Mitochondrial dynamics and their intracellular traffic in porcine oocytes

Abstract

SummaryMeiotic maturation of oocytes requires a variety of ATP-dependent reactions, such as germinal vesicle breakdown, spindle formation, and rearrangement of plasma membrane structure, which is required for fertilization. Mitochondria are accordingly expected be localized to subcellular sites of energy utilization. Although microtubule-dependent cellular traffic for mitochondria has been studied extensively in cultured neuronal (and some other somatic) cells, the molecular mechanism of their dynamics in mammalian oocytes at different stages of maturation remains obscure. The present work describes dynamic aspects of mitochondria in porcine oocytes at the germinal vesicle stage. After incubation of oocytes with MitoTracker Orange followed by centrifugation, mitochondria-enriched ooplasm was obtained using a glass needle and transferred into a recipient oocyte. The intracellular distribution of the fluorescent mitochondria was then observed over time using a laser scanning confocal microscopy equipped with an incubator. Kinetic analysis revealed that fluorescent mitochondria moved from central to subcortical areas of oocytes and were dispersed along plasma membranes. Such movement of mitochondria was inhibited by either cytochalasin B or cytochalasin D but not by colcemid, suggesting the involvement of microfilaments. This method of visualizing mitochondrial dynamics in live cells permits study of the pathophysiology of cytoskeleton-dependent intracellular traffic of mitochondria and associated energy metabolism during meiotic maturation of oocytes.

C-phycocyanin protects against low fertility by inhibiting reactive oxygen species in aging mice

“…After PC administration, 88.95% of oocytes were evenly distributed around mitochondria, which was similar to the oocytes in control (Figure 6C and 6D , Table S6-2 ). Mitochondrial distribution is a cytoskeleton-dependent intracellular traffic behavior [ 41 ]. The distribution of mitochondria in oocytes determines spindle translocation [ 42 ].…”

“…We speculate that PC improved mitochondrial distribution mainly via its inhibition of ROS. A previous study reported that mitochondrial distribution is a cytoskeleton-dependent intracellular traffic behavior that relies on microtubule organization [ 41 ]. The disruption of mitochondrial distribution is therefore a consequence of malfunctioned cytoskeleton.…”

Phycocyanin Improves Reproductive Ability in Obese Female Mice by Restoring Ovary and Oocyte Quality

“…However, obesity induces an abnormal distribution pattern for mitochondria in oocytes, and increases compensatory responses to oxidative stress, mitochondrial biogenesis, and mtDNA replication, which eventually leads to mitochondrial dysfunction (Grindler and Moley, 2013). Previous studies have reported that the distribution of mitochondria is cytoskeleton-dependent and depends on microtubule organization (Yamochi et al, 2016). Therefore, the disruption in the distribution of mitochondria is likely the result of cytoskeletal disorders in HFD mice (Islam et al, 2016).…”

Mitochondria Synthesize Melatonin to Ameliorate Its Function and Improve Mice Oocyte’s Quality under in Vitro Conditions

“…Indeed, melatonin supplementation significantly increased mtDNA copy number in MII-stage oocyte and influenced the degree of mitochondria granulated clustering ( Figure 4 A,B). Though the mitochondria distribution is a dynamic process [ 44 ], it is an important indicator of oocyte quality. A uniform, granulated distribution of active mitochondria in oocyte maturation and the early embryo specific period is necessary [ 45 , 46 , 47 ].…”