The role of TRPV4 in programmed cell deaths.

Programmed cell death is a major life activity of both normal development and disease. Necroptosis is early recognized as a caspase-independent form of programmed cell death followed obviously inflammation. Apoptosis is a gradually recognized mode of cell death that is characterized by a special morphological changes and unique caspase-dependent biological process. Ferroptosis, pyroptosis and autophagy are recently identified non-apoptotic regulated cell death that each has its own characteristics. The transient receptor potential vanilloid 4 (TRPV4) is a kind of nonselective calcium-permeable cation channel, which is received more and more attention in biology studies. It is widely expressed in human tissues and mainly located on the membrane of cells. Several researchers have identified that the influx Ca2+ from TRPV4 acts as a key role in the loss of cells by apoptosis, ferroptosis, necroptosis, pyroptosis and autophagy via mediating endoplasmic reticulum (ER) stress, oxidative stress and inflammation. This effect is bad for the normal function of organs on the one hand, on the other hand, it is benefit for anticancer activities. In this review, we will summarize the current discovery on the role and impact of TRPV4 in these programmed cell death pathological mechanisms to provide a new prospect of gene therapeutic target of related diseases.

The Effect of Melatonin on OCT4 Expression and Granulosa Cell Growth in Female Mice.

Melatonin is mainly secreted by the pineal gland as a neurotransmitter. Moreover, melatonin is also produced by the ovary and plays important roles in female reproduction. However, it is unclear whether melatonin has any effect on the transition from the preantral follicle to the early antral follicle. Octamer-binding transcription factor 4 (OCT4) is important to granulosa cells development, which is regulated by gonadotropin. And these regulations are mediated by the GSK3ß/ß-catenin pathway via the activated PI3K/Akt signaling. The aim of the present study was to determine the effects and the possible mechanisms of melatonin on ovarian cells development. The results showed that melatonin inhibited granulosa cells development, which was accompanied by the downregulation of OCT4 expression. Meanwhile, melatonin also decreased the expression of p-GSK3ß (glycogen synthase kinase 3 beta), p-Akt, ß-catenin, and its translocation to the nucleus in granulosa cells. Moreover, melatonin attenuated the effects of FSH in vitro and eCG in vivo on these regulations. In conclusion, this study shows that melatonin inhibits ovarian cell development by downregulating the OCT4 expression level, which is possibly mediated by inhibiting the PI3K/Akt and GSK3ß/ß-catenin pathway. Melatonin attenuates the effects of gonadotropin on ovarian granulosa cells as a negative regulator.

Mechanisms of OCT4 on 3,5,3'-Tri-iodothyronine and FSH-induced Granulosa Cell Development in Female Mice.

Octamer-binding transcription factor 4 (OCT4) regulates the pluripotency of stem cells and also plays important roles in granulosa cells growth, which is regulated by follicle-stimulating hormone (FSH). Thyroid hormone (TH) is important for the development and maturation of follicles and the maintenance of various endocrine functions. Although 3,5,3'-triiodothyronine (T3) enhances the effects of FSH on the regulation of the growth of granulosa cells and development of follicles, it is unclear whether and, if so, how TH combines with FSH to regulate OCT4 expression in granulosa cells during the preantral to early antral transition stage. Our results showed that T3 enhanced FSH-induced OCT4 expression. However, T3/FSH-induced cellular growth was reduced by OCT4 small interfering RNA. OCT4 knockdown significantly increased the number of apoptotic cell. Moreover, T3 combined with FSH to increase estrogen receptor ß (ERß) expression but did not significantly affect estrogen receptor α expression. ERß knockdown dramatically decreased T3/FSH-induced OCT4 expression and cell development and increased cell apoptosis. The phosphoinositide 3-kinases/protein kinase B pathway was involved in hormones inducing OCT4 and ERß expressions. Furthermore, the hormones regulating OCT4 and ERß expressions were regulated by cytochrome P450 lanosterol 14a-demethylase (CYP51), a key enzyme in sterol and steroid biosynthesis. T3 and FSH cotreatment potentiated cellular development by upregulating OCT4 expression, which is mediated by CYP51 and ERß. These regulatory processes are mediated by the phosphoinositide 3-kinase/protein kinase B signaling pathway. These findings suggest that OCT4 mediates the T3 and FSH-induced development of follicles.

Effects of thyroid hormone on ovarian cell apoptosis in the rat.

Follicle development is a complicated process regulated by thyroid hormone (TH). TH dysregulation is associated with reproductive disorders; however, the mechanism underlying these relationships remains unclear. Glucose-related protein 78 (GRP78) is a well-characterised endoplasmic reticulum stress protein related to ovarian cell apoptosis. To clarify whether GRP78 is regulated by TH and the involvement of GRP78 in follicle development, we established rat models of hypothyroidism and hyperthyroidism and investigated the effects of TH dysregulation on levels of GRP78, C/EBP homologous protein (CHOP) and cleaved caspase-3. TH dysregulation decreased levels of GRP78 and increased those of CHOP and cleaved caspase-3 in both rat models. However, treatment with equine chorionic gonadotrophin reversed these effects, as well as granulosa cell apoptosis induced by TH dysregulation. Together, these results provide evidence that TH dysregulation alters the GRP78 expression profile, triggering the apoptotic signalling pathway, and suggest that GRP78 is a novel mediator of TH in follicle development.

