GPR30 estrogen receptor expression in the growth plate declines as puberty progresses

Objective: Our objective was to study whether GPR30 is expressed in the epiphyseal growth plate and its potential role as a modulator of pubertal growth. Background: Estrogens play a crucial role in the regulation of skeletal maturation and longitudinal bone growth. We have previously shown that both estrogen receptors (ERs) alpha and beta are expressed in the human epiphyseal growth plate. Recently, a membrane-bound ER referred to as GPR30 was discovered, but the role played by this receptor in the regulation of longitudinal bone growth is not yet known. Patients/Methods: Biopsies were collected from the tibial growth plates of 14 boys and seven girls that underwent epiphyseal surgery to arrest longitudinal bone growth. The patients were in different stages of puberty and suffered from inequality in leg length or extreme tall stature. Paraffin-embedded sections of the growth plates were used to detect expression of the GPR30 protein. Results: The highest level of GPR30 expression was observed in hypertrophic chondrocytes, although cells with positive immunostaining were also detected in the resting zone. In contrast, no immunoreactivity was found in the proliferative zone. During pubertal progression there was a clear decline in the level of GPR30 expression in both boys and girls. Conclusions: The novel ER GPR30 is expressed in the human growth plate, and the level of expression declines during pubertal progression. Although a relationship between GPR30 expression and age may underlie the observed pubertal decline in the GPR30 level, our observations suggest that this receptor could be involved in the modulation of longitudinal bone growth during puberty.