title: A cytosolic sperm factor triggers calcium oscillations in rat hepatocytes.
abstract: Previously it has been shown that injecting a cytosolic sperm protein factor into mammalian eggs induces sustained repetitive transients of cytosolic free Ca2+ ([Ca2+]i), or [Ca2+]i oscillations [Swann (1990) Development 110, 1295-1302]. These sperm-factor (SF)-induced [Ca2+]i oscillations are similar to those seen at fertilization. Here we demonstrate that injecting the same cytosolic extracts of mammalian sperm into single rat hepatocytes induces a series of [Ca2+]i oscillations, as measured by aequorin luminescence. SF injection into hepatocytes induced [Ca2+]i oscillations that were of longer duration, lower frequency and greater amplitude than those seen with the Ins (1,4,5)P3-generating agonist phenylephrine. The SF-induced [Ca2+]i responses appeared to be due to internal release of Ca2+, since transients could occur in Ca(2+)-free media. Addition of the phorbol ester phorbol 12,13-dibutyrate (PDBu) at low concentrations did not inhibit the SF-induced [Ca2+]i oscillations; high concentrations of PDBu led to a sustained increase in [Ca2+]i concentrations. These data demonstrate that sperm contain a protein factor capable of inducing a characteristic series of [Ca2+]i oscillations in a somatic cell, the hepatocyte. Along with previous observations in dorsal root ganglion neurons, the data suggest a widespread efficacy of the factor in triggering Ca2+ oscillations.
authors.affiliation: Department of Human Anatomy and Cell Biology, University of Liverpool, U.K.
authors.forename: C P
authors.initials: CP
authors.lastname: Berrie
authors.forename: K S
authors.initials: KS
authors.lastname: Cuthbertson
authors.forename: J
authors.initials: J
authors.lastname: Parrington
authors.forename: F A
authors.initials: FA
authors.lastname: Lai
authors.forename: K
authors.initials: K
authors.lastname: Swann
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism*; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008845:Microinjections; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013094:Spermatozoa / Q000378:metabolism*
chemical_list: D011506:Proteins; D015240:Phorbol 12,13-Dibutyrate