Identification of egr1 direct target genes in the uterus by in silico analyses with expression profiles from mRNA microarray data

EGR1 knockdown confers protection against ferroptosis and ameliorates intervertebral disc cartilage degeneration by inactivating the MAP3K14/NF-κB axis

This study explored whether EGR1-MAP3K14-NF-κB axis regulated ferroptosis and IVD cartilage generation. EGR1 and MAP3K14 expression levels were determined in CEP tissues of IVDD patients and intermittent cyclic mechanical tension (ICMT)-treated CEP cells. After EGR1 and MAP3K14 were altered in ICMT-treated CEP cells, the expression levels of degeneration- and ferroptosis-related proteins were measured. Binding relationship between EGR1 and MAP3K14 was evaluated. Additionally, the impacts of EFR1 knockdown on ferroptosis and cartilage degeneration in vivo were analyzed. EGR1 and MAP3K14 were overexpressed in clinical samples and cell models of IVDD. In IVDD cell models, EGR1 knockdown reduced ferroptosis and cartilage degeneration, which was reversed by MAP3K14 overexpression or Erastin treatment. NF-κB pathway inhibition nullified these effects of sh-EGR1 + oe-MAP3K14 treatment. EGR1 knockdown inhibited ferroptosis and relieved CEP degeneration via MAP3K14-NF-κB axis inactivation in vivo. Collectively, our findings highlighted that EGR1 promoted ferroptosis and IVD cartilage degeneration through MAP3K14-NF-κB axis.

ADAMTS-1: a novel target gene of an estrogen-induced transcription factor, EGR1, critical for embryo implantation in the mouse uterus

BACKGROUND

Recently, we demonstrated that estrogen (E₂) induces early growth response 1 (Egr1) to mediate its actions on the uterine epithelium by controlling progesterone receptor signaling for successful embryo implantation. EGR1 is a transcription factor that regulates the spectrum of target genes in many different tissues, including the uterus. E₂-induced EGR1 regulates a set of genes involved in epithelial cell remodeling during embryo implantation in the uterus. However, only few target genes of EGR1 in the uterus have been identified.

RESULT

The expression of ADAM metallopeptidase with thrombospondin type 1 motif 1 (Adamts-1) was significantly downregulated in the uteri of E₂-treated ovariectomized (OVX) Egr1(-/-) mice. Immunostaining of ADAMTS-1 revealed its exclusive expression in the uterine epithelium of OVX wild-type but not Egr1(-/-) mice treated with E₂. The expression profiles of Adamts-1 and Egr1 were similar in the uteri of E₂-treated OVX mice at various time points tested. Pre-treatment with ICI 182, 780, a nuclear estrogen receptor (ER) antagonist, effectively inhibited the E₂-dependent induction of Egr1 and Adamts-1. Pharmacologic inhibition of E₂-induced ERK1/2 or p38 phosphorylation interfered with the induction of EGR1 and ADAMTS-1. Furthermore, ADAMTS-1, as well as EGR1, was induced in stroma cells surrounding the implanting blastocyst during embryo implantation. Transient transfection with EGR1 expression vectors significantly induced the expression of ADAMTS-1. Luciferase activity of the Adamts-1 promoter containing EGR1 binding sites (EBSs) was increased by EGR1 in a dose-dependent manner, suggesting functional regulation of Adamts-1 transcription by EGR1. Site-directed mutagenesis of EBS on the Adamts-1 promoter demonstrated that EGR1 directly binds to the EBS at -1151/-1134 among four putative EBSs.

CONCLUSIONS

Collectively, we have demonstrated that Adamts-1 is a novel target gene of E₂-ER-MAPK-EGR1, which is critical for embryo implantation in the mouse uterus during early pregnancy.

