Differential Assembly of Native ENaC Complexes Across Mouse Epithelial Tissues

Area of Science:

• Biochemistry
• Molecular Biology
• Physiology

Background:

• The epithelial sodium channel (ENaC) is crucial for sodium and fluid absorption in vital organs like the lungs, kidneys, and colon.
• Defining the structure of native ENaC complexes is challenging due to their low abundance and biochemical instability.

Purpose of the Study:

• To develop a method for direct analysis of intact native ENaC complexes.
• To investigate tissue-specific differences in ENaC abundance, assembly, and regulation.

Main Methods:

• Generated a knock-in mouse model (ENaCγ-VF) with a tagged γ subunit to preserve ENaC function.
• Employed fluorescence-detection size-exclusion chromatography and single-molecule pull-down assays.
• Utilized dual-color analysis to distinguish fully assembled channels from broader populations.

Main Results:

• The ENaCγ-VF mouse model accurately reflects physiological ENaC function.
• Direct monitoring revealed significant tissue-specific variations in ENaC abundance and complex size.
• Demonstrated heterogeneous ENaC architecture in vivo.

Conclusions:

• The ENaCγ-VF mouse line provides a valuable tool for studying native ENaC complexes.
• This platform facilitates the identification of proteins interacting with ENaC.
• Epithelial environments significantly influence ENaC assembly, composition, and regulation.