Testosterone/bicalutamide antagonism at the predicted extracellular androgen binding site of ZIP9

Area of Science:

• Molecular Biology
• Cellular Signaling
• Pharmacology

Background:

• ZIP9 functions as a zinc transporter and testosterone receptor, but its physiological roles are unclear.
• Testosterone signaling pathways are crucial in various biological processes.
• Understanding ZIP9's role is vital for addressing its physiological and pathophysiological significance.

Purpose of the Study:

• To investigate the role of ZIP9 in testosterone-mediated cellular signaling.
• To determine if ZIP9 functions as a direct testosterone receptor.
• To explore ZIP9 as a potential pharmacological target.

Main Methods:

• Utilized a cell line lacking the classical androgen receptor.
• Assessed testosterone-induced phosphorylation (Erk1/2, CREB, ATF-1) and gene expression (claudin-5, zonula occludens-1).
• Performed computational modeling, docking experiments, and utilized a membrane-impermeable testosterone analogue (T-BSA-FITC).

Main Results:

• Testosterone-mediated signaling via ZIP9 was antagonized by bicalutamide (anti-androgen).
• Computational analysis revealed an extracellular testosterone binding site on ZIP9, accommodating bicalutamide.
• Experimental data confirmed ZIP9's membrane localization and bicalutamide's blockage of testosterone binding.

Conclusions:

• ZIP9 directly binds testosterone extracellularly, mediating signaling pathways.
• Bicalutamide effectively antagonizes ZIP9-mediated testosterone signaling.
• ZIP9 represents a potential pharmacological target for modulating testosterone actions.