The polycystic ovary syndrome-associated gene Yap1 is regulated by gonadotropins and sex steroid hormones in hyperandrogenism-induced oligo-ovulation in mouse.

STUDY QUESTION: What is the physiological function of Yes-associated protein-1 (Yap1), a susceptibility gene for polycystic ovary syndrome (PCOS), in ovarian granulosa cells (GCs)? SUMMARY ANSWER: Physiologically, steroid sex hormones stimulate follicle growth by activating YAP1; however, the preovulatory inhibition of YAP1 activity in GCs is a prerequisite of LH actions. WHAT IS KNOWN ALREADY: PCOS is a common gynecologic and endocrine disease with multiple short and long-term consequences. Many PCOS patients suffer anovulation caused by hyperandrogenism, but its etiology remains unclear. STUDY DESIGN, SIZE, DURATION: To study the effect of acute hyperandrogenism on ovulation, we injected pregnant mare serum gonadotrophin (PMSG)-primed (44 h) pubertal mice with dihydrotestosterone (DHT), the major biologically active form of androgen, in a superovulation assay. We investigated if YAP1 is regulated by testosterone and if it is potentially involved in follicle development and ovulation. Cultured primary GCs were subjected to Yap1 depletion by RNA interference and Yap1 overexpression by adenoviral infections. PARTICIPANTS/MATERIALS, SETTING, METHODS: Female mice at postnatal day (PD)-21~23 were analyzed to avoid the complexity of ovarian functions associated with estrous cycles and endogenous surges of gonadotropins. Immature mice were injected intraperitoneally with five IU PMSG to stimulate preovulatory follicle development followed 44 h later with five IU hCG to stimulate ovulation. For DHT treatments, female mice at PD23 were injected intraperitoneally with five IU PMSG followed 44 h later with five IU hCG alone (as control) or five IU hCG plus 100 µg DHT, which was dissolved in 0.1 ml DMSO. Methods of gene expression detection used include immunohistochemistry, immunofluorescence, Western blotting and quantitative PCR. More than three biological and technical replicates were included in each experiments. MAIN RESULTS AND THE ROLE OF CHANCE: we provide novel evidence in a mouse model that YAP1 is required for proliferation of ovarian GCs, but is down-regulated by LH through the extracellular-regulated kinase-1/2 (ERK1/2) cascade. Acute hyperandrogenism blocks LH actions and causes oligo-ovulation by activating YAP1. LARGE SCALE DATA: N/A. LIMITATIONS, REASONS FOR CAUTION: Results shown were obtained only in mouse, and need to be further confirmed in human samples. WIDER IMPLICATIONS OF THE FINDINGS: These findings not only elucidated the role of YAP1 in maintaining normal ovarian functions, but also link the YAP1 deregulation to the pathogenesis of PCOS. STUDY FUNDING AND COMPETING INTEREST(S): This study is funded by the National Key Research and Development Program of China (2016YFC1000600 and 2017YFSF1001500) and National Natural Science Foundation of China (31528016, 31371449 and 31671558). The authors have no competing interests.

TET1 inhibits cell proliferation by inducing RASSF5 expression.

Tet methylcytosine dioxygenases (TETs) catalyze the oxidative reactions of 5-methylcytosine to 5-hydroxymethylcytosine (5hmC). However, TET1 roles in ovarian cancer cell growth are unknown. Here, we show that ectopic expression of TET1 increased 5hmC levels, and inhibited proliferation and colony formation in ovarian cancer cell lines. Furthermore, in vitro and in vivo functional studies demonstrated that TET1 overexpression is necessary for the suppression of ovarian cancer growth, whereas depletion of TET1 expression had the opposite effect. Furthermore, the results of RNA-seq and qRT-PCR analyses identified a tumor suppressor, Ras association domain family member 5 (RASSF5), as the key downstream target of TET1. TET1 promotes RASSF5 expression by demethylating a CpG site within RASSF5 promoter. Up-regulated RASSF5 expression leads to the suppression of ovarian cancer cells growth. Additionally, we demonstrated that inhibition of CUL4-DDB1 ubiquitin ligase complex decrease 5hmC levels in ovarian cancer cells. These results provide new insights into the understanding of how ovarian cancers develop and grow, and identify TET1 as a key player in this process.

CFP1 Regulates Histone H3K4 Trimethylation and Developmental Potential in Mouse Oocytes.

Trimethylation of histone H3 at lysine-4 (H3K4me3) is associated with eukaryotic gene promoters and poises their transcriptional activation during development. To examine the in vivo function of H3K4me3 in the absence of DNA replication, we deleted CXXC finger protein 1 (CFP1), the DNA-binding subunit of the SETD1 histone H3K4 methyltransferase, in developing oocytes. We find that CFP1 is required for H3K4me3 accumulation and the deposition of histone variants onto chromatin during oocyte maturation. Decreased H3K4me3 in oocytes caused global downregulation of transcription activity. Oocytes lacking CFP1 failed to complete maturation and were unable to gain developmental competence after fertilization, due to defects in cytoplasmic lattice formation, meiotic division, and maternal-zygotic transition. Our study highlights the importance of H3K4me3 in continuous histone replacement for transcriptional regulation, chromatin remodeling, and normal developmental progression in a non-replicative system.

Mitoguardin-1 and -2 promote maturation and the developmental potential of mouse oocytes by maintaining mitochondrial dynamics and functions.

Mitochondrial dynamics change mitochondrial morphological features and numbers as a part of adaptive cellular metabolism, which is vital for most eukaryotic cells and organisms. A disease or even death of an animal can occur if these dynamics are disrupted. Using large-scale genetic screening in fruit flies, we previously found the gene mitoguardin (Miga), which encodes a mitochondrial outer-membrane protein and promotes mitochondrial fusion. Knockout mouse strains were generated for the mammalian Miga homologs Miga1 and Miga2. Miga1/2-/- females show greatly reduced quality of oocytes and early embryos and are subfertile. Mitochondria became clustered in the cytoplasm of oocytes from the germinal-vesicle stage to meiosis II; production of reactive oxygen species increased in mitochondria and caused damage to mitochondrial ultrastructures. Additionally, reduced ATP production, a decreased mitochondrial-DNA copy number, and lower mitochondrial membrane potential were detected in Miga1/2-/- oocytes during meiotic maturation. These changes resulted in low rates of polar-body extrusion during oocyte maturation, reduced developmental potential of the resulting early embryos, and consequently female subfertility. We provide direct evidence that MIGA1/2-regulated mitochondrial dynamics is crucial for mitochondrial functions, ensure oocyte maturation, and maintain the developmental potential.

Pseudomonas reactans, a bacterial strain isolated from the intestinal flora of Blattella germanica with anti-Beauveria bassiana activity.

Anti-Beauveria bassiana activity of aqueous fecal extracts from conventional German cockroaches [Blattella germanica (L.)] was detected, but was not detected in samples from germ-free German cockroaches. Subsequently, bacterial strain BGI-14 was isolated from the gut of conventional German cockroaches and was identified as Pseudomonas reactans based on 16S rDNA sequence. The strain BGI-14 not only inhibited the germination of conidia, but also inhibited the growth of B. bassiana hyphae. Further studies demonstrated that B. bassiana infections in German cockroaches orally treated with the extracts of BGI-14 fermentation were significantly weakened. Compared with the control group, the cumulative mortality rate of treatment group was reduced by 10.3% at 20 d postinoculation. These studies imply that intestinal flora with anti-B. bassiana activity might contribute to resistance of infection by entomopathogenic fungi.