Detection of estrogen receptors ER-alpha and ER-beta in human ejaculated immature spermatozoa with excess residual cytoplasm

Vittoria Rago,Amalia Carpino,Laura Siciliano,Saveria Aquila

doi:10.1186/1477-7827-4-36

Vittoria Rago, Amalia Carpino + Show 2 more

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https://doi.org/10.1186/1477-7827-4-36

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Abstract

BackgroundA key role of estrogens in human sperm biology has been recently suggested by aromatase and estrogen receptor detection in human testicular germ cells and ejaculated spermatozoa. However, the involvement of these hormones in the sperm maturation process is still not defined. The aim of this work was to investigate the expression of estrogen receptors, ER-alpha and ER-beta, in human ejaculated immature spermatozoa with excess residual cytoplasm.MethodsImmunofluorescence labelling has been used to localize ER-alpha and ER-beta proteins in immature spermatozoa isolated by Percoll gradient, while Western blot analysis was carried out on sperm protein extracts.ResultsBoth estrogen receptors were localized in excess residual cytoplasm of immature sperm, while sperm tails showed only ER-beta. Furthermore, in the same cells, immunoblots detected the presence of the full-length (~67 kDa) ER-alpha and (~59 kDa) ER-beta proteins, together with a ~50 kDa ER-beta species, lacking in mature sperm.ConclusionThe present investigation demonstrated ER-alpha and ER-beta presence in excess residual cytoplasm of human abnormal sperm cells, suggesting the hypothesis that both the 'classical' ERs could be able to mediate estrogen action in spermatogenetic cells. Furthermore, the presence of the short ER-beta form in abnormal germ cells and its disappearance in mature sperm, support estrogen modulation via different ER forms during sperm maturation.

Highlights

A key role of estrogens in human sperm biology has been recently suggested by aromatase and estrogen receptor detection in human testicular germ cells and ejaculated spermatozoa
It is known that estrogen action on target cells is mediated by two estrogen receptors, ERα and ERβ, each encoded by a unique gene, differing in the C-terminal ligand-binding domain and in the N-terminal trans-activation domain [4]
Reproductive Biology and Endocrinology 2006, 4:36 http://www.rbej.com/content/4/1/36 observed in a single case of human inactivating mutation of the ERα gene [6]. These findings suggest the estrogen receptor involvement in the achievement of sperm function

Summary

Introduction

A key role of estrogens in human sperm biology has been recently suggested by aromatase and estrogen receptor detection in human testicular germ cells and ejaculated spermatozoa. A key role of estrogens in differentiation and function of mammalian male germ cells has been suggested by the detection of proteins involved in estrogen biosynthesis and activity. Aromatase and estrogen receptors (ERs) have been revealed in sperm cells at different stages of their maturation process [1,2,3]. Information about the loss of estrogen receptor activity has been provided by the estrogen receptor gene knock out (ERKO) mouse These animals showed altered sperm count, motility and morphology in the adulthood [5]. A diminuished sperm viability has been (page number not for citation purposes)

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