title: Short-term cultivation of porcine cumulus cells influences the cyclin-dependent kinase 4 (Cdk4) and connexin 43 (Cx43) protein expression--a real-time cell proliferation approach.
abstract: The CC (cumulus cell) proliferation index in relation to the expression and distribution of Cdk4 and Cx43 proteins, which are crucial factors for oocyte maturation, was investigated. Cumulus-oocyte complexes (COCs) were recovered from pubertal crossbred Landrace gilts and treated with collagenase, and separated CCs were cultured in standard TCM199 medium for 44 h. At each step of in vitro cultivation (IVC) of CCs (0, 12, 24 and 44 h), a normalized proliferation index was assessed. Cdk4 and Cx43 protein expression and the CC-specific cellular distribution were analyzed by confocal microscopic observation. The normalized proliferation index (number of cells attached, measured by impedance) was increased in the first 12 h of IVC (P<0.01) and differed between 12 h and 24 h of cultivation (P<0.001). Later, between 24 h-44 h of IVC, the CC proliferation rate was stable, and no significant differences were observed. Based on the confocal microscopic observation, increased expression of both Cdk4 and Cx43 was found after 44 h of IVC compared with the expression of these proteins before IVC. Moreover, after IVC, a substantial translocation of Cdk4 and Cx43 was noted from the nucleus to the cytoplasm of CCs. In conclusion, it was demonstrated for the first time that CCs can be cultured in vitro separately without oocytes and that the proliferation index was significantly increased in the first 12 h of IVC, which may reflect the process of ordinary cumulus cell expansion. Furthermore, the expression of both Cdk4 and Cx43 in CCs suggested that these proteins may be regarded as markers not only of proper oocyte maturation but also of CC differentiation. Translocation of these proteins into the cytoplasm of CCs after 44 h of IVC may be related to the expansion process.
authors.affiliation: Department of Histology and Embryology, Poznań University of Medical Sciences, 60-781 Poznań, Poland.
authors.forename: Bartosz
authors.initials: B
authors.lastname: Kempisty
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Ziółkowska
authors.forename: Hanna
authors.initials: H
authors.lastname: Piotrowska
authors.forename: Sylwia
authors.initials: S
authors.lastname: Ciesiółka
authors.forename: Paweł
authors.initials: P
authors.lastname: Antosik
authors.forename: Dorota
authors.initials: D
authors.lastname: Bukowska
authors.forename: Piotr
authors.initials: P
authors.lastname: Zawierucha
authors.forename: Magdalena
authors.initials: M
authors.lastname: Woźna
authors.forename: Jędrzej M
authors.initials: JM
authors.lastname: Jaśkowski
authors.forename: Klaus P
authors.initials: KP
authors.lastname: Brüssow
authors.forename: Michał
authors.initials: M
authors.lastname: Nowicki
authors.forename: Maciej
authors.initials: M
authors.lastname: Zabel
mesh_terms: D000818:Animals; D048708:Cell Growth Processes / Q000502:physiology; D018031:Connexin 43 / Q000096:biosynthesis*; D054885:Cumulus Cells / Q000166:cytology* / Q000201:enzymology / Q000378:metabolism*; D051358:Cyclin-Dependent Kinase 4 / Q000096:biosynthesis*; D005260:Female; D018613:Microscopy, Confocal / Q000662:veterinary; D013552:Swine / Q000378:metabolism / Q000502:physiology*
chemical_list: D018031:Connexin 43; D051358:Cyclin-Dependent Kinase 4