Activation of protein kinase C suppresses fragmentation of pig oocytes aged in vitro

Abstract

When cultured for an extended time, pig oocytes that matured in vitro to the stage of metaphase II undergo the complex process designated as ageing. Under our conditions, some pig oocytes aged 3 days remained at the stage of metaphase II (22%), but others underwent spontaneous parthenogenetic activation (45%), and still others perished through fragmentation (28%) or lysis (5%). Activation of protein kinases C (PKCs) using phorbol-12-myristate-13-acetate (PMA) protects oocytes from fragmentation. None of the oocytes were fragmented after 3 days of aging in 50 nM of PMA. A similar effect (8% of fragmented oocytes) was observed after a 3-day treatment of aging oocytes with 100 mM of 1-stearoyl-2arachidonoyl-sn-glycerol (STEAR). PMA and STEAR activate both calcium-dependent and calcium-independent PKCs. This combined effect on PKCs seems to be essential for the protection of oocytes from fragmentation. Neither the specific activator of calcium-dependent PKCs 1-oleoyl-2-acetyl-sn-glycerol (OLE) nor the specific activator of calcium-independent PKCs dipalmitoyl-L-a-phosphatidylinositol-3,4,5-triphosphate heptaammonium salt (DIPALM) suppressed the fragmentation of aging pig oocytes. Twenty-one percentage of oocytes fragmented when aged for 3 days in 10 mM OLE and 26% of aged oocytes fragmented in 100 nM of DIPALM. However, fragmentation was significantly suppressed to 7% when the oocytes were exposed to the combination of both 10 mM OLE and 100 nM DIPALM. Aging pig oocytes cultured for 1 day with PMA maintained a high capability of being parthenogenetically activated (86% of activated oocytes), using calcium ionophore with 6-dimethylaminopurine. Ageing oocytes treated with PMA also had high capability of cleavage (82%) after their artificial parthenogenetic activation. However, their ability to develop to the stage of blastocyst (12%) was suppressed when compared with oocytes activated immediately after their maturation (29%).

Sirt1 protects pig oocyte against in vitro aging

“…As shown in Figure A, there was no significant difference in maturation rate between controls and in vitro ‐aged oocytes, indicated by the first polar body (pb1) extrusion rate (79.9 ± 7.1 vs. 84.1 ± 2.3% control vs. 79.6 ± 4.0 % resveratrol treatment, P > 0.05), which is consistent with previous reports (Petr et al . ; Wu et al . ).…”

The effect of protein kinase C activator and nitric oxide donor on oocyte activation and cortical granule exocytosis in porcine eggs

“…To study the combined effect of an NO-donor and PKC-activators, some oocytes were also incubated for 10 h with SNAP (0.5 mM) together with PKC-activators at the same concentration as above: SNAP-PMA, SNAP-OAG and SNAP-DPAM groups. The concentrations of PKC-activators and the NO-donor were selected based on previous results (Petr et al, 2005 and2011). Since DMSO has been reported to induce a loss of electrodensity in pig CGs (Campagna et al, 2006), an aliquot of oocytes was also incubated for 10 h in a medium supplemented with 1% DMSO (DMSO group).…”

Rat eggs cannot wait: Spontaneous exit from meiotic metaphase‐II arrest

“…Interestingly, effects of postovulatory ageing (i.e. fragmentation and susceptibility to parthenogenetic activation) can be manipulated by activators of PKC or by regulation of MPF phosphorylation status (Kikuchi et al, 2000; Lee and Campbell, 2008; Petr et al, 2011). While postovulatory ageing can lead to spontaneous release from metaphase‐II arrest, the significance of postovulatory age in spontaneous rat egg activation has not been unequivocally proven (see discussion above).…”