β-catenin is a molecular switch that regulates transition of cell-cell adhesion to fusion

When a sperm and an oocyte unite upon fertilization, their cell membranes adhere and fuse, but little is known about the factors regulating sperm-oocyte adhesion. Here we explored the role of β-catenin in sperm-oocyte adhesion. Biochemical analysis revealed that E-cadherin and β-catenin formed a complex in oocytes and also in sperm. Sperm-oocyte adhesion was impaired when β-catenin-deficient oocytes were inseminated with sperm. Furthermore, expression of β-catenin decreased from the sperm head and the site of an oocyte to which a sperm adheres after completion of sperm-oocyte adhesion. UBE1-41, an inhibitor of ubiquitin-activating enzyme 1, inhibited the degradation of β-catenin, and reduced the fusing ability of wild-type (but not β-catenin-deficient) oocytes. These results indicate that β-catenin is not only involved in membrane adhesion, but also in the transition to membrane fusion upon fertilization

Identical NR5A1 Missense Mutations in Two Unrelated 46,XX Individuals with Testicular Tissues

The role of monogenic mutations in the development of 46,XX testicular/ovotesticular disorders of sex development (DSD) remains speculative. Although mutations in NR5A1 are known to cause 46,XY gonadal dysgenesis and 46,XX ovarian insufficiency, such mutations have not been implicated in testicular development of 46,XX gonads. Here, we identified identical NR5A1 mutations in two unrelated Japanese patients with 46,XX testicular/ovotesticular DSD. The p.Arg92Trp mutation was absent from the clinically normal mothers and from 200 unaffected Japanese individuals. In silico analyses scored p.Arg92Trp as probably pathogenic. In vitro assays demonstrated that compared with wild‐type NR5A1, the mutant protein was less sensitive to NR0B1‐induced suppression on the SOX9 enhancer element. Other sequence variants found in the patients were unlikely to be associated with the phenotype. The results raise the possibility that specific mutations in NR5A1 underlie testicular development in genetic females

Mamld1 Knockdown Reduces Testosterone Production and Cyp17a1 Expression in Mouse Leydig Tumor Cells

MAMLD1 is known to be a causative gene for hypospadias. Although previous studies have indicated that MAMLD1 mutations result in hypospadias primarily because of compromised testosterone production around the critical period for fetal sex development, the underlying mechanism(s) remains to be clarified. Furthermore, although functional studies have indicated a transactivation function of MAMLD1 for the non-canonical Notch target Hes3, its relevance to testosterone production remains unknown. To examine these matters, we performed Mamld1 knockdown experiments.Mamld1 knockdown was performed with two siRNAs, using mouse Leydig tumor cells (MLTCs). Mamld1 knockdown did not influence the concentrations of pregnenolone and progesterone but significantly reduced those of 17-OH pregnenolone, 17-OH progesterone, dehydroepiandrosterone, androstenedione, and testosterone in the culture media. Furthermore, Mamld1 knockdown significantly decreased Cyp17a1 expression, but did not affect expressions of other genes involved in testosterone biosynthesis as well as in insulin-like 3 production. Hes3 expression was not significantly altered. In addition, while 47 genes were significantly up-regulated (fold change >2.0×) and 38 genes were significantly down-regulated (fold change <0.5×), none of them was known to be involved in testosterone production. Cell proliferation analysis revealed no evidence for compromised proliferation of siRNA-transfected MLTCs.The results, in conjunction with the previous data, imply that Mamld1 enhances Cyp17a1 expression primarily in Leydig cells and permit to produce a sufficient amount of testosterone for male sex development, independently of the Hes3-related non-canonical Notch signaling

CD9 Tetraspanin Interacts with CD36 on the Surface of Macrophages: A Possible Regulatory Influence on Uptake of Oxidized Low Density Lipoprotein

CD36 is a type 2 scavenger receptor with multiple functions. CD36 binding to oxidized LDL triggers signaling cascades that are required for macrophage foam cell formation, but the mechanisms by which CD36 signals remain incompletely understood. Mass spectrometry analysis of anti-CD36 immuno-precipitates from macrophages identified the tetraspanin CD9 as a CD36 interacting protein. Western blot showed that CD9 was precipitated from mouse macrophages by anti-CD36 monoclonal antibody and CD36 was likewise precipitated by anti-CD9, confirming the mass spectrometry results. Macrophages from cd36 null mice were used to demonstrate specificity. Membrane associations of the two proteins on intact cells was analyzed by confocal immunofluorescence microscopy and by a novel cross linking assay that detects proteins in close proximity (<40 nm). Functional significance was determined by assessing lipid accumulation, foam cell formation and JNK activation in wt, cd9 null and cd36 null macrophages exposed to oxLDL. OxLDL uptake, lipid accumulation, foam cell formation, and JNK phosphorylation were partially impaired in cd9 null macrophages. The present study demonstrates that CD9 associates with CD36 on the macrophage surface and may participate in macrophage signaling in response to oxidized LDL

