title: Presence, localization, and origin of clusterin in normal human spermatozoa.
abstract: OBJECTIVE
  Clusterin in mammalian semen is a secretory form of clusterin (sCLU) with the heterodimeric structure. It is secreted by the epididymis and seminal vesicle. It is generally agreed that clusterin mainly exists on the surface of abnormal spermatozoa and is implicated in decreased sperm motility, sperm aggregation and infertility. However, few studies observe clusterin in normal spermatozoa, which is presumed to be a novel form. Up to now, the systematical information about the presence, localization, origin and function of clusterin in normal human spermatozoa has yet not been established. The aim of our current study is to systematically research clusterin in normal human spermatozoa.
  
  
  METHODS
  We detected the presence of clusterin via western blot, explored the localization of clusterin using immunofluorescence, and investigated the origin and distribution of clusterin in human testis by western blot and immunohistochemistry.
  
  
  RESULTS
  We found native clusterin in the inner plasma membrane of normal human spermatozoa. It was derived from the testis and showed similar molecular weight and heterodimeric structure compared with sCLU in semen and on the surface of abnormal spermatozoa.
  
  
  CONCLUSIONS
  Clusterin in normal spermatozoa should be self-synthesized during the later stage of spermatogenesis. The different localization and origin suggested that the clusterin observed by us may be a novel form compared with conventional sCLU on the surface of abnormal spermatozoa.
authors.affiliation: Department of Urology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China.
authors.forename: Zhijian
authors.initials: Z
authors.lastname: Han
authors.forename: Zengjun
authors.initials: Z
authors.lastname: Wang
authors.forename: Gong
authors.initials: G
authors.lastname: Cheng
authors.forename: Bianjiang
authors.initials: B
authors.lastname: Liu
authors.forename: Pengchao
authors.initials: P
authors.lastname: Li
authors.forename: Jie
authors.initials: J
authors.lastname: Li
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Changjun
authors.initials: C
authors.lastname: Yin
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
mesh_terms: D015153:Blotting, Western; D002462:Cell Membrane / Q000737:chemistry; D051152:Clusterin / Q000737:chemistry* / Q000302:isolation & purification*; D005455:Fluorescent Antibody Technique; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008297:Male; D012708:Sertoli Cells / Q000737:chemistry; D013081:Sperm Motility; D013091:Spermatogenesis; D013094:Spermatozoa / Q000737:chemistry*; D013737:Testis / Q000737:chemistry
chemical_list: C495242:CLU protein, human; D051152:Clusterin