A cyclase-associated protein regulates actin and cell polarity during Drosophila oogenesis and in yeast.
BACKGROUND
A polarised cytoskeleton is required to pattern cellular space, and for many aspects of cell behaviour. While the mechanisms ordering the actin cytoskeleton have been extensively studied in yeast, little is known about the analogous processes in other organisms. We have used Drosophila oogenesis as a model genetic system in which to investigate control of cytoskeletal organisation and cell polarity in multicellular eukaryotes.


RESULTS
In a screen to identify genes required for Drosophila oocyte polarity, we isolated a Drosophila homologue of the yeast cyclase-associated protein, CAP. Here we show that CAP preferentially accumulates in the oocyte, where it inhibits actin polymerisation. CAP also has a role in oocyte polarity, as cap mutants fail to establish the proper, asymmetric distribution of mRNA determinants within the oocyte. Similarly in yeast, loss of CAP causes analogous polarity defects, altering the distribution of actin filaments and mRNA determinants.


CONCLUSIONS
This study identifies CAP as a new effector of actin dynamics in Drosophila. As CAP controls the spatial distribution of actin filaments and mRNA determinants in both yeast and Drosophila, we conclude that CAP has an evolutionarily conserved function in the genesis of eukaryotic cell polarity.
Baum
B
B
Department of Genetics, Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts 02215, USA.
Li
W
W
Perrimon
N
N
D000199:Actins / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D016764:Cell Polarity / Q000502:physiology*; D003598:Cytoskeletal Proteins; D003599:Cytoskeleton / Q000378:metabolism; D004330:Drosophila / Q000235:genetics / Q000502:physiology*; D029721:Drosophila Proteins; D018507:Gene Expression Regulation, Developmental; D015966:Gene Expression Regulation, Fungal; D006801:Humans; D008840:Microfilament Proteins; D008969:Molecular Sequence Data; D009865:Oocytes / Q000502:physiology*; D009866:Oogenesis / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins
D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; C489549:CAP1 protein, human; C410502:Capt protein, Drosophila; D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; D029721:Drosophila Proteins; D008840:Microfilament Proteins; C073751:SRV2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins