title: Expression and immunolocalization of the calpain-calpastatin system in the human oocyte.
abstract: OBJECTIVE
  To investigate the expression of the calpain-calpastatin system in the human oocyte.
  
  
  METHODS
  The expression of the calpain-calpastatin system was determined by immunohistochemistry and immunoblot analysis.
  
  
  METHODS
  Academic research laboratory.
  
  
  METHODS
  Twenty Israeli women who underwent IVF for fertility problems.
  
  
  METHODS
  Oocytes that had no pronuclei 24 hours after insemination by either conventional IVF or intracytoplasmic sperm injection were retrieved for the study.
  
  
  METHODS
  Analysis of calpain isoforms (m, mu) and calpastatin distribution within the human oocyte.
  
  
  RESULTS
  Western blot analysis confirmed the expression of calpain and calpastatin. Immunohistochemistry of fixed, permeabilized oocytes exhibited localization of both calpains to the cortical region of the oocyte, as well as the cytosol. Calpastatin seemed to be distributed throughout the cytosol, with a marked accumulation in the cell membrane. We have demonstrated a negative correlation between the occurrence of cortical granule exocytosis and the stability of the metaphase plate.
  
  
  CONCLUSIONS
  A complete calpain-calpastatin system is expressed in the human oocyte and might play a role in the various calcium-mediated processes occurring during activation of human oocytes.
authors.affiliation: Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel-Aviv, Israel.
authors.forename: Irit
authors.initials: I
authors.lastname: Ben-Aharon
authors.forename: Dalit
authors.initials: D
authors.lastname: Ben-Yosef
authors.forename: Ami
authors.initials: A
authors.lastname: Amit
authors.forename: Ruth
authors.initials: R
authors.lastname: Shalgi
mesh_terms: D015153:Blotting, Western; D002135:Calcium-Binding Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D002154:Calpain / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000737:chemistry / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000502:physiology; D015853:Cysteine Proteinase Inhibitors / Q000096:biosynthesis* / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D006801:Humans; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D009865:Oocytes / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism / Q000502:physiology
chemical_list: D002135:Calcium-Binding Proteins; D015853:Cysteine Proteinase Inhibitors; D007527:Isoenzymes; C033668:calpastatin; D002154:Calpain