The class I PITP giotto is required for Drosophila cytokinesis.
Phosphatidylinositol transfer proteins (PITPs) are highly conserved polypeptides that bind phosphatidylinositol or phosphatidylcholine monomers, facilitating their transfer from one membrane compartment to another . Although PITPs have been implicated in a variety of cellular functions, including lipid-mediated signaling and membrane trafficking, the precise biological roles of most PITPs remain to be elucidated . Here we show for the first time that a class I PITP is involved in cytokinesis. We found that giotto (gio), a Drosophila gene that encodes a class I PITP, serves an essential function required for both mitotic and meiotic cytokinesis. Neuroblasts and spermatocytes from gio mutants both assemble regular actomyosin rings. However, these rings fail to constrict to completion, leading to cytokinesis failures. Moreover, gio mutations cause an abnormal accumulation of Golgi-derived vesicles at the equator of spermatocyte telophases, suggesting that Gio is implicated in membrane-vesicle fusion. Consistent with these results, we found that Gio is enriched at the cleavage furrow, the ER, and the spindle envelope. We propose that Gio mediates transfer of lipid monomers from the ER to the equatorial membrane, causing a specific local enrichment in phosphatidylinositol. This change in membrane composition would ultimately facilitate vesicle fusion, allowing membrane addition to the furrow and/or targeted delivery of proteins required for cytokinesis.
Giansanti
Maria Grazia
MG
Dipartimento di Genetica e Biologia Molecolare, Istituto Pasteur-Fondazione Cenci Bolognetti, Istituto di Biologia e Patologia Molecolari del CNR, Università di Roma La Sapienza, P.le A. Moro 5, 00185 Roma, Italy.
Bonaccorsi
Silvia
S
Kurek
Roman
R
Farkas
Rebecca M
RM
Dimitri
Patrizio
P
Fuller
Margaret T
MT
Gatti
Maurizio
M
D000205:Actomyosin / Q000378:metabolism; D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D048749:Cytokinesis / Q000502:physiology*; D004330:Drosophila / Q000166:cytology* / Q000378:metabolism; D029721:Drosophila Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D005816:Genetic Complementation Test; D008297:Male; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D049294:Phospholipid Transfer Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D022142:Secretory Vesicles / Q000378:metabolism; D013090:Spermatocytes / Q000166:cytology / Q000378:metabolism
D029721:Drosophila Proteins; C502291:Lva protein, Drosophila; D008869:Microtubule-Associated Proteins; D049294:Phospholipid Transfer Proteins; C509515:Vib protein, Drosophila; D000205:Actomyosin