scholarly journals Regulation of [Ca2+]i Oscillations and Mitochondrial Activity by Various Calcium Transporters in Mouse Oocytes

2020 ◽  
Author(s):  
Feng Wang ◽  
Ang Li ◽  
Tie-Gang Meng ◽  
Li-Juan Wang ◽  
Yi Hou ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Potential ◽  
Calcium Channel ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Membrane ◽  
Transient Receptor Potential ◽  
Critical Role ◽  
Receptor Potential ◽  
Mitochondrial Activity ◽  
Oocyte Activation

Abstract Oocyte activation inefficiency is one of the reasons for female infertility and Ca 2+ functions play a critical role in the regulation of oocyte activation. We used various inhibitors of Ca 2+ channels and pumps located on the plasma membrane, the endoplasmic reticulum or both, including sarcoplasmic/endoplasmic reticulum Ca 2+ ATPases (SERCAs, the main Ca 2+ pumps which decrease the intracellular Ca 2+ level by reaccumulating Ca 2+ into the sarcoplasmic reticulum), transient receptor potential (TRP) ion channel subfamily member 7 (TRPM7, a Ca 2+ /Mg 2+ -permeable non-selective cation channel), T-type Ca 2+ channels and calcium channel Orai1, to investigate their roles in[Ca 2+ ] i oscillation patterns and mitochondrial membrane potential during oocyte activation by real-time recording. Our results show that SERCAs, TRPM7 and T-type Ca 2+ channels are important for initiation and maintenance of [Ca 2+ ] i oscillations, which is required for mitochondrial membrane potential changes during oocyte activation, as well as for subsequent pronuclear formation and transition to embryo development, while the function of calcium channel Orai1 is not confirmed. Increasing the knowledge of these transporters may provide a theoretical basis for improving oocyte activation in human assisted reproduction clinics.

scholarly journals Genomic instability induced by radiation-mimicking chemicals is not associated with persistent mitochondrial degeneration

2021 ◽  
Author(s):  
Luukkonen Jukka ◽  
Höytö Anne ◽  
Sokka Miiko ◽  
Syväoja Juhani ◽  
Juutilainen Jukka ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Ionizing Radiation ◽  
Genomic Instability ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Function ◽  
Mitochondrial Membrane ◽  
Neuroblastoma Cells ◽  
Superoxide Production ◽  
Mitochondrial Activity ◽  
Mitochondrial Superoxide

AbstractIonizing radiation has been shown to cause induced genomic instability (IGI), which is defined as a persistently increased rate of genomic damage in the progeny of the exposed cells. In this study, IGI was investigated by exposing human SH-SY5Y neuroblastoma cells to hydroxyurea and zeocin, two chemicals mimicking different DNA-damaging effects of ionizing radiation. The aim was to explore whether IGI was associated with persistent mitochondrial dysfunction. Changes to mitochondrial function were assessed by analyzing mitochondrial superoxide production, mitochondrial membrane potential, and mitochondrial activity. The formation of micronuclei was used to determine immediate genetic damage and IGI. Measurements were performed either immediately, 8 days, or 15 days following exposure. Both hydroxyurea and zeocin increased mitochondrial superoxide production and affected mitochondrial activity immediately after exposure, and mitochondrial membrane potential was affected by zeocin, but no persistent changes in mitochondrial function were observed. IGI became manifested 15 days after exposure in hydroxyurea-exposed cells. In conclusion, immediate responses in mitochondrial function did not cause persistent dysfunction of mitochondria, and this dysfunction was not required for IGI in human neuroblastoma cells.

scholarly journals The spatio-temporal dynamics of mitochondrial membrane potential during oocyte maturation

2019 ◽  
Vol 25 (11) ◽  
pp. 695-705 ◽  
Author(s):  
Usama AL-Zubaidi ◽  
Jun Liu ◽  
Ozgur Cinar ◽  
Rebecca L Robker ◽  
Deepak Adhikari ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Oocyte Maturation ◽  
Mitochondrial Function ◽  
Mitochondrial Membrane ◽  
Local Level ◽  
Meiotic Spindle ◽  
Mitochondrial Activity ◽  
Wide Range ◽  
Spatio Temporal

