Author(s): Larman MG, Saunders CM, Carroll J, Lai FA, Swann K
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Abstract During the first cell cycle Ca2+ oscillations are regulated in a cell cycle-dependent manner, such that the oscillations are unique to M phase. How the Ca2+ oscillations are regulated with such cell cycle stage-dependency is unknown, despite their importance for egg activation and embryo development. We recently identified a novel, sperm-specific phospholipase C (PLCzeta; PLCzeta) that triggers Ca2+ oscillations similar to those caused by sperm. We show that PLCzeta-induced Ca2+ oscillations also occur exclusively during M phase. The cell cycle-dependency can be explained by PLCzeta's localisation to the pronuclei, which depends specifically upon a nuclear localisation signal sequence. Preventing pronuclear localisation of PLCzeta by mutation of the nuclear localisation signal, or by inhibiting pronuclear formation/import, can prolong Ca2+ oscillations or allow them to occur during interphase. These data suggest a novel mechanism for regulating a PLC through nuclear sequestration and may explain the cell cycle-dependent regulation of Ca2+ oscillations following fertilisation.
This article was published in J Cell Sci
and referenced in Journal of Physical Chemistry & Biophysics