Sirtuin-1(Sirt1)은 NAD+ dependent deacetylase로써 유전자 침묵, 포도당과 지질대사, 세포자살 등 다양한 cellular process에 연관되어 있다. 최근 이뤄진 여러 연구에서 Sirt1 Knockout mouse가 정자형성 장애와 불임증상을 가진다는 것이 보고되었다. Egr1(Early Growth Response 1)은 Egr family에 속하는 전사인자로서 mitogenesis와 differentiation에 필요한 유전자들의 전사를 활성화시킨다. 또한 이는 Sirt1의 전사를 조절하는 것으로 알려져 있다. 본 연구에서는 생쥐 정소 내에서 Egr1의 유무에 의한 Sirt1의 발현 수준 차이를 밝히고자 Egr1 knockout mouse와 wild type mouse를 이용하여 Sirt1의 발현패턴을 분석하였다. Sirt1의 발현을 분석하기 위하여 Quantitative RT-PCR과 conventional RT-PCR을 이용하여 각각 ICR strain adult male mice와 Egr1 Knockout adult male mice의 testicular cDNA에서 mRNA 수준에서 Sirt1의 발현수준을 분석하였다. 또한 Immunohistochemistry를 이용하여 Sirt1단백질의 localization을 분석하였다. 분석한 결과, Wild type과 Egr1 Knockout mouse의 정소 내에서 Sirt1 mRNA의 발현 수준은 큰 차이를 보이지 않았으나, Egr1 Knockout mouse의 정소 내에서 Sirt1 단백질의 발현수준은 wild type과 비교하여 현저히 떨어졌으며, 이 변화는 특히 pachytene spermatocyte에서 큰 차이를 보였다. 반면, Sertoli cell에서는 Pachytene spermatocyte에서만큼 뚜렷한 차이를 관찰할 수 없었다. 본 연구에서 얻은 결과를 바탕으로 Egr1이 pachytene spermatocyte에서 Sirt1 단백질의 발현에 중요한 역할을 할 것이라는 결론을 얻을 수 있었다. Sirt1 Knockout mouse가 불임 증상을 보이며, 정자형성에 장애가 있는 반면, Egr1 KO mouse는 정상적인 생식능력을 가짐으로 보아 premeiotic 또는 meiotic stage에서의 Sirt1 결핍이 이러한 infertility의 원인이 될 것으로 추측된다.

Harmonized actions of ovarian estrogen (E2) and progesterone (P4) regulate cell proliferation and differentiation in the uterus with a spatiotemporal manner. Imbalance between the actions and levels of two major regulators often lead to infertility and gynecological diseases, such as endometriosis and endometrial cancer. While numerous works have shown that reduced expression and/or deletion of uterine factors associated with P4 signaling could disturb uterine physiology, local factor(s) to mediate E2 actions has not been extensively studied yet. Here we demonstrate that early growth response 1 (Egr1), a transcription factor which is rapidly induced in the uterus by E2, is required to maintain coordinated actions of E2 and P4 for uterine receptivity for embryo implantation. Given exogenous gonadotrophins to overcome LHβ deficiency in the pituitary of Egr1(－/－) mice, ovulation, fertilization and embryo development normally occurred in these mice. However, they showed complete failure of embryo implantation with reduced uterine responses to artificial decidualization stimuli. While serum levels of E2 and P4 in Egr1(－/－) mice were comparable, genes regulated by E2 and/or P4 in uterine epithelial cells (ECs) were aberrantly expressed on day 4 of pregnancy. Impaired P4 signaling along with absence of PR in ECs caused hypersensitive E2 responses shown as enhanced expression of E2-responsive genes such Muc1 and Ltf as well as reduced levels of P4-dependent genes, such as Ihh and Areg, in ECs of Egr1(－/－) mice. This is consistent with persistent proliferation in ECs and severely impaired proliferation in stromal cells (SCs) in Egr1(－/－) mice treated with E2+P4. Furthermore, primary co-culture of Egr1(－/－) ECs with Egr1(+/+) SCs and vice versa supported a notion that Egr1 itself is required for proper responses to two major regulators, E2 and P4, in both uterine cell compartments. Collectively, our results show that E2-induced Egr1 participates in P4-dependent modulation on E2 activities in the uterus by regulating a spectrum of genes essential for uterine receptivity and embryo implantation.