Oestrogen-induced expression of decay accelerating factor is spatiotemporally antagonised by progesterone-progesterone receptor signalling in mouse uterus

Decay accelerating factor (DAF) is upregulated in the fetoplacental trophoblast, which protects the fetus from maternal complement injury. DAF was found to be downregulated in the endometrium of patients with repeated implantation failure. Thus, we examined the molecular mechanisms of DAF expression regulation by ovarian steroid hormones in the mouse uterus. Immunofluorescence staining demonstrated its exclusive localisation in the apical region of the epithelium in the uterus. Oestrogen (E2) significantly induced Daf mRNA in a time-dependent manner. Progesterone (P4) did not have any significant effect on Daf expression; however, it negatively modulated E2-induced DAF expression and RU486 effectively interfered with the inhibitory action of P4 in the uterus. During early pregnancy DAF was higher on Day 1 of pregnancy, but significantly decreased from Day 3, which is consistent with its E2-dependent regulation. Interestingly, DAF expression seemed to be influenced by the implanting blastocyst on Day 5 and it was gradually increased during preimplantation embryo development with peak levels at blastocyst stages. We demonstrated that E2-dependent DAF expression is antagonised by P4-progesterone receptor signalling in the uterine epithelium. Spatiotemporal regulation of DAF in the uterus and preimplantation embryos suggest that DAF functions as an immune modulator for embryo implantation and early pregnancy in mice.

Regulation of Cyclic AMP-Response Element Binding Protein Zhangfei (CREBZF) Expression by Estrogen in Mouse Uterus

CREBZF (cAMP-response element binding protein zhangfei) is a member of ATF/CREB family, and which regulates various cellular functions by suppressing major factors with direct interaction. In this study, we have examined the expression of CREBZF on mouse endometrium during uterus estrous cycles and estrogen (E2) treatment. In uterus, CREBZF mRNA expression was higher than other organs and mRNA and protein of CREBZF was increased in proestrus phase and decreased in estrus phase. The expression of CREBZF in 3-weeks old mouse uterus was reduced by E2 injection in endometrium. In addition, the expression of progesterone receptor, a marker of E2 in ovariectomized mice was found to be strongly expressed in stroma, while CREBZF was only expressed in epithelium. Also, we conformed that E2-suppressed CREBZF was restored by co-injection of ICI 182,780, an estrogen receptor antagonist. Overall, these results suggest that CREBZF is regulated by estrogen and involved in ER signaling pathway in mouse uterus.

Estrogen induces EGR1 to fine-tune its actions on uterine epithelium by controlling PR signaling for successful embryo implantation

The harmonized actions of ovarian E₂ and progesterone (P₄) regulate the proliferation and differentiation of uterine cells in a spatiotemporal manner. Imbalances between these hormones often lead to infertility and gynecologic diseases. Whereas numerous factors that are involved in P₄ signaling have been identified, few local factors that mediate E₂ actions in the uterus have been revealed. Here, we demonstrate that estrogen induces the transcription factor, early growth response 1 ( Egr1), to fine-tune its actions in uterine epithelial cells (ECs) that are responsible for uterine receptivity for embryo implantation. In the presence of exogenous gonadotrophins, ovulation, fertilization, and embryonic development normally occur in Egr1^-/- mice, but these animals experience the complete failure of embryo implantation with reduced artificial decidualization. Although serum levels of E₂ and P₄ were comparable between Egr1^+/+ and Egr1^-/- mice on d 4 of pregnancy, aberrantly reduced levels of progesterone receptor in Egr1^-/- uterine ECs caused enhanced E₂ activity and impaired P₄ response. Ultrastructural analyses revealed that Egr1^-/- ECs are not fully able to provide proper uterine receptivity. Uterine mRNA landscapes in Egr1^-/- mice revealed that EGR1 controls the expression of a subset of E₂-regulated genes. In addition, P₄ signaling was unable to modulate estrogen actions, including those that are involved in cell-cycle progression, in ECs that were deficient in EGR1. Furthermore, primary coculture of Egr1^-/- ECs with Egr1^+/+ stromal cells, and vice versa, supported the notion that Egr1 is required to modulate E₂ actions on ECs to prepare the uterine environment for embryo implantation. In contrast to its role in ECs, loss of Egr1 in stroma significantly reduced stromal cell proliferation. Collectively, our results demonstrate that E₂ induces EGR1 to streamline its actions for the preparation of uterine receptivity for embryo implantation in mice.-Kim, H.-R., Kim, Y. S., Yoon, J. A., Yang, S. C., Park, M., Seol, D.-W., Lyu, S. W., Jun, J. H., Lim, H. J., Lee, D. R., Song, H. Estrogen induces EGR1 to fine-tune its actions on uterine epithelium by controlling PR signaling for successful embryo implantation.