Progesterone receptors on human spermatozoa

Area of Science:

• Reproductive Biology
• Endocrinology
• Molecular Biology

Background:

• Progesterone, a key female hormone, influences critical sperm functions like capacitation, motility, and acrosome reaction.
• These effects are mediated by progesterone receptors (PR) located on the sperm's acrosomal membrane.
• Sperm PR activation triggers non-genomic signaling pathways, notably increasing intracellular calcium (Ca2+) levels.

Purpose of the Study:

• To characterize the progesterone receptor (PR) in human spermatozoa.
• To investigate the molecular nature and localization of sperm PR.
• To explore the relationship between sperm PR and conventional PR.

Main Methods:

• Utilized antibodies targeting the C-terminal region of conventional PR for receptor recognition.
• Employed non-ionic detergents to expose the masked sperm PR.
• Analyzed sperm mRNA to detect sequences encoding PR DNA and hormone-binding domains.

Main Results:

• Sperm PR is localized to the acrosome and recognized by antibodies against conventional PR's C-terminus.
• The molecular weight of sperm PR ranges from 27 kDa to 85 kDa.
• Spermatozoa possess mRNA encoding the full DNA and hormone-binding domains of conventional PR, with no mutations detected.

Conclusions:

• The C-terminal region of the conventional PR appears conserved in sperm.
• Sperm PR may represent a variant of the conventional PR, potentially due to post-translational modifications or peptide splicing.
• Further characterization of sperm PR is crucial for understanding non-genomic steroid hormone receptor actions.