Centrosome abnormalities during porcine oocyte aging

Abstract

Centrosomes are critically important for maintaining meiotic spindle integrity in the meiosis II (MII) stage where oocytes are arrested in most mammalian species before fertilization takes place. In women of advanced ages or during in vitro fertilization (IVF) procedures, aneuploidy is frequently seen as a result of oocyte aging, which is strongly related to centrosome instability. Abnormal distribution of centrosomes and microtubules has been reported in aging human and mouse oocytes. This study reports the dynamic changes of centrosomes and the microtubule cytoskeleton in porcine oocytes during aging and treatment by caffeine to restore spindle integrity in aging oocytes. We tested the effects of caffeine on the MII spindle with focus on microtubules and on the centrosome proteins gamma-tubulin and NuMA (nuclear mitotic apparatus protein). The results revealed that in porcine oocytes aged for 48 hr., centrosomes were absent and spindles became abnormal and disorganized; however, caffeine could prevent these changes or restore centrosome integrity in the meiotic spindle poles and displayed similar MII spindles as those seen in fresh oocytes.

New insights into the role of centrosomes in mammalian fertilization and implications for ART

“…The MI and MII spindles are highly susceptible to environmental influences (reviewed in ) including aging (Miao et al 2009a(Miao et al , 2009b Miao et al (2009b)). It has generally been observed that in oocytes affected by aging or by environmental factors, centrosomes disintegrate from the MII spindle poles followed by loss of microtubule tension, loss of microtubule connections to the kinetochores, and MII spindle deterioration (reviewed in Miao et al (2009b)).…”

Evaluation of maturation competence of metaphase II oocytes in mice based on the distance between pericentriolar materials of meiotic spindle

“…In phase II, this bipolar configuration could be stabilized, thereby reducing the distance between 2 points of PCMs and affording maturation competence to the oocytes. However, it has been reported that metaphase spindle in over-matured oocytes exhibit characteristic patterns of centrosome deterioration and frequently display tri-or multipolar spindle poles; these oocytes could not be fertilized, or alternatively, the fertilized oocytes exhibited aneuploidy or developmental abnormalities [48,49]. It has been shown that MAPK activities gradually decrease in aging oocytes.…”

Centrosome Dysfunction and Senescence: Coincidence or Causality?

“…Interestingly, increasing evidence also supports a link between centrosome dysfunction and senescence, suggesting that this organelle could directly or indirectly play a role in aging. Aged porcine oocytes exhibit a loss of γ-tubulin and NuMA, critical components of the PCM at the meiotic spindle, giving rise to abnormal and disorganized spindles [31]. Similarly, microtubules are gradually lost from the spindle of aged mouse oocytes, a feature highly suggestive of compromised centrosome structure and function [32,33].…”