Requirement of cyclin B2, but not cyclin B1, for bipolar spindle formation in frog (<i>Rana japonica</i>) oocytes

Kotani, Tomoya; Yoshida, Noriyuki; Mita, Koichi; Yamashita, Masakane

doi:10.1002/mrd.1023

Cited by 29 publications

(22 citation statements)

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“…Nevertheless, in vertebrate cells, cyclins B1 and B2, which both associate with cdc2/ CDK1, and whose levels rise during G2 and peak in mitosis, have probably distinct roles: in interphase, cyclin B1 is localized mostly to microtubules whereas cyclin B2 is found in the Golgi apparatus (Jackman et al, 1995); cyclin B1/CDK1 complex controls chromosome condensation, reorganization of microtubules, destruction of the nuclear membrane, Golgi apparatus fragmentation whereas cyclin B2/CDK1 seems to be only involved in the disassembly of the Golgi apparatus (Draviam et al, 2001); cyclin B1 degradation precedes that of cyclin B2 during metaphase/anaphase transition (Minshull et al, 1990;Ohsumi et al, 1994;Brandeis et al, 1998); in contrast to cyclin B1, cyclin B2 does not translocate from the cytoplasm to the nucleus at the beginning of prophase (Jackman et al, 1995); cyclin B1 is an essential gene since its deletion in mice results in embryonic lethality whereas cyclin B2 7/7 mice develop normally (Brandeis et al, 1998). Cyclin B2, but not cyclin B1, was recently shown to be essential for a proper bipolar spindle formation in frog (Kotani et al, 2001), which is reminiscent of the biological role of Clb5 in yeast (Segal et al, 1998). The present study shows that overexpression of human cyclin B2, like overexpression of Clb5, alters the spindle checkpoint and chromosome segregation.…”

Section: Discussionmentioning

confidence: 99%

Overexpression of B-type cyclins alters chromosomal segregation

et al. 2002

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To identify genes which overexpression results into chromosomal instability (CIN), we developed a biological approach based on a yeast indicator strain in which CIN can be detected by a sectoring phenotype. Screening in this strain of a yeast genomic library cloned into a high copy vector led us to identify, among the clones generating 100% of sectoring colonies, Clb5, one of the six B-type cyclins present in yeast. Overexpression of cyclin B2 and cyclin B1, the two human homologs of Clb5, in the CIN indicator strain resulted also into a sectoring phenotype and induced, like overexpression of Clb5, an abnormal sensitivity to benomyl, indicating that overexpression of B-type cyclins alters the spindle checkpoint. In a series of 38 primary colorectal cancers, we detected in ®ve tumors (13%) an accumulation of cyclin B1, which was neither related to mRNA overexpression nor to mutation within the coding region, and in ®ve other tumors (13%) a 2 ± 10-fold increase of cyclin B2 mRNA which was not related to gene ampli®cation. These results suggest that overexpression of cyclins B, resulting from di erent mechanisms, could contribute, through an alteration of the spindle checkpoint, to the chromosomal instability observed in cancer.

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Section: Discussionmentioning

confidence: 99%

Overexpression of B-type cyclins alters chromosomal segregation

et al. 2002

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“…The cyclin B binding with tubulin has also been shown in biochemical experiments [20]. [5,23,25,26]showing cyclin B localization on the spindle did not exclude its presence in the cytoplasm during the Mphase. Weak signals were always detected in the cytoplasm on immunostaining with cyclin B-specific antibodies, indicating partiality to their localization on the spindle.…”

Section: Intracellular Localization Of Cyclin B1 and Cyclin B2 Duringmentioning

confidence: 92%

“…2C). Indeed, the requirement of cyclin B2, but not cyclin B1, for the first meiotic spindle formation has been reported in Xenopus and Rana japonica oocytes [5,23]. In porcine oocytes, however, cyclin B2 might not always be necessary for the first meiotic spindle formation, as described below.…”

Section: Intracellular Localization Of Cyclin B1 and Cyclin B2 Duringmentioning

confidence: 99%

Localization and Function of Cyclin B1 and Cyclin B2 during Porcine Oocyte Maturation

Kuroda¹,

Naito²

2003

J.Mamm.Ova.Res.

