Alterations in the protein kinase C signaling activated by a parthenogenetic agent in oocytes from reproductively old mice.
To investigate the effect of female age on oocyte developmental competence, we focused on protein kinase C (PKC), a major component of the signalling pathway involved in oocyte activation, and put forward the hypothesis that, as it occurs in many organs and tissues, aging affects PKC function in mouse oocytes. Biochemical activity of PKC along with the expression and subcellular distribution of some PKC isoforms were monitored in young and old mouse oocytes parthenogenetically activated by SrCl(2). We found that PKC activity increased reaching a level that was lower in old compared to young oocytes in association with an incomplete translocation of PKCbetaI to the plasma membrane. Moreover, old oocytes exhibited a reduced expression of PKCbeta1 and PKCalpha at the protein level, without significant effects on the expression of the Ca(2+)-independent PKCdelta. Detectable amounts of PKCbeta1 mRNA were observed in young and old oocytes at GV stage with no difference between the two groups of age. When meiotic progression to anaphase II up to first cleavage were analyzed, a delay in meiosis resumption and significantly lower rates of pronuclei formation and first cleavage were observed in old compared to young oocytes. Moreover, we found that, in contrast to SrCl(2), PMA (12-O-tetradecanoyl phorbol-13-acetate), a PKC agonist, was ineffective in activating old oocytes. Present findings provide evidence that aging affects the correct storage and activation of some PKCs, functional components of the machinery involved in oocyte activation, and suggest that these changes may negatively influence the activation competence of old oocytes.
Carbone
M C
MC
Department of Biomedical Sciences and Technologies, University of L'Aquila, L'Aquila, Italy.
Tatone
C
C
D000367:Age Factors; D000818:Animals; D015153:Blotting, Western; D002462:Cell Membrane / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D005260:Female; D008540:Meiosis / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D018613:Microscopy, Confocal; D009865:Oocytes / Q000378:metabolism* / Q000502:physiology; D011493:Protein Kinase C / Q000378:metabolism*; D021381:Protein Transport / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D018709:Statistics, Nonparametric; D013324:Strontium / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D017931:DNA Primers; D011493:Protein Kinase C; C025700:strontium chloride; D013755:Tetradecanoylphorbol Acetate; D013324:Strontium