Effect of follicle-stimulating hormone and luteinizing hormone on apoptosis, autophagy, and the release and reception of some steroid hormones in yak granulosa cells through miR-23a/ASK1 axis

Follicle-stimulating hormone (FSH), luteinizing hormone (LH), miR-23a, apoptosis signal-regulating kinase 1(ASK1)/c-Jun N-terminal kinase (JNK), autophagy and apoptosis play crucial roles in follicular development. However, their role in yak granulosa cells (GCs) remains unknown. Therefore, we examined the effect of miR-23a, ASK1, FSH, and LH on apoptosis, autophagy, and the release and reception of some steroid hormones in these cells. Our results showed that miR-23a overexpression significantly increased the abundance of Beclin1, the LC3II/I ratio, and the number of Ad-mRFP-GFP-LC3-labeled autophagosomes, and decreased p62 abundance. Additionally, Bax abundance and the number of terminal deoxynucleotidyl transferase deoxynucleotide triphosphate nick end labeling-positive cells were reduced, while Bcl2 expression was increased. Overexpression of miR-23a also significantly increased the abundance of estradiol receptor α (ER-α) and β (ER-β) and the concentrations of estradiol (E2), progesterone (P4) in yak GCs. Here, treating yak GCs with miR-23a decreased ASK1 expression, which regulates ASK1/JNK-mediated apoptosis, autophagy, E2 and P4 levels, and ER-α/β abundance. In contrast, treatment of yak GCs with FSH (10 μg/mL) and LH (100 μg/mL) increased miR-23a abundance, regulating the subsequent effect on ASK1/JNK-mediated apoptosis, autophagy, ER-α/β abundance, and E2 and P4 concentrations. In conclusion, miR-23a enhances autophagy in yak GCs, attenuates apoptosis, and increases ER-α/β abundance and E2 and P4 concentrations by downregulating ASK1. Additionally, FSH and LH can regulate these effects of miR-23a by altering its expression. These results provide important insights that can inform the development of strategies to reduce abnormal follicular atresia and improve the reproductive rate of yaks.

MiR-23a promotes autophagy of yak cumulus cells to alleviate apoptosis via the apoptosis signal-regulating kinase 1/c-Jun N-terminal kinase pathway

The ultimate fate of Graafian follicles is ovulation or atresia which relies on the highly coordinated processes of apoptosis and autophagy in ovarian cells. Long non-coding RNA maternally expressed gene 3 (LncRNA MEG3), miR-23a, and apoptosis signal-regulating kinase 1 (ASK1) are factors associated with autophagy. However, whether these factors can regulate autophagy in cumulus cells (CCs) of yak is unclear. Here, miR-23a overexpression upregulated the LC3-II/LC3-I ratio and Beclin1 abundance while reducing p62 accumulation (p < 0.05). The monodansylcadaverine assay exhibited a marked increase in punctate green fluorescence, and the GFP-LC3B displayed increased yellow fluorescence (p < 0.05). The opposite effect was observed for miR-23a inhibitors. Furthermore, miR-23a overexpression downregulated the abundance of ASK1 mRNA and total ASK1 protein (t-ASK1), whereas miR-23a inhibitors up-regulated them (p < 0.05). The effects of miR-23a overexpression on ASK1 phosphorylated protein at serine 845 (P-845), total JNK (c-Jun N-terminal kinase) (t-JNK) and the JNK phosphorylated protein (p-JNK) were similar to those of t-ASK1 but elicited the opposite effect on ASK1 phosphorylated protein at serine 967 (P-967) (p < 0.05). We further demonstrated that ASK1 expression can be silenced by small-interfering RNA (siRNA), which had no significant effect on t-JNK abundance (p > 0.05) but significantly suppressed the p-JNK expression (p < 0.05). Silencing ASK1 significantly improved Beclin1 abundance and the LC3-II/LC3-I ratio, but decreased p62 abundance (p < 0.05). An increase in yellow GFP-LC3B puncta and green MDC staining puncta were observed (p < 0.05). Overexpression of LncRNA MEG3 significantly increased the expression of t-ASK1, P-845, and JNK and decreased the abundance of P-967 and miR-23a (p < 0.05). In addition, miR-23a upregulation reduced the number of the TUNEL-positive cells, and the addition of 8 mM 3-methyladenine (3-MA) reversed this downregulation (p < 0.05). Similar trends were observed for the Bax/Bcl2 ratio and cleaved-caspase3 abundance. In summary, miR-23a promotes autophagy by inhibiting ASK1 abundance, which reduces apoptosis of yak CCs. This effect can be inhibited by LncRNA MEG3, which has implications for decreasing abnormal Graafian follicular atresia and maintaining development.

