Egg activation events are regulated by the duration of a sustained [Ca2+]cyt signal in the mouse

Ozil, Jean-Pierre; Markoulaki, Styliani; Tóth, Szabolcs; Matson, Sara; Banrezes, Bernadette; Knott, Jack H.; Schultz, Richard M.; Huneau, D.; Ducibella, Tom

doi:10.1016/j.ydbio.2005.02.035

Cited by 154 publications

(152 citation statements)

References 53 publications

Supporting

Mentioning

143

Contrasting

Order By: Relevance

“…Alterations in oocyte calcium signaling affected not only the early events of embryonic development (Ducibella et al 2002, Ozil et al 2005, but also gene expression in eight cell ) and blastocyst-stage embryos , implantation (Ozil & Huneau 2001, and even development to term . It is possible that the long-lasting effect of [Ca 2C ] i oscillations was mediated by alterations in chromatin structure and reprogramming of gene expression occurring after fertilization (Ozil & Huneau 2001).…”

Section: Introductionmentioning

confidence: 99%

Activation of bovine somatic cell nuclear transfer embryos by PLCZ cRNA injection

Ross¹,

Rodríguez²,

Iager³

et al. 2009

Reproduction

View full text Add to dashboard Cite

The production of cloned animals by the transfer of a differentiated somatic cell into an enucleated oocyte circumvents fertilization. During fertilization, the sperm delivers a sperm-specific phospholipase C (PLCZ) that is responsible for triggering Ca 2C oscillations and oocyte activation. During bovine somatic cell nuclear transfer (SCNT), oocyte activation is artificially achieved by combined chemical treatments that induce a monotonic rise in intracellular Ca 2C and inhibit either phosphorylation or protein synthesis. In this study, we tested the hypothesis that activation of bovine nuclear transfer embryos by PLCZ improves nuclear reprogramming. Injection of PLCZ cRNA into bovine SCNTunits induced Ca 2C oscillations similar to those observed after fertilization and supported high rates of blastocyst development similar to that seen in embryos produced by IVF. Furthermore, gene expression analysis at the eight-cell and blastocyst stages revealed a similar expression pattern for a number of genes in both groups of embryos. Lastly, levels of trimethylated lysine 27 at histone H3 in blastocysts were higher in bovine nuclear transfer embryos activated using cycloheximide and 6-dimethylaminopurine (DMAP) than in those activated using PLCZ or derived from IVF. These results demonstrate that exogenous PLCZ can be used to activate bovine SCNT-derived embryos and support the hypothesis that a fertilization-like activation response can enhance some aspects of nuclear reprogramming.

show abstract

Section: Introductionmentioning

confidence: 99%

Activation of bovine somatic cell nuclear transfer embryos by PLCZ cRNA injection

Ross¹,

Rodríguez²,

Iager³

et al. 2009

Reproduction

View full text Add to dashboard Cite

show abstract

“…Other events of egg activation such as cortical granule (CG) exocytosis and cell cycle resumption, also do not occur in eggs in which increased [Ca 2C ] cyt is completely inhibited. It is further known from a variety of studies, such as those using either partial suppression of sperm-induced Ca 2C transients or parthenogenetic activation resulting from different types of manipulated [Ca 2C ] cyt increases, that different egg activation responses require different 'levels' of calciummediated signals for initiation and then completion (Kline & Kline 1992, Ducibella et al 2002, Ozil et al 2005. For example, studies using electropermeabilization of mouse eggs to induce pulses of Ca 2C influx that mimic post-fertilization Ca 2C transients show that one pulse is sufficient to initiate CG exocytosis, 4-8 pulses in mouse eggs induce exit from metaphase II arrest and pronuclear formation requires 8-24 pulses (Ducibella et al 2002).…”

Section: Introductionmentioning

confidence: 99%

Establishment of the mammalian membrane block to polyspermy: evidence for calcium-dependent and -independent regulation

2007

View full text Add to dashboard Cite

One crucial result of egg activation is the establishment of blocks on the zona pellucida and the egg plasma membrane to prevent fertilization by additional sperm. The mechanism(s) by which a mammalian egg regulates the establishment of the membrane block to polyspermy is largely unknown. Since Ca 2C signaling regulates several egg activation events, this study investigates how sperm-induced Ca 2C transients affect the membrane block to polyspermy, building on our previous work (Biology of ] cyt regulate the timing of membrane block establishment, as this block is established more slowly in eggs that experience one or no sperm-induced Ca 2C transients. Finally, our studies produce the intriguing discovery that there is also a Ca 2C -independent event that is associated with fertilization in the pathway leading to membrane block establishment. Taken together, these data indicate that Ca 2C plays a role in facilitating membrane block establishment by regulating the timing with which this change in egg membrane function occurs, and also that the membrane block differs from other post-fertilization egg activation responses as Ca 2C is not the only stimulus.The membrane block to polyspermy in mammalian eggs is likely to be the culmination of multiple post-fertilization events that together modify the egg membrane's receptivity to sperm.

