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General Comment |
NCBI Summary:
Ephrin receptors and their ligands, the ephrins, mediate numerous developmental processes, particularly in the nervous system. Based on their structures and sequence relationships, ephrins are divided into the ephrin-A (EFNA) class, which are anchored to the membrane by a glycosylphosphatidylinositol linkage, and the ephrin-B (EFNB) class, which are transmembrane proteins. The Eph family of receptors are divided into 2 groups based on the similarity of their extracellular domain sequences and their affinities for binding ephrin-A and ephrin-B ligands. Ephrin receptors make up the largest subgroup of the receptor tyrosine kinase (RTK) family. The protein encoded by this gene binds to ephrin-B2 and plays an essential role in vascular development. [provided by RefSeq, Jul 2008]
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Comment |
Expression and localisation of ephrin-B1 and EphB4 in steroidogenic cells in the naturally cycling mouse ovary. Alam J et al. (2021) Ephrin receptors and ligands are membrane-bound molecules that modulate diverse cellular functions such as cell adhesion, epithelial-mesenchymal transition, motility, differentiation and proliferation. We recently reported the co-expression of ephrin-B1 and EphB4 in adult and foetal Leydig cells of the mouse testis, and thus speculated that their co-expression is a common property in gonadal steroidogenic cells. Therefore, in this study we examined the expression and localisation of ephrin-B1 and EphB4 in the naturally cycling mouse ovary, as their expression patterns in the ovary are virtually unknown. We found that ephrin-B1 and EphB4 were co-expressed in steroidogenic cells of all kinds, i.e. granulosa cells and CYP17A1-positive steroidogenic theca cells as well as in 3β-HSD-positive luteal cells and the interstitial glands; their co-expression potentially serves as a good marker to identify sex steroid-producing cells even in extra-gonadal organs/tissues. We also found that ephrin-B1 and EphB4 expression in granulosa cells was faint and strong, respectively; ephrin-B1 expression in luteal cells was weak in developing and temporally mature corpora lutea (those of the current cycle) and likely strong in regressing corpora lutea (those of the previous cycle) and EphB4 expression in luteal cells was weak in corpora lutea of the current cycle and likely faint/negative in the corpora lutea of the previous cycle. These findings suggest that a luteinising hormone surge triggers the upregulation of ephrin-B1 and downregulation of EphB4, as this expression fluctuation occurs after the surge. Overall, ephrin-B1 and EphB4 expression patterns may represent benchmarks for steroidogenic cells in the ovary.//////////////////
Egawa M, et al reported that Ephrin B1 Is Expressed on Human Luteinizing Granulosa Cells in Corpora Lutea of the Early Luteal Phase:and the Possible Involvement of the B Class Eph-Ephrin System during Corpus Luteum Formation.
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Ephrins and their Eph receptors are both membrane-bound proteins that function in various cell-cell recognition processes, such as morphogenesis and angiogenesis. In this study we examined the expression of B class ephrins-Ephs in the human ovary during corpus luteum formation, a process of tissue remodeling accompanied by angiogenesis. RT-PCR analysis detected mRNAs for Eph B1, B2, and B4 and ephrin B1 and B2, but not Eph B3 and B6 or ephrin B3, in human corpora lutea of the early luteal phase. By immunohistochemistry, ephrin B1 was moderately expressed on theca interna cells, but was expressed at a low level on granulosa cells in the preovulatory follicles. After ovulation, a rapid increase in ephrin B1 expression was observed on luteinizing granulosa cells, whereas its expression on luteinizing theca interna cells decreased. The mRNA expression of ephrin B1 in luteinizing granulosa cells was confirmed by Northern blotting. Flow cytometry showed that ephrin B1 was expressed on the surface of isolated luteinizing granulosa cells. Moreover, these cells had the ability to bind to recombinant Eph B2-Fc fusion protein. These findings suggest that ephrin B1-expressing granulosa cells can directly interact with Eph-bearing cells during corpus luteum formation in vivo, suggesting that Eph-ephrin system is involved in this process.
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