Isolation and characterization of sea urchin egg lipid rafts and their possible function during fertilization

Belton, Robert J.; Adams, Nikki; Foltz, Kathy R.

doi:10.1002/mrd.1034

Cited by 57 publications

(34 citation statements)

References 85 publications

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“…We do not know whether and, if so, how, the sperm factor is anchored to or near the PM but it might be through the association with membrane lipid rafts. It has been shown that lipid rafts function as a signalling scaffold where several cell signalling molecules, including PLCs and Src kinases accumulate (reviewed in Zajchowski and Robbins, 2002) and recent reports have shown that the disruption of these domains perturbs the fertilization signalling pathway in sea urchin and Xenopus eggs (Belton et al, 2001;Sato et al, 2002).…”

Section: Mechanism Of Ca 2+ -Wave Pacemaker Operationmentioning

confidence: 99%

Exploring the mechanism of action of the sperm-triggered calcium-wave pacemaker in ascidian zygotes

Carroll

Levasseur

Wood

et al. 2003

Journal of Cell Science

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dislodge the Ca 2+ -wave pacemaker from that site. Next, when we prevented the accumulation of cER at the CP, all of the Ca 2+ waves came from the site of sperm-egg fusion and the frequency of Ca 2+ oscillations was unaltered. These data show that local Ca 2+ influx, the accumulation of PtdIns(4,5)P2 and cER at the CP are not required for Ca 2+ -wave pacemaker function and instead suggest that a factor associated with the sperm determines the site of the Ca 2+ -wave pacemaker. Finally, when we injected ascidian sperm extract into the centre of unfertilized ascidian eggs that had been treated with microfilament-and microtubuledisrupting drugs, all the Ca 2+ waves still originated from near the plasma membrane, showing that the sperm factor does not require an intact cortex if it is enriched near the plasma membrane (PM). We suggest that the Ca 2+ -releasing sperm factor might be tethered near or on the PM and that following the cortical contraction, it is translocated to the vegetal CP, thus making that site act as a Ca 2+ -wave pacemaker.

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Section: Mechanism Of Ca 2+ -Wave Pacemaker Operationmentioning

confidence: 99%

Exploring the mechanism of action of the sperm-triggered calcium-wave pacemaker in ascidian zygotes

Carroll

Levasseur

Wood

et al. 2003

Journal of Cell Science

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“…Originally isolated from mammalian endothelial cells in culture (14), lipid rafts have been identified in three invertebrate species: Drosophila, Dictyostelium, and Strongylocentrotus (2,13,32). The proposed functions for UNC-1 have led us to study whether lipid rafts exist in C. elegans and to determine whether UNC-1 or UNC-8 is present in lipid rafts.…”

mentioning

confidence: 99%

A stomatin and a degenerin interact in lipid rafts of the nervous system of Caenorhabditis elegans

Sedensky

Siefker

Koh³

et al. 2004

American Journal of Physiology-Cell Physiology

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In Caenorhabditis elegans, the gene unc-1 controls anesthetic sensitivity and normal locomotion. The protein UNC-1 is a close homolog of the mammalian protein stomatin and is expressed primarily in the nervous system. Genetic studies in C. elegans have shown that the UNC-1 protein interacts with a sodium channel subunit, UNC-8. In humans, absence of stomatin is associated with abnormal sodium and potassium levels in red blood cells. Stomatin also has been postulated to participate in the formation of lipid rafts, which are membrane microdomains associated with protein complexes, cholesterol, and sphingolipids. In this study, we isolated a low-density, detergent-resistant fraction from cell membranes of C. elegans. This fraction contains cholesterol, sphingolipids, and protein consistent with their identification as lipid rafts. We then probed Western blots of protein from the rafts and found that the UNC-1 protein is almost totally restricted to this fraction. The UNC-8 protein is also found in rafts and coimmunoprecipitates UNC-1. A second stomatin-like protein, UNC-24, also affects anesthetic sensitivity, is found in lipid rafts, and regulates UNC-1 distribution. Mutations in the unc-24 gene alter the distribution of UNC-1 in lipid rafts. Each of these mutations alters anesthetic sensitivity in C. elegans. Because lipid rafts contain many of the putative targets of volatile anesthetics, they may represent a novel class of targets for volatile anesthetics.

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“…In addition, the cholesterol-binding compound methyl-␤-cyclodextrin abolishes sperm-egg interaction and/or subsequent Src activation (31). The functional importance of egg rafts has also been suggested in sea urchin fertilization (34). However, the significance of the structural and functional interaction of rafts with the egg cytoplasm and the involvement of Src-PLC␥ pathway in this interaction remain to be established.…”

mentioning

confidence: 99%

Reconstitution of Src-dependent Phospholipase Cγ Phosphorylation and Transient Calcium Release by Using Membrane Rafts and Cell-free Extracts from Xenopus Eggs

Sato

Tokmakov

et al. 2003

Journal of Biological Chemistry

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We reported previously that egg membrane rafts serve as a subcellular microdomain for sperm-dependent tyrosine kinase signaling in Xenopus fertilization. Moreover, we demonstrated that raft-associated Src tyrosine kinase was activated by sperm in vitro. Here we show that egg rafts incubated with sperm or hydrogen peroxide (H 2 O 2 ) can promote Src-dependent phosphorylation of phospholipase C␥ (PLC␥) and transient calcium release in the extracts of unfertilized Xenopus eggs. In vivo egg activation by sperm or H 2 O 2 also promotes tyrosinephosphorylation and raft-translocalization of PLC␥. Immunodepletion of PLC␥ from the egg extracts inhibits the raft-dependent calcium release. Rafts prepared from H 2 O 2 -activated eggs also promote Src-dependent dephosphorylation of p42 mitogen-activated protein kinase and cell cycle transition from metaphase II to interphase in egg extracts. PLC␥ phosphorylation and calcium release in egg extracts can be promoted by rafts prepared from COS-7 cells expressing the Xenopus Src gene. These results demonstrate that the signaling events elicited by fertilization in Xenopus eggs can be reconstituted in vitro. The development of such experimental platforms will allow us to dissect the molecular mechanism of sperm-dependent activation of raft-associated Src and subsequent up-regulation of PLC␥ and egg activation machinery in Xenopus eggs.

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Isolation and characterization of sea urchin egg lipid rafts and their possible function during fertilization

Cited by 57 publications

References 85 publications

Exploring the mechanism of action of the sperm-triggered calcium-wave pacemaker in ascidian zygotes

Exploring the mechanism of action of the sperm-triggered calcium-wave pacemaker in ascidian zygotes

A stomatin and a degenerin interact in lipid rafts of the nervous system of Caenorhabditis elegans

Reconstitution of Src-dependent Phospholipase Cγ Phosphorylation and Transient Calcium Release by Using Membrane Rafts and Cell-free Extracts from Xenopus Eggs

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