The prostate plasma membrane as an androgen receptor

Area of Science:

• Biochemistry
• Molecular Biology
• Cell Biology

Background:

• The traditional view implicates the cell nucleus in androgenic control of target organs like the prostate.
• Receptor activities for androgens have also been observed in the cytosol, endoplasmic reticulum, and plasma membrane.
• The mechanism by which sex steroids regulate cellular processes solely through chromatin-directed signals remains unclear.

Purpose of the Study:

• To investigate a novel mediator of androgen action beyond nuclear pathways.
• To identify the specific binding site and nature of androgen interaction with cellular components.
• To explore the functional consequences of androgen binding to a non-nuclear target.

Main Methods:

• Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to analyze protein binding.
• Selective enzyme enrichment using concanavalin A and DHT-affinity chromatography.
• Assays for ouabain binding and phosphorylation.
• Spectroscopic techniques to detect conformational changes.

Main Results:

• Androgen binding to the beta-subunit of prostatic Na,K-ATPase was demonstrated.
• Enzyme activity was confirmed through selective enrichment studies.
• Androgen binding dynamically altered enzyme properties, including increased ouabain binding and enhanced phosphorylation.
• Spectroscopic data indicated hormone-induced conformational shifts in the enzyme.

Conclusions:

• Prostate plasma membrane Na,K-ATPase serves as a direct androgen binding protein and functions as a metabolic pacemaker.
• This finding offers a new paradigm for understanding androgen action, involving non-genomic mechanisms.
• The dynamic modulation of Na,K-ATPase activity by androgens suggests a significant role in regulating cellular metabolism and function.