title: Expression and intracytoplasmic distribution of staufen and calreticulin in maturing human oocytes.
abstract: OBJECTIVE
  In this study we hypothesized that the mRNA vector Staufen mediates RNA relocalization during meiotic maturation, and by virtue of its interactions with endoplasmic reticulum, provides a possible mechanism by which protein synthesis is regulated.
  
  
  METHODS
  We assessed the expression of staufen (STAU) and calreticulin (CALR), the latter adopted as a marker of the endoplasmic reticulum, in human oocytes at different stages of maturation: GV, metaphase MI and MII. Oocytes were subjected to polymerase chain reaction in order to investigate the expression of STAU and CALR. The corresponding protein products were identified by immunofluorescence and confocal laser scanning microscopy.
  
  
  RESULTS
  STAU and CALR were constantly expressed and selectively localized during oocyte maturation. At the GV stage the both proteins displayed a dispersed distribution localization throughout the cytoplasm. Progressing to the MII stage, STAU tended to compartmentalize towards the cortical area of the oocyte clustering in granules of larger sizes. At the MII stage, CALR assumed a pattern reminiscent and possibly coincident with the position of the meiotic spindle.
  
  
  CONCLUSIONS
  The changing pattern of STAU distribution during meiotic maturation of human oocytes implicates a novel mechanism for the regulation of protein synthesis based on mRNA localization. Moreover, the unique disposition of CALR at the MII spindle uncovers a physical interaction with endoplasmic reticulum that may mediate cytoskeletal remodelling during oocyte maturation.
authors.affiliation: Department of Ob/Gyn IVF Unit, San Raffele Scientific Institute, Milan, Italy, desantis.lucia@hsr.it.
authors.forename: L
authors.initials: L
authors.lastname: De Santis
authors.forename: F
authors.initials: F
authors.lastname: Gandolfi
authors.forename: G
authors.initials: G
authors.lastname: Pennarossa
authors.forename: S
authors.initials: S
authors.lastname: Maffei
authors.forename: E
authors.initials: E
authors.lastname: Gismano
authors.forename: G
authors.initials: G
authors.lastname: Intra
authors.forename: M
authors.initials: M
authors.lastname: Candiani
authors.forename: T A L
authors.initials: TA
authors.lastname: Brevini
mesh_terms: D037282:Calreticulin / Q000235:genetics / Q000378:metabolism*; D015925:Cryopreservation; D003593:Cytoplasm / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006801:Humans; D008540:Meiosis / Q000235:genetics; D009865:Oocytes / Q000378:metabolism*; D009866:Oogenesis / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D008941:Spindle Apparatus / Q000235:genetics / Q000378:metabolism
chemical_list: D037282:Calreticulin; D003598:Cytoskeletal Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C492185:STAU1 protein, human