Roles of different n-3/n-6 PUFA ratios in ovarian cell development and steroidogenesis in PCOS rats.

Polycystic ovary syndrome (PCOS) is a complex and common endocrine disorder characterized by hyperandrogenism, which is accompanied by follicle growth arrest at the small antral stage, minimal granulosa cell proliferation, and chronic anovulation. Polyunsaturated fatty acids (PUFAs) are necessary for the body's metabolism, growth and development. Although PUFAs play an important role in the regulation of female reproduction, their role in ovarian development in PCOS is still unclear. The present study was conducted to investigate the effects of different ratios of n-3/n-6 PUFAs (omega-3/omega-6) on ovary development in PCOS rats. Serum levels of reproductive hormones and enzymes related to steroidogenesis were assessed. The results indicated that PUFAs (n-3/n-6: 1/15) significantly increased ovarian weight and improved the ovarian structure although they had no significant effect on body weight in PCOS rats. Meanwhile, apoptosis was attenuated accompanied by increased cell proliferation by PUFAs (n-3/n-6: 1/15). Moreover, serum levels of hormones (FSH and E2) were also significantly increased by PUFAs (n-3/n-6: 1/15) accompanied by decreased T levels. To investigate whether PUFAs regulate the expression of enzymes related to hormone synthesis, western blotting was used to determine the protein levels of CYP51, CYP19, StAR and 3ß-HSD. The results showed that PUFAs significantly increased the protein levels of all of these enzymes. These results indicate that PUFAs enhance the reproductive performance of PCOS by increasing the expression of steroidogenesis enzymes, which are related to hormone secretion and ovarian functions. These findings provide evidence that a balanced n-3/n-6 PUFA ratio is beneficial for PCOS reproduction.

Effect of hypothyroidism on CYP51 and FSHR expression in rat ovary.

Although thyroid hormone (TH) plays important roles in regulating ovarian development, the mechanism are still unclear. Cytochrome P450 lanosterol 14α-demethylase (CYP51) is a key enzyme in sterols and steroids biosynthesis that involved in folliculogenesis and oocyte maturation, which is regulated by follicle stimulating hormone (FSH). However, the effect of TH on CYP51 expression in ovarian cells is unclear. The objective of this study was to determine the effects of TH on CYP51 in rat ovary. Hypothyroidism rats were induced by 6-propyl-2-thiouracil (PTU), genes expressions in ovary were analyzed by Western blot or qRT-PCR. The data showed that CYP51 was significantly decreased in hypothyroidism, which was accompanied by the down-regulation of mRNA level. Meanwhile, similar tendency was also showed in FSHR expression in hypothyroidism. To evaluate the effect of the gonadotropin on CYP51 and FSHR expression in ovarian cells in vivo, hypo rats were injected subcutaneously with equine chorionic gonadotropin (eCG) respectively. The results showed that eCG reversed CYP51 and FSHR expression in hypo group. Moreover, FSH-induced CYP51 expression was meditated by FSHR. In addition, serum concentration of FSH and E2 were also decreased in hypothyroidism, and E2 was up-regulated by eCG treatment. These results indicate that hypothyroidism changes CYP51 and FSHR expression in ovary, which are regulated by gonadotropin. Moreover, genes changes in ovary are at least partially attributed to steroids biosynthesis.

Role of OCT4 in the Regulation of FSH-Induced Granulosa Cells Growth in Female Mice.

As a member of the POU (Pit-Oct-Unc) transcription factor family, OCT4 (Octamer-binding transcription factor 4) is associated with the cellular proliferative. However, the roles of OCT4 in regulating the transition from preantral follicle to early antral follicle are still remains unclear. To evaluate the effect of OCT4 on cellular development in ovary, mice were injected with eCG in vivo or granulosa cells were co-cultured with FSH in vitro. The results showed that eCG up-regulated ovarian OCT4 expression. Meanwhile, OCT4 expression in granulosa cells was also up-regulated by FSH, and knockdown of OCT4 by siRNA significantly decreased FSH-induced cellular viability. Moreover, gonadotropin increased p-GSK3ß (Glycogen synthase kinase 3-beta) level, ß-catenin expression and its translocation to nuclear in ovarian cells. In addition, the inhibition of GSK3ß activity by CT99021 significantly increased the expression of ß-catenin and OCT4 in granulosa cells. And knockdown ß-catenin by siRNA dramatically abolished FSH-induced OCT4 expression and cellular development. Furthermore, FSH-induced the phosphorylation of GSK3ß, expression of ß-catenin and OCT4, and translocation of ß-catenin were mediated by the PI3K/Akt pathway. Taken together, the present study demonstrates that FSH regulated OCT4 expression via GSK3ß/ß-catenin pathway, which was mediated by the PI3K/Akt pathway. And these regulations are involved in ovarian cell development.