Systemic distribution of estrogen-responsive finger protein (Efp) in human tissues

Estrogen-responsive finger protein (Efp), a target gene product of estrogen receptor (ER), is considered essential for estrogen-dependent cell proliferation. The biological significance of Efp remains unclear in human tissues, and therefore, we examined systemic distribution of Efp in human adult and fetal tissues using RT-PCR and immunohistochemistry. Efp mRNA expression was marked in the placenta and uterus, high in the thyroid gland, aorta, and spleen in adult, and relatively low in other human adult and fetal tissues examined in this study. Efp immunoreactivity was detected in epithelium of various adult tissues, and was also detected in cytotrophoblasts of the placenta and splenic macrophages. Efp immunolocalization in human fetus was generally similar as that in adult. These Efp-positive cells were previously reported to be associated with ERalpha and/or ERbeta expression. Therefore, these results indicate that Efp is widely expressed and may play important roles in various human tissues possibly through ERs.