Functional analysis of Cyclin A/Cdk2 for chromosome condensation

• Project/Area Number: 13680788
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Cell biology
• Research Institution: Hiroshima University (2002); Kyushu University (2001)
• Principal Investigator: FURUNO Nobuaki Hiroshima Univ., Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (80219120)
• Co-Investigator(Kenkyū-buntansha): YOSHITOME Satoshi Tottori Univ. School of Life Sciences, Research Assistant, 医学部, 助手 (30325790)
• Project Period (FY): 2001 – 2002
• Project Status: Completed (Fiscal Year 2002)
• Budget Amount: ¥1,200,000 (Direct Cost: ¥1,200,000); Fiscal Year 2002: ¥1,200,000 (Direct Cost: ¥1,200,000)
• Keywords: Chromosome condensation / MPF / Cyclin / Centrosome / Xenopuslaevis / embryo / oocyte maturation / Cyclin dependent kinase / サイクリンB2 / 卵母細胞 / 紡錘体 / 細胞周期 / サイクリンA

Research Abstract

We have shown that Xenopus cyclin B2 is involved in bipolar spindle formation through its cytoplasmic retention signal (CRS) region. However, an NES-like sequence (NELS) present in the CRS region of cyclin B2 might be involved in bipolar spindle formation. We show here that cyclin B2 is actually exported from the nucleus via its NELS, but that overexpression of the cyclin B2 CRS region, having a mutated NELS, still inhibits bipolar spindle formation in oocytes. In contrast, overexpression of the cyclin B2 CRS region lacking its C-terminal seven amino acids no longer inhibits bipolar spindle formation in oocytes or embryos. These results suggest strongly that the CRS region, especially its C-terminal seven acidic residues, of cyclin B2 is required for bipolar spindle formation in both the meiotic and mitotic cell divisions.
In full-grown Xenopus oocytes, cell-cycle regulators and pre-MPF are stored ready to bring about a specific cell cycle for oocyte maturation. We examined the expression pattern of these cell-cycle regulators as well as pre-MPF formation during oogenesis. Cdc2 and Cyclin B2 were already present in stage I oocytes and pre-MPF formation was also detected in stage I oocytes. Some negative regulators of MPF, Myt1 and Chk1, were synthesized early in oogenesis. In contrast, positive regulators of MPF, MEK, MAPK and Cdc25C, were mainly synthesized late in oogenesis. Northern blotting analysis suggested that the synthesis of these cell-cycle regulators was controlled by translation.

Research Products

• [Publications] Furuno et al.: "Expression of cell-cycle regulators during Xenopus oogenesis"Gene Expression Patterns. 3. 165-168 (2003)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] Yoshitome et al.: "The C-terminal seven amino acids in the CRS region of cyclin B2 are required for normal bipolar spindle formation in Xenopus oocytes and embryos"Molecular Cancer Research. (in press). (2003)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] Yoshitome et al.: "Mr 25,000 protein (pp25), a cytosolic non-crystallized yolk protein, is derived from Xenopus vitellogenin B1"Development Growth and differentiation. (in press). (2003)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] Furuno et al.: "Expression of cell-cycle regulators during Xenopus oogenesis"Gene Expression patterns. 3. 165-168 (2003)
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] Yoshitome et al.: "Mr 25,000 protein (pp25), a cytosolic non-crystallized yolk protein, is derived from Xenopus vitellogenin B1"DGD. in press. (2003)
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] Yoshitome et al.: "The C-terminal seven amino acids in the CRS region of cyclin B2 are required for normal bipolar spindle formation in Xenopus oocytes and embryos"Molecular Cancer Research. in press. (2003)
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] N.Furuno, A.Kawasaki, N.Sagata: "Expression of cell-cycle regulators during Xenopus oogenesis"Gene Expression Patterns. 1. 1-4 (2003)