| Citation |
Till, D.D., Linz, B., Seago, J.E., Elgar, S.J., Marujo, P.E., de L. Elias, M., Arraiano, C.M., McClellan, J.A., McCarthy, J.E.G., Newbury, S.F. (1998). Identification and developmental expression of a 5'-3' exoribonuclease from Drosophila melanogaster. Mech. Dev. 79(1,2): 51--55.
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| PubMed Abstract |
In multicellular organisms, very little is known about the role of mRNA stability in development, and few proteins involved
in degradation pathways have been characterized. We have identified the Drosophila homologue of XRN1, which is the major cytoplasmic
5'-3' exoribonuclease in Saccharomyces cerevisiae. The protein sequence of this homologue (pacman) has 59% identity to S.
cerevisiae XRN1 and 67% identity to the mouse homologue (mXRN1p) in certain regions. Sequencing of this cDNA revealed that
it includes a trinucleotide repeat (CAG)9 which encodes polyglutamine. By directly measuring pacman exoribonuclease activity
in yeast, we demonstrate that pacman can complement the yeast XRN1 mutation. Northern blots show a single transcript of approximately
5.2 kb which is abundant only in 0-8-h embryos and in adult males and females. In situ hybridization analysis revealed that
the pcm transcripts are maternally derived, and are expressed at high levels in nurse cells. During early embryonic syncytial
nuclear divisions, pcm transcripts are homogenously distributed. pcm mRNA is expressed abundantly and ubiquitously throughout
the embryo during gastrulation, with high levels in the germ band and head structures. After germ band retraction, pcm transcripts
are present at much lower levels, in agreement with the Northern results. Our experiments provide the first example of an
exoribonuclease which is differentially expressed throughout development.
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