GDF8 activates p38 MAPK signaling during porcine oocyte maturation in vitro.

Growth Differentiation Factor 8 (GDF8) is a member of the transforming growth factor-β (TGF-β) family and has been identified as a strong physiological regulator. This factor is expressed as a paracrine factor in mural granulosa cells. To investigate the effects of GDF8 on the in vitro maturation (IVM) of porcine oocytes, we assessed the quality of matured oocytes as well as the specific gene transcription and protein activation levels in oocytes and cumulus cells (CCs) after IVM and subsequent embryonic development after in vitro fertilization (IVF) and parthenogenetic activation (PA). Supplemental concentrations (0, 1, 10, and 100 ng/ml) of GDF8 were provided in IVM medium. Supplementation with GDF8 during IVM induced transcription of specific TGF-β receptor genes, such as ActRIIb and Alk4/5, and the recognition of the GDF8 by these receptors induced phosphorylation of p38 MAPK. Activated p38 MAPK signaling changed oocyte maturation and cumulus expansion-related gene transcription: Nrf2 and Bcl-2 in oocytes and PCNA, Nrf2, Has2, Ptx3, and TNFAIP6 in CCs. The altered gene expression pattern during IVM resulted in a 10% lower level of intracellular ROS in mature oocytes. The improved cytoplasmic maturation led to an increase in the fertilization efficiency and subsequent embryonic developmental competence. The embryonic development showed increases in the blastocyst formation rate and higher transcription levels of POU5F1 and BCL-2 in the blastocysts. The present study suggests that supplementation of GDF8 during IVM synergistically improved the developmental potential of IVF- and PA-derived porcine embryos by reducing the intracellular ROS level in oocytes by altering the transcription of specific genes and increasing the phosphorylation of p38 MAPK during IVM. In conclusion, for the first time, our results demonstrate that GDF8 can act as a paracrine factor to modulate oocyte maturation by regulating p38 MAPK phosphorylation and intracellular ROS level during porcine IVM.

Yoon JD ，Hwang SU ，Kim E ，Jin M ，Kim S ，Hyun SH ... -  《-》

Growth differentiation factor 8 regulates SMAD2/3 signaling and improves oocyte quality during porcine oocyte maturation in vitro†.

Growth differentiation factor 8 (GDF8), also known as myostatin, is a member of the transforming growth factor-β (TGF-β) family and has been identified as a strong physiological regulator of muscle differentiation. Recently, the functional role of GDF8 in reproductive organs has received increased interest following its detection in the human placenta and uterus. To investigate the effects of GDF8 during porcine oocyte in vitro maturation (IVM), we assessed the quality of matured oocytes. Furthermore, we investigated the specific gene transcription and protein activation levels in oocytes and cumulus cells after IVM and subsequent embryonic development after in vitro fertilization and parthenogenetic activation. Prior to these experiments, the concentration of GDF8 in porcine follicular fluid was determined. During the entire IVM period, 1.3 ng/mL GDF8 and its signaling inhibitor SB431542 (SB) at 5 μM were added as control, SB, SB + GDF8, and GDF8 groups, respectively. Our results demonstrate that supplementation with GDF8 during porcine oocyte IVM enhanced both meiotic and cytoplasmic maturation, with altered transcriptional patterns, via activation of Sma- and Mad-related protein 2/3 (SMAD2/3). Using the pharmacological inhibitor SB431542, we demonstrated that inhibition of GDF8-induced Smad2/3 signaling reduces matured oocyte quality. In conclusion, for the first time, we demonstrated paracrine factor GDF8 in porcine follicular fluid in vivo. Furthermore, we showed that GDF8 supplementation improved mature oocyte quality by regulating p38 mitogen-activated protein kinase phosphorylation and intracellular glutathione and reactive oxygen species levels during porcine IVM.

Yoon JD ，Hwang SU ，Kim M ，Jeon Y ，Hyun SH ... -  《-》

Effects of coculture with cumulus-derived somatic cells on in vitro maturation of porcine oocytes.

In the process of IVM, cumulus-oocyte complexes (COCs) separate from the follicular microenvironment, leading to the loss of endocrine interactions between follicular mural somatic cells and COCs. To restore the microenvironment, a coculture system was established using cumulus-derived somatic cells (CSCs) for IVM. The CSCs were cultured in Dulbecco's modified Eagle's medium for 48 hours with varying numbers of CSCs (0.0, 2.5 × 10(4), 5.0 × 10(4), and 10.0 × 10(4)) and then cultured in tissue culture medium 199 (TCM 199) for 4 hours before adding the oocytes. Cumulus-oocyte complexes from 3- to 6-mm follicles were matured in 500 μL of TCM 199 with eCG and hCG for 22 hours and then cultured in TCM 199 without hormones for 22 hours. After IVM, the group with 2.5 × 10(4) CSCs showed a significant increase in intracellular glutathione levels compared with the control group. In the evaluation of sperm penetration, efficient fertilization was increased in the groups with 2.5 × 10(4) and 5.0 × 10(4) CSCs compared with controls (44.9 and 46.5 vs. 32.1, respectively). The mRNA expression pattern analysis in matured COCs showed a significant upregulation of PCNA, COX-2, Has2, Ptx3, and Nrf2 in the 2.5 × 10(4) CSC group compared with controls. During COC maturation at 0, 11, 22, 33, and 44 hours, the 2.5 × 10(4) and 5.0 × 10(4) CSC groups showed a significantly altered mRNA expression of BMP15 and GDF9. The developmental competence of the matured oocytes in all groups was evaluated after IVF and parthenogenetic activation (PA). After IVF, the 2.5 × 10(4) CSC group showed significantly higher cleavage, blastocyst formation rate, and total cell numbers compared with controls (60.0%, 35.7%, and 127.3 vs. 43.2%, 21.1%, and 89.3, respectively). After PA, the 2.5 × 10(4) CSC group had significantly higher blastocyst formation rate and total cell number than the control group (52.0% and 120.4 vs. 35.4% and 90.9, respectively). In conclusion, these results suggest that the presence of a population of 2.5 × 10(4) CSCs during IVM synergistically improved the developmental potential of IVF- and PA-derived porcine embryos by increasing the intracellular glutathione level via changing of a specific gene expression pattern during oocyte maturation.

