Protein kinase A stimulates Kv7.1 surface expression by regulating Nedd4-2-dependent endocytic trafficking

Martin Nybo Andersen; Louise Leth Hefting; Annette Buur Steffensen; Nicole Schmitt; Søren-Peter Olesen; Jesper Velgaard Olsen; Alicia Lundby; Hanne Borger Rasmussen

doi:10.1152/ajpcell.00383.2014

Protein kinase A stimulates Kv7.1 surface expression by regulating Nedd4-2-dependent endocytic trafficking

Martin Nybo Andersen, Louise Leth Hefting, Annette Buur Steffensen, Nicole Schmitt, Søren-Peter Olesen, Jesper Velgaard Olsen, Alicia Lundby, Hanne Borger Rasmussen

4 Citations (Scopus)

Abstract

The potassium channel Kv7.1 plays critical physiological roles in both heart and epithelial tissues. In heart, Kv7.1 and the accessory subunit KCNE1 forms the slowly activating delayed-rectifier potassium current current, which is enhanced by protein kinase A (PKA)-mediated phosphorylation. The observed current increase requires both phosphorylation of Kv7.1 and the presence of KCNE1. However, PKA also stimulates Kv7.1 currents in epithelial tissues, such as colon, where the channel does not coassemble with KCNE1. Here, we demonstrate that PKA activity significantly impacts the subcellular localization of Kv7.1 in Madin-Darby canine kidney cells. While PKA inhibition reduced the fraction of channels at the cell surface, PKA activation increased it. We show that PKA inhibition led to intracellular accumulation of Kv7.1 in late endosomes/ lysosomes. By mass spectroscopy we identified eight phosphorylated residues on Kv7.1, however, none appeared to play a role in the observed response. Instead, we found that PKA acted by regulating endocytic trafficking involving the ubiquitin ligase Nedd4-2. We show that a Nedd4-2-resistant Kv7.1-mutant displayed significantly reduced intracellular accumulation upon PKA inhibition. Similar effects were observed upon siRNA knockdown of Nedd4-2. However, although Nedd4-2 is known to regulate Kv7.1 by ubiquitylation, biochemical analyses demonstrated that PKA did not influence the amount of Nedd4-2 bound to Kv7.1 or the ubiquitylation level of the channel. This suggests that PKA influences Nedd4-2-dependent Kv7.1 transport though a different molecular mechanism. In summary, we identify a novel mechanism whereby PKA can increase Kv7.1 current levels, namely by regulating Nedd4-2-dependent Kv7.1 transport.

Original language	English
Journal	American Journal of Physiology: Cell Physiology
Volume	309
Issue number	10
Pages (from-to)	C693-C706
Number of pages	14
ISSN	0363-6143
DOIs	https://doi.org/10.1152/ajpcell.00383.2014
Publication status	Published - 15 Nov 2015

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Protein kinase A stimulates Kv7.1 surface expression by regulating Nedd4-2-dependent endocytic trafficking. / Andersen, Martin Nybo; Hefting, Louise Leth; Steffensen, Annette Buur et al.
In: American Journal of Physiology: Cell Physiology, Vol. 309, No. 10, 15.11.2015, p. C693-C706.

Research output: Contribution to journal › Journal article › Research › peer-review

@article{44f5ae37ac6e43c79c809d2857ffbbad,

title = "Protein kinase A stimulates Kv7.1 surface expression by regulating Nedd4-2-dependent endocytic trafficking",

abstract = "The potassium channel Kv7.1 plays critical physiological roles in both heart and epithelial tissues. In heart, Kv7.1 and the accessory subunit KCNE1 forms the slowly activating delayed-rectifier potassium current current, which is enhanced by protein kinase A (PKA)-mediated phosphorylation. The observed current increase requires both phosphorylation of Kv7.1 and the presence of KCNE1. However, PKA also stimulates Kv7.1 currents in epithelial tissues, such as colon, where the channel does not coassemble with KCNE1. Here, we demonstrate that PKA activity significantly impacts the subcellular localization of Kv7.1 in Madin-Darby canine kidney cells. While PKA inhibition reduced the fraction of channels at the cell surface, PKA activation increased it. We show that PKA inhibition led to intracellular accumulation of Kv7.1 in late endosomes/ lysosomes. By mass spectroscopy we identified eight phosphorylated residues on Kv7.1, however, none appeared to play a role in the observed response. Instead, we found that PKA acted by regulating endocytic trafficking involving the ubiquitin ligase Nedd4-2. We show that a Nedd4-2-resistant Kv7.1-mutant displayed significantly reduced intracellular accumulation upon PKA inhibition. Similar effects were observed upon siRNA knockdown of Nedd4-2. However, although Nedd4-2 is known to regulate Kv7.1 by ubiquitylation, biochemical analyses demonstrated that PKA did not influence the amount of Nedd4-2 bound to Kv7.1 or the ubiquitylation level of the channel. This suggests that PKA influences Nedd4-2-dependent Kv7.1 transport though a different molecular mechanism. In summary, we identify a novel mechanism whereby PKA can increase Kv7.1 current levels, namely by regulating Nedd4-2-dependent Kv7.1 transport.",

