence; D002467:Cell Nucleus / Q000201:enzymology; D002478:Cells, Cultured; D015971:Gene Expression Regulation, Enzymologic; D035683:MicroRNAs / Q000378:metabolism; D008969:Molecular Sequence Data; D009865:Oocytes / Q000201:enzymology* / Q000502:physiology; D014176:Protein Biosynthesis; D059367:RNA Cleavage; D017393:RNA Editing; D043244:Ribonuclease III / Q000235:genetics / Q000378:metabolism*; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis
D035683:MicroRNAs; D029867:Xenopus Proteins; D043244:Ribonuclease III; C000595355:drosha protein, Xenopus