title: Secretory phospholipase A2 group IID Is involved in progesterone-induced acrosomal exocytosis of human spermatozoa.
abstract: Phospholipase A2 (PLA(2)) plays a major role during acrosomal  exocytosis (AE) in mammalian spermatozoa, but the identity of PLA(2)  subtypes present in spermatozoa remains elusive. This study explored whether  secretory PLA(2) Group IID (sPLA(2)-IID) isoform is present  in human spermatozoa and whether it is involved in AE. Localization and  expression of sPLA(2)-IID in human spermatozoa were explored by  immunofluorescence staining and Western blot analysis. Occurrence of AE was  evaluated by triple staining, and arachidonic acid (AA) levels were quantified  by gas chromatography-mass spectrometry. Sperm motion parameters and  hyperactivation were analyzed by computer-assisted sperm analysis.  sPLA(2)-IID was localized in the postacrosomal region of the head and  the midpiece of tail in human sperm. A 16-kd protein band was detected by  Western blotting in sperm extracts. Progesterone-induced AE was significantly  inhibited in a concentration-dependent manner using a sPLA(2)-IID  neutralizing antibody. The increase in AA levels seen during  progesterone-stimulated exocytosis was significantly abrogated by the  antibody. The sPLA(2)-IID antibody significantly inhibited  hyperactivation, sperm curvilinear velocity, and amplitude of lateral head  displacement, but it did not affect the proportion of motile sperm. In  conclusion, sPLA(2)-IID is present at the head and midpiece in the  human sperm, and activation of such sPLA(2)-IID seems to be involved  in AE. Therefore, sPLA(2)-IID isoform plays a functional role during  the AE in human sperm.
authors.affiliation: Unit of Reproductive Physiology, Zhejiang Academy of Medical Sciences, 182 Tian Mu Shan Rd, Hangzhou, Zhejiang 310013, China.
authors.forename: Kun
authors.initials: K
authors.lastname: Li
authors.forename: Jian-Yuan
authors.initials: JY
authors.lastname: Jin
authors.forename: Wen-Ying
authors.initials: WY
authors.lastname: Chen
authors.forename: Qi-Xian
authors.initials: QX
authors.lastname: Shi
authors.forename: Ya
authors.initials: Y
authors.lastname: Ni
authors.forename: Eduardo R S
authors.initials: ER
authors.lastname: Roldan
mesh_terms: D000177:Acrosome / Q000187:drug effects / Q000201:enzymology*; D020101:Acrosome Reaction / Q000187:drug effects; D057134:Antibodies, Neutralizing / Q000494:pharmacology; D016718:Arachidonic Acid / Q000378:metabolism; D015153:Blotting, Western; D005089:Exocytosis / Q000187:drug effects; D005455:Fluorescent Antibody Technique; D008401:Gas Chromatography-Mass Spectrometry; D054501:Group II Phospholipases A2 / Q000037:antagonists & inhibitors / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D008297:Male; D011374:Progesterone / Q000378:metabolism*; D032961:Sperm Midpiece / Q000187:drug effects / Q000201:enzymology*; D013081:Sperm Motility
chemical_list: D057134:Antibodies, Neutralizing; D016718:Arachidonic Acid; D011374:Progesterone; D054501:Group II Phospholipases A2; C516293:PLA2G2D protein, human