Publications by authors named "Gaizhen Ru"

4 Publications

  • Page 1 of 1

High Dosages of Equine Chorionic Gonadotropin Exert Adverse Effects on the Developmental Competence of IVF-Derived Mouse Embryos and Cause Oxidative Stress-Induced Aneuploidy.

Front Cell Dev Biol 2020 9;8:609290. Epub 2021 Feb 9.

Department of Reproductive Center, The First Affiliated Hospital of Shantou University Medical College, Shantou University, Shantou, China.

Gonadotropins play vital roles in the regulation of female reproductive ability and fertility. Our study aimed to determine the effects of superovulation induced by increasing doses of equine chorionic gonadotropin [eCG; also referred to as pregnant mare serum gonadotropin (PMSG)] on the developmental competence of mouse embryos and on aneuploidy formation during fertilization (IVF). eCG dose-dependently enhanced the oocyte yield from each mouse. Administration of 15 IU eCG significantly reduced the fertilization rate and the formation of four-cell embryos and blastocysts and increased the risk of chromosome aneuploidy. The IVF-derived blastocysts in the 15 IU eCG treatment group had the fewest total cells, inner cell mass (ICM) cells and trophectoderm (TE) cells. Moreover, more blastocysts and fewer apoptotic cells were observed in the 0, 5, and 10 IU eCG treatment groups than in the 15 IU eCG treatment group. We also investigated reactive oxygen species (ROS) levels and variations in several variables: mitochondrial membrane potential (MMP); active mitochondria; mitochondrial superoxide production; adenosine triphosphate (ATP) content; spindle structures; chromosome karyotypes; microfilament distribution; and the expression of Aurora B [an important component of the chromosomal passenger complex (CPC)], the spindle assembly checkpoint (SAC) protein mitotic arrest deficient 2 like 1 (MAD2L1), and the DNA damage response (DDR) protein γH2AX. Injection of 15 IU eCG increased ROS levels, rapidly reduced MMP, increased active mitochondria numbers and mitochondrial superoxide production, reduced ATP content, increased abnormal spindle formation rates, and induced abnormalities in chromosome number and microfilament distribution, suggesting that a high dose of eCG might alter developmental competence and exert negative effects on IVF-obtained mouse embryos. Additionally, the appearance of γH2AX and the significantly increased expression of Aurora B and MAD2L1 suggested that administration of relatively high doses of eCG caused Aurora B-mediated SAC activation triggered by ROS-induced DNA damage in early mouse IVF-derived embryos for self-correction of aneuploidy formation. These findings improve our understanding of the application of gonadotropins and provide a theoretical basis for gonadotropin treatment.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fcell.2020.609290DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7900142PMC
February 2021

AMPK Activity Contributes to G2 Arrest and DNA Damage Decrease via p53/p21 Pathways in Oxidatively Damaged Mouse Zygotes.

Front Cell Dev Biol 2020 8;8:539485. Epub 2020 Sep 8.

Department of Reproductive Center, The First Affiliated Hospital of Shantou University Medical College, Shantou, China.

In zygotes, the capacity of G2/M checkpoint and DNA repair mechanisms to respond to DNA damage varies depending on different external stressors. In our previous studies, we found that mild oxidative stress induced a G2/M phase delay in mouse zygotes fertilized , due to the activation of the spindle assembly checkpoint. However, it is unclear whether the G2/M phase delay involves G2 arrest, triggered by activation of the G2/M checkpoint, and whether AMPK, a highly conserved cellular energy sensor, is involved in G2 arrest and DNA damage repair in mouse zygotes. Here, we found that mouse zygotes treated with 0.03 mM HO at 7 h post-insemination (G1 phase), went into G2 arrest in the first cleavage. Furthermore, phosphorylated H2AX, a specific DNA damage and repair marker, can be detected since the early S phase. We also observed that oxidative stress induced phosphorylation and activation of AMPK. Oxidative stress-activated AMPK first localized in the cytoplasm of the mouse zygotes in the late G1 phase and then translocated to the nucleus from the early S phase. Overall, most of the activated AMPK accumulated in the nuclei of mouse zygotes arrested in the G2 phase. Inhibition of AMPK activity with Compound C and SBI-0206965 abolished oxidative stress-induced G2 arrest, increased the activity of CDK1, and decreased the induction of cell cycle regulatory proteins p53 and p21. Moreover, bypassing G2 arrest after AMPK inhibition aggravated oxidative stress-induced DNA damage at M phase, increased the apoptotic rate of blastocysts, and reduced the formation rate of 4-cell embryos and blastocysts. Our results suggest the G2/M checkpoint and DNA repair mechanisms are operative in coping with mild oxidative stress-induced DNA damage. Further, AMPK activation plays a vital role in the regulation of the oxidative stress-induced G2 arrest through the inhibition of CDK1 activity via p53/p21 pathways, thereby facilitating the repair of DNA damage and the development and survival of oxidative stress-damaged embryos. Our study provides insights into the molecular mechanisms underlying oxidative-stress induced embryonic developmental arrest, which is crucial for the development of novel strategies to ensure viable embryo generation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fcell.2020.539485DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7505953PMC
September 2020

