Direct stimulation of de novo nucleotide synthesis by O-GlcNAcylation.

O-linked ß-N-acetyl glucosamine (O-GlcNAc) is at the crossroads of cellular metabolism, including glucose and glutamine; its dysregulation leads to molecular and pathological alterations that cause diseases. Here we report that O-GlcNAc directly regulates de novo nucleotide synthesis and nicotinamide adenine dinucleotide (NAD) production upon abnormal metabolic states. Phosphoribosyl pyrophosphate synthetase 1 (PRPS1), the key enzyme of the de novo nucleotide synthesis pathway, is O-GlcNAcylated by O-GlcNAc transferase (OGT), which triggers PRPS1 hexamer formation and relieves nucleotide product-mediated feedback inhibition, thereby boosting PRPS1 activity. PRPS1 O-GlcNAcylation blocked AMPK binding and inhibited AMPK-mediated PRPS1 phosphorylation. OGT still regulates PRPS1 activity in AMPK-deficient cells. Elevated PRPS1 O-GlcNAcylation promotes tumorigenesis and confers resistance to chemoradiotherapy in lung cancer. Furthermore, Arts-syndrome-associated PRPS1 R196W mutant exhibits decreased PRPS1 O-GlcNAcylation and activity. Together, our findings establish a direct connection among O-GlcNAc signals, de novo nucleotide synthesis and human diseases, including cancer and Arts syndrome.

MicroRNA-338-3p helps regulate ovarian function by affecting granulosa cell function and early follicular development.

BACKGROUND: Follicular development in mammalian ovaries is a complex and dynamic process, and the interactions and regulatory-feedback loop between the follicular microenvironment, granulosa cells (GCs), and oocytes can affect follicular development and normal ovary functions. Abnormalities in any part of the process may cause abnormal follicular development, resulting in infertility. Hence, exploring the pathogenesis of abnormal follicular development is extremely important for diagnosing and treating infertile women. METHODS: RNA sequencing was performed with ovarian cortical tissues established in vitro. In situ-hybridization assays were performed to study microRNA-338-3p (miR-338-3p) expressed in GCs and oocytes. In vitro culture models were established with GCs and neonatal mouse ovaries to study the biological effects of miR-338-3p. We also performed in vivo experiments by injecting adeno-associated virus vectors that drive miR-338-3p overexpression into the mouse ovarian bursae. RESULTS: Sequencing analysis showed that miR-338-3p was expressed at significantly higher levels in ovarian cortical tissues derived from patients with ovarian insufficiency than in cortical tissues derived from patients with normal ovarian function; miR-338-3p was also significantly highly expressed in the GCs of patients with diminished ovarian reserve (P < 0.05). In situ-hybridization assays revealed that miR-338-3p was expressed in the cytoplasm of GCs and oocytes. Using in vitro culture models of granulosa cells, we found that miR-338-3p overexpression significantly suppressed the proliferation and oestradiol-production capacity of GCs (P < 0.05). In vitro culture models of neonatal mouse ovaries indicated that miR-338-3p overexpression suppressed the early follicular development in mouse ovaries. Further analysis revealed that miR-338-3p might be involved in transforming growth factor ß-dependent regulation of granulosa cell proliferation and, thus, early follicular development. Injecting miR-338-3p-overexpression vectors into the mouse ovarian bursae showed that miR-338-3p down-regulated the oocyte mitochondrial membrane potential in mice and disrupted mouse oestrous cycles. CONCLUSION: miR-338-3p can affect early follicular development and normal ovary functions by interfering with the proliferation and oestradiol production of GCs. We systematically elucidated the regulatory effect of miR-338-3p on follicular development and the underlying mechanism, which can inspire new studies on the diagnosis and treatment of diseases associated with follicular development abnormalities.

FOXK2 affects cancer cell response to chemotherapy by promoting nucleotide de novo synthesis.

AIMS: Nucleotide de novo synthesis is essential to cell growth and survival, and its dysregulation leads to cancers and drug resistance. However, how this pathway is dysregulated in cancer has not been well clarified. This study aimed to identify the regulatory mechanisms of nucleotide de novo synthesis and drug resistance. METHODS: By combining the ChIP-Seq data from the Cistrome Data Browser, RNA sequencing (RNA-Seq) and a luciferase-based promoter assay, we identified transcription factor FOXK2 as a regulator of nucleotide de novo synthesis. To explore the biological functions and mechanisms of FOXK2 in cancers, we conducted biochemical and cell biology assays in vitro and in vivo. Finally, we assessed the clinical significance of FOXK2 in hepatocellular carcinoma. RESULTS: FOXK2 directly regulates the expression of nucleotide synthetic genes, promoting tumor growth and cancer cell resistance to chemotherapy. FOXK2 is SUMOylated by PIAS4, which elicits FOXK2 nuclear translocation, binding to the promoter regions and transcription of nucleotide synthetic genes. FOXK2 SUMOylation is repressed by DNA damage, and elevated FOXK2 SUMOylation promotes nucleotide de novo synthesis which causes resistance to 5-FU in hepatocellular carcinoma. Clinically, elevated expression of FOXK2 in hepatocellular carcinoma patients was associated with increased nucleotide synthetic gene expression and correlated with poor prognoses for patients. CONCLUSION: Our findings establish FOXK2 as a novel regulator of nucleotide de novo synthesis, with potentially important implications for cancer etiology and drug resistance.

