scholarly journals Release of phospholipase C ζand [Ca2+]i oscillation-inducing activity during mammalian fertilization

Reproduction ◽  
2007 ◽  
Vol 134 (5) ◽  
pp. 695-704 ◽  
Author(s):  
Sook-Young Yoon ◽  
Rafael A Fissore
Keyword(s):  
Phospholipase C ◽  
Embryo Development ◽  
Intracytoplasmic Sperm Injection ◽  
Egg Activation ◽  
Mouse Sperm ◽  
Mammalian Sperm ◽  
Sperm Entry ◽  
Sperm Factor ◽  
Mammalian Fertilization ◽  
Mammalian Eggs

During fertilization of mammalian eggs a factor from the sperm, the sperm factor (SF), is released into the ooplasm and induces persistent [Ca2+]i oscillations that are required for egg activation and embryo development. A sperm-specific phospholipase C (PLC), PLCz, is thought to be the SF. Here, we investigated whether the SF activity and PLCζare simultaneously and completely released into the ooplasm soon after sperm entry. To accomplish this, we enucleated sperm heads within 90 min of intracytoplasmic sperm injection (ICSI) and monitored the persistence of the [Ca2+]i oscillations in eggs in which the sperm had been withdrawn. We also stained the enucleatedsperm heads to ascertain the presence/absence of PLCζ. Our results show that by 90 min all the SF activity had been released from the sperm, as fertilized enucleated eggs oscillated as fertilized controls, even in cases in which oscillations were prolonged by arresting eggs at metaphase. In addition, we found that the released SF activity became associated with the pronucleus (PN), as induction of PN envelope breakdown evoked comparable [Ca2+]i responses in enucleated and non-manipulated zygotes. Lastly, we found that PLCzlocalized to the equatorial area of bull sperm and to the post-acrosomal region of mouse sperm and that by 90 min after ICSI all the sperm’s PLCζimmunoreactivity was lost in both species. Altogether, our findings show that during fertilization the SF activity and PLCζimmunoreactivity are simultaneously released from the sperm, suggesting that PLCζmay be the only [Ca2+]i oscillation-inducing factor of mammalian sperm.

PLCζ: a sperm-specific trigger of Ca2+ oscillations in eggs and embryo development

Development ◽  
2002 ◽  
Vol 129 (15) ◽  
pp. 3533-3544 ◽  
Author(s):  
Christopher M. Saunders ◽  
Mark G. Larman ◽  
John Parrington ◽  
Llewellyn J. Cox ◽  
Jillian Royse ◽  
...  
Keyword(s):  
Phospholipase C ◽  
Embryo Development ◽  
Specific Protein ◽  
Normal Embryo ◽  
Egg Activation ◽  
Sperm Factor ◽  
Mammalian Eggs ◽  
Mouse Eggs ◽  
Cytosolic Factor ◽  
Specific Trigger

Upon fertilisation by sperm, mammalian eggs are activated by a series of intracellular Ca2+ oscillations that are essential for embryo development. The mechanism by which sperm induces this complex signalling phenomenon is unknown. One proposal is that the sperm introduces an exclusive cytosolic factor into the egg that elicits serial Ca2+ release. The ‘sperm factor’ hypothesis has not been ratified because a sperm-specific protein that generates repetitive Ca2+ transients and egg activation has not been found. We identify a novel, sperm-specific phospholipase C, PLCζ, that triggers Ca2+ oscillations in mouse eggs indistinguishable from those at fertilisation. PLCζ removal from sperm extracts abolishes Ca2+ release in eggs. Moreover, the PLCζ content of a single sperm was sufficient to produce Ca2+ oscillations as well as normal embryo development to blastocyst. Our results are consistent with sperm PLCζ as the molecular trigger for development of a fertilised egg into an embryo.

The sperm phospholipase C-ζ and Ca2+ signalling at fertilization in mammals

2016 ◽  
Vol 44 (1) ◽  
pp. 267-272 ◽  
Author(s):  
Karl Swann ◽  
F. Anthony Lai
Keyword(s):  
Phospholipase C ◽  
Embryo Development ◽  
Early Embryo ◽  
Egg Activation ◽  
Stable Form ◽  
Ph Domain ◽  
Vitro Fertilization ◽  
Sperm Factor ◽  
Internal Sources

