PIKfyve sensitivity of hERG channels

Area of Science:

• Cardiovascular physiology
• Molecular biology
• Oncology

Background:

• Human ether-a-go-go (hERG) channels are crucial for cardiac repolarization and tumor cell proliferation.
• Mutations in hERG channels are linked to long QT syndrome and sudden cardiac death.
• hERG channel activity is known to be modulated by SGK1, SGK3, and PKB/Akt kinases, which activate PIKfyve.

Purpose of the Study:

• To investigate the previously uncharacterized effect of PIKfyve on hERG channel expression and activity.
• To elucidate the role of PIKfyve in the regulation of hERG channel function.

Main Methods:

• hERG channels were expressed in Xenopus oocytes with or without PIKfyve and/or PKB.
• hERG channel activity was measured using dual electrode voltage clamp.
• hERG protein abundance in the cell membrane was assessed via confocal microscopy and chemiluminescence.

Main Results:

• Coexpression of PIKfyve significantly increased hERG channel activity and cell membrane protein abundance.
• Protein kinase B (PKB/Akt) further enhanced hERG activity, an effect dependent on PIKfyve's kinase activity.
• PIKfyve enhances hERG channel insertion into the cell membrane.

Conclusions:

• PIKfyve directly up-regulates hERG channel expression and activity.
• Protein kinase B (PKB/Akt) activates PIKfyve, establishing a signaling cascade that modulates hERG channel function.
• This study reveals a novel regulatory mechanism for hERG channels with implications for cardiac electrophysiology and cancer biology.