Alternative titles; symbols
HGNC Approved Gene Symbol: EBAG9
Cytogenetic location: 8q23.2 Genomic coordinates (GRCh38) : 8:109,539,702-109,565,996 (from NCBI)
EBAG9 is an estrogen-responsive gene whose gene product is involved in immune cell apoptosis (Zhang et al., 2013).
Estrogen is essential for the growth, development, differentiation, and function of female organs as well as other nonreproductive organ systems. Estrogen action is mediated by estrogen receptors (ESRs; see 133430), which bind to estrogen-responsive elements (EREs) in the enhancer regions of target genes, directly regulating their transcription. Watanabe et al. (1998) used the CpG-GBS (genomic binding site) method to isolate novel estrogen-responsive genes. By screening a breast cancer cDNA library with the ESR-binding fragments isolated from the CpG island library, they isolated cDNAs encoding EBAG9, GRIN2D (602717), and COX7A2L (605771), which the authors termed EB9, EB11, and EB1 (or COX7RP), respectively. EBAG9 encodes a deduced 214-amino acid protein. Northern blot analysis revealed expression of a 1.8-kb transcript in endometrial carcinoma and breast cancer cell lines and, to a lesser extent, in an osteosarcoma cell line.
Ikeda et al. (2000) noted that EBAG9 is identical with RCAS1, a human cancer cell surface antigen isolated by Nakashima et al. (1999).
Ikeda et al. (2000) determined that the 5-prime flanking region of EBAG9 is 65% GC-rich, lacks a TATA motif, and contains a perfect palindromic ERE element at -60 to -48 upstream of the transcription initiation site.
Using FISH, Ikeda et al. (2000) mapped the EBAG9 gene to chromosome 8q23, a region that is frequently amplified in tumors.
Using gel mobility shift analysis, Watanabe et al. (1998) confirmed that the ERE of EBAG9 bound to ESR. Northern blot analysis detected an upregulation of EBAG9 after estrogen treatment of a breast cancer cell line.
By promoter analysis, Ikeda et al. (2000) found that the ERE-containing region of EBAG9 could respond to estrogen in a breast cancer cell line. Electrophoretic mobility shift and supershift analysis demonstrated that ESR1 (133430) was involved in binding to the ERE element.
By knockdown analysis in MCF-7 cells, Han et al. (2007) showed that RCAS1 expression inhibited T-cell proliferation and development, promoted T-cell apoptosis, and decreased cytokine secretion by T cells.
Zhang et al. (2013) found that RCAS1 expression induced apoptosis in T lymphocytes and immune cells derived from leukemia cell lines. RCAS1 expression inhibited proliferation of cultured K562 and Jurkat cells and was negatively correlated with GSK3-beta (GSK3B; 605004) expression but positively with phosphorylated GSK3-beta expression. Moreover, RCAS1 receptor (RCAS1R) was not expressed in Jurkat cells, but its expression was moderately upregulated following activation of Jurkat cells by phytohemagglutinin. The authors concluded that RCAS1 induces immune cell apoptosis via an RCAS1-RCAS1R pathway. In addition, immunohistochemical analysis showed that RCAS1 was expressed in breast cancer tissue, but not in normal breast tissue.
Associations Pending Confirmation
Heyne et al. (2023) analyzed data from the nationwide electronic health records of 176,899 Finnish individuals and identified a significant association between female infertility (see 615774) and biallelic variation in the EBAG9 gene. Among 106,732 Finnish women born between 1925 and 1975, for whom the entire reproductive life span was available, the authors found that 357 homozygous carriers of an intronic C-G transversion at chr8:109551075 (GRCh38) had fewer children, and later age at first child, compared to wildtype women. The authors noted that the effect was primarily driven by 71 homozygotes who were diagnosed with infertility, and that compared to all 7,980 women diagnosed with infertility, the 71 homozygotes still had significantly fewer children and later age at first child.
