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This Article Full Text Full Text (PDF) All Versions of this Article: 78/6/1081    most recent biolreprod.108.067801v1 Alert me when this article is cited Alert me if a correction is posted Citation Map 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 Google Scholar Articles by Ito, M. Articles by Miyazaki, S. PubMed PubMed Citation Articles by Ito, M. Articles by Miyazaki, S. Agricola Articles by Ito, M. Articles by Miyazaki, S.

Difference in Ca²⁺ Oscillation-Inducing Activity and Nuclear Translocation Ability of PLCZ1, an Egg-Activating Sperm Factor Candidate, Between Mouse, Rat, Human, and Medaka Fish¹

Department of Physiology,³ Tokyo Women's Medical University School of Medicine, Shinjuku-ku, Tokyo 162-8666, Japan Department of Safety Research on Blood and Biological Products,⁴ National Institute of Infectious Diseases, Musashimurayama-shi, Tokyo 208-0011, Japan Department of Integrated Biosciences,⁵ Graduate School of Frontier Sciences, University of Tokyo, Kashiwa City, Chiba 277-8562, Japan Department of Biology, Faculty of Science,⁶ Toho University, Funabashi City, Chiba 274-8510, Japan Department of Pharmacology,⁷ Saitama Medical University School of Medicine, Moro-machi, Saitama 350-0495, Japan Tokyo Women's Medical University School of Medicine,⁸ Shinjuku-ku, Tokyo 162-8666, Japan

ABSTRACT

Mouse phospholipase C, zeta 1 (PLCZ1), a strong candidate of egg-activating sperm factor, induces Ca²⁺ oscillations and accumulates into formed pronucleus (PN) when expressed by cRNA injection. These activities were compared among mouse and human PLCZ1, newly cloned rat Plcz1, and medaka fish plcz1. The PLCZ1 proteins of the four species have an approximately homologous sequence of nuclear localization signal. However, the nuclear translocation ability was defective in rat, human, and medaka PLCZ1 expressed in mouse eggs. Rat PLCZ1 could not enter rat PN, whereas mouse PLCZ1 could. Mouse and human PLCZ1 translocated into the nucleus of COS-7 cells transfected with cDNA. There was little medaka PLCZ1 accumulated in the nucleus, and rat PLCZ1 was never located in the nucleus. All PLCZ1 proteins including fish could induce Ca²⁺ oscillations in mouse eggs, but the activity was variable in the order of human >> mouse > medaka >> rat, estimated from minimal RNA concentration to induce Ca²⁺ spikes. Ca²⁺ oscillations by human PLCZ1 continued far beyond the time of PN formation (T_PN), whereas those by mouse PLCZ1 ceased slightly before T_PN. High-frequency Ca²⁺ spikes by overexpressed rat PLCZ1 stopped far before T_PN, possibly by feedback inhibition. Ca²⁺ oscillations by fertilization of rat eggs stopped at T_PN, despite defective nuclear translocation of rat PLCZ1. Thus, PLCZ1 sequestration into PN participates in termination of Ca²⁺ oscillations at the interphase of mouse embryos but does not always operate in other mammals, notably in rat embryos.

calcium, Ca²⁺ oscillation-inducing activity, early development, egg-activating sperm factor, fertilization, nuclear translocation ability, phospholipase C zeta 1, species difference, sperm

¹Supported by grants-in-aid for general scientific research (B) to S.M. and young scientists (B) to M.I. from the Japanese Ministry of Education, Science, Sports, and Culture.

Correspondence: ²Masahiko Ito, Department of Physiology, Tokyo Women's Medical University School of Medicine, 8–1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan. FAX: 81 3 5269 7414; e-mail: mito557{at}nih.go.jp

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