Calcium pathway machinery at fertilization in echinoderms

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• 作者：Isabela Ramos ; Gary M. Wessel ; ^{rhet@brown.edu}
• 关键词：SERCA ; sarco/endoplasmic reticulum calcium-ATPase ; IP3 ; inositol-3-phoshate ; cADPR ; cyclic ADP ribose ; NAADP ; nicotinic acid adenine dinucleotide-phosphate ; TPC ; two-pore channel ; ARC ; ADP-ribosyl cyclase ; SpARCs ; S. purpuratus ARC ; PLC ; phospholipase ; ER
• 刊名：Cell Calcium
• 出版年：2013
• 出版时间：January, 2013
• 年：2013
• 卷：53
• 期：1
• 页码：16-23
• 全文大小：607 K

文摘

Calcium signaling in cells directs diverse physiological processes. The calcium waves triggered by fertilization is a highly conserved calcium signaling event essential for egg activation, and has been documented in every egg tested. This activity is one of the few highly conserved events of egg activation through the course of evolution. Echinoderm eggs, as well as many other cell types, have three main intracellular Ca²⁺ mobilizing messengers - IP3, cADPR and NAADP. Both cADPR and NAADP were identified as Ca²⁺ mobilizing messengers using the sea urchin egg homogenate, and this experimental system, along with the intact urchin and starfish oocyte/egg, continues to be a vital tool for investigating the mechanism of action of calcium signals. While many of the major regulatory steps of the IP3 pathway are well resolved, both cADPR and NAADP remain understudied in terms of our understanding of the fundamental process of egg activation at fertilization. Recently, NAADP has been shown to trigger Ca²⁺ release from acidic vesicles, separately from the ER, and a new class of calcium channels, the two-pore channels (TPCs), was identified as the likely targets for this messenger. Moreover, it was found that both cADPR and NAADP can be synthesized by the same family of enzymes, the ADP-rybosyl cyclases (ARCs). In this context of increasing amount of information, the potential coupling and functional roles of different messengers, intracellular stores and channels in the formation of the fertilization calcium wave in echinoderms will be critically evaluated.