Ruder et al. (2009) found that Ebag9 -/- mice were healthy and fertile without any apparent morphologic abnormalities. Ebag9 -/- mice were born at the expected mendelian frequency, maintained normal pregnancy, and had normal development of erythroid cells and lymphocytes. However, in vitro analysis of splenocytes from Ebag9 -/- mice revealed enhanced release of granzyme A (GZMA; 140050) from cytotoxic T lymphocytes (CTLs), resulting in increased cytotoxicity. Accordingly, deletion of Ebag9 enhanced primary and secondary Cd8 (see 186910)-positive T-cell responses in mice in vivo. The cytolytic response in Ebag9 -/- mice was specific to CTLs and not natural killer (NK) cells, despite Ebag9 expression in NK cells. Moreover, priming and expansion of naive antigen-specific T cells indicated that the response was not a consequence of altered T-cell effector frequencies. Ebag9 predominantly localized to Golgi in primary Cd8-positive T cells, but it was redistributed to the plasma membrane upon T-cell receptor activation. Ebag9 physically interacted with gamma-2-adaptin (AP1G2; 603534) to modulate generation of secretory granules in CTLs, and as a result, Ebag9 deficiency affected the endosomal-lysosomal trafficking pathway in Cd8-positive T cells. However, formation of the immunologic synapse remained unaffected in Ebag9 -/- CTLs, because Ebag9 was not involved in the secretion process at the plasma membrane itself, but rather acted upstream through regulation of trafficking steps and maturation of secretory lysosomes. In agreement, targeting of perforin (PRF1; 170280) and granzyme B (GZMB; 123910) to secretory lysosomes was more efficient in Ebag9-deficient CTLs, and sorting of the lysosomal hydrolase cathepsin D (CTSD; 116840) to secretory lysosomes was enhanced.
Han, Y., Qin, W., Huang, G. Knockdown of RCAS1 expression by RNA interference recovers T cell growth and proliferation. Cancer Lett 257: 182-190, 2007. [PubMed: 17825484] [Full Text: https://doi.org/10.1016/j.canlet.2007.07.016]
Heyne, H. O., Karjalainen, J., Karczewski, K. J., Lemmela, S. M., Zhou, W., FinnGen, Havulinna, A. S., Kurki, M., Rehm, H. L., Palotie, A., Daly, M. J. Mono- and biallelic variant effects on disease at biobank scale. Nature 613: 519-525, 2023. [PubMed: 36653560] [Full Text: https://doi.org/10.1038/s41586-022-05420-7]
Ikeda, K., Sato, M., Tsutsumi, O., Tsuchiya, F., Tsuneizumi, M., Emi, M., Imoto, I., Inazawa, J., Muramatsu, M., Inoue, S. Promoter analysis and chromosomal mapping of human EBAG9 gene. Biochem. Biophys. Res. Commun. 273: 654-660, 2000. [PubMed: 10873660] [Full Text: https://doi.org/10.1006/bbrc.2000.2920]
Nakashima, M., Sonoda, K., Watanabe, T. Inhibition of cell growth and induction of apoptotic cell death by the human tumor-associated antigen RCAS1. Nature Med. 5: 938-942, 1999. [PubMed: 10426319] [Full Text: https://doi.org/10.1038/11383]
Ruder, C., Hopken, U. E., Wolf, J., Mittrucker, H. W., Engels, B., Erdmann, B., Wollenzin, S., Uckert, W., Dorken, B., Rehm, A. The tumor-associated antigen EBAG9 negatively regulates the cytolytic capacity of mouse CD8+ T cells. J. Clin. Invest. 119: 2184-2203, 2009. [PubMed: 19620783] [Full Text: https://doi.org/10.1172/JCI37760]
Watanabe, T., Inoue, S., Hiroi, H., Orimo, A., Kawashima, H., Muramatsu, M. Isolation of estrogen-responsive genes with a CpG island library. Molec. Cell. Biol. 18: 442-449, 1998. [PubMed: 9418891] [Full Text: https://doi.org/10.1128/MCB.18.1.442]
Zhang, Y., Zhu, J., Hong, X., Zhou, Y., Ren, K., Shu, X., Wang, Q. The membrane molecule RCAS1 induces immune cell apoptosis via the RCAS1-RCAS1R pathway. Int. J. Molec. Med. 31: 1319-1326, 2013. [PubMed: 23563217] [Full Text: https://doi.org/10.3892/ijmm.2013.1326]