The transcription factor, early growth response protein 1 (EGR1), act as immediate early response genes to control various cellular and reproductive events. Egr1-deficient female mice show infertility by anovulation resulting from luteinizing hormone-β (LH-β) subunit deficiency. While ovulation, fertilization and embryo development normally occur in Egr1-deficient mice treated with a superovulation regime to rescue LH deficiency, embryo implantation was completely failed. The morphology and ultrastructure of uterine tissues were observed by light and transmission electron microscopy during the peri-implantation period in Egr1-deficient mice. To examine alterations in cellular organelles, the uterine horns were fixed with 2.5% glutaraldehyde and postfixed with 1% osmium tetroxide in PBS. After dehydration and infiltration, the samples were embedded in Epon 812. Semi-thin sections 0.5 μm thick were cut with an ultramicrotome and stained with toluidine blue for light microscopy. Thin sections were cut with a diamond knife of the ultramicrotome and placed on copper grids. The sections were double stained and examined under a transmission electron microscope. The height of luminal epithelial cells was decreased and the polarity was poorly differentiated in the Egr1-deficient comparing to the wild mice. The abundant mucinous materials were observed in the surface of luminal epithelial cells of the Egr1-deficient. It was confirmed the microarray and real time qPCR data. The luminal epithelial cells of wild mice had many dense lipophilic granules and healthy mitochondria, but not in the Egr1-deficient. It may related to production and secretion of steroid hormones and prostaglandins in the luminal epithelial cells for successful implantation. These results show that Egr1 is a critical transcription factor to fine-tune subcellular morphological and functional changes for the receptive phase of peri-implantation period of uterine tissue in mice.

Early growth response 1(Egr1)은 zinc finger transcription factor로 다양한 성장인자, 물리적 자극에 따른 세포분화, 생장 및 사멸조절에 관여한다. Egr1 KO 생쥐 정소에서 maturation arrest, Sertoli cell only 등의 비정상 세정관이 증가한다. Glial Cell Derived Neurotrophic Factor(GDNF) 는 정원줄기세포(spermatogonial stem cell)의 자가재생 및 분화를 조절한다. 본 연구에서는 정원줄기세포에서 GDNF 수용체 하위 전사조절네트웍 규명의 일환으로 생쥐 정원줄기세포에서 Egr1 발현 특성을 분석하였다. 출생 0~56일 사이의 생쥐 정소에서 Egr1 발현을 면역조직화학적으로 분석하였다. 생후 6일 생쥐 정소의 세포들을 분산시킨 후 THY1 항체를 이용한 MACS법으로 정원줄기세포를 분리하여 GDNF (100 ng/ml)을 처리하였다. GDNF(100 ng/ml)을 처리 후 0, 2, 12시간에 Egr1, Egr2, Egr3, Egr4, GDNF 수용체인 RET와 GFRA1, 자가재생에 관련된 Etv5, Bcl6b mRNA 발현과 Egr1 단백질 발현량을 분석하였다. 한편 MAPK inhibitor(U0126, 10 μM) 처리 후 GDNF를 각각 2, 12시간 처리하여 mRNA 발현을 분석하였다. 그리고 Egr1 knock out mouse 정원줄기세포에서 GDNF를 12시간 처리하여 mRNA 발현을 분석하였다. 면역조직화학적 분석결과 Egr1은 gonocytes, spermatogonia, peritubular cells, Leydig cell에서 발현하였으나 분화된 세포에서는 발현이 저조하였다. 정원줄기세포에 GDNF 처리 후 2시간에 Egr1 mRNA가 유도되는 반면 Egr2, Egr3 mRNA는 12시간에 유도되었고, Egr4 mRNA는 변화하지 않았다. GDNF 수용체인 RET과 GFRA1 mRNA는 GDNF 처리군에서 증가하였다. Self-renewal에 관련된 Etv5와 Bcl6b mRNA는 12시간에 유도되었다. Egr1 단백질은 2시간에서 GDNF에 의해 증가하였다. U0126과 GDNF를 동시에 처리한 경우 2시간에 Egr1 mRNA가 유도되지 않았으며, 12시간에 Etv5와 Bcl6b mRNA발현도 변화가 없었다. Egr1 knock out mouse 정원줄기세포에 GDNF처리 시 Etv5, Egr2, Egr4 mRNA는 증가하는 반면 Bcl6b, Egr3 mRNA는 감소하였다. Egr1은 미성숙정소에서 gonocyte, spermatogonial stem cell, peritubular cell, Leydig cell에서 주로 발현된다. GDNF는 정원줄기세포에서 MAPK pathway에 의존적으로 Egr1을 유도하며, Egr1은 GDNF 수용체 및 자가재생 유전자발현을 통해 정원줄기세포의 stemness 유지에 중요한 기능을 담당하는 상위 전사인자로 사료된다. 또한 Egr1이 결손되어지면 세포자가재생에 관련된 Bcl6b의 전사가 억제되는 것으로 보아 세포생존, 증식에 중요한 역할을 할 것으로 사료된다.

