The histamine H1 receptor activates the nitric oxide pathway at fertilization.
Sperm fusion with the egg initiates a signaling cascade that releases intracellular calcium (Ca(i) (2+)) from the endoplasmic reticulum (ER). In sea urchins, Ca(2+) is released as a single, large transient via two distinct pathways. The first depends on inositol 1,4,5-triphosphate (IP(3)) production and triggers the initial phase of Ca(2+) release, while the second depends on nitric oxide (NO) production and is thought to maintain the duration of the Ca(2+) wave. We identified a sea urchin homolog of the seven trans-membrane G protein-coupled receptor for histamine (suH(1)R) on the egg cell surface that activates NO production. Treatment with histamine (HA) causes fluctuations in the resting levels of NO in the egg, while antagonists or antibodies of H(1)R inhibit the rise of NO normally observed at fertilization. Inhibition of suH(1)R function decreases the maintenance, but not the amplitude, of the Ca(2+) transient and suggests that it is an integral part of the overall pathway leading to egg activation at fertilization in sea urchins.
Leguia
Mariana
M
Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island 02912, USA.
Wessel
Gary M
GM
D000595:Amino Acid Sequence; D000818:Animals; D000954:Antigens, Surface / Q000378:metabolism; D005306:Fertilization / Q000502:physiology*; D008954:Models, Biological; D008969:Molecular Sequence Data; D009569:Nitric Oxide / Q000096:biosynthesis / Q000378:metabolism*; D010063:Ovum / Q000378:metabolism; D011969:Receptors, Histamine H1 / Q000378:metabolism / Q000502:physiology*; D012617:Sea Urchins / Q000378:metabolism / Q000502:physiology; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction
D000954:Antigens, Surface; D011969:Receptors, Histamine H1; D009569:Nitric Oxide