A Cell Junctional Protein Network Associated with Connexin-26

Area of Science:

• Cell Biology
• Genetics
• Otolaryngology

Background:

• Mutations in GJB2, encoding connexin-26 (CX26), are a primary cause of non-syndromic inherited hearing loss.
• Connexin-26 is a protein found in the cochlea, skin, liver, and brain, characterized by short cytoplasmic N- and C-termini.

Purpose of the Study:

• To identify proteins that bind to the C-terminus of connexin-26.
• To investigate the interactions of connexin-26 with other cellular components.

Main Methods:

• Affinity capture and mass spectrometry were used to identify CX26 C-terminus binding partners.
• Co-immunoprecipitation and co-fractionation assays were employed to validate protein interactions.
• Immunofluorescence microscopy was used to determine the cellular localization of proteins.

Main Results:

• Twelve unique proteins associated with cell junctions or the cytoskeleton were identified as CX26 binding partners.
• CX26 was shown to co-fractionate with TJP1, VCL, EB2, and ASS1.
• The adaptor protein cingulin (CGN) was found to co-immunoprecipitate with CX26, ASS1, and TJP1, and its association with connexins is independent of C-terminus length.
• CX26, CGN, FLNB, and DAAM1 were localized to the organ of Corti and hepatocyte plasma membranes, with CX26 and TJP1 co-localizing in mouse liver.

Conclusions:

• Connexin-26 interacts with multiple cell junction and cytoskeleton proteins.
• These interactions suggest a role for CX26 in integrating membrane junctions with the cytoskeleton.
• Understanding these interactions may provide insights into the mechanisms of inherited hearing loss.