QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online 9 August 2005
doi: 10.1242/jcs.02506

This Article Figures Only Full Text All Versions of this Article: jcs.02506v1 118/17/3849    most recent Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Madgwick, S. Articles by Jones, K. T. Search for Related Content PubMed PubMed Citation Articles by Madgwick, S. Articles by Jones, K. T.

Calmodulin-dependent protein kinase II, and not protein kinase C, is sufficient for triggering cell-cycle resumption in mammalian eggs

Institute for Cell and Molecular Biosciences, The Medical School, Framlington Place, University of Newcastle, Newcastle, NE2 4HH, UK

^* Author for correspondence (e-mail: k.t.jones{at}newcastle.ac.uk)

Accepted 20 May 2005

Mouse eggs arrest at metaphase II following ovulation and are only triggered to complete meiosis when fertilized. Sperm break the cell-cycle arrest by a long-lasting series of Ca²⁺ spikes that lead to an activation of the anaphase-promoting complex/cyclosome. The signal transduction pathway is not fully resolved but both protein kinase C (PKC) and calmodulin-dependent protein kinase II (CamKII) activities increase at fertilization and previous pharmacological studies have implicated both in cell-cycle resumption. We have used a combination of pharmacological inhibitors and constitutively active cRNA constructs of PKC and CamKII microinjected into mouse eggs to show that it is CamKII and not PKC that is the sufficient trigger for cell-cycle resumption from metaphase II arrest.

Constitutively active PKC constructs had no effect on the resumption of meiosis but caused an immediate and persistent elevation in intracellular Ca²⁺ when store-operated Ca²⁺ entry was stimulated. With respect to resumption of meiosis, the effects of constitutively active CamKII on eggs were the same as sperm. Eggs underwent second polar body extrusion and pronucleus formation with normal timings; while both securin and cyclin B1 destruction, visualised by coupling to fluorescent protein tags, were complete by the time of polar body extrusion. Induction of a spindle checkpoint by overexpression of Mad2 or by spindle poisons blocked CamKII-induced resumption of meiosis, but the Ca²⁺ chelator BAPTA did not. Furthermore direct measurement of Ca²⁺ levels showed that CamKII did not induce exit from metaphase II arrest by raising Ca²⁺. Therefore, we conclude that PKCs may play an important role in maintaining Ca²⁺ spiking at fertilization by promoting store-operated Ca²⁺ entry, while CamKII transduces cell-cycle resumption, and lies downstream of sperm-induced Ca²⁺ release but upstream of a spindle checkpoint. These data, combined with the knowledge that CamKII activity increase at fertilization, suggest that mouse eggs undergo cell-cycle resumption through stimulation of CamKII.

Key words: Calcium, Calmodulin-dependent protein kinase II, Fertilization, Mouse, Protein kinase C, Spindle checkpoint

This article has been cited by other articles:

				L. Tsaadon, R. Kaplan-Kraicer, and R. Shalgi Myristoylated alanine-rich C kinase substrate, but not Ca2+/calmodulin-dependent protein kinase II, is the mediator in cortical granules exocytosis Reproduction, May 1, 2008; 135(5): 613 - 624. [Abstract] [Full Text] [PDF]

				L. Sun, R. Hodeify, S. Haun, A. Charlesworth, A. M. MacNicol, S. Ponnappan, U. Ponnappan, C. Prigent, and K. Machaca Ca2+ Homeostasis Regulates Xenopus Oocyte Maturation Biol Reprod, April 1, 2008; 78(4): 726 - 735. [Abstract] [Full Text] [PDF]

				S. Markoulaki, M. Kurokawa, S.-Y. Yoon, S. Matson, T. Ducibella, and R. Fissore Comparison of Ca2+ and CaMKII responses in IVF and ICSI in the mouse Mol. Hum. Reprod., April 1, 2007; 13(4): 265 - 272. [Abstract] [Full Text] [PDF]

				S. Madgwick, D. V. Hansen, M. Levasseur, P. K. Jackson, and K. T. Jones Mouse Emi2 is required to enter meiosis II by reestablishing cyclin B1 during interkinesis J. Cell Biol., September 11, 2006; 174(6): 791 - 801. [Abstract] [Full Text] [PDF]

				N T Rogers, G Halet, Y Piao, J Carroll, M S H Ko, and K Swann The absence of a Ca2+ signal during mouse egg activation can affect parthenogenetic preimplantation development, gene expression patterns, and blastocyst quality Reproduction, July 1, 2006; 132(1): 45 - 57. [Abstract] [Full Text] [PDF]

				D. V. Hansen, J. J. Tung, and P. K. Jackson CaMKII and Polo-like kinase 1 sequentially phosphorylate the cytostatic factor Emi2/XErp1 to trigger its destruction and meiotic exit PNAS, January 17, 2006; 103(3): 608 - 613. [Abstract] [Full Text] [PDF]

				S. Matson, S. Markoulaki, and T. Ducibella Antagonists of Myosin Light Chain Kinase and of Myosin II Inhibit Specific Events of Egg Activation in Fertilized Mouse Eggs Biol Reprod, January 1, 2006; 74(1): 169 - 176. [Abstract] [Full Text] [PDF]

				K. T Jones Mammalian egg activation: from Ca2+ spiking to cell cycle progression Reproduction, December 1, 2005; 130(6): 813 - 823. [Abstract] [Full Text] [PDF]