A series of intracellular oscillations in the free cytosolic Ca2+ concentration is responsible for activating mammalian eggs at fertilization, thus initiating embryo development. It has been proposed that the sperm causes these Ca2+ oscillations after membrane fusion by delivering a soluble protein into the egg cytoplasm. We previously identified sperm-specific phospholipase C (PLC)-ζ as a protein that can trigger the same pattern of Ca2+ oscillations in eggs seen at fertilization. PLCζ appears to be the elusive sperm factor mediating egg activation in mammals. It has potential therapeutic use in infertility treatments to improve the rate of egg activation and early embryo development after intra-cytoplasmic sperm injection. A stable form of recombinant human PLCζ could be a prototype for use in such in vitro fertilization (IVF) treatments. We do not yet understand exactly how PLCζ causes inositol 1,4,5-trisphosphate (InsP3) production in eggs. Sperm PLCζ is distinct among mammalian PI-specific PLCs in that it is far more potent in triggering Ca2+ oscillations in eggs than other PLCs, but it lacks a PH domain that would otherwise be considered essential for binding to the phosphatidylinositol 4,5-bisphosphate (PIP2) substrate. PLCζ is also unusual in that it does not appear to interact with or hydrolyse plasma membrane PIP2. We consider how other regions of PLCζ may mediate its binding to PIP2 in eggs and how interaction of PLCζ with egg-specific factors could enable the hydrolysis of internal sources of PIP2.

scholarly journals PLCζ or PAWP: revisiting the putative mammalian sperm factor that triggers egg activation and embryogenesis

2015 ◽  
Vol 21 (5) ◽  
pp. 383-388 ◽  
Author(s):  
Junaid Kashir ◽  
Michail Nomikos ◽  
Karl Swann ◽  
F. Anthony Lai
Keyword(s):  
Egg Activation ◽  
Mammalian Sperm ◽  
Sperm Factor

scholarly journals Potential role of a sperm-derived phospholipase C in triggering the egg-activating Ca2+ signal at fertilization

Reproduction ◽  
2001 ◽  
pp. 839-846 ◽  
Author(s):  
K Swann ◽  
J Parrington ◽  
KT Jones
Keyword(s):  
Membrane Fusion ◽  
Phospholipase C ◽  
Potential Role ◽  
Egg Activation ◽  
Gamete Fusion ◽  
Inositol 1,4,5 Trisphosphate ◽  
Sperm Factor

An increase in intracellular Ca2+ at fertilization is the trigger for egg activation in all species that have been studied. Exactly how sperm-egg interaction leads to this Ca2+ increase has not been established. There is increasing support for the hypothesis that the spermatozoon introduces a Ca2+-releasing protein into the egg cytoplasm after gamete membrane fusion. This review discusses the merits of this 'sperm factor' hypothesis and presents evidence indicating that the sperm factor, at least in mammals, consists of a phospholipase C with distinctive properties. This evidence leads us to propose that, after gamete fusion, a sperm-derived phospholipase C causes production of inositol 1,4,5- trisphosphate, which then generates Ca2+ waves from within the egg cytoplasm.

scholarly journals Phospholipase C isoforms in mammalian spermatozoa: potential components of the sperm factor that causes Ca2+ release in eggs

Reproduction ◽  
2002 ◽  
pp. 31-39 ◽  
Author(s):  
J Parrington ◽  
ML Jones ◽  
R Tunwell ◽  
C Devader ◽  
M Katan ◽  
...  
Keyword(s):  
Phospholipase C ◽  
Sea Urchin ◽  
Soluble Protein ◽  
Gel Filtration ◽  
Protein Factor ◽  
Sea Urchin Egg ◽  
Inositol 1,4,5 Trisphosphate ◽  
Sperm Factor ◽  
Mammalian Eggs ◽  
Mammalian Spermatozoa

Injection of a soluble protein factor from mammalian spermatozoa triggers Ca2+ oscillations in mammalian eggs similar to those seen at fertilization. This sperm factor also generates inositol 1,4,5-trisphosphate and causes Ca2+ release in sea urchin egg homogenates and frog eggs. Recent studies have indicated that the sperm factor may be an inositol-specific phospholipase C (PLC) activity. This study investigated whether any of the commonly known PLC isoforms are components of the sperm factor. PLCbeta, PLCgamma and PLCdelta isoforms were shown to be present in boar sperm extracts. However, upon column fractionation of sperm extracts, none of the PLC isoforms detected correlated with the ability to cause Ca2+ release in eggs. In addition to our previous work on recombinant PLCs, it was also shown that PLCdelta3, PLCdelta4 and its splice variant PLCdelta4 Alt1 fail to cause Ca2+ release. The recently discovered 255 kDa PLCepsilon isoform also appears unlikely to be a component of the sperm factor, as fractionation of sperm extracts on a gel filtration column demonstrated that the peak of Ca2+-releasing activity was associated with fractions of 30-70 kDa. These findings indicate that the sperm factor that triggers Ca2+ release in eggs does not appear to have a known PLC isoform as one of its components.

scholarly journals Phosphatidylserine on viable sperm and phagocytic machinery in oocytes regulate mammalian fertilization

