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Biochem Soc Trans. 2007 Nov;35(Pt 5):1060-3.

hERG channel trafficking: novel targets in drug-induced long QT syndrome.

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Rammelkamp Center for Education and Research, MetroHealth Campus, Case Western Reserve University, Cleveland, OH 44109, U.S.A.


The cardiac potassium channel hERG (human ether-a-go-go-related gene) encodes the alpha-subunit of the rapid delayed rectifier current I(Kr) in the heart, which contributes to terminal repolarization in human cardiomyocytes. Direct block of hERG/I(Kr) channels by a large number of therapeutic compounds produces acLQTS [acquired LQTS (long QT syndrome)] characterized by drug-induced QT prolongation and torsades de pointes arrhythmias. The cardiotoxicity associated with unintended hERG block has prompted pharmaceutical companies to screen developmental compounds for hERG blockade and made hERG a major target in drug safety programmes. More recently, a novel form of acLQTS has been discovered that may go undetected in most conventional safety assays. Several therapeutic compounds have been identified that reduce hERG/I(Kr) currents not by direct block but by inhibition of hERG/I(Kr) trafficking to the cell surface. Important examples are antineoplastic Hsp90 (heat-shock protein 90) inhibitors such as (i) geldanamycin, (ii) the leukaemia drug arsenic trioxide, (iii) the antiprotozoical pentamidine, (iv) probucol, a cholesterol-lowering drug, and (v) fluoxetine, a widely used antidepressant. Increased awareness of drug-induced hERG trafficking defects will help to further reduce the potentially lethal adverse cardiac events associated with acLQTS.

[Indexed for MEDLINE]

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