Characterization of endogenous Kv1.3 channel isoforms in T cells

Area of Science:

• Immunology
• Cell Biology
• Molecular Biology

Background:

• Voltage-dependent potassium channel Kv1.3 is crucial for T-cell activation.
• Accurate detection of endogenous Kv1.3 has been hindered by a lack of reliable antibodies.

Purpose of the Study:

• To develop a method for detecting endogenous Kv1.3 channels in T cells.
• To characterize the expression, localization, and function of native Kv1.3 channel isoforms upon T-cell activation.

Main Methods:

• CRISPR-Cas9 gene editing to tag endogenous Kv1.3 in Jurkat T-cells.
• Western blot analysis and imaging techniques to study channel expression and localization.
• Functional characterization using HEK cell overexpression and Jurkat knockout/isoform-specific clones.

Main Results:

• Identified three Kv1.3 isoforms (canonical, longer, and truncated/short form) with differing N-termini.
• All three isoforms were upregulated upon T-cell activation.
• The truncated isoform (SF) localizes intracellularly, does not form functional currents, and impairs T-cell signaling and calcium influx.

Conclusions:

• Alternative translation initiation generates at least three endogenous Kv1.3 isoforms in T cells.
• These isoforms exhibit distinct functional roles and differential contributions to T-cell activation and immunological synapse formation.
• Kv1.3 proteins can influence signaling pathways without forming functional plasma membrane channels.