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Requirement of cyclin B2, but not cyclin B1, for bipolar spindle formation in frog ( Rana japonica ) oocytes
Author(s) -
Kotani Tomoya,
Yoshida Noriyuki,
Mita Koichi,
Yamashita Masakane
Publication year - 2001
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/mrd.1023
Subject(s) - cyclin b , biology , maturation promoting factor , cyclin a2 , microbiology and biotechnology , cyclin a , cyclin , cyclin b1 , germinal vesicle , metaphase , meiosis , cyclin d , oocyte , cell cycle , genetics , chromosome , embryo , cyclin dependent kinase 1 , cancer , gene
Cyclin B, the regulatory subunit of maturation‐promoting factor (MPF), comprises several subtypes that are presumed to confer different functions on MPF although no direct evidence has been provided to date. To clarify the difference in the roles of cyclins B1 and B2, we used frog ( Rana japonica ) oocytes in which MPF is formed only after progesterone stimulation because it is possible to produce oocytes containing either cyclin B1‐MPF or cyclin B2‐MPF by antisense RNA‐mediated translational inhibition of each mRNA. Using this advantage, we investigated the functions of cyclins B1 and B2 and obtained the following results: (a) oocytes synthesizing cyclin B2‐MPF underwent meiosis I and II with formation of a bipolar spindle at each metaphase; (b) oocytes synthesizing cyclin B1‐MPF formed a monopolar spindle at metaphase I and extruded an abnormal polar body; and (c) both oocytes underwent germinal vesicle breakdown (GVBD) and chromosome condensation. Immunocytochemical observations also revealed continuous localization of cyclin B2 on the spindle during meiosis. These results provide evidence of the requirement of cyclin B2, but not cyclin B1, for organizing the bipolar spindle, though either cyclin B1 or B2 is redundant for inducing GVBD and chromosome condensation. Mol. Reprod. Dev. 59:199–208, 2001. © 2001 Wiley‐Liss, Inc.