A mutation in telethonin alters Nav1.5 function.

Area of Science:

• Cardiovascular Science
• Gastroenterology
• Molecular Biology

Background:

• Excitable cells utilize ion channels for rapid ion exchange, crucial for cellular functions like depolarization.
• The Nav1.5 sodium channel, encoded by SCN5A, is vital in the heart, brain, and GI tract, with its function modulated by interacting proteins.
• SCN5A genetic defects cause arrhythmias like Long QT and Brugada syndromes; mutations also link to GI symptoms, suggesting Nav1.5's role in gut physiology.

Observation:

• A patient with intestinal pseudo-obstruction exhibited a mutation in TCAP, the gene for telethonin.
• Telethonin is expressed in human GI smooth muscle, co-localizes with Nav1.5, and interacts with sodium channels.
• Co-expression of mutated telethonin and SCN5A in HEK 293 cells altered Nav1.5 activation kinetics, increasing window current.

Findings:

• Telethonin interacts with Nav1.5 sodium channels.
• Mutations in telethonin can modify Nav1.5 channel kinetics.
• Telethonin is identified as a novel sodium channel-interacting protein.

Implications:

• This study reveals a new role for telethonin in regulating sodium channel function.
• Telethonin mutations may contribute to the pathophysiology of intestinal pseudo-obstruction.
• Understanding telethonin-Nav1.5 interactions could lead to new therapeutic strategies for GI motility disorders.