Activating Transcription Factor 3 Is Estrogen-Responsive in utero and Upregulated during Sexual Differentiation

Abstract

Background/Aims: Synthetic estrogens induce hypospadias, an anomaly of genital tubercle/urethral development. Activating transcription factor 3 (ATF3), which is estrogen-responsive in vitro, is upregulated in hypospadiac human tissue. We used a mouse model of steroid-dependent genital tubercle development to elucidate the ontogeny of ATF3 expression and the developmental response of ATF3 in vivo to estrogen exposure. Methods: We used quantitative RT-PCR to assess ontogenic expression of ATF3 and its response to estrogen treatment in utero. Immunohistochemistry was used to localize the protein. Results: Quantitative RT-PCR showed that ATF3 mRNA is upregulated in all estrogen-exposed fetal genital tubercles compared to controls (p = 0.024), including specifically in males exposed in utero (p = 0.049). Additionally, its expression increases significantly during the period of sexual differentiation in both sexes and significantly correlates with female development (p = 0.004), a phenomenon that appears to be attributable to higher levels at birth in females. The protein localizes in the nucleus, as expected. Conclusions: ATF3 is estrogen-responsive in vivo. The response of ATF3 to estrogenic stimulation in utero at an earlier stage may contribute to urethral abnormalities observed in estrogen-exposed male fetuses, although it is likely not the only gene involved, which supports the general understanding that hypospadias is subject to multifactorial influences. ATF3 may therefore be an appropriate gene for further investigations in an endocrine context.

Activating transcription factor 3: a hormone responsive gene in the etiology of hypospadias

“…From these genes, the activating transcription factor 3 (ATF3), a member of the ATF/CREB family of transcription factors (17), has been the gene with the greatest up-regulation. This gene has also been shown to be generally up-regulated during sexual differentiation (18). This evidence indicates a potential role of ATF3 in hypospadias and lead us to investigate ATF3 gene sequence in patients with this inborn error of development.…”

“…This effect may be due to disturbances on estrogenic responses during development (15,16,18). Moreover, ATF3 expression has also been reported to be up-regulated by the androgen receptor's activation by both androgens and estrogens in cell lines (27); this aspect indicate that variants in ATF3 may underlie androgenestrogen imbalances and influence the responsiveness to endocrine disrupters.…”

Di‐(2‐ethylhexyl) Phthalate Upregulates ATF3 Expression and Suppresses Apoptosis in Mouse Genital Tubercle

“…ATF3 was also upregulated in the penile skin tissues of boys with hypospadias 11) . It is of note that ATF3 has been strongly indicated as contributing to the development of hypospadias due to its estrogenresponsive character, since external estrogen causes mouse hypospadias and significantly upregulates ATF3 expression [12][13][14] . Because phthalates have been shown to mimic estrogen and are capable of binding to estrogen receptor 15,16) , we hypothesized that DEHP might also activate ATF3 of mouse GT.…”

Hypospadias in Three Generations: Is There a Dominant Responsible Gene for Hypospadias?

“…Also in vitro and some animal studies confirmed this finding [12]. Liu et al reported that fetal exposure to estrogen increased the level of ATF3 messenger RNA [13], whereas this group also indicated that fetal exposure to DEHP (di-2-ethylexyl phthalate) activated transcirption and transduciton of the ATF3 gene [14]. According to our clinical findings, we believed that there should be a dominant gene responsible for hypospadias formation in this family, but due to technical reasons, we could not have a chance to evaluate preputial samples and blood of patients for expression of ATF3 gene and genetic mutations.…”