Abstract Mitochondria are highly dynamic organelles and their distribution, structure and activity affect a wide range of cellular functions. Mitochondrial membrane potential (∆Ψm) is an indicator of mitochondrial activity and plays a major role in ATP production, redox balance, signaling and metabolism. Despite the absolute reliance of oocyte and early embryo development on mitochondrial function, there is little known about the spatial and temporal aspects of ΔΨm during oocyte maturation. The one exception is that previous findings using a ΔΨm indicator, JC-1, report that mitochondria in the cortex show a preferentially increased ΔΨm, relative to the rest of the cytoplasm. Using live-cell imaging and a new ratiometric approach for measuring ΔΨm in mouse oocytes, we find that ΔΨm increases through the time course of oocyte maturation and that mitochondria in the vicinity of the first meiotic spindle show an increase in ΔΨm, compared to other regions of the cytoplasm. We find no evidence for an elevated ΔΨm in the oocyte cortex. These findings suggest that mitochondrial activity is adaptive and responsive to the events of oocyte maturation at both a global and local level. In conclusion, we have provided a new approach to reliably measure ΔΨm that has shed new light onto the spatio-temporal regulation of mitochondrial function in oocytes and early embryos.

scholarly journals Dynamic coupling between TRPV4 and Ca2+-activated SK1/3 and IK1 K+ channels plays a critical role in regulating the K+-secretory BK channel in kidney collecting duct cells

2017 ◽  
Vol 312 (6) ◽  
pp. F1081-F1089 ◽  
Author(s):  
Yue Li ◽  
Hongxiang Hu ◽  
Jin-Bin Tian ◽  
Michael X. Zhu ◽  
Roger G. O’Neil
Keyword(s):  
Membrane Potential ◽  
Transient Receptor Potential ◽  
Collecting Duct ◽  
Critical Role ◽  
Receptor Potential ◽  
Bk Channel ◽  
Transient Receptor Potential Vanilloid ◽  
Cortical Collecting Duct ◽  
Intracellular Ca ◽  
Transient Receptor

The large-conductance Ca2+-activated K+ channel, BK (KCNMA1), is expressed along the connecting tubule (CNT) and cortical collecting duct (CCD) where it underlies flow- and Ca2+-dependent K+ secretion. Its activity is partially under the control of the mechanosensitive transient receptor potential vanilloid type 4 (TRPV4) Ca2+-permeable channel. Recently, we identified three small-/intermediate-conductance Ca2+-activated K+ channels, SK1 (KCNN1), SK3 (KCNN3), and IK1 (KCNN4), with notably high Ca2+-binding affinities, that are expressed in CNT/CCD and may be regulated by TRPV4-mediated Ca2+ influx. The K+-secreting CCD mCCDcl1 cells, which express these channels, were used to determine whether SK1/3 and IK1 are activated on TRPV4 stimulation and whether they contribute to Ca2+ influx and activation of BK. Activation of TRPV4 (GSK1016790A) modestly depolarized the membrane potential and robustly increased intracellular Ca2+, [Ca2+]i. Inhibition of both SK1/3 and IK1 by application of apamin and 1-[(2-chlorophenyl)diphenylmethyl]-1H-pyrazole (TRAM-34), respectively, further depolarized the membrane potential and markedly suppressed the TRPV4-mediated rise in [Ca2+]i. Application of BK inhibitor iberiotoxin after activation of TRPV4 without apamin/TRAM-34 also reduced [Ca2+]i and further intensified membrane depolarization, demonstrating BK involvement. However, the BK-dependent effects on [Ca2+]i and membrane potential were largely abolished by pretreatment with apamin and TRAM-34, identical to that observed by separately suppressing TRPV4-mediated Ca2+ influx, demonstrating that SK1/3-IK1 channels potently contribute to TRPV4-mediated BK activation. Our data indicate a direct correlation between TRPV4-mediated Ca2+ signal and BK activation but where early activation of SK1/3 and IK1 channels are critical to sufficiently enhanced Ca2+ entry and [Ca2+]i levels required for activation of BK.

scholarly journals Acrosomal status and mitochondrial activity of human spermatozoa vitrified with sucrose

