title: Light-mediated activation reveals a key role for protein kinase A and sarcoma protein kinase in the development of sperm hyper-activated motility.
abstract: BACKGROUND
  Hyper-activated motility (HAM) is part of the sperm capacitation process, which is necessary for fertilization. In this study, we investigated the effect of visible light on sperm motility and hyperactivation and evaluated pathways mediating these effects.
  
  
  METHODS
  Human sperm (1 × 10⁷ cells/ml) in capacitation media were irradiated for 3 min with 40 mW/cm² visible light (400-800 nm with maximum energy at 600 nm). Sperm motility was assessed and analyzed by computer-assisted sperm analysis. The involvement of sperm capacitation factors was investigated as follows. The generation of reactive oxygen species (ROS) was measured using 20,70-dichlorofluorescein diacetate. Protein kinase A (PKA) and sarcoma protein kinase (Src) activity were measured using western blot analysis and inhibited using 50 µM H89 and 10 µM PP2, respectively. Soluble adenlyl cyclase was inhibited using 20 µM 2-OH-Estradiol. The intracellular concentration of free Ca(2+) was assessed using the fluorescent calcium indicator, Fluo-4/AM. Sperm DNA fragmentation was determined using the sperm chromatin dispersion test.
  
  
  RESULTS
  Light irradiation of human sperm caused a significant increase in hyper-HAM but not total motility. The production of ROS and activation of soluble adenylyl cyclase and PKA mediated the effect of light on HAM. Light irradiation also activated Src, and inhibition of Src significantly reduced the effect of light on HAM. Light irradiation caused a rapid increase in intracellular Ca²⁺ concentration and the increase in HAM was significantly reduced when voltage-dependent-Ca²⁺-channel activity was blocked or when Ca²⁺-deficient medium was used.
  
  
  CONCLUSIONS
  Light irradiation of human sperm for a short time causes a significant increase in HAM in a mechanism mediated by ROS production, activation of PKA, Src and Ca²⁺ influx.
authors.affiliation: The Mina & Everard Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 52900, Israel.
authors.forename: S
authors.initials: S
authors.lastname: Shahar
authors.forename: A
authors.initials: A
authors.lastname: Wiser
authors.forename: D
authors.initials: D
authors.lastname: Ickowicz
authors.forename: R
authors.initials: R
authors.lastname: Lubart
authors.forename: A
authors.initials: A
authors.lastname: Shulman
authors.forename: H
authors.initials: H
authors.lastname: Breitbart
mesh_terms: D020013:Calcium Signaling; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology*; D053938:DNA Fragmentation; D006801:Humans; D008027:Light; D008297:Male; D017382:Reactive Oxygen Species / Q000378:metabolism; D013075:Sperm Capacitation / Q000528:radiation effects*; D013081:Sperm Motility / Q000502:physiology / Q000528:radiation effects; D013094:Spermatozoa / Q000502:physiology / Q000528:radiation effects*; D019061:src-Family Kinases / Q000502:physiology*
chemical_list: D017382:Reactive Oxygen Species; D000242:Cyclic AMP; D019061:src-Family Kinases; D017868:Cyclic AMP-Dependent Protein Kinases