title: Glycogen synthase kinase 3 regulates acrosomal exocytosis in mouse spermatozoa via dynamin phosphorylation.
abstract: The dynamin family of GTPases has been implicated as novel regulators of the acrosome reaction, a unique exocytotic event that is essential for fertilization. Dynamin activity during the acrosome reaction is accompanied by phosphorylation of key serine residues. We now tested the hypothesis that glycogen synthase kinase 3 (GSK3) is the protein kinase responsible for dynamin phosphorylation at these phosphosites in mouse spermatozoa. Pharmacologic inhibition of GSK3 in mature mouse spermatozoa (CHIR99021: IC50 = 6.7 nM) led to a significant reduction in dynamin phosphorylation (10.3% vs. 27.3%; P < 0.001), acrosomal exocytosis (9.7% vs. 25.7%; P < 0.01), and in vitro fertilization (53% vs. 100%; P < 0.01). GSK3 was shown to be present in developing germ cells where it colocalized with dynamin in the peri-acrosomal domain. However, additional GSK3 was acquired by maturing mouse spermatozoa within the male reproductive tract, via a novel mechanism involving direct interaction of sperm heads with extracellular structures known as epididymal dense bodies. These data reveal a novel mode for the cellular acquisition of a protein kinase and identify a key role for GSK3 in the regulation of sperm maturation and acrosomal exocytosis.
authors: *School of Environmental and Life Sciences, Discipline of Biological Sciences, and School of Environmental and Life Sciences, Discipline of Chemistry, The University of Newcastle, Callaghan, New South Wales, Australia; and Children's Medical Research Institute, The University of Sydney, Westmead, New South Wales, Australia.
authors: Andrew T
authors: AT
authors: Reid
authors: *School of Environmental and Life Sciences, Discipline of Biological Sciences, and School of Environmental and Life Sciences, Discipline of Chemistry, The University of Newcastle, Callaghan, New South Wales, Australia; and Children's Medical Research Institute, The University of Sydney, Westmead, New South Wales, Australia.
authors: Amanda L
authors: AL
authors: Anderson
authors: *School of Environmental and Life Sciences, Discipline of Biological Sciences, and School of Environmental and Life Sciences, Discipline of Chemistry, The University of Newcastle, Callaghan, New South Wales, Australia; and Children's Medical Research Institute, The University of Sydney, Westmead, New South Wales, Australia.
authors: Shaun D
authors: SD
authors: Roman
authors: *School of Environmental and Life Sciences, Discipline of Biological Sciences, and School of Environmental and Life Sciences, Discipline of Chemistry, The University of Newcastle, Callaghan, New South Wales, Australia; and Children's Medical Research Institute, The University of Sydney, Westmead, New South Wales, Australia.
authors: Eileen A
authors: EA
authors: McLaughlin
authors: *School of Environmental and Life Sciences, Discipline of Biological Sciences, and School of Environmental and Life Sciences, Discipline of Chemistry, The University of Newcastle, Callaghan, New South Wales, Australia; and Children's Medical Research Institute, The University of Sydney, Westmead, New South Wales, Australia.
authors: Adam
authors: A
authors: McCluskey
authors: *School of Environmental and Life Sciences, Discipline of Biological Sciences, and School of Environmental and Life Sciences, Discipline of Chemistry, The University of Newcastle, Callaghan, New South Wales, Australia; and Children's Medical Research Institute, The University of Sydney, Westmead, New South Wales, Australia.
authors: Phillip J
authors: PJ
authors: Robinson
authors: *School of Environmental and Life Sciences, Discipline of Biological Sciences, and School of Environmental and Life Sciences, Discipline of Chemistry, The University of Newcastle, Callaghan, New South Wales, Australia; and Children's Medical Research Institute, The University of Sydney, Westmead, New South Wales, Australia.
authors: R John
authors: RJ
authors: Aitken
authors: *School of Environmental and Life Sciences, Discipline of Biological Sciences, and School of Environmental and Life Sciences, Discipline of Chemistry, The University of Newcastle, Callaghan, New South Wales, Australia; and Children's Medical Research Institute, The University of Sydney, Westmead, New South Wales, Australia brett.nixon@newcastle.edu.au.
authors: Brett
authors: B
authors: Nixon
mesh_terms: D020101:Acrosome Reaction / Q000187:drug effects / Q000502:physiology; D000818:Animals; D051360:Cyclin-Dependent Kinase 5 / Q000378:metabolism; D034284:Dynamin I / Q000737:chemistry / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004822:Epididymis / Q000378:metabolism / Q000648:ultrastructure; D005089:Exocytosis / Q000502:physiology; D005260:Female; D005307:Fertilization in Vitro; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008297:Male; D051379:Mice; D016253:Microscopy, Immunoelectron; D010766:Phosphorylation; D011374:Progesterone / Q000494:pharmacology; D013077:Sperm Head / Q000378:metabolism; D013079:Sperm Maturation / Q000187:drug effects / Q000502:physiology; D013094:Spermatozoa / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D004791:Enzyme Inhibitors; D011374:Progesterone; D051360:Cyclin-Dependent Kinase 5; C495906:Cdk5 protein, mouse; D038362:Glycogen Synthase Kinase 3; D034284:Dynamin I
keywords: acrosome reaction; epididymal dense bodies; sperm maturation