Merlin, the Drosophila homologue of neurofibromatosis-2, is specifically required in posterior follicle cells for axis formation in the oocyte.
In Drosophila, the formation of the embryonic axes is initiated by Gurken, a transforming growth factor alpha signal from the oocyte to the posterior follicle cells, and an unknown polarising signal back to the oocyte. We report that Drosophila Merlin is specifically required only within the posterior follicle cells to initiate axis formation. Merlin mutants show defects in nuclear migration and mRNA localisation in the oocyte. Merlin is not required to specify posterior follicle cell identity in response to the Gurken signal from the oocyte, but is required for the unknown polarising signal back to the oocyte. Merlin is also required non-autonomously, only in follicle cells that have received the Gurken signal, to maintain cell polarity and limit proliferation, but is not required in embryos and larvae. These results are consistent with the fact that human Merlin is encoded by the gene for the tumour suppressor neurofibromatosis-2 and is a member of the Ezrin-Radixin-Moesin family of proteins that link actin to transmembrane proteins. We propose that Merlin acts in response to the Gurken signal by apically targeting the signal that initiates axis specification in the oocyte.
MacDougall
N
N
Wellcome Centre for Cell Biology, ICMB, King's Buildings, University of Edinburgh, Edinburgh EH9 3JR, UK.
Lad
Y
Y
Wilkie
G S
GS
Francis-Lang
H
H
Sullivan
W
W
Davis
I
I
D000199:Actins / Q000378:metabolism; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D016764:Cell Polarity; D048429:Cell Size; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000196:embryology / Q000235:genetics* / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000502:physiology*; D047108:Embryonic Development; D005260:Female; D016515:Genes, Neurofibromatosis 2; D006801:Humans; D017403:In Situ Hybridization; D019476:Insect Proteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008856:Microscopy, Fluorescence; D008870:Microtubules / Q000378:metabolism; D025581:Neurofibromin 2; D009865:Oocytes / Q000254:growth & development / Q000502:physiology*; D010053:Ovary / Q000166:cytology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051880:Receptors, Notch; D011993:Recombinant Fusion Proteins; D015398:Signal Transduction / Q000502:physiology; D013049:Spectrin / Q000378:metabolism; D013696:Temperature; D016211:Transforming Growth Factor alpha; D015291:Transforming Growth Factors / Q000378:metabolism*
D000199:Actins; D029721:Drosophila Proteins; D019476:Insect Proteins; D008565:Membrane Proteins; C497759:N protein, Drosophila; D025581:Neurofibromin 2; D012333:RNA, Messenger; D051880:Receptors, Notch; D011993:Recombinant Fusion Proteins; D016211:Transforming Growth Factor alpha; C083730:grk protein, Drosophila; C099885:merlin, Drosophila; D013049:Spectrin; D015291:Transforming Growth Factors