Human Endometrial CD98 Is Essential for Blastocyst Adhesion

BACKGROUND: Understanding the molecular basis of embryonic implantation is of great clinical and biological relevance. Little is currently known about the adhesion receptors that determine endometrial receptivity for embryonic implantation in humans. METHODS AND PRINCIPAL FINDINGS: Using two human endometrial cell lines characterized by low and high receptivity, we identified the membrane receptor CD98 as a novel molecule selectively and significantly associated with the receptive phenotype. In human endometrial samples, CD98 was the only molecule studied whose expression was restricted to the implantation window in human endometrial tissue. CD98 expression was restricted to the apical surface and included in tetraspanin-enriched microdomains of primary endometrial epithelial cells, as demonstrated by the biochemical association between CD98 and tetraspanin CD9. CD98 expression was induced in vitro by treatment of primary endometrial epithelial cells with human chorionic gonadotropin, 17-β-estradiol, LIF or EGF. Endometrial overexpression of CD98 or tetraspanin CD9 greatly enhanced mouse blastocyst adhesion, while their siRNA-mediated depletion reduced the blastocyst adhesion rate. CONCLUSIONS: These results indicate that CD98, a component of tetraspanin-enriched microdomains, appears to be an important determinant of human endometrial receptivity during the implantation window

The fusing ability of sperm is bestowed by CD9-containing vesicles released from eggs in mice

Membrane fusion is an essential step in the encounter of two nuclei from sex cells—sperm and egg—in fertilization. However, aside from the involvement of two molecules, CD9 and Izumo, the mechanism of fusion remains unclear. Here, we show that sperm–egg fusion is mediated by vesicles containing CD9 that are released from the egg and interact with sperm. We demonstrate that the CD9−/− eggs, which have a defective sperm-fusing ability, have impaired release of CD9-containing vesicles. We investigate the fusion-facilitating activity of CD9-containing vesicles by examining the fusion of sperm to CD9−/− eggs with the aid of exogenous CD9-containing vesicles. Moreover, we show, by examining the fusion of sperm to CD9−/− eggs, that hamster eggs have a similar fusing ability as mouse eggs. The CD9-containing vesicle release from unfertilized eggs provides insight into the mechanism required for fusion with sperm

Supplementary Material for: SOX3 Overdosage Permits Normal Sex Development in Females with Random X Inactivation

Submicroscopic duplications involving <i>SOX3</i> and/or its flanking regions have been identified in 46,XX individuals both with and without disorders of sex development, raising the question whether <i>SOX3</i> overdosage is sufficient to induce testicular development in genetically female individuals. Here, we report a mother-daughter pair with female phenotypes and random X inactivation. The individuals carry complex X chromosomal rearrangements leading to a copy number gain of genomic regions involving <i>SOX3</i> and its upstream region. The amplified DNA fragments were detected at Xq27. These results provide evidence that <i>SOX3 </i>overdosage permits normal sex development in 46,XX individuals with random X inactivation

Aberrant regulation of bone trace elements in motheaten and osteopetrosis mutant mice.

Increasing numbers of genetic diseases involving bone development and models for these diseases have been identified recently. Analysis of these bone diseases have revealed that regulated action of multiple growth factors and subsequent signal transduction are essential for normal bone formation. In this paper, two murine mutant mice viable motheaten and osteopetrosis are analyzed. Mice with the recessive \u27viable motheaten\u27 mutation express a severe immunodeficiency syndrome and bone defects. Mutations at the motheaten locus were shown to be the result of aberrant splicing of the gene encoding hematopoietic cell phosphatase (Hcph). Mice homozygous for the osteopetrosis mutation develop congenital osteopetrosis due to a severe deficiency of osteoclasts. It has been recognized that bone trace element composition analysis helps to define bone-related physiological conditions. We have analyzed bone trace element composition in viable motheaten and osteopetrosis mutant animal models in this study. In order to gain insights into the effects of particular genetic defects on bone trace element composition, inductively coupled plasma atomic emissions spectrometry (ICP-AES) analysis was performed. Marked changes in bone trace element levels were found in limb bones of viable motheaten and osteopetrosis mutant mice. An assessment of these trace element spectrum in the two mutant models with respect to each genetic defects are discussed in this paper