Dynamic changes of the Golgi apparatus during bovine in vitro oocyte maturation

Abstract

<jats:p>For successful fertilization by the male gamete, oocyte cytoplasmic organelles such as the Golgi apparatus have to undergo specific changes: the entire process is known as cytoplasmic maturation. The goal of this study was to unravel the dynamics of the Golgi apparatus in bovine oocytes at critical stages of<jats:italic>in vitro</jats:italic>maturation, i.e. germinal vesicle (GV), GV breakdown (GVBD), metaphase I (MI) and metaphase II, and to investigate the role of various molecules critically involved therein. The cytoplasmic distribution of proteins was assessed by immunocytochemistry and laser confocal microscopy. We applied specific inhibitors, including nocodazole to unravel the functional role of the microtubular elements; sodium orthovanadate, which primarily inhibits cytoplasmic dynein ATPase activity; monastrol which inhibits the kinesin EG5; and roscovitine to inhibit the kinase cyclin-dependent kinase 2A (CDC2A). Prior to GVBD, the Golgi apparatus was translocated from the centre of the cytoplasm to the cortical area in the periphery, where it underwent fragmentation. A second translocation was observed between GVBD and MI stages, when the Golgi apparatus was moved from the cortex to the centre of the cytoplasm. Incubation with the specific inhibitors revealed that microtubules played an active role in the final localization at GVBD, while CDC2A was essential for Golgi fragmentation at GVBD stage. This partitioning was a precondition for the second movement. In conclusion, for the first time we show basic mechanisms critically involved in the regulation of the dynamic changes of Golgi apparatus during meiosis of the bovine oocyte.</jats:p>

Behaviour of cytoplasmic organelles and cytoskeleton during oocyte maturation

“…Incubation with specific inhibitors revealed that microtubules plays an active role in the final localization at GVBD, while cyclin-dependent kinase 2A is essential for Golgi fragmentation at GVBD stage in bovine oocytes (Racedo et al, 2012). Notably, GM130, a marker of the Golgi apparatus, colocalizes with Sec23, a marker for endoplasmic reticulum (ER) vesicle export sites, suggesting that the Golgi apparatus is not only fragmented, but it is also translocalized into the ER during bovine oocyte maturation (Payne and Schatten, 2003).…”

Metabolic Cooperation in the Ovarian Follicle

“…The first meiotic division includes the formation of the metaphase I spindle and its migration to the cortex in an actin-dependent manner with subsequent polar body extrusion (FitzHarris et al 2007, Maro et al 1984, Maro and Verlhac 2002. A dramatic reorganization of the endomembrane system occurs; similarly the Golgi apparatus undergoes a substantial re-organization between the germinal vesicle (GV) stage and the metaphase II (MII) stage (Moreno et al 2002, Racedo et al 2012. During the oocyte maturation a reorganization of the endoplasmic reticulum (ER) occurs including a remodelling of the ER into the characteristic cortical clusters.…”

Golgi Apparatus and Endoplasmic Reticulum Dynamic during Meiotic Development in Canine Oocytes

“…; Racedo et al. ). These trafficking events include a flux of newly synthesized proteins and lipids coming from the ER to the plasma membrane and the extracellular medium, as well as the synthesis of many lipid species (Vinke et al.…”

“…The cytoplasmic movements and rearrangements of components within the cytoplasm include dynamic changes in the distribution and integrity of the Golgi apparatus (GA) and endoplasmic reticulum (ER) (Vinke et al 2011). This GA-ER system plays an essential role in intracellular signalling and trafficking events distribution through a complex multi-step process, regulated by fusion and fission events (Moreno et al 2002;Racedo et al 2012). These trafficking events include a flux of newly synthesized proteins and lipids coming from the ER to the plasma membrane and the extracellular medium, as well as the synthesis of many lipid species (Vinke et al 2011).…”