show abstract

“…In mammalian eggs, this increase in [Ca 2+ ] i takes the form of repetitive Ca 2+ transients (oscillations) that last several hours (4,5). Although Ca 2+ oscillations can induce all of the EEA, individual events require different numbers of [Ca 2+ ] i transients to be initiated and completed, with early events requiring fewer oscillations than late events (6).…”

mentioning

confidence: 99%

The γ isoform of CaM kinase II controls mouse egg activation by regulating cell cycle resumption

Backs

Stein

Backs

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

107

110

View full text Add to dashboard Cite

Fertilization triggers a rise in intracellular Ca 2+ concentration ([Ca 2+ ] i ) in the egg that initiates a series of events known as egg activation. These events include cortical granule exocytosis that establishes a block to polyspermy, resumption of meiosis, and recruitment of maternal mRNAs into polysomes for translation. Several calcium-dependent proteins, including calcium/calmodulin-dependent protein kinase II (CaMKII), have been implicated in egg activation. However, the precise role of CaMKII in mediating specific events of egg activation and the identity of the isoform(s) present in mouse eggs have not been unequivocally established. Through targeted deletion of the γ isoform of CaMKII, we find that CaMKIIγ is the predominant CaMKII isoform in mouse eggs and that it is essential for egg activation. Although CaMKIIγ −/− eggs exhibit a normal pattern of Ca 2+ oscillations after insemination and undergo cortical granule exocytosis, they fail to resume meiosis or to recruit maternal mRNAs. Surprisingly, we find that the recruitment of maternal mRNAs does not directly depend on CaMKII, but requires elevated [Ca 2+ ] i and metaphase II exit. We conclude that CaMKIIγ specifically controls mouse egg activation by regulating cell cycle resumption.T he transition from a fertilization-competent mammalian egg to a developing embryo entails a sequence of events collectively known as egg activation. Early events of egg activation include modifications of the zona pellucida (ZP) that prevent polyspermy, exit from metaphase II arrest, and completion of meiosis, whereas late events include recruitment of maternal mRNAs into polysomes for translation and formation of male and female pronuclei (1). In all animal species studied to date, a rise in intracellular calcium ([Ca 2+ ] i ) is the universal trigger of all of the events of egg activation (EEA) (2). Release of a spermspecific phospholipase C isoform (PLCζ) likely initiates the inositol 1,4,5-trisphosphate (IP 3 )-mediated increase in [Ca 2+ ] i (3). In mammalian eggs, this increase in [Ca 2+ ] i takes the form of repetitive Ca 2+ transients (oscillations) that last several hours (4, 5). Although Ca 2+ oscillations can induce all of the EEA, individual events require different numbers of [Ca 2+ ] i transients to be initiated and completed, with early events requiring fewer oscillations than late events (6).The pathways that connect the rise in [Ca 2+ ] i to the different EEA have only been partially elucidated. Protein kinases, including calcium/calmodulin-dependent protein kinase II (CaM-KII), and the phosphatase calcineurin have been postulated as integrators of the Ca 2+ signal during egg activation (7-9). However, direct genetic evidence for involvement of these enzymes through loss-of-function studies is lacking, leaving open questions as to whether any single enzyme is essential for all of the EEA or whether these Ca 2+ -dependent events are mediated by different effectors.The CaMKII family of serine/threonine kinases mediates many cellular responses to C...

show abstract

Egg activation events are regulated by the duration of a sustained [Ca2+]cyt signal in the mouse

Cited by 154 publications

References 53 publications

Activation of bovine somatic cell nuclear transfer embryos by PLCZ cRNA injection

Activation of bovine somatic cell nuclear transfer embryos by PLCZ cRNA injection

Establishment of the mammalian membrane block to polyspermy: evidence for calcium-dependent and -independent regulation

The γ isoform of CaM kinase II controls mouse egg activation by regulating cell cycle resumption

Contact Info

Product

Resources

About