Mars promotes dTACC dephosphorylation on mitotic spindles to ensure spindle stability.
Microtubule-associated proteins (MAPs) ensure the fidelity of chromosome segregation by controlling microtubule (MT) dynamics and mitotic spindle stability. However, many aspects of MAP function and regulation are poorly understood in a developmental context. We show that mars, which encodes a Drosophila melanogaster member of the hepatoma up-regulated protein family of MAPs, is essential for MT stabilization during early embryogenesis. As well as associating with spindle MTs in vivo, Mars binds directly to protein phosphatase 1 (PP1) and coimmunoprecipitates from embryo extracts with minispindles and Drosophila transforming acidic coiled-coil (dTACC), two MAPs that function as spindle assembly factors. Disruption of binding to PP1 or loss of mars function results in elevated levels of phosphorylated dTACC on spindles. A nonphosphorylatable form of dTACC is capable of rescuing the lethality of mars mutants. We propose that Mars mediates spatially controlled dephosphorylation of dTACC, which is critical for spindle stabilization.
Tan
Shengjiang
S
Department of Zoology, Oxford University, Oxford OX1 3PS, England, UK.
Lyulcheva
Ekaterina
E
Dean
Jon
J
Bennett
Daimark
D
D000818:Animals; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000166:cytology / Q000378:metabolism*; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D054645:Protein Phosphatase 1 / Q000378:metabolism; D021381:Protein Transport; D000074407:SAP90-PSD95 Associated Proteins; D008941:Spindle Apparatus / Q000378:metabolism*
D029721:Drosophila Proteins; C000614192:Mars protein, Drosophila; D008869:Microtubule-Associated Proteins; D009419:Nerve Tissue Proteins; D000074407:SAP90-PSD95 Associated Proteins; C404402:TACC protein, Drosophila; D054645:Protein Phosphatase 1