Yoon JD ，Jeon Y ，Cai L ，Hwang SU ，Kim E ，Lee E ，Kim DY ，Hyun SH ... -  《-》

Treatment with acetyl-l-carnitine during in vitro maturation of buffalo oocytes improves oocyte quality and subsequent embryonic development.

Oocyte quality is one of the important factors in female fertility, in vitro maturation (IVM), and subsequent embryonic development. In the present study, we assessed whether acetyl-l-carnitine (ALC) supplementation during in vitro maturation of buffalo oocytes could improve oocyte quality and subsequent embryonic development. To determine the optimal level of ALC supplementation, we matured cumulus-oocyte complexes in maturation medium supplemented with 0, 2.5, and 5 mM ALC. The oocytes with a polar body were selected for parthenogenetic activation (PA) and in vitro fertilization (IVF). We found that oocytes matured in 2.5 mM ALC had significantly higher PA blastocyst rate (P < 0.05) and blastocyst cell number than those of unsupplemented oocytes (P < 0.05) and a significantly higher IVF blastocyst rate than that of oocytes matured in 5 mM ALC (P < 0.05). In all further experiments, we supplemented the maturation medium with 2.5 mM ALC. We then tested whether ALC supplementation could improve various markers of oocytes and cumulus cells. We compared cell proliferation; concentrations of reactive oxygen species (ROS), intracellular ATP, estradiol, and progesterone; mitochondrial distribution; mitochondrial DNA copy number (mtDNA); and expression levels of four genes encoding oocyte-derived factors (GDF9, BMP15) and steroid hormones (StAR, P450scc) between the supplemented and unsupplemented oocytes and cumulus cells. Cumulus cells matured with ALC supplementation were more prolific than those matured without ALC supplementation (P < 0.05). Oocytes treated with ALC had lower concentrations of intracellular ROS (P < 0.05) and a higher rate of diffuse mitochondrial distributions (P < 0.05) than those of untreated oocytes. Additionally, the mtDNA was higher in the ALC-treated oocytes (P < 0.05) and cumulus cells (P < 0.05) than that in the untreated cells. The ALC-treated maturation medium had a higher postmaturation concentration of estradiol than that of the untreated medium (P < 0.05). Finally, the gene expression levels of P450scc and GDF9 were greater in ALC-treated oocytes and cumulus cells than those in untreated cells (P < 0.05). Therefore, in buffalo, our results suggest that ALC affects mitochondrial function, regulates oocyte-derived paracrine factors, and increases the production of steroid hormones, leading to increased quality of matured oocytes and improved embryonic development in vitro.

Xu HY ，Yang XG ，Lu SS ，Liang XW ，Lu YQ ，Zhang M ，Lu KH ... -  《-》

The effects of resveratrol on porcine oocyte in vitro maturation and subsequent embryonic development after parthenogenetic activation and in vitro fertilization.

We investigated the effects of resveratrol, a phytoalexin with various pharmacologic activities, on in vitro maturation (IVM) of porcine oocytes. We investigated intracellular glutathione (GSH) and reactive oxygen species (ROS) levels, as well as gene expression in mature oocytes, cumulus cells, and in vitro fertilization (IVF)-derived blastocysts, and subsequent embryonic development after parthenogenetic activation (PA) and IVF. After 44 h of IVM, no significant difference was observed in maturation of the 0.1, 0.5, and 2.0 μM resveratrol groups (83.0%, 84.1%, and 88.3%, respectively) compared with the control (84.1%), but the 10.0 μM resveratrol group showed significantly decreased nuclear maturation (75.0%) (P < 0.05). The 0.5- and 2.0-μm groups showed a significant (P < 0.05) increase in intracellular GSH levels compared with the control and 10.0 μM group. Intracellular ROS levels in oocytes matured with 2.0 μM resveratrol decreased significantly (P < 0.05) compared with those in the other groups. Oocytes treated with 2.0 μM resveratrol during IVM had significantly higher blastocyst formation rates and total cell numbers after PA (62.1% and 49.1 vs. 48.8%, and 41.4, respectively) and IVF (20.5% and 54.0 vs. 11.0% and 43.4, respectively) than the control group. Cumulus-oocytes complex treated with 2.0 μM resveratrol showed lower expression of apoptosis-related genes compared with mature oocytes and cumulus cells. Cumulus cells treated with 2.0 μM resveratrol showed higher (P < 0.05) expression of proliferating cell nuclear antigen than the control group. IVF-derived blastocysts derived from 2.0 μM resveratrol-treated oocytes also had less (P < 0.05) Bak expression than control IVF-derived blastocysts. In conclusion, 2.0 μM resveratrol supplementation during IVM improved the developmental potential of PA and IVF porcine embryos by increasing the intracellular GSH level, decreasing ROS level, and regulating gene expression during oocyte maturation.

Kwak SS ，Cheong SA ，Jeon Y ，Lee E ，Choi KC ，Jeung EB ，Hyun SH ... -  《-》