Molecular and Functional Characterization of Inositol Trisphosphate Receptors during Early Zebrafish Development

• Published in: The Journal of biological chemistry Vol. 282; no. 19; pp. 13984 - 13993
• Main Authors: Ashworth, Rachel, Devogelaere, Benoit, Fabes, Jez, Tunwell, Richard E., Koh, Kevin R., De Smedt, Humbert, Patel, Sandip
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 11-05-2007; American Society for Biochemistry and Molecular Biology
• Subjects: Animals; Calcium - metabolism; Danio rerio; Embryo, Nonmammalian - metabolism; Enzyme Inhibitors - pharmacology; Freshwater; Gene Expression Regulation, Developmental; Inositol 1,4,5-Trisphosphate Receptors - classification; Inositol 1,4,5-Trisphosphate Receptors - genetics; Inositol 1,4,5-Trisphosphate Receptors - metabolism; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - genetics; RNA, Messenger - metabolism; Ryanodine Receptor Calcium Release Channel - metabolism; Thapsigargin - pharmacology; Zebrafish - embryology; Zebrafish Proteins - genetics; Zebrafish Proteins - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M700940200

Fluctuations in cytosolic Ca2+ are crucial for a variety of cellular processes including many aspects of development. Mobilization of intracellular Ca2+ stores via the production of inositol trisphosphate (IP3) and the consequent activation of IP3-sensitive Ca2+ channels is a ubiquitous means by which diverse stimuli mediate their cellular effects. Although IP3 receptors have been well studied at fertilization, information regarding their possible involvement during subsequent development is scant. In the present study we examined the role of IP3 receptors in early development of the zebrafish. We report the first molecular analysis of zebrafish IP3 receptors which indicates that, like mammals, the zebrafish genome contains three distinct IP3 receptor genes. mRNA for all isoforms was detectable at differing levels by the 64 cell stage, and IP3-induced Ca2+ transients could be readily generated (by flash photolysis) in a controlled fashion throughout the cleavage period in vivo. Furthermore, we show that early blastula formation was disrupted by pharmacological blockade of IP3 receptors or phospholipase C, by molecular inhibition of the former by injection of IRBIT (IP3 receptor-binding protein released with IP3) and by depletion of thapsigargin-sensitive Ca2+ stores after completion of the second cell cycle. Inhibition of Ca2+ entry or ryanodine receptors, however, had little effect. Our work defines the importance of IP3 receptors during early development of a genetically and optically tractable model vertebrate organism.