title: Sperm GIRK2-containing K+ inward rectifying channels participate in sperm capacitation and fertilization.
abstract: The GIRK2-containing inward-rectifying K(+) ion channels have been implicated in mammalian spermatogenesis. While the Girk2 null mice are fertile, the male weaver transgenic mice carrying a gain-of-function mutation in the Girk2 gene are infertile. To establish the exact period of spermatogenesis affected by this mutation, we performed StaPut isolation and morphological characterization of the germ cells present in the weaver testis. Germ cells representing all periods of spermatogenesis were identified. However, no spermatozoa were present, suggesting that this mutation only affected the haploid phase of spermatogenesis. Real-time PCR studies performed on StaPut purified germ cells from wild-type mice indicated that the Girk2 transcripts were exclusively expressed in spermatids. Immunofluorescence studies of mouse and boar spermatids/spermatozoa localized the GIRK2 K(+) containing channels to the acrosomal region of the sperm plasma membrane. During porcine in vitro fertilization (IVF), GIRK2-containing channels remained associated with the acrosomal shroud following zona-induced acrosome reaction. Fertilization was blocked by tertiapin-Q (TQ), a specific inhibitor of GIRK channels, and by anti-GIRK2 antibodies. Altogether, studies in two different mammalian species point to a conserved mechanism by which the GIRK2 inward-rectifying K(+) ion channels support sperm function during fertilization.
authors: Division of Animal Sciences, University of Missouri-Columbia, Columbia, MO, USA. yiyo@missouri.edu
authors: Young-Joo
authors: YJ
authors: Yi
authors: Dae Yong
authors: DY
authors: Sung
authors: Clarke
authors: C
authors: Millette
authors: Miriam
authors: M
authors: Sutovsky
authors: Chelsey
authors: C
authors: Kennedy
authors: Peter
authors: P
authors: Sutovsky
authors: Winston
authors: W
authors: Thompson
authors: Kelwyn
authors: K
authors: Thomas
mesh_terms: D000818:Animals; D005306:Fertilization / Q000502:physiology*; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels / Q000235:genetics / Q000502:physiology*; D008297:Male; D051379:Mice; D009154:Mutation; D060888:Real-Time Polymerase Chain Reaction; D013075:Sperm Capacitation / Q000502:physiology*; D013094:Spermatozoa / Q000502:physiology*
chemical_list: D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels; C497069:Kcnj6 protein, mouse