The inhibition of polo kinase by matrimony maintains G2 arrest in the meiotic cell cycle.
Many meiotic systems in female animals include a lengthy arrest in G2 that separates the end of pachytene from nuclear envelope breakdown (NEB). However, the mechanisms by which a meiotic cell can arrest for long periods of time (decades in human females) have remained a mystery. The Drosophila Matrimony (Mtrm) protein is expressed from the end of pachytene until the completion of meiosis I. Loss-of-function mtrm mutants result in precocious NEB. Coimmunoprecipitation experiments reveal that Mtrm physically interacts with Polo kinase (Polo) in vivo, and multidimensional protein identification technology mass spectrometry analysis reveals that Mtrm binds to Polo with an approximate stoichiometry of 1:1. Mutation of a Polo-Box Domain (PBD) binding site in Mtrm ablates the function of Mtrm and the physical interaction of Mtrm with Polo. The meiotic defects observed in mtrm/+ heterozygotes are fully suppressed by reducing the dose of polo+, demonstrating that Mtrm acts as an inhibitor of Polo. Mtrm acts as a negative regulator of Polo during the later stages of G2 arrest. Indeed, both the repression of Polo expression until stage 11 and the inactivation of newly synthesized Polo by Mtrm until stage 13 play critical roles in maintaining and properly terminating G2 arrest. Our data suggest a model in which the eventual activation of Cdc25 by an excess of Polo at stage 13 triggers NEB and entry into prometaphase.
Xiang
Youbin
Y
Stowers Institute for Medical Research, Kansas City, Missouri, United States of America.
Takeo
Satomi
S
Florens
Laurence
L
Hughes
Stacie E
SE
Huo
Li-Jun
LJ
Gilliland
William D
WD
Swanson
Selene K
SK
Teeter
Kathy
K
Schwartz
Joel W
JW
Washburn
Michael P
MP
Jaspersen
Sue L
SL
Hawley
R Scott
RS
D000596:Amino Acids / Q000235:genetics / Q000378:metabolism; D000818:Animals; D030801:Animals, Genetically Modified; D001665:Binding Sites; D002503:Centromere / Q000235:genetics; D020090:Chromosome Segregation / Q000235:genetics; D015536:Down-Regulation; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000196:embryology / Q000235:genetics / Q000378:metabolism; D016195:G2 Phase; D018628:Gene Dosage / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D006579:Heterozygote; D008540:Meiosis; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D009685:Nuclear Envelope / Q000378:metabolism; D049471:Pachytene Stage; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D008941:Spindle Apparatus / Q000378:metabolism
D000596:Amino Acids; D029721:Drosophila Proteins; C072004:polo protein, Drosophila; D017346:Protein Serine-Threonine Kinases