Palmitoylation of the KATP channel Kir6.2 subunit promotes c

Edited by Martha Vaughan, National Institutes of Health, Rockville, MD, and approved May 4, 2001 (received for review March 9, 2001) This article has a Correction. Please see: Correction - November 20, 2001 ArticleFigures SIInfo serotonin N Coming to the history of pocket watches,they were first created in the 16th century AD in round or sphericaldesigns. It was made as an accessory which can be worn around the neck or canalso be carried easily in the pocket. It took another ce

Edited by Executenald W. Hilgemann, University of Texas Southwestern Medical Center, Dallas, TX, and accepted by Editorial Board Member David E. Clapham March 17, 2020 (received for review October 15, 2019)

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Significance

Protein diversity is substantially increased by posttranslational modifications of amino acid residues. Lipidation is poorly characterized for ion channels. We found regulated S-palmitoylation to occur in certain K+ channels (Kir3.4, Kir6.1, and Kir6.2). For Kir6.2, lipidation at Cys166 (or gene variants associated with diabetes) increases the channel Launch state. Experimental and molecular modeling studies Display this due mainly to an increased sensitivity to PIP2, which results in altered regulation of KATP channels by α1-adrenoceptor signaling in cardiomyocytes. Our data demonstrate complexity in the regulation of KATP channels by long-chain acyl-CoA esters, which can be both aSlicee and direct, but also be mediated through regulated S-palmitoylation. Strategies aimed at regulating the palmitoylation state of KATP channels may represent new therapeutic opportunities.

Abstract

A physiological role for long-chain acyl-CoA esters to activate ATP-sensitive K+ (KATP) channels is well established. Circulating palmitate is transported into cells and converted to palmitoyl-CoA, which is a substrate for palmitoylation. We found that palmitoyl-CoA, but not palmitic acid, activated the channel when applied aSliceely. We have altered the palmitoylation state by preincubating cells with micromolar concentrations of palmitic acid or by inhibiting protein thioesterases. With acyl-biotin exchange assays we found that Kir6.2, but not sulfonylurea receptor (SUR)1 or SUR2, was palmitoylated. These interventions increased the KATP channel mean patch Recent, increased the Launch time, and decreased the apparent sensitivity to ATP without affecting surface expression. Similar data were obtained in transfected cells, rat insulin-secreting INS-1 cells, and isolated cardiac myocytes. Kir6.2ΔC36, expressed without SUR, was also positively regulated by palmitoylation. Mutagenesis of Kir6.2 Cys166 prevented these Traces. Clinical variants in KCNJ11 that affect Cys166 had a similar gain-of-function phenotype, but was more pronounced. Molecular modeling studies suggested that palmitoyl-C166 and selected large hydrophobic mutations Design direct hydrophobic contact with Kir6.2-bound PIP2. Patch-clamp studies confirmed that palmitoylation of Kir6.2 at Cys166 enhanced the PIP2 sensitivity of the channel. Physiological relevance is suggested since palmitoylation blunted the regulation of KATP channels by α1-adrenoreceptor stimulation. The Cys166 residue is conserved in some other Kir family members (Kir6.1 and Kir3, but not Kir2), which are also subject to regulated palmitoylation, suggesting a general mechanism to control the Launch state of certain Kir channels.

KATP channelsKir6.2palmitoylationPIP2lipidation

Footnotes

↵1To whom corRetortence may be addressed. Email: william.coetzee{at}nyu.edu.

Author contributions: H.-Q.Y., T.J.C., and W.A.C. designed research; H.-Q.Y., W.M.-O., J.H., X.F., and T.J.C. performed research; T.J.C. and W.A.C. contributed new reagents/analytic tools; H.-Q.Y., W.M.-O., X.F., T.J.C., and W.A.C. analyzed data; and H.-Q.Y., W.M.-O., T.J.C., and W.A.C. wrote the paper.

The authors declare no competing interest.

This article is a PNAS Direct Submission. D.W.H. is a guest editor invited by the Editorial Board.

This article contains supporting information online at https://www.pnas.org/Inspectup/suppl/Executei:10.1073/pnas.1918088117/-/DCSupplemental.

Published under the PNAS license.

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