LncRNA MEG3 regulates ASK1/JNK axis-mediated apoptosis and autophagy via sponging miR-23a in granulosa cells of yak tertiary follicles

Apoptosis and autophagy in granulosa cells (GCs) are highly related to follicular development and atresia. It has also been reported that they are related to LncRNA MEG3, miR-23a and apoptosis signal-regulating kinase 1 (ASK-1). However, their relationship to follicular development and the extent to which follicle stimulating hormone (FSH) or luteinizing hormone (LH) can regulate this process remain unknown. Here, we found that ASK1 and JNK were expressed in the GCs of gonadotropin-dependent follicles, and those levels were significantly higher (p < 0.05) in yak Tertiary follicles compared to that of Secondary follicles and Graafian follicles. Then, the effect of LncRNA MEG3 / miR-23a on apoptosis and autophagy via ASK1/JNK (c-Jun N-terminal kinase) in yak GCs was studied. Overexpressing LncRNA MEG3 reduced miR-23a levels and p-967 protein expression, but enhanced ASK1 and JNK mRNA levels as well as t-ASK1, p-845, t-JNK, and p-JNK proteins levels. And Up-regulation of LncRNA MEG3 promoted apoptosis while attenuating autophagy. The targeting relationship between miR-23a and the binding sites of LncRNA MEG3 and ASK1 was also confirmed with the dual luciferase reporter assay. And, the relationship between LncRNA MEG3 and miR-23a was observed as a negative feedback regulation, and changes in LncRNA MEG3 and miR-23a levels can alter the expression of ASK1/JNK axis in yaks GCs. In addition, FSH (10 μg/mL) or LH (100 μg/mL) ability to reverse the effects of LncRNA MEG3 on miR-23a levels and ASK1/JNK axis-mediated apoptosis and autophagy was verified in yak GCs. This is significantly beneficial for decreasing abnormal follicular atresia for yaks tertiary follicles.

Bisphenol AF induces apoptosis via estrogen receptor beta (ERβ) and ROS-ASK1-JNK MAPK pathway in human granulosa cell line KGN

Bisphenol AF (BPAF) is an emerging environmental pollutant. Although BPAF is widely spread in the environment and human surroundings, its interference with ovarian function has not been fully elucidated. The aim of this study was to identify the mechanism underlying the effect of BPAF on the apoptosis of KGN cells, which maintain the physiological characteristics of ovarian granulosa cells. Our results indicated that BPAF induces KGN cell apoptosis in a concentration- and time-dependent manner. Meanwhile, BPAF exposure significantly promoted the expression of pro-apoptotic proteins, including Bax, Bid and Bak, while the expression of anti-apoptotic proteins, such as Bcl-2, Bcl-xL and Mcl-1, decreased significantly. We further detected a significant increase in intracellular ROS levels in response to high concentrations of BPAF exposure. After blocking the corresponding pathway, it was found that ROS mediates ASK1 and JNK activation. Furthermore, the role of Ca²⁺ overload and estrogen receptor β (ERβ) in BPAF-induced KGN cell apoptosis was also confirmed by using inhibitors. These results suggest that BPAF has potential reproductive toxicity for females, and ROS-ASK1-JNK axis may play a key role in BPAF-induced ovarian dysfunction. In addition, Ca²⁺ overload and ERβ pathway activation may also be an important mechanism of reproductive toxicity of BPAF.

Interrelationships between metabolic hormones, leptin and ghrelin, and oil-related contaminants in control of oxytocin and prostaglandin F release by feline ovaries

We examined the effects of metabolic hormones leptin and ghrelin, and the oil-related environmental contaminants toluene and xylene on the release of ovarian hormones by gravid and non-gravid cats, as well as the functional interrelationships between metabolic hormones and contaminants. Ovarian fragments of non-gravid cats were cultured with and without leptin and toluene. Next, ovarian fragments of either non-gravid or gravid animals were cultured with and without ghrelin and xylene. Oxytocin (OT) and prostaglandin F (PGF) release was measured using ELISA. We confirm ovarian OT and PGF production by feline ovary, demonstrate the involvement of leptin and ghrelin in controlling OT and PGF release, show the direct influence of toluene and xylene on feline ovarian secretory activity, indicate the ability of leptin and ghrelin to mimic and promote the main contaminant effects, demonstrate that oil-related contaminants can prevent and even invert the effects of leptin and ghrelin on the ovary, and suggest the gravidity-associated changes in ability of ghrelin to promote xylene action on PGF (but not to OT), but not in basic ovarian OT and PGF release and their response to ghrelin or xylene.