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Oocyte maturation is regulated by maturation/Mphase promoting factor (MPF), a crucial M-phase regulating enzyme composed of a catalytic subunit, p34 cdc2 , and a regulatory subunit, cyclin B. The amount of p34 cdc2 is almost constant during oocyte maturation, and the amount of cyclin B is the principal factor determining MPF activity [1]. The presence of two types of cyclin B, cyclin B1 and cyclin B2, has been shown in vertebrates. In human cells, cyclin B1 can cause chromosome condensation, reorganization of the microtubules, and disassembly of the nuclear lamina and of the Golgi apparatus, whereas the role of cyclin B2 is restricted only to disassembly of the Golgi apparatus [2,3]. In maturing oocytes, differences between cyclin B1 and cyclin B2 functions have been reported in the first meiotic spindle formation and the second metaphase arrest in frog and mouse oocytes, respectively [4][5][6]. In our laboratory, we have studied cyclin B functions during porcine oocyte maturation for the past several years. The present review describes our recent observations with regard to protein levels, intracellular localizations and roles of cyclin B. We focus here on the differences between cyclin B1 and cyclin B2. Protein Levels of Cyclin B1 and Cyclin B2 during Meiotic Maturation of Porcine OocytesWe used immunoblotting to examine the protein levels of cyclin B1 and cyclin B2, looking at the density of the bands at 62 kDa and 45 kDa, respectively. In immature porcine oocytes, the presence of a small amount of pre-MPF, a hyperphosphorylated inactive-MPF, has been suggested [7][8][9], but the relative amount and the kind of cyclin B comprising the pre-MPF have never been clarified. Our resent experiment with 200 porcine oocytes revealed that cyclin B1 was absent from the immature oocytes, whereas the amount of cyclin B2 in immature oocytes was between 1/20 and 1/ 40 of that in the first metaphase oocytes (the intensity of the cyclin B2 band of 200 non-cultured oocytes was between 5 and 10 oocytes in oocytes cultured for 24-h: Fig. 1A).Cyclin B1 and cyclin B2 were detected just before germinal vesicle breakdown (GVBD), which was induced in most of the oocytes at 20-24 h in the present culture conditions [10][11][12]. Thereafter, cyclin B1 gradually increased, with a transient decrease at the first polar body extrusion, and reached its peak level at the second meiotic metaphase (48 h of culturing). In contrast, cyclin B2 reached its peak level at the first metaphase, then decreased abruptly in correlation with the first polar body extrusion and maintained a low level during the second meiosis (Fig. 1B). In Xenopus oocytes, the degradation of cyclin B2 at the first meiosis/ second meiosis transition and the requirement of cyclin B1 synthesis for the second meiosis induction have been reported [13]. Except for the cyclin B levels in immature oocytes, the cyclin B fluctuation patterns in porcine oocytes agreed well with those reported in Xenopus and mouse oocytes [14][15][16]. These results suggest that cyclin B2 works during ...

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“…GST-Mys-(201-435) protein was expressed in Escherichia coli, gel-purified, and injected into a rabbit as described previously (21). The full ORF of zebrafish Prkar1a protein was cloned into pGEX-KG.…”

Section: Methodsmentioning

confidence: 99%

Mys Protein Regulates Protein Kinase A Activity by Interacting with Regulatory Type Iα Subunit during Vertebrate Development

Kotani

Iemura

Natsume

et al. 2010

Journal of Biological Chemistry

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During embryonic development, protein kinase A (PKA) plays a key role in cell fate specification by antagonizing the Hedgehog (Hh) signaling pathway. However, the mechanism by which PKA activity is regulated remains unknown. Here we show that the Misty somites (Mys) protein regulates the level of PKA activity during embryonic development in zebrafish. We isolate PKA regulatory type I␣ subunit (Prkar1a) as a protein interacting with Mys by pulldown assay in HEK293 cells followed by mass spectrometry analysis. We show an interaction between endogenous Mys and Prkar1a in the zebrafish embryo. Mys binds to Prkar1a in its C terminus region, termed PRB domain, and activates PKA in vitro. Conversely, knockdown of Mys in zebrafish embryos results in reduction in PKA activity. We also show that knockdown of Mys induces ectopic activation of Hh target genes in the eyes, neural tube, and somites downstream of Smoothened, a protein essential for transduction of Hh signaling activity. The altered patterning of gene expression is rescued by activation of PKA. Together, our results reveal a molecular mechanism of regulation of PKA activity that is dependent on a protein-protein interaction and demonstrate that PKA activity regulated by Mys is indispensable for negative regulation of the Hh signaling pathway in Hh-responsive cells.

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Requirement of cyclin B2, but not cyclin B1, for bipolar spindle formation in frog (Rana japonica) oocytes

Cited by 29 publications

References 50 publications

Overexpression of B-type cyclins alters chromosomal segregation

Overexpression of B-type cyclins alters chromosomal segregation

Localization and Function of Cyclin B1 and Cyclin B2 during Porcine Oocyte Maturation

Mys Protein Regulates Protein Kinase A Activity by Interacting with Regulatory Type Iα Subunit during Vertebrate Development

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