Differential cytoplasmic mRNA localisation adjusts pair-rule transcription factor activity to cytoarchitecture in dipteran evolution.
Establishment of segmental pattern in the Drosophila syncytial blastoderm embryo depends on pair-rule transcriptional regulators. mRNA transcripts of pair-rule genes localise to the apical cytoplasm of the blastoderm via a selective dynein-based transport system and signals within their 3'-untranslated regions. However, the functional and evolutionary significance of this process remains unknown. We have analysed subcellular localisation of mRNAs from multiple dipteran species both in situ and by injection into Drosophila embryos. We find that although localisation of wingless transcripts is conserved in Diptera, localisation of even-skipped and hairy pair-rule transcripts is evolutionarily labile and correlates with taxon-specific changes in positioning of nuclei. We show in Drosophila that localised pair-rule transcripts target their proteins in close proximity to the nuclei and increase the reliability of the segmentation process by augmenting gene activity. Our data suggest that mRNA localisation signals in pair-rule transcripts affect nuclear protein uptake and thereby adjust gene activity to a variety of dipteran blastoderm cytoarchitectures.
Cancer Research UK, Developmental Genetics Laboratory, PO Box 123, 44 Lincoln's Inn Fields, London WC2A 3PX, UK.
Simon L
SL
Bullock
Michael
M
Stauber
Alexander
A
Prell
Julian R
JR
Hughes
David
D
Ish-Horowicz
Urs
U
Schmidt-Ott
D020413:3' Untranslated Regions; D000818:Animals; D005075:Biological Evolution; D001756:Blastoderm / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D003593:Cytoplasm / Q000378:metabolism*; D004175:Diptera; D004330:Drosophila; D004625:Embryo, Nonmammalian / Q000378:metabolism*; D019143:Evolution, Molecular; D018507:Gene Expression Regulation, Developmental; D005838:Genotype; D017403:In Situ Hybridization; D010641:Phenotype; D010802:Phylogeny; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D013045:Species Specificity; D014158:Transcription, Genetic
D020413:3' Untranslated Regions; D012333:RNA, Messenger; D012313:RNA