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Comment |
Non-canonical WNT5a regulates Epithelial-to-Mesenchymal Transition in the mouse ovarian surface epithelium. Abedini A et al. (2020) The ovarian surface epithelium (OSE) is a monolayer that covers the ovarian surface and is involved in ovulation by rupturing and enabling release of a mature oocyte and by repairing the wound after ovulation. Epithelial-to-mesenchymal transition (EMT) is a mechanism that may promote wound healing after ovulation. While this process is poorly understood in the OSE, in other tissues wound repair is known to be under the control of the local microenvironment and different growth factors such as the WNT signaling pathway. Among WNT family members, WNT4 and WNT5a are expressed in the OSE and are critical for the ovulatory process. The objective of this study was to determine the potential roles of WNT4 and WNT5a in regulating the OSE layer. Using primary cultures of mouse OSE cells, we found WNT5a, but not WNT4, promotes EMT through a non-canonical Ca2+-dependent pathway, up-regulating the expression of Vimentin and CD44, enhancing cell migration, and inhibiting the CTNNB1 pathway and proliferation. We conclude that WNT5a is a stimulator of the EMT in OSE cells, and acts by suppressing canonical WNT signaling activity and inducing the non-canonical Ca2+ pathway.////////////////// Fam70A binds Wnt5a to regulate meiosis and quality of mouse oocytes. Zhang NN et al. (2020) Little is known about the roles of integral membrane proteins beyond channels, carriers or receptors in meiotic oocytes. The transmembrane protein Fam70A was previously identified as a likely "female fertility factor" in Fox3a-knockout mouse ovaries where almost all follicles underwent synchronous activation and the mice became infertile very early. However, whether Fam70A functions in oocyte meiosis remains unknown. Therefore, the present study aimed to address this question. Co-immunoprecipitation, immunogold labelling-electron microscopy, co-localization and yeast two-hybrid assays were used to verify the interaction. Antibody or small interfering RNA transfection was used to deplete the proteins. Immunofluorescence, immunohistochemistry and live tracker staining were used to examine the localization or characterize phenotypes. Western blot was used to examine the protein level. Fam70A was enriched in oocyte membranes important for normal meiosis. Fam70A depletion remarkably disrupted spindle assembly, chromosome congression and first polar body extrusion, which subsequently increased aneuploidy and abnormal fertilization. Moreover, Fam70A directly bound Wnt5a, the most abundant Wnt member within oocytes. Depletion of either Fam70A or Wnt5a remarkably increased adenomatous polyposis coli (APC), which stabilizes active β-catenin and microtubules. Consequently, depletion of either Fam70A or Wnt5a remarkably increased p-β-catenin (inactive form) and acetylated tubulin, while APC knockdown remarkably decreased these two. Furthermore, Fam70A depletion remarkably reduced Akt phosphorylation. Fam70A regulates meiosis and quality of mouse oocytes through both canonical and non-canonical Wnt5a signalling pathways.//////////////////
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Comment |
The WNT/-catenin signaling pathway and expression of survival promoting genes in luteinized granulosa cells: endometriosis as a paradigm for a dysregulated apoptosis pathway. Sanchez AM 2014 et al.
OBJECTIVE
To analyze the WNT/-catenin signaling pathway in luteinized granulosa cells from women with and without endometriosis in relation to cellular apoptosis.
DESIGN
Basic.
SETTING
University hospital.
PATIENT(S)
Patients with a laparoscopic diagnosis of endometriosis (n=30) and women undergoing intracytoplasmic sperm injection for male infertility (control group n=39).
INTERVENTION(S)
Isolation of luteinized granulosa cells.
MAIN OUTCOME MEASURE(S)
Gene expression analysis of components of the WNT/-catenin pathway, protein expression levels of -catenin, and cell cycle studies in luteinized granulosa cells.
RESULT(S)
Compared with luteinized granulosa cells from control women, cells derived from endometriosis patients had significantly higher transcript levels of the -catenin-independent molecules WNT4 and WNT5a and lower levels of the -catenin-dependent molecule WNT1. A decrease of total -catenin as well as of its dephosphorylated active form, together with an aberrant gene expression of the downstream targets survivin and BMP4, was detected in cells from affected women. Flow cytometry analysis confirmed an enhanced apoptosis of luteinized granulosa cells from patients with endometriosis.
CONCLUSION(S)
The concomitant dysregulation of specific members of the WNT pathway and of its pivot molecule -catenin in granulosa cells characterized by an increased apoptosis suggests that the WNT/-catenin signaling pathway might be involved in leading to granulosa cell atresia.
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Albert Ricken et al reported the
Wnt Signaling in the Ovary and the identification and Compartmentalized Expression of wnt-2, wnt-2b, and Frizzled-4 mRNAs .