Early growth response 1 (Egr1) is a zinc-finger transcription factor to direct second-wave gene expression leading to cell growth, differentiation and/or apoptosis. While it is well-known that Egr1 controls transcription of an array of targets in various cell types, downstream target gene(s) whose transcription is regulated by Egr1 in the uterus has not been identified yet. Thus, we have tried to identify a list of potential target genes of Egr1 in the uterus by performing multi-step in silico promoter analyses. Analyses of mRNA microarray data provided a cohort of genes (102 genes) which were differentially expressed (DEGs) in the uterus between Egr1(+/+) and Egr1(–/–) mice. In mice, the frequency of putative EGR1 binding sites (EBS) in the promoter of DEGs is significantly higher than that of randomly selected non-DEGs, although it is not correlated with expression levels of DEGs. Furthermore, EBS are considerably enriched within –500 bp of DEG’s promoters. Comparative analyses for EBS of DEGs with the promoters of other species provided power to distinguish DEGs with higher probability as EGR1 direct target genes. Eleven EBS in the promoters of 9 genes among analyzed DEGs are conserved between various species including human. In conclusion, this study provides evidence that analyses of mRNA expression profiles followed by two-step in silico analyses could provide a list of putative Egr1 direct target genes in the uterus where any known direct target genes are yet reported for further functional studies.

The Egr family of zinc finger transcription factors is rapidly induced by various mitogens and regulates cell growth, differentiation, and apoptosis. While it is clear that loss of Egr1 leads to anovulatory infertility due to LHβ deficiency in female mice, molecular function of Egr1 in male reproduction has not been clearly investigated. Here, we demonstrate that Egr1 acts as an intrinsic transcription factor in Leydig cells to regulate their proliferation and steroidogenesis in the testis as well as an extrinsic factor for male reproduction via LHβ transcription in the pituitary. Egr1 is predominantly expressed in spermatogonia and Leydig cells in immature testes and later detected in some of these cell types in mature testes. The fertility potential of Egr1(-/-) male mice is relatively deteriorated even at 2 month-old age and aggravated with aging. The incidence of abnormalities of seminiferous tubules such as Sertoli cell only was dramatically increased with aging. The number and mean size of Leydig cells were significantly reduced in Egr1(-/-) testes. The impairment of Leydig cells is consistent with significant reduction in levels of testosterone and expression of factors critical for steroidogenesis such as StAR in Egr1(-/-) testes. Exogenous administration of hCG rapidly and transiently induced Egr1 expression in Leydig cells culture in vitro. hCG could reinstate reduced mean size of Leydig cells but not reduced number of Leydig cells and aberrantly low StAR expression, suggesting that Egr1 has critical functions for Leydig cell proliferation and their steroidgenesis. In addition, daily sperm production and in vitro fertilization (IVF) competence were significantly reduced, and apoptosis was facilitated in these mice. Furthermore, hCG administration to compensate for relatively low LH levels in Egr1(-/-) males could not restore the compromised reproductive phenotypes such as IVF competence and apoptosis in these mice. Interestingly, expression of Egr2, a member of Egr family, is significantly elevated in Egr1(-/-) Leydig cells suggesting that genetic compensation of Egr2 may alleviate phenotypic aberration of Egr1(-/-) male testes. Collectively, these results suggest that Egr1 act as an intrinsic transcription factor required for proliferation and steroidogenesis of Leydig cells to govern spermatogenesis in the testis.

