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Deregulation of WNT2/FZD3/β-catenin pathway compromises the estrogen synthesis in cumulus cells from patients with polycystic ovary syndrome. Qiao GY et al. (2017) Mechanistic insight into estrogen deficiency by polycystic ovary syndrome (PCOS) remains a longstanding challenge in reproductive medicine. Recent advance suggest that Wingless-type MMTV integration site family members (WNTs), in concert with its Frizzled (FZD) receptors, regulate normal folliculogenesis, luteogenesis and ovarian steroidogenesis. However, no studies have so far investigated any causality between WNT-FZDs interactions and disrupted estrogen synthesis under certain pathological conditions. Here, we show that (i) FZD3 expression was significantly up-regulated in the cumulus cells (CCs) from PCOS patients. This up-regulation, along with the activation of WNT2/β-Catenin pathway, was tightly associated with insulin resistance and estrogen deficiency, two hallmarks of PCOS. (ii) Overexpression of exogenous FZD3 in human granulosa cell COV434 impaired long-term FSH incubation-induced CYP19A1 transactivation and the recruitment of β-Catenin onto CYP19A1 promoter, and subsequently compromised FSH-stimulated estrogen production. (iii) Conversely, inhibition of FZD3 expression exhibited a therapeutic effect on estrogen synthesis in PCOS CCs. Thus, excessive FZD3 expression in CCs may act as a brake on steroidogenic activation that is normally overcome by FSH stimulation. Future endeavor in this field should help to elucidate the complicated crosstalk between energy metabolism and endocrine cells through WNT/FZD signaling molecules.//////////////////
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Temporal and spatial expression profiles of Frizzled 3 in the ovary during the estrous cycle. Wang SB et al. (2016) Frizzled 3 is an important receptor in the Wnt/β-catenin pathway, a conserved signaling pathway that regulates gene expression and controls diverse developmental processes. However, the role of this protein during follicular development in the adult ovary is not known. The present study was designed to investigate the expression and localization of Frizzled 3 mRNA and protein during the estrous cycle in the mouse ovary through in situ hybridization (ISH), real-time quantitative polymerase chain reaction, immunohistochemistry and western blot. ISH results showed that in proestrus, high expression of Frizzled 3 was found in the granulosa and stroma with weak levels in the corpus luteum. In estrus and diestrus, the stroma had high Frizzled 3 expression, but levels were low in granulosa cells and corpus luteum. In the metestrus, moderate expression of Frizzled 3 was found in the stroma but low to no expression was found in luteal cells and follicles. The mRNA and protein levels of Frizzled 3 were found to be the highest in proestrus and diestrus compared to estrus and metestrus (P < 0.05), confirming the ISH results. During estrus and diestrus, high Frizzled 3 expression was observed in the stroma and moderate levels in granulosa cells, and during estrus and proestrus, low expression was seen in the oocyte cell membrane. The western blot results further confirmed this change during the estrous cycle. Together, these results indicate that Frizzled 3 is involved in regulating follicular development and oocyte maturation during the estrous cycle.//////////////////
Identification of WNT/{beta}-CATENIN signaling pathway components in human cumulus cells. Wang HX et al. Signaling via the conserved WNT/beta-CATENIN pathway controls diverse developmental processes. To explore its potential role in the ovary, we investigated the expression of WNTs, frizzled (FZD) receptors, and other pathway components in human cumulus cells obtained from oocytes collected for in vitro fertilization. Proteins were detected in cultured cells using immunofluorescence microscopy. Protein-protein interactions were analyzed by means of immunoprecipitation. WNT2, FZD2, FZD3, and FZD9 were identified but WNT1, WNT4 and FZD4 were not detected. WNT2 is co-expressed with FZD2, FZD3, and FZD9. Co-immunoprecipitation using WNT2 antibody demonstrated that WNT2 interacts with both FZD3 and FZD9, but only FZD9 antibody precipitated WNT2. We also identified DVL (disheveled), AXIN, GSK-3beta (glycogen synthase kinase-3beta), and beta-CATENIN. beta-CATENIN is concentrated in the plasma membranes. DVL co-localizes with FZD9 and AXIN in the membranes, but GSK-3beta has little colocalization with AXIN and beta-CATENIN. Interestingly, beta-CATENIN is highly co-localized with FZD9 and AXIN. CDH1 (E-cadherin) was also detected in the plasma membranes and cytoplasm, co-localized with beta-CATENIN, and CDH1 antibody precipitated beta-CATENIN. The results suggest that WNT2 could act through its receptor FZD9 to regulate the beta-CATENIN pathway in cumulus cells, recruiting beta-CATENIN into plasma membranes and promoting the formation of adherens junctions involving CDH1.
The human cumulus-oocyte complex gene-expression profile. Assou S et al. BACKGROUND: The understanding of the mechanisms regulating human oocyte maturation is still rudimentary. We have identified transcripts differentially expressed between immature and mature oocytes and cumulus cells. METHODS: Using oligonucleotide microarrays, genome-wide gene expression was studied in pooled immature and mature oocytes or cumulus cells from patients who underwent IVF. RESULTS: In addition to known genes, such as DAZL, BMP15 or GDF9, oocytes up-regulated 1514 genes. We show that PTTG3 and AURKC are respectively the securin and the Aurora kinase preferentially expressed during oocyte meiosis. Strikingly, oocytes overexpressed previously unreported growth factors such as TNFSF13/APRIL, FGF9, FGF14 and IL4 and transcription factors including OTX2, SOX15 and SOX30. Conversely, cumulus cells, in addition to known genes such as LHCGR or BMPR2, overexpressed cell-to-cell signalling genes including TNFSF11/RANKL, numerous complement components, semaphorins (SEMA3A, SEMA6A and SEMA6D) and CD genes such as CD200. We also identified 52 genes progressively increasing during oocyte maturation, including CDC25A and SOCS7. CONCLUSION: The identification of genes that were up- and down-regulated during oocyte maturation greatly improves our understanding of oocyte biology and will provide new markers that signal viable and competent oocytes. Furthermore, genes found expressed in cumulus cells are potential markers of granulosa cell tumours.
Sala CF, et al. (Biochem Biophys Res Commun. 2000 )identified the FZD3 gene and found that FZD3 is expressed in all analyzed human tissues, with quantitatively higher expression in the CNS and in urogenital structures. Tapper J, et al. (Cancer Genet Cytogenet. 2001) performed a large scale survey for the identification of differentially expressed genes in serous ovarian carcinoma by using cDNA array analysis. They found that the most prominent differences between advanced and local adenocarcinoma were upregulation of COL3A1, CFGR, and MET in advanced carcinoma, and downregulation of HGFAC, FZD3, and BFL1 in the same tumors.
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