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Claudia M. Rival ◽  
Wenhao Xu ◽  
Laura S. Shankman ◽  
Sho Morioka ◽  
Sanja Arandjelovic ◽  
...  
Keyword(s):  
Motile Sperm ◽  
Head Region ◽  
Skeletal Myoblasts ◽  
Mammalian Sperm ◽  
Species Survival ◽  
Key Players ◽  
Sperm Entry ◽  
Viable Sperm ◽  
Mammalian Fertilization ◽  
Initial Interaction

Abstract Fertilization is essential for species survival. Although Izumo1 and Juno are critical for initial interaction between gametes, additional molecules necessary for sperm:egg fusion on both the sperm and the oocyte remain to be defined. Here, we show that phosphatidylserine (PtdSer) is exposed on the head region of viable and motile sperm, with PtdSer exposure progressively increasing during sperm transit through the epididymis. Functionally, masking phosphatidylserine on sperm via three different approaches inhibits fertilization. On the oocyte, phosphatidylserine recognition receptors BAI1, CD36, Tim-4, and Mer-TK contribute to fertilization. Further, oocytes lacking the cytoplasmic ELMO1, or functional disruption of RAC1 (both of which signal downstream of BAI1/BAI3), also affect sperm entry into oocytes. Intriguingly, mammalian sperm could fuse with skeletal myoblasts, requiring PtdSer on sperm and BAI1/3, ELMO2, RAC1 in myoblasts. Collectively, these data identify phosphatidylserine on viable sperm and PtdSer recognition receptors on oocytes as key players in sperm:egg fusion.

scholarly journals The cytosolic sperm factor that triggers Ca2+ oscillations and egg activation in mammals is a novel phospholipase C: PLCζ

Reproduction ◽  
2004 ◽  
Vol 127 (4) ◽  
pp. 431-439 ◽  
Author(s):  
K Swann ◽  
M G Larman ◽  
C M Saunders ◽  
F A Lai
Keyword(s):  
Membrane Fusion ◽  
Phospholipase C ◽  
Potential Role ◽  
Egg Activation ◽  
Specific Factor ◽  
Sperm Protein ◽  
Protein Factor ◽  
Inositol 1,4,5 Trisphosphate ◽  
Intracellular Ca ◽  
Sperm Factor

When sperm activate eggs at fertilization the signal for activation involves increases in the intracellular free Ca2+concentration. In mammals the Ca2+changes at fertilization consist of intracellular Ca2+oscillations that are driven by the generation of inositol 1,4,5-trisphosphate (InsP3). It is not established how sperm trigger the increases in InsP3and Ca2+at fertilization. One theory suggests that sperm initiate signals to activate the egg by introducing a specific factor into the egg cytoplasm after membrane fusion. This theory has been mainly based upon the observation that injecting a cytosolic sperm protein factor into eggs can trigger the same pattern of Ca2+oscillations induced by the sperm. We have recently shown that this soluble sperm factor protein is a novel form of phospholipase C (PLC), and it is referred to as PLCζ(zeta). We describe the evidence that led to the identification of PLCζ and discuss the issues relating to its potential role in fertilization.

scholarly journals Deletion of TRPV3 and CaV3.2 T-type channels in mice undermines fertility and Ca2+ homeostasis in oocytes and eggs

2021 ◽  
Author(s):  
Aujan Mehregan ◽  
Goli Ardestani ◽  
Hiroki Akizawa ◽  
Ingrid Carvacho ◽  
Rafael Fissore
Keyword(s):  
Divalent Cation ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Egg Activation ◽  
Transient Receptor Potential Vanilloid ◽  
Double Knockout ◽  
Complete Filling ◽  
Sperm Entry ◽  
Mammalian Fertilization ◽  
Transient Receptor

Calcium (Ca2+) influx during oocyte maturation and after sperm entry is necessary to fill the internal Ca2+ stores and for complete egg activation. We knocked out the transient receptor potential vanilloid member 3 (TRPV3) and the T-type channel, CaV3.2 to determine their necessity for maintaining these functions in mammalian oocytes/eggs. Double knockout (dKO) females were subfertile, their oocytes and eggs showed reduced internal Ca2+ stores, and following sperm entry or PLCz cRNA injection, fewer dKO eggs displayed Ca2+ responses compared to wildtype (WT) eggs, which were also of lower frequency. These parameters were rescued and/or enhanced by removing extracellular Mg2+, suggesting the residual Ca2+ influx could be mediated by the TRPM7 channel, consistent with the termination of divalent-cation oscillations in dKO eggs by a TRPM7 inhibitor. In total, we demonstrated that TRPV3 and CaV3.2 mediate the complete filling of the Ca2+ stores in mouse oocytes and eggs. We also show they are required for initiating and maintaining regularly spaced-out oscillations, suggesting that Ca2+ influx through PM ion channels dictates the periodicity and persistence of Ca2+ oscillations during mammalian fertilization.

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