Early growth response 1 (Egr1) belongs to the Egr family of zinc finger transcription factors (Egr1 to Egr4) that regulates cell growth, differentiation, and apoptosis. Egr1(-/-) female mice are infertile due to anovulation resulting from luteinizing hormone β subunit (LHβ) deficiency. While it is clear that Egr1 is critical for LHβ transcription in the pituitary gland, function of Egr1 in uterus still remain unexplored. Uteri on various experimental conditions or days of pregnancy were collected for mRNA microarrays, realtime-RT-PCR, Western blotting, and histological analyses for immunofluorescence and BrdU staining. Egr1 and other Egr family members, Egr2 and Egr3 are highly expressed in the uterus on day 4 of pregnancy (Day 4). While ovulation, fertilization and embryo development normally occur in Egr1(-/-) mice treated with a superovulation regime to rescue LH deficiency, embryo implantation was completely failed. In addition to implantation failure, oviductal transport of embryos is also impaired in these mice. 17/24 Egr1(-/-) mice (71%) retained blastocysts in the oviduct as well as in the uterus of Egr1(-/-) mice on Day 4 whereas all Egr1(+/+) mice have them in the uterus. While serum levels of E2 and P4 in Egr1(-/-) mice on Day 4 were comparable to those of wildtypes, expression of E2 responsive genes which are expressed in luminal epithelium, such as Mucin 1 and lactoferrin, is aberrantly increased in Egr1(-/-) mice with embryos in the oviduct on Day 4. In contrast, P4 responsive genes such as Hoxa10 and amphiregulin are normally expressed in these mice. Collectively, these data suggest that Egr1 deficiency in the oviduct and uterus leads to estrogen hypersensitivity. BrdU incorporation experiments provided evidence that epithelial cells undergo hyperproliferation in Egr1(-/-) mice. This is consistent with microarray data that several key factors for cell cycle progression such as cyclin Ds and E2F1 are overexpressed in these mice. Furthermore, in the uteri of Egr1(-/-) mice treated with E2+P4, stromal cell proliferation is severely impaired and epithelial cells persistently proliferating. With respect to decidualization, Egr1 as well as Egr2 and Egr3 are induced immediately after decidualization stimuli were given. Although the responses were relatively less than those of wildtype mice, decidualization does occur in Egr1(-/-) mice. Relatively compromised decidualization responses seems to result from functional compensation of Egr2 and Egr3 in Egr1(-/-) deficient uteri. Collectively, our results show that Egr1 is a critical transcription factor to fine-tune estrogen responses via regulation of a spectrum of genes for embryo implantation in the uterus.

Early growth response 1 (Egr1) is an immediate early response gene which is induced by various external stimuli and acts as transcription factor to direct second-wave gene expression leading to cell growth, differentiation and/or apoptosis. It is well known that Egr1 regulates transcription of a cluster of genes in cancers and luteinizing hormone (LH) beta subunit in the pituitary. In addition to function of Egr1 in cancers and pituitary, we recently showed that Egr1 acts as a local master regulator to mediate estrogenic actions in the uterus. However, regulatory mechanism by which Egr1 directs transcription of its downstream target genes in the uterus remains to be yet explored. Thus, we have tried to identify direct target genes of Egr1 in the uterus by analyzing mRNA microarray data sets followed by in silico promoter analyses with chromatin immunoprecipitation (CHIP). mRNA expression profiles of Egr1(－/－) uteri and Egr1(－/－) ovaries were compared to those of wildtype mice to provide a potential list of direct target genes of Egr1 in the uterus. Whereas Egr1 is rapidly and transiently induced in the ovary and the uterus by external stimuli, LH and estrogen, respectively with a similar manner, a list of differentially expressed genes between Egr1(+/+) and Egr1(－/－) mice were barely overlapped between these two datasets. This result suggests that the transcriptional network of Egr1 in the uterus is quite different from that in the ovary. The list of differentially expressed genes in Egr1(－/－) uterus was enriched by RT-PCR. In silico analyses with MatInspector provided evidence that Egr1 binding sites are relatively enriched in －500 bp promoter regions of genes in the list. CHIP assays for Egr1 antibody with uterine tissues 2 h after estrogen treatment reinforced the possibility that genes identified in this study such as Gadd45g and Lbh could be directly regulated by Egr1 in uterine context. Collectively, we show that bioinformatic analyses of expression profiles with in silico analyses could be a useful tool to enrich potential candidates of direct target genes of transcription factors.

