Signal transduction pathways leading to Ca2+ release in a vertebrate model system: lessons from Xenopus eggs.
At fertilization, eggs unite with sperm to initiate developmental programs that give rise to development of the embryo. Defining the molecular mechanism of this fundamental process at the beginning of life has been a key question in cell and developmental biology. In this review, we examine sperm-induced signal transduction events that lead to release of intracellular Ca(2+), a pivotal trigger of developmental activation, during fertilization in Xenopus laevis. Recent data demonstrate that metabolism of inositol 1,4,5-trisphosphate (IP(3)), a second messenger for Ca(2+) release, is carefully regulated and involves phospholipase C (PLC) and the tyrosine kinase Src. Roles of other potential regulators in this pathway, such as phosphatidylinositol 3-kinase, heterotrimeric GTP-binding protein, phospholipase D (PLD) and phosphatidic acid (PA) are also discussed. Finally, we address roles of egg lipid/membrane microdomains or 'rafts' as a platform for the sperm-egg membrane interaction and subsequent signaling events of egg activation.
Laboratory of Molecular Biology, The Research Center for Environmental Genomics, Kobe University, Kobe 657-8501, Japan. kksato@kobe-u.ac.jp
Ken-ichi
K
Sato
Yasuo
Y
Fukami
Bradley J
BJ
Stith
D000818:Animals; D020013:Calcium Signaling; D005260:Female; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D008297:Male; D023421:Models, Animal; D010063:Ovum / Q000201:enzymology / Q000378:metabolism*; D010712:Phosphatidic Acids / Q000378:metabolism; D013045:Species Specificity; D013084:Sperm-Ovum Interactions; D010738:Type C Phospholipases / Q000378:metabolism; D014982:Xenopus laevis / Q000378:metabolism*; D019061:src-Family Kinases / Q000378:metabolism
D010712:Phosphatidic Acids; D015544:Inositol 1,4,5-Trisphosphate; D019061:src-Family Kinases; D010738:Type C Phospholipases