Skin disease-associated GJB4 variants differentially influence connexin stability, cell viability and channel...

Area of Science:

• Cell Biology
• Genetics
• Dermatology

Background:

• Erythrokeratodermia variabilis et progressiva (EKVP) is a rare skin disorder.
• Connexin 30.3 (Cx30.3) gene variants are clinically associated with EKVP.
• Understanding the molecular impact of these variants is crucial for EKVP research.

Purpose of the Study:

• To characterize seven EKVP-associated Cx30.3 gene variants.
• To investigate the functional consequences of these variants in rat epidermal keratinocytes (REKs).
• To determine how variants affect Cx30.3 trafficking, turnover, cell viability, and gap junction function.

Main Methods:

• Expression of wildtype (WT) Cx30.3 and seven variants (R22H, S26Y, P61R, C86S, E99K, T130M, M190L) in REKs.
• Analysis of protein trafficking, gap junction formation, and turnover rates.
• Assessment of cell viability and membrane permeability using fluorescent dyes.
• Dual patch clamp studies in connexin-null AD-293 cells to evaluate gap junction channel function.

Main Results:

• All Cx30.3 variants trafficked and formed gap junctions similarly to WT Cx30.3.
• The R22H and P61R variants exhibited more rapid turnover than WT Cx30.3.
• The P61R variant reduced REK viability and increased cell permeability.
• Variants C86S, S26Y, and T130M showed reduced or absent gap junction function.
• Other variants displayed enhanced voltage-dependent gating, with some having lower open probability at high voltages.

Conclusions:

• Each EKVP-associated Cx30.3 variant alters Cx30.3 characteristics, including protein stability, cell viability, and/or channel function.
• The observed molecular changes, such as altered turnover, reduced viability, and modified channel gating, may contribute to EKVP.
• Further genetic analysis in familial EKVP patients is needed to confirm the causal role of these variants.