Early growth response 1 (Egr1) belongs to the Egr family of zinc finger transcription factors that regulates cell growth, differentiation, and apoptosis. Egr1(－/－) female mice are infertile due to anovulation resulting from luteinizing hormone β subunit (LHβ) deficiency. While it is clear that Egr1 is a critical factor to regulate transcription of LHβ in the pituitary gland, function of Egr1 and mechanisms by which estrogen (E2) and/or progesterone (P4) regulates Egr1 in uterus still remain unexplored. Using multiple approaches, here we have characterized regulatory mechanism of Egr1 induction in the uterus and uterine phenotypes of Egr1(－/－) mice. Eight-week-old female mice were ovariectomized (OVX) and rested for a week. Uteri of OVX mice treated with various concentrations of E2 and/or other hormones were collected at 2h after hormone treatment unless otherwise indicated. Collected uteri were utilized for mRNA microarrays, realtime-RT-PCR, Western blotting, and histological analyses for immunofluorescence and BrdU staining. Egr1 mRNA was rapidly induced with the highest level at 2h after E2 treatment and gradually decreased to basal levels at 12 h. E2-induced phosphorylation of ERK1/2 and AKT, and Egr1 transcription were effectively inhibited by pretreatment of ICI 182,780. Pharmacological inhibition of ERK1/2, but not AKT significantly blocked E2-induced Egr1 expression in the uterus. P4 effectively dampened E2-dependent Egr1 transcription and its antagonistic effects were partially interfered with RU486 pretreatment. Interestingly, BrdU incorporation experiments provided evidence that epithelial cells undergo hyperproliferation in Egr1(－/－) mice. This is consistent with microarray data that several key factors for cell cycle progression such as cyclin Ds and E2F1 are overexpressed in these mice. Furthermore, in the uteri of OVX Egr1(－/－) mice treated with E2+P4, stromal cell proliferation is severely impaired and epithelial cells persistently proliferating. While ovulation, fertilization and embryo development normally occur in Egr1(－/－) mice treated with a superovulation regime to rescue LH deficiency, embryo implantation is severely impaired. Blastocysts were not able to implant even on day 6 of pregnancy in Egr1(－/－) mice. In addition to embryo implantation, uterine response to artificial decidualization in hormone-primed Egr1(－/－) OVX mice was relatively less than that of wildtype mice. Collectively, our results show that Egr1, which is rapidly induced by E2-ER-ERK1/2 pathways, is a critical factor to control E2-dependent cell proliferation via regulation of a spectrum of genes for embryo implantation in the uterus.

The Egr family of zinc finger transcription factors consisting of 4 members (Egr1 to Egr4) regulates critical genetic programs involved in cellular growth, differentiation, and function. They are co-ex-pressed in many different tissues, suggesting that they may have some redundant functions. While it is clear that estrogen regulates Egr1 in estrogen sensitive breast cancer cells, function of Egr1 and mechanisms by which estrogen (E2) and/or progesterone (P4) regulates Egr1 in uterus still remain unexplored. Thus, we have examined regulatory mechanisms by which Egr1 is regulated in the uterus and abnormal uterine phenotypes of Egr1(－/－) mice. Eight-week-old female mice were ovariectomized (OVX) and rested for a week. Uteri of OVX mice treated with various concentrations of E2 and/or other hormones were collected at 2 h after hormone treatment unless otherwise indicated. ICI 182,780 [estrogen receptor (ER) antagonist] or RU486 [progesterone receptor (PR) antagonist] was injected to OVX mice 30 min prior to hormone treatments. OVX Egr1(+/+) and Egr1(－/－) mice were treated with E2 and/or P4 to examine expression patterns of genes important for estrogen responses, and steroid hormone-induced cell proliferation in the uterus. Collected uteri were utilized for RT-PCR, realtime RT-PCR, Western blotting and histological analyses. Egr1 mRNA was rapidly induced with the highest level at 2h after E2 treatment and gradually deceased to basal levels at 12 h. Pretreatment of ICI 182,780 significantly reduced E2-induced increase of Egr1. However, an agonist for GPR30, a membrane estrogen receptor failed to induce mRNA expression of Egr1, suggesting that E2-dependent Egr1 transcription is mainly regulated via nuclear estrogen receptor, ER. P4 effectively dampened E2-dependent Egr1 transcription and its antagonistic effects were partially interfered with RU486 pretreatment. Histological analyses with BrdU incorporation experiments showed that vascular permeability (an early estrogen response) but not cell proliferation (a late response) was significantly impaired in the uteri of E2 treated OVX Egr1(－/－) mice. Interestingly, some genes involved in early estrogen responses such as Bip and HIF-1a but not those in late responses are dysregulated in uteri of Egr1(－/－) mice. Collectively, our results show that E2 transiently induces Egr1 via activation of nuclear ER. P4 antagonizes E2-dependent Egr1 regulation via PR. Impaired early estrogenic responses in Egr1(－/－) uteri could be due to aberrant gene expression affected by loss of Egr1 which act as a master regulator of estrogen actions in the uterus.-ex

The amphetamine derivative 3,4-methylenedioxymethamphetamine (MDMA) is a potent monoaminergic neurotoxin with the potential to cause serotonergic neurotoxicity, but has become a popular recreational drug. Little has been known about the cellular effects induced by MDMA. This report shows that MDMA inhibits neuronal cell growth and differentiation. MDMA suppressed neuronal cell growth. The results of quantitative real-time PCR analysis showed that Egr-1 expression is elevated in mouse embryo and neuroblastoma cells after MDMA treatment. Transiently transfected Egr-1 interfered with the neuronal differentiation of neuroblastoma cells such as SH-SY5Y and PC12 cells. These findings provide evidence that the abuse of MDMA during pregnancy may impair neuronal development via an induction of Egr-1 over-expression.