Reproduction ◽  
2008 ◽  
Vol 136 (2) ◽  
pp. 167-173 ◽  
Author(s):  
E Isachenko ◽  
V Isachenko ◽  
J M Weiss ◽  
R Kreienberg ◽  
I I Katkov ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Membrane ◽  
Acrosome Reaction ◽  
Staining Technique ◽  
Significant Loss ◽  
Human Spermatozoa ◽  
Mitochondrial Activity ◽  
Hoechst 33258 ◽  
Gentle Agitation

This study investigates the ability of sucrose to protect spermatozoa against mitochondrial damage, artificial cryoinduction of capacitation, and acrosome reaction. Spermatozoa were isolated using the swim-up procedure performed using three different media: (a) human tubal fluid (HTF, control) medium; (b) HTF with 1% human serum albumin (HSA); and (c) HTF with 1% HSA and 0.25 M sucrose. From each group, 30 μl suspensions of cells were dropped directly into liquid nitrogen and stored for at least 24 h. Cells were thawed by quickly submerging the spheres in HTF with 1% HSA at 37 °C with gentle agitation. Sperm motility, viability, mitochondrial membrane potential integrity, spontaneous capacitation, and acrosome reaction were investigated. Sperm viability, acrosome reaction, and capacitation were detected using the double fluorescence chlortetracycline-Hoechst 33258 staining technique. Mitochondrial function was evaluated using a unique fluorescent cationic dye, 5,5′,6,6′-tetrachloro-1-1′,3,3′-tetraethyl-benzamidazolocarbocyanin iodide, commonly known as JC-1. The number of progressively motile spermatozoa was significantly higher in the sucrose-supplemented medium group (57.1±3.2%,P<0.05) when compared with controls (19.4±1.9%). The combination of HSA and sucrose (65.2±2.6%) has a stronger cryoprotective effect on the integrity of mitochondrial membrane potential (P<0.05) compared with HSA alone (32.6±4.7%). In conclusion, vitrification of human spermatozoa with non-permeable cryoprotectants such as HSA and sucrose can effectively cryopreserve the cells without significant loss of important physiological parameters.

scholarly journals Mitochondrial activity and cytoskeleton organization in three pronuclei oocytes after intracytoplasmic sperm injection

Zygote ◽  
2018 ◽  
Vol 26 (4) ◽  
pp. 319-325
Author(s):  
Tuğba Kotil ◽  
M. Ertan Kervancıoğlu ◽  
Gülçin Ekter Kanten ◽  
Gülden Tunalı ◽  
Seyhun Solakoğlu
Keyword(s):  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Intracytoplasmic Sperm Injection ◽  
Mitochondrial Membrane ◽  
Polar Body ◽  
Meiotic Spindle ◽  
Mitochondrial Activity ◽  
Electron Microscopic ◽  
Second Polar Body ◽  
Polar Body Extrusion

SummaryDigyny, the presence of a third pronucleus due to the failure of second polar body extrusion, is problematic after intracytoplasmic sperm injection (ICSI) practices. Mitochondria have critical roles such as production of adenosine triphosphate (ATP) and regulation of Ca2+ homeostasis during oocyte maturation, fertilization and the following development, while the regulation of meiotic spindle formation, chromosome segregation, pronuclear apposition and cytokinesis is closely associated with the cytoskeleton. In this study, mitochondrial membrane potential, distribution of F-actin and γ-tubulin, and the ultrastructure of three pronuclear (3PN) oocytes were investigated. 3PN oocytes after ICSI procedure were taken from patients who were enrolled in assisted reproduction programmes. For mitochondrial membrane potential analysis, fresh oocytes stained with the mitochondrial membrane potential probe JC-1, were evaluated under fluorescence microscopy. The mitochondrial membrane potential of three pronuclear oocytes showed similar results to normal zygotes. γ-Tubulin was stained strongly at the subplasmalemmal domain and microfilaments were localized at the cortical, but not the perinuclear, area. Cytoplasmic halos were moderately or not detected by electron microscopy; lipofuscin granules, degenerated mitochondria, and multilamellated bodies were seen in the ooplasm. Immunohistochemistry and electron microscopic findings suggested that mitochondrial membrane potential has no direct effect on second polar body extrusion. This abnormality can be associated with an altered cytoskeleton due to poor oocyte quality.

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