Par3/Par6 polarity complex coordinates apical ectoplasmic specialization and blood-testis barrier restructuring...

Area of Science:

• Reproductive Biology
• Cell Biology
• Molecular Endocrinology

Background:

• The Par3/Par6/aPKC and CRB3/Pals1/PATJ complexes are crucial for cell polarity.
• These complexes regulate apical ectoplasmic specialization (ES) and blood-testis barrier (BTB) restructuring in the testis.
• Par6 is a key component of both apical ES and BTB.

Purpose of the Study:

• To investigate the role of the Par6/Par3 polarity complex in regulating apical ES and BTB dynamics.
• To understand how adjudin treatment affects Par6 localization and complex formation.
• To assess the impact of Par6 and Par3 knockdown on BTB integrity in Sertoli cells.

Main Methods:

• Immunofluorescence staining to observe Par6 localization in testes.
• Co-immunoprecipitation to analyze protein complex formation (Par6/Pals1/JAM-C/Src).
• RNA interference (RNAi) in primary Sertoli cell cultures to knock down Par6 and Par3.

Main Results:

• Par6 levels decreased significantly at apical ES and BTB during stage VIII of the cycle.
• Adjudin treatment caused Par6 disappearance from apical ES and destabilized the Par6/Pals1 complex, associating it with Src kinase and dissociating it from JAM-C.
• Knockdown of Par6 or Par3 in Sertoli cells led to reduced aPKC levels and transient loss of BTB proteins, compromising BTB integrity.

Conclusions:

• The Par6/Par3 polarity complex is essential for coordinating apical ES and BTB restructuring during spermatogenesis.
• Disruption of this complex, as observed with adjudin treatment or RNAi, leads to spermatid loss and impaired BTB function.
• These findings highlight the complex interplay between polarity proteins in maintaining testicular structure and function.