A comparison of currents carried by HERG, with and without coexpression of MiRP1, and the native rapid delayed rectifier current. Is MiRP1 the missing link?

Weerapura, Manjula; Nattel, Stanley; Chartier, Denis; Caballero, Ricardo; Hébert, Terence E.

doi:10.1113/jphysiol.2001.013296

Cited by 179 publications

(131 citation statements)

References 27 publications

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“…As early as 1995, it was suggested that the KCNE1 protein (also known as MiRP1 or minK) is a subunit of I Kr channels based on experiments in which antisense KCNE1 oligonucleotides reduced I Kr current levels in AT1 cardiomyocyte-like cells (38). A subsequent report using HEK293 cells supported this idea by showing that KCNE1 alters hERG function (39), whereas another study using CHO cells did not (40). If KCNE1/minK participates as subunits or regulators of I Kr channels, it appears from our findings that it does so posttranslationally, perhaps as described for I Ks channels (41); alternatively, it may assemble from nonassociating transcripts, or in cell types other than the two examined here.…”

Section: Discussionsupporting

confidence: 51%

Cotranslational association of mRNA encoding subunits of heteromeric ion channels

Liu

Jones

Lange

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Oligomers of homomeric voltage-gated potassium channels associate early in biogenesis as the nascent proteins emerge from the polysome. Less is known about how proteins emerging from different polysomes associate to form hetero-oligomeric channels. Here, we report that alternate mRNA transcripts encoding human ether-à-go-go-related gene (hERG) 1a and 1b subunits, which assemble to produce ion channels mediating cardiac repolarization, are physically associated during translation. We show that shRNA specifically targeting either hERG 1a or 1b transcripts reduced levels of both transcripts, but only when they were coexpressed heterologously. Both transcripts could be copurified with an Ab against the nascent hERG 1a N terminus. This interaction occurred even when translation of 1b was prevented, indicating the transcripts associate independent of their encoded proteins. The association was also demonstrated in cardiomyocytes, where levels of both hERG transcripts were reduced by either 1a or 1b shRNA, but native KCNE1 and ryanodine receptor 2 (RYR2) transcripts were unaffected. Changes in protein levels and membrane currents mirrored changes in transcript levels, indicating the targeted transcripts were undergoing translation. The physical association of transcripts encoding different subunits provides the spatial proximity required for nascent proteins to interact during biogenesis, and may represent a general mechanism facilitating assembly of heteromeric protein complexes involved in a range of biological processes.KCNH2 | hERG | cotranslational assembly | microtranslatome | hERG 1a/1b

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Section: Discussionsupporting

confidence: 51%

Cotranslational association of mRNA encoding subunits of heteromeric ion channels

Liu

Jones

Lange

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…Stably transfected CHO cells were cultured as previously described 9,10 and perfused with an external solution containing (in mmol/L): NaCl 130, KCl 4, CaCl 2 1, MgCl 2 1, HEPES 10, and glucose 10 (pH adjusted to 7.4 with NaOH). The internal solution contained (in mmol/L): K-aspartate 80, KCl 42, KH 2 PO 4 10, MgATP 5, phosphocreatine 3, HEPES 5, and EGTA 5 (pH adjusted to 7.2 with KOH).…”

Section: Methodsmentioning

confidence: 99%

Spironolactone and Its Main Metabolite, Canrenoic Acid, Block Human Ether-a-Go-Go–Related Gene Channels

et al. 2003

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“…KCNE2 (MiRP1) co-assembles with HERG (31,32), although the functional implications have been debated (33), and it has been difficult to demonstrate expression of KCNE2 in human heart (34). The KCNE2 polymorphism T8A, which abrogates complex glycosylation of KCNE2, mildly increases I Kr sensitivity to block by the antibiotic sulfamethoxazole (35).…”

Section: N-linked Glycosylation-induced Protection Of Herg Doesmentioning

confidence: 99%

HERG Is Protected from Pharmacological Block by α-1,2-Glucosyltransferase Function

Nakajima¹,

Hayashi²,

Viswanathan

et al. 2007

Journal of Biological Chemistry

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The HERG (human ether-à-go-go-related gene) protein, which underlies the cardiac repolarizing current I Kr , is the unintended target for many pharmaceutical agents. Inadvertent block of I Kr , known as the acquired long QT syndrome (aLQTS), is a leading cause for drug withdrawal by the United States Food and Drug Administration. Hence, an improved understanding of the regulatory factors that protect most individuals from aLQTS is essential for advancing clinical therapeutics in broad areas, from cancer chemotherapy to antipsychotics and antidepressants. Here, we show that the K ؉ channel regulatory protein KCR1, which markedly reduces I Kr drug sensitivity, protects HERG through glucosyltransferase function. KCR1 and the yeast ␣-1,2-glucosyltransferase ALG10 exhibit sequence homology, and like KCR1, ALG10 diminished HERG block by dofetilide. Inhibition of cellular glycosylation pathways with tunicamycin abrogated the effects of KCR1, as did expression in Lec1 cells (deficient in glycosylation). Moreover, KCR1 complemented the growth defect of an alg10-deficient yeast strain and enhanced glycosylation of an Alg10 substrate in yeast. HERG itself is not the target for KCR1-mediated glycosylation because the dofetilide response of glycosylation-deficient HERG(N598Q) was still modulated by KCR1. Nonetheless, our data indicate that the ␣-1,2-glucosyltransferase function is a key component of the molecular pathway whereby KCR1 diminishes I Kr drug response. Incorporation of in vitro data into a computational model indicated that KCR1 expression is protective against arrhythmias. These findings reveal a potential new avenue for targeted prevention of aLQTS.I Kr , an important component of the cardiac delayed rectifier K ϩ current, is required for repolarization of the human cardiac action potential. Mutations in HERG (human ether-à-go-gorelated gene), which encodes the ␣-subunit of the channel complex, are responsible for the chromosome 7-linked form (LQT2) of the congenital long QT syndrome (LQTS), 2 an arrhythmia syndrome characterized by action potential prolongation and delayed cardiac repolarization. LQTS causes the atypical polymorphic ventricular tachycardia torsade de pointes, leading to sudden cardiac death (1-3). A far more commonly acquired form of LQTS (aLQTS) is precipitated by exposure to a wide range of therapeutic compounds that block HERG. aLQTS represents a significant problem for public health and the pharmaceutical industry 3 and is typically observed in predisposed patients receiving treatment for noncardiac illnesses. Indeed, about half of all drug withdrawals since 1998 were in response to potential pro-arrhythmic effects linked to aLQTS (5-7).Numerous drug families bind the HERG channel and suppress I Kr in vitro, yet, surprisingly, few patients experience aLQTS. Clinically silent ion channel gene mutations have been characterized in families with cases of aLQTS, indicating that even the drug-induced form of the disorder may carry a genetic component (8 -15). However, mutations in the gene that ...

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A comparison of currents carried by HERG, with and without coexpression of MiRP1, and the native rapid delayed rectifier current. Is MiRP1 the missing link?

Cited by 179 publications

References 27 publications

Cotranslational association of mRNA encoding subunits of heteromeric ion channels

Cotranslational association of mRNA encoding subunits of heteromeric ion channels

Spironolactone and Its Main Metabolite, Canrenoic Acid, Block Human Ether-a-Go-Go–Related Gene Channels

HERG Is Protected from Pharmacological Block by α-1,2-Glucosyltransferase Function

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