Phospholipase C zeta rescues failed oocyte activation in a prototype of male factor infertility

Capsule:
Oocytes expressing mutant sperm phospholipase Cz (PLCz) fail to activate, but microinjection of wild-type human PLCz rescues failed activation and triggers embryo development.

Authors:
Michail Nomikos, Ph.D., Yuansong Yu, Ph.D., Khalil Elgmati, M.Sc., Maria Theodoridou, M.Sc., Karen Campbell, Ph.D., Vyronia Vassilakopoulou, M.Sc., Christos Zikos, Ph.D., Evangelia Livaniou, Ph.D., Nazar Amso, Ph.D., George Nounesis, Ph.D., Karl Swann, Ph.D., F. Anthony Lai, Ph.D.

Volume 99, Issue 1, Pages 76-85, January 2013

Abstract:

Objective:
To determine the effect of infertility-linked sperm PLC mutations on their ability to trigger oocyte Ca2+ oscillations and development, and also to evaluate the potential therapeutic utility of wild-type, recombinant PLC protein to rescue the failure of oocyte activation and embryo development.

Design:
Test of a novel therapeutic approach to male factor infertility.

Setting:
University Medical School research laboratory.

Patients:
Donated unfertilized human oocytes from follicle reduction.

Interventions(s):
Microinjection of oocytes with recombinant human PLCζ protein or PLCζ cRNA and a Ca2+-sensitive fluorescent dye.

Main Outcome Measure(s):
Measurement of the efficacy of mutant and wild-type PLCζ-mediated enzyme activity, oocyte Ca2+ oscillations, activation, and early embryo development.

Result(s):
In contrast to the wild-type protein, mutant forms of human sperm PLCζ display aberrant enzyme activity and a total failure to activate unfertilized oocytes. Subsequent microinjection of recombinant human PLCζ protein reliably triggers the characteristic pattern of cytoplasmic Ca2+ oscillations at fertilization, which are required for normal oocyte activation and successful embryo development to the blastocyst stage.

Conclusion(s):
Dysfunctional sperm PLC is unable to trigger oocyte activation and results in male factor infertility. Therefore, a potential therapeutic approach is oocyte microinjection of active, wild-type PLC protein. We have demonstrated that recombinant human PLC can phenotypically rescue the failed activation in oocytes expressing dysfunctional PLC and this intervention culminates in efficient blastocyst formation.

  • lait@cf.ac.uk

    We are looking forward to participation in discussions on our paper – Phospholipase C zeta rescues failed oocyte activation in a prototype of male factor infertility.
    Tony Lai, for the authors

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