Response of Mouse Zygotes Treated with Mild Hydrogen Peroxide as a Model to Reveal Novel Mechanisms of Oxidative Stress-Induced Injury in Early Embryos.

Oxid Med Cell Longev 2016 22;2016:1521428. Epub 2016 Sep 22.

Reproductive Center, The First Affiliated Hospital of Shantou University Medical College, Shantou University, Shantou, Guangdong, China.

Our study aimed to develop embryo models to evaluate the impact of oxidative stress on embryo development. Mouse zygotes, which stayed at G1 phase, were treated with prepared culture medium (containing 0.00, 0.01, 0.02, 0.03, 0.04, 0.05, or 0.1 mM hydrogen peroxide (HO)) for 30 min in experiment 1. The dose-effects of HO on embryo development were investigated via comparisons of the formation rate at each stage (2- and 4-cell embryos and blastocysts). Experiment 2 was carried out to compare behaviors of embryos in a mild oxidative-stressed status (0.03 mM HO) with those in a control (0 mM HO). Reactive oxygen species (ROS) levels, variation of mitochondrial membrane potential (MMP), expression of H2AX, and cell apoptosis rate of blastocyst were detected. We observed a dose-dependent decrease on cleavage and blastocyst rates. Besides, higher level of ROS, rapid reduction of MMP, and the appearance of H2AX revealed that embryos are injured early in mild oxidative stress. Additionally, H2AX may involve during DNA damage response in early embryos. And the apoptotic rate of blastocyst may significantly increase when DNA damage repair is inadequate. Most importantly, our research provides embryo models to study cell cycle regulation and DNA damage response under condition of different levels of oxidative stress.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1155/2016/1521428DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5055977PMC
March 2017

Oxidative stress-induced DNA damage of mouse zygotes triggers G2/M checkpoint and phosphorylates Cdc25 and Cdc2.

Cell Stress Chaperones 2016 07 26;21(4):687-96. Epub 2016 Apr 26.

Reproductive Center, The First Affiliated Hospital of Shantou University Medical College, Shantou University, Shantou, Guangdong, People's Republic of China.

In vitro fertilized (IVF) embryos show both cell cycle and developmental arrest. We previously showed oxidative damage activates the ATM → Chk1 → Cdc25B/Cdc25C cascade to mediate G2/M cell cycle arrest for repair of hydrogen peroxide (H2O2)-induced oxidative damage in sperm. However, the mechanisms underlying the developmental delay of zygotes are unknown. To develop a model of oxidative-damaged zygotes, we treated mouse zygotes with different concentrations of H2O2 (0, 0.01, 0.02, 0.03, 0.04, 0.05 mM), and evaluated in vitro zygote development, BrdU incorporation to detect the duration of S phase. We also examined reactive oxygen species level and used immunofluorescence to detect activation of γH2AX, Cdc2, and Cdc25. Oxidatively damaged zygotes showed a delay in G2/M phase and produced a higher level of ROS. At the same time, γH2AX was detected in oxidatively damaged zygotes as well as phospho-Cdc25B (Ser323), phospho-Cdc25C (Ser216), and phospho-Cdc2 (Tyr15). Our study indicates that oxidative stress-induced DNA damage of mouse zygotes triggers the cell cycle checkpoint, which results in G2/M cell cycle arrest, and that phospho-Cdc25B (Ser323), phospho-Cdc25C (Ser216), and phospho-Cdc2 (Tyr15) participate in activating the G2/M checkpoint.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s12192-016-0693-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4907999PMC
July 2016