Baicalin improves the functions of granulosa cells and the ovary in aged mice through the mTOR signaling pathway.

BACKGROUND: The mammalian follicle is the basic functional unit of the ovary, and its normal development is required to obtaining oocytes capable of fertilization. As women get older or decline in ovarian function due to certain pathological factors, the growth and development of follicles becomes abnormal, which ultimately leads to infertility and other related female diseases. Kuntai capsules are currently used in clinical practice to improve ovarian function, and they contain the natural compound Baicalin, which is a natural compound with important biological activities. At present, the role and mechanism of Baicalin in the development of ovarian follicles is unclear. METHODS: Human primary granulosa cells collected from follicular fluid, and then cultured and treated with Baicalin or its normal control, assessed for viability, subjected to RT-PCR, western blotting, flow cytometry, and hormone analyses. The estrus cycle and oocytes of CD-1 mice were studied after Baicalin administration and compared with controls. Ovaries were collected from the mice and subjected to hematoxylin-eosin staining and immunohistochemistry analysis. RESULTS: We showed that Baicalin had a dose-dependent effect on granulosa cells cultured in vitro. A low concentration of Baicalin (for example, 10 µM) helped to maintain the viability of granulosa cells; however, at a concentration exceeding 50 µM, it exerted a toxic effect. A low concentration significantly improved the viability of granulosa cells and inhibited cell apoptosis, which may be related to the resultant upregulation of Bcl-2 expression and downregulation of Bax and Caspase 3. By constructing a hydrogen peroxide-induced cell oxidative stress damage model, we found that Baicalin reversed the cell damage caused by hydrogen peroxide. In addition, Baicalin increased the secretion of estradiol and progesterone by upregulating P450arom and stAR. The results of the in vivo experiment showed that the intragastric administration of Baicalin to aged mice improved the estrous cycle and oocyte quality. Furthermore, we observed that Baicalin enhanced the viability of granulosa cells through the mTOR pathway, which in turn improve ovarian function. CONCLUSION: These results indicate that Baicalin could improve the viability of ovarian granulosa cells and the secretion of steroid hormones and thus could help to improve degenerating ovarian function and delay ovarian aging.

Theaflavin 3, 3'-Digallate Delays Ovarian Aging by Improving Oocyte Quality and Regulating Granulosa Cell Function.

Ovarian aging refers to the gradual decline of ovarian function with increasing physiological age, manifested as decreased ovarian reserve, elevated aging-related markers, and reduced oocyte quality. With a declining female fertility and a growing aging population, it is urgent to delay ovarian aging to maintain fertility and improve the life quality of women. Theaflavin 3, 3'-digallate (TF3) is a naturally bioactive polyphenol compound extracted from black tea, and its antioxidant properties play an important role in maintaining human health and delaying aging; however, the effects of TF3 on female reproduction and ovarian function are not yet clear. Here, we show that TF3 can preserve primordial follicle pool, partially restore the estrous cycle, and increase the offspring number of aged mice. Meanwhile, TF3 gavage increased the number of oocytes retrieved, decreased the level of reactive oxygen species, increased the level of glutathione, and decreased the abnormal rate of oocyte spindle after ovulation induction. Moreover, TF3 inhibited human granulosa cell apoptosis and improved their antioxidative stress ability. High-throughput sequencing and small-molecule-targeted pharmacological prediction show that TF3 affects multiple pathways and gene expression levels, mainly involved in reproductive and developmental processes. It may also affect cellular function by targeting mTOR to regulate the autophagic pathway, thereby delaying the process of ovarian aging. This study shows that TF3 can be used as a potential dietary supplement to protect ovary function from aging and thereby improving the life quality of advanced-age women.

Expression Level of ADAMTS1 in Granulosa Cells of PCOS Patients Is Related to Granulosa Cell Function, Oocyte Quality, and Embryo Development.

