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J Biol Chem. 2018 Mar 23;293(12):4289-4303. doi: 10.1074/jbc.RA117.000432. Epub 2018 Jan 5.

Fluid flow modulates electrical activity in cardiac hERG potassium channels.

Author information

1
From the National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru 560065.
2
the Biocon Bristol Myers Squibb Research Center, Bengaluru 560099, and.
3
the School of Biotechnology, Kalinga Institute of Industrial Technology (KIIT) University, Bhubaneswar 751024, India.
4
From the National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru 560065, mathew@ncbs.res.in.

Abstract

Fluid movement within the heart generates substantial shear forces, but the effect of this mechanical stress on the electrical activity of the human heart has not been examined. The fast component of the delayed rectifier potassium currents responsible for repolarization of the cardiac action potential, Ikr, is encoded by the human ether-a-go-go related gene (hERG) channel. Here, we exposed hERG1a channel-expressing HEK293T cells to laminar shear stress (LSS) and observed that this mechanical stress increased the whole-cell current by 30-40%. LSS shifted the voltage dependence of steady-state activation of the hERG channel to the hyperpolarizing direction, accelerated the time course of activation and recovery from inactivation, slowed down deactivation, and shifted the steady-state inactivation to the positive direction, all of which favored the hERG open state. In contrast, the time course of inactivation was faster, favoring the closed state. Using specific inhibitors of focal adhesion kinase, a regulator of mechano-transduction via the integrin pathway, we also found that the LSS-induced modulation of the whole-cell current depended on the integrin pathway. The hERG1b channel variant, which lacks the Per-Arnt-Sim (PAS) domain, and long QT syndrome-associated variants having point mutations in the PAS domain were unaffected by LSS, suggesting that the PAS domain in hERG1a channel may be involved in sensing mechanical shear stress. We conclude that a mechano-electric feedback pathway modulates hERG channel activity through the integrin pathway, indicating that mechanical forces in the heart influence its electrical activity.

KEYWORDS:

LSS; Per-Arnt-Sim (PAS); action potential duration (APD); cardiac fluid movement; cytoskeleton; electrophysiology; focal adhesion kinase (FAK); focal adhesions; hERG; heart; integrin; laminar shear stress; mechanical stress; mechanotransduction; membrane biophysics; patch clamp; potassium channel; shear stress

PMID:
29305421
PMCID:
PMC5868271
[Available on 2019-03-23]
DOI:
10.1074/jbc.RA117.000432

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