Endoplasmic reticulum distribution during bovine oocyte activation is regulated by protein kinase C via actin filaments

Abstract

Fertilization‐induced [Ca2+]i oscillations generally depend on the release of calcium ions from the endoplasmic reticulum (ER). Since ER is the main store of calcium ions, it plays an important role in oocyte fertilization. However, the mechanism of ER organization at oocyte activation is unknown. Here, we show that protein kinase C (PKC) is involved in ER distribution during bovine oocyte activation, but not involved in cell cycle resumption and spindle organization. Actin filaments were affected by PKC pharmacological inhibition. In addition, similar to PKC results, the actin‐depolymerizing drug cytochalasin B affected the ER distribution during oocyte activation. Specifically, we have demonstrated that ER organization during bovine oocyte activation is regulated by PKC possibly through its action on actin filaments regulation. Taken together, the results presented here provide further information on the pathway involved in the regulation of ER organization during oocyte activation and new insight into the functional role of PKC and actin filaments during this process.

A novel automated image analysis pipeline for quantifying morphological changes to the endoplasmic reticulum in cultured human cells

“…Here we show that treatment with a low concentration of palmitic acid increases the area of SER polygons. Similarly, actin filaments have a conserved role in maintenance of the ER network [35,64,65] and treatment with the actin-depolymerising drug cytochalasin B alters ER content in developing oocytes (resulting in ER accumulation at the cortical region during oocyte activation) [37,66]. Consistent with this, our pipeline was able to detect that brief treatment with cytochalasin B induces ER reorganisation with a significant increase in the area of SER polygons.…”

“…Several studies have reported alteration of ER organisation by different chemical compounds [32,37,49]. A limitation of all these studies however is that they employed qualitative analysis and did not enable an objective description of the changes observed.…”

“…Maintaining ER organisation is vital to preserve the essential functions carried out by the ER [11]. Altered ER morphology has been reported in the context of several pathological conditions, for example (1) during viral infection viruses co-opt host cell membranes for their replication and in many cases remodel the ER membrane through interactions with ER proteins creating so-called replication factories (RFs), which promote enrichment of cellular and viral components necessary for viral replication [26,27]; (2) the presence of protein aggregates, the hallmark of many neurodegenerative diseases, is linked to alteration of ER organisation by increased presence of enlarged peripheral ER sheets [28,29]; (3) defects in misfolded protein clearance by impaired ER-associated degradation, or accumulation of misfolded proteins in cystic fibrosis cells, both result in dilated ER elements [30,31]; (4) the cytotoxic effects of several chemicals have been linked to changes on ER structure [32][33][34][35][36][37]; and (5) mutations in ER-shaping proteins, known to cause neurodegenerative disorders such as hereditary spastic paraplegias (HSPs), have been shown to disrupt ER organisation in both in vitro and in vivo models [24,[38][39][40].…”

Differential Transcript Profiles in Cumulus-Oocyte Complexes Originating from Pre-Ovulatory Follicles of Varied Physiological Maturity in Beef Cows

“…This subclass is known to have an important role in oocyte maturation, meiotic resumption, and fertilization [89][90][91]. Protein kinase C modulates intracellular calcium oscillations, within the oocyte, following fertilization, leading to cortical granule release and a subsequent polyspermy block [90][91][92]. Calcium oscillations at the time of fertilization have also been demonstrated to increase mitochondrial ATP production to support metabolic requirements of fertilization [93].…”

Ultra-fast vitrification: Minimizing toxicity of cryoprotective agents and osmotic stress in mouse oocyte cryopreservation

“…Additionally, the cortical region of mature oocytes, characterized by cluster formation, showed a similar distribution pattern between UF-VIT and control group. These clusters contain inositol 1,4,5-trisphosphate (IP 3 ) receptors (IP 3 R1), which are activated by sperm entry and play a role in [Ca 2+ ]i release and periodic calcium oscillation, thus contributing to oocyte activation (15,(31)(32)(33)(34).…”