A disintegrin and metalloproteinase with thrombospondin motifs 1 (ADAMTS1) is an extracellular matrix metalloproteinase that plays an important role in the process of ovulation. According to previous studies, the expression level of ADAMTS1 in the granulosa cells of polycystic ovarian syndrome (PCOS) patients and the mechanism for regulating oocyte quality and embryonic development potential are still unclear. Our research clarified that ADAMTS1 was significantly increased in granulosa cells of PCOS patients as compared to ovulatory controls. After silencing ADAMTS1 in granulosa cells, cell proliferation and E2 secretion were significantly inhibited, which may be related to the down-regulation of B-cell lymphoma 2 (Bcl2) family genes and key genes involved in E2 synthesis. Through retrospective analysis of the clinical data, it was found that the expression level of ADAMTS1 was significantly positively correlated to the oocyte maturation rate and good-quality embryo rate in PCOS patients. The downregulation of ADAMTS1 in primary granulosa cells lead to the changes in the expression of marker genes for oocyte and embryonic quality. By using immunofluorescence staining, it was found ADAMTS1 was expressed in various stages of pre-implantation embryo but its expression level gradually decreases with the development of the embryo. In addition, the silence of ADAMTS1 in 3PN zygotes significantly prolonged the development time of the zygote to the morula stage. This is, to our knowledge, the first time to explored the mechanism by which ADAMST1 is involved in affecting the quality of oocytes and embryonic development potential, which will provide new evidence for further understanding of the follicular microenvironment and embryo development.

Expression of sirtuins in ovarian follicles of postnatal mice.

Mammalian ovarian follicular development is an intricate, elaborate, and well-organized phenomenon regulated by various signaling pathways; however, the underlying mechanism remains unclear. Mammalian sirtuins (sirtuin 1 to sirtuin 7) are a group of NAD+ -dependent deacetylases implicated in various physiological processes including cell proliferation, apoptosis, cell cycle progression, and insulin signaling. Mammalian ovarian sirtuins have been studied using adult and aged bovine, porcine, and murine models. However, limited information is available regarding their precise expression patterns and the localization of follicle development in mice. This study aimed to assess the dynamic expression and localization of all seven sirtuins in early postnatal mouse ovaries through real-time polymerase chain reaction analysis and immunohistochemistry, respectively. During postnatal ovarian follicle development, sirtuin 1, sirtuin 4, and sirtuin 6 were downregulated compared with those in 1-day postnatal mouse ovaries (p < .05), indicating that these three sirtuin genes may be markers of follicular development. Combining their localization in granulosa cells through immunohistochemical studies, sirtuin 1, sirtuin 4, and sirtuin 6 are suggested to play negative regulatory roles in mammal ovarian follicular granulosa cell development. Furthermore, we found that sirtuin 2 (p < .05) and sirtuin 7 (p < .05) mRNA were constantly upregulated relative to sirtuin 1, although limited information is available regarding sirtuin 7. Among all sirtuins in mouse ovaries, sirtuin 1 was relatively and steadily downregulated. Upon sirtuin 1 overexpression in 1-day postnatal mouse ovaries via sirtuin 1-harboring adenoviruses in vitro, the emergence of primary follicles was delayed, as was the emergence of secondary follicles in 4-day postnatal ovaries. Further studies on KGN cell lines reported that interfering with sirtuin 1 expression in granulosa cell significantly affected granulosa cell proliferation and the expression of mitochondrial genes. This study presents the first systemic analysis of dynamic patterns of sirtuin family expression in early postnatal mice ovaries, laying the foundation for further studies on less discussed sirtuin subtypes, such as sirtuin 5 and sirtuin 7.

The Efficacy And Safety Of Apatinib Treatment For Patients With Metastatic Or Recurrent Cervical Cancer: A Retrospective Study.

BACKGROUND: This study was performed to assess the efficacy and safety of apatinib in patients with metastatic or recurrent cervical cancer. METHODS: Twenty-six patients with metastatic or recurrent cervical cancer and treated with apatinib until progressive disease or unacceptable toxicity were included in this multicenter, retrospective, observational study from January 2016 to April 2018. The primary end point was progression free survival (PFS). Secondary end points included overall survival (OS), objective response rate (ORR), disease control rate (DCR), and toxicity. Toxicities were assessed according to Common Terminology Criteria for Adverse Events. RESULTS: A total of 26 metastatic or recurrent cervical cancer patients were enrolled in this study. No complete response (CR) occurred, 4 patients (15.4%) showed partial response (PR), 11 patients (42.3%) had stable disease (SD), and 11 patients (42.3%) had progressive disease (PD), with DCR of 57.7% and ORR of 15.4%. Median progression-free survival (PFS) was 3.0 months (95% confidence interval [CI]: 0-6.3 months) and overall survival (OS) was 7.0 months (95% CI: 5.1-8.9 months) respectively. The most common adverse effects were hand-foot syndrome (50.0%), secondary hypertension (26.9%) and fatigue (26.9%). Three patients discontinued treatment due to grade 3 toxicities (one case for hand-foot syndrome, two cases for diarrhea) and 6 patients required dose reduction because of adverse effects. CONCLUSION: Apatinib seems active in heavily-pretreated metastatic or recurrent cervical cancer. The adverse effects were moderate but manageable.