Using RT-PCR with degenerate primers on RNA from ovaries of hormone-stimulated immature rats, the authors identified transcripts for wnt-2 and wnt-2b. RT-PCR and in situ hybridization (ISH) demonstrated that granulosa cells express wnt-2 mRNA.. RT-PCR analysis, using primers designed from this wnt-2b cDNA sequence, failed to detect transcripts in the ovarian follicular compartment (granulosa and oocyte). ISH revealed that the ovarian surface epithelium expresses wnt-2b mRNA.
Using a similar degenerate RT-PCR approach, the authors detected expression of a putative wnt receptor, frizzled-4 (fzd-4), and a cytoplasmic component of the wnt signaling cascade, disheveled-2 (dsh-2), in the rat ovary. Further analyses using both RT-PCR and ISH indicated that granulosa cells express fzd-4 mRNA.
RT-PCR, using degenerate and specific primers for wnts, on RNA from five ovarian cancer cell lines confirmed the expression of transcripts for wnt-2b. Two additional wnt transcripts (wnt-5a and wnt-11) were detected in the cancer cell lines and in the rat ovary.
These results demonstrate that transcripts corresponding to components of the wnt signaling cascade are expressed in the immature rat ovary. The localization of these transcripts in specific ovarian compartments suggests that this signal transduction pathway may be involved in follicular development and ovarian function. Furthermore, because wnts have been implicated in the oncogenic transformation of epithelial cells, our results raise the possibility that aberrant wnt expression may be involved in ovarian tumorigenesis in humans.
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Mutations |
2 mutations
Species: mouse
Mutation name:
type: None
fertility: None
Comment: Loss of Wnt5a Disrupts Primordial Germ Cell Migration and Male Sexual Development in Mice. Chawengsaksophak K et al. Disruptions in the regulatory pathways controlling sex determination and differentiation can cause disorders of sex development (DSD), often compromising reproductive function. Although extensive efforts have been channeled into elucidating the regulatory mechanisms controlling the many aspects of sexual differentiation, the majority of DSD phenotypes are still unexplained at the molecular level. In this study, we have analyzed the potential involvement of Wnt5a in sexual development and show in mice that Wnt5a is male-specifically up-regulated within testicular interstitial cells at the onset of gonad differentiation. Homozygous deletion of Wnt5a affected sexual development in male mice, causing testicular hypoplasia and bilateral cryptorchidism despite the Leydig cells producing factors such as Hsd3b1 and Insl3. Additionally, Wnt5a-null embryos of both sexes showed a significant reduction in gonadal germ cell numbers, which was caused by aberrant primordial germ cell migration along the hindgut endoderm prior to gonadal colonization. Our results indicate multiple roles for Wnt5a during mammalian reproductive development, and help to clarify further the aetiology of Robinow syndrome (OMIM 268310), a disease previously linked to the WNT5A pathway.
Species: mouse
Mutation name:
type: null mutation
fertility: subfertile
Comment: WNT5a is required for normal ovarian follicle development and antagonizes gonadotropin responsiveness in granulosa cells by suppressing canonical WNT signaling. Abedini A et al. (2015) Whereas the roles of the canonical wingless-type MMTV (mouse mammary tumor virus) integration site family (WNT) signaling pathway in the regulation of ovarian follicle growth and steroidogenesis are now established, noncanonical WNT signaling in the ovary has been largely overlooked. Noncanonical WNTs, including WNT5a and WNT11, are expressed in granulosa cells (GCs) and are differentially regulated throughout follicle development, but their physiologic roles remain unknown. Using conditional gene targeting, we found that GC-specific inactivation of Wnt5a (but not Wnt11) results in the female subfertility associated with increased follicular atresia and decreased rates of ovulation. Microarray analyses have revealed that WNT5a acts to down-regulate the expression of FSH-responsive genes in vitro, and corresponding increases in the expression of these genes have been found in the GCs of conditional knockout mice. Unexpectedly, we found that WNT5a regulates its target genes not by signaling via the WNT/Ca(2+) or planar cell polarity pathways, but rather by inhibiting the canonical pathway, causing both β-catenin (CTNNB1) and cAMP responsive element binding (CREB) protein levels to decrease via a glycogen synthase kinase-3β-dependent mechanism. We further found that WNT5a prevents follicle-stimulating hormone and luteinizing protein from up-regulating the CTNNB1 and CREB proteins and their target genes, indicating that WNT5a functions as a physiologic inhibitor of gonadotropin signaling. Together, these findings identify WNT5a as a key regulator of follicle development and gonadotropin responsiveness.-Abedini, A., Zamberlam, G., Lapointe, E., Tourigny, C., Boyer, A., Paquet, M., Hayashi, K., Honda, H., Kikuchi, A., Price, C., Boerboom, D. WNT5a is required for normal ovarian follicle development and antagonizes gonadotropin responsiveness in granulosa cells by suppressing canonical WNT signaling.//////////////////
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