Cytoplasmic dynein participates in meiotic checkpoint inactivation in mouse oocytes by transporting cytoplasmic mitotic arrest-deficient (Mad) proteins from kinetochores to spindle poles.
The present study was designed to investigate the localization and function of cytoplasmic dynein (dynein) during mouse oocyte meiosis and its relationship with two major spindle checkpoint proteins, mitotic arrest-deficient (Mad) 1 and Mad2. Oocytes at various stages during the first meiosis were fixed and immunostained for dynein, Mad1, Mad2, kinetochores, microtubules, and chromosomes. Some oocytes were treated with nocodazole before examination. Anti-dynein antibody was injected into the oocytes at germinal vesicle (GV) stage before the examination of its effects on meiotic progression or Mad1 and Mad2 localization. Results showed that dynein was present in the oocytes at various stages from GV to metaphase II and the locations of Mad1 and Mad2 were associated with dynein's movement. Both Mad1 and Mad2 had two existing states: one existed in the cytoplasm (cytoplasmic Mad1 or cytoplasmic Mad2), which did not bind to kinetochores, while the other bound to kinetochores (kinetochore Mad1 or kinetochore Mad2). The equilibrium between the two states varied during meiosis and/or in response to the changes of the connection between microtubules and kinetochores. Cytoplasmic Mad1 and Mad2 recruited to chromosomes when the connection between microtubules and chromosomes was destroyed. Inhibition of dynein interferes with cytoplasmic Mad1 and Mad2 transportation from chromosomes to spindle poles, thus inhibits checkpoint silence and delays anaphase onset. These results indicate that dynein may play a role in spindle checkpoint inactivation.
Zhang
Dong
D
State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, China.
Yin
Shen
S
Jiang
Man-Xi
MX
Ma
Wei
W
Hou
Yi
Y
Liang
Cheng-Guang
CG
Yu
Ling-Zhu
LZ
Wang
Wei-Hua
WH
Sun
Qing-Yuan
QY
D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D000963:Antimetabolites / Q000494:pharmacology; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000032:analysis / Q000378:metabolism; D001692:Biological Transport / Q000187:drug effects; D018797:Cell Cycle Proteins / Q000032:analysis / Q000378:metabolism*; D002478:Cells, Cultured; D004247:DNA / Q000032:analysis; D004398:Dyneins / Q000032:analysis / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005260:Female; D018386:Kinetochores / Q000737:chemistry*; D064246:Mad2 Proteins; D008540:Meiosis / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D018613:Microscopy, Confocal; D015739:Nocodazole / Q000494:pharmacology; D009865:Oocytes / Q000378:metabolism* / Q000648:ultrastructure; D012097:Repressor Proteins / Q000032:analysis / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D008941:Spindle Apparatus / Q000737:chemistry*
D000911:Antibodies, Monoclonal; D000963:Antimetabolites; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D018797:Cell Cycle Proteins; C499479:Mad protein, mouse; D064246:Mad2 Proteins; C577698:Mad2l1 protein, mouse; D012097:Repressor Proteins; D004247:DNA; D004398:Dyneins; D015739:Nocodazole