title: An anti-actin monoclonal antibody inhibits the zona pellucida-induced acrosome reaction and hyperactivated motility of human sperm.
abstract: We report an inhibitory effect of an anti-actin monoclonal antibody (mAb) on the human zona pellucida (ZP)-induced acrosome reaction (AR). Motile sperm were incubated with native human ZP for 2 h in medium containing either the anti-actin mAb, an irrelevant control mAb or cytochalasins B or D (40 micromol/l). Sperm bound to the ZP were recovered and the AR was determined by fluorescein-labelled Pisum Sativum agglutinin. Anti-mouse immunoglobulin G (mIgG) Dynabeads, immunofluorescence and immunogold were used to detect the location of the anti-actin mAb in sperm. The anti-actin mAb significantly inhibited the ZP-induced AR (equivalent to cytochalasins), the ionophore A23187-induced AR and hyperactivation of sperm in medium. After incubation with anti-actin mAb, anti-mIgG beads bound to the head of >50% of sperm recovered after binding to the ZP and 10% of sperm remaining in the medium. The proportion of sperm that bound anti-mIgG beads after recovery from binding to the ZP in the presence of the anti-actin mAb was significantly correlated with the ZP-induced AR in the absence of the antibody. Immunofluorescence and immunogold demonstrated entry of the anti-actin mAb into sperm. This study suggests that the sperm plasma membrane becomes permeable to the anti-actin mAb during capacitation and initiation of the AR.
authors.affiliation: Department of Obstetrics and Gynecology, Anatomy and Cell Biology and Medicine, University of Melbourne, Royal Women's Hospital, Melbourne, Australia. dyl@unimelb.edu.au
authors.forename: D Y
authors.initials: DY
authors.lastname: Liu
authors.forename: M
authors.initials: M
authors.lastname: Martic
authors.forename: G N
authors.initials: GN
authors.lastname: Clarke
authors.forename: I
authors.initials: I
authors.lastname: Grkovic
authors.forename: C
authors.initials: C
authors.lastname: Garrett
authors.forename: M E
authors.initials: ME
authors.lastname: Dunlop
authors.forename: H W G
authors.initials: HW
authors.lastname: Baker
mesh_terms: D020101:Acrosome Reaction / Q000502:physiology*; D000199:Actins / Q000276:immunology / Q000378:metabolism*; D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism*; D000001:Calcimycin / Q000494:pharmacology; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D003571:Cytochalasin B / Q000494:pharmacology; D015638:Cytochalasin D / Q000494:pharmacology; D005260:Female; D006801:Humans; D007476:Ionophores / Q000494:pharmacology; D008297:Male; D051379:Mice; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D013081:Sperm Motility / Q000502:physiology*; D013094:Spermatozoa / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D013223:Statistics as Topic; D015044:Zona Pellucida / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D000199:Actins; D000911:Antibodies, Monoclonal; D007476:Ionophores; D019384:Nucleic Acid Synthesis Inhibitors; D015638:Cytochalasin D; D000001:Calcimycin; D003571:Cytochalasin B