author = "Andersen, {Martin Nybo} and Hefting, {Louise Leth} and Steffensen, {Annette Buur} and Nicole Schmitt and S{\o}ren-Peter Olesen and Olsen, {Jesper Velgaard} and Alicia Lundby and Rasmussen, {Hanne Borger}",

note = "Copyright {\textcopyright} 2015, American Journal of Physiology - Cell Physiology.",

year = "2015",

month = nov,

day = "15",

doi = "10.1152/ajpcell.00383.2014",

language = "English",

volume = "309",

pages = "C693--C706",

journal = "American Journal of Physiology: Cell Physiology",

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T1 - Protein kinase A stimulates Kv7.1 surface expression by regulating Nedd4-2-dependent endocytic trafficking

AU - Andersen, Martin Nybo

AU - Hefting, Louise Leth

AU - Steffensen, Annette Buur

AU - Schmitt, Nicole

AU - Olesen, Søren-Peter

AU - Olsen, Jesper Velgaard

AU - Lundby, Alicia

AU - Rasmussen, Hanne Borger

PY - 2015/11/15

Y1 - 2015/11/15

N2 - The potassium channel Kv7.1 plays critical physiological roles in both heart and epithelial tissues. In heart, Kv7.1 and the accessory subunit KCNE1 forms the slowly activating delayed-rectifier potassium current current, which is enhanced by protein kinase A (PKA)-mediated phosphorylation. The observed current increase requires both phosphorylation of Kv7.1 and the presence of KCNE1. However, PKA also stimulates Kv7.1 currents in epithelial tissues, such as colon, where the channel does not coassemble with KCNE1. Here, we demonstrate that PKA activity significantly impacts the subcellular localization of Kv7.1 in Madin-Darby canine kidney cells. While PKA inhibition reduced the fraction of channels at the cell surface, PKA activation increased it. We show that PKA inhibition led to intracellular accumulation of Kv7.1 in late endosomes/ lysosomes. By mass spectroscopy we identified eight phosphorylated residues on Kv7.1, however, none appeared to play a role in the observed response. Instead, we found that PKA acted by regulating endocytic trafficking involving the ubiquitin ligase Nedd4-2. We show that a Nedd4-2-resistant Kv7.1-mutant displayed significantly reduced intracellular accumulation upon PKA inhibition. Similar effects were observed upon siRNA knockdown of Nedd4-2. However, although Nedd4-2 is known to regulate Kv7.1 by ubiquitylation, biochemical analyses demonstrated that PKA did not influence the amount of Nedd4-2 bound to Kv7.1 or the ubiquitylation level of the channel. This suggests that PKA influences Nedd4-2-dependent Kv7.1 transport though a different molecular mechanism. In summary, we identify a novel mechanism whereby PKA can increase Kv7.1 current levels, namely by regulating Nedd4-2-dependent Kv7.1 transport.

AB - The potassium channel Kv7.1 plays critical physiological roles in both heart and epithelial tissues. In heart, Kv7.1 and the accessory subunit KCNE1 forms the slowly activating delayed-rectifier potassium current current, which is enhanced by protein kinase A (PKA)-mediated phosphorylation. The observed current increase requires both phosphorylation of Kv7.1 and the presence of KCNE1. However, PKA also stimulates Kv7.1 currents in epithelial tissues, such as colon, where the channel does not coassemble with KCNE1. Here, we demonstrate that PKA activity significantly impacts the subcellular localization of Kv7.1 in Madin-Darby canine kidney cells. While PKA inhibition reduced the fraction of channels at the cell surface, PKA activation increased it. We show that PKA inhibition led to intracellular accumulation of Kv7.1 in late endosomes/ lysosomes. By mass spectroscopy we identified eight phosphorylated residues on Kv7.1, however, none appeared to play a role in the observed response. Instead, we found that PKA acted by regulating endocytic trafficking involving the ubiquitin ligase Nedd4-2. We show that a Nedd4-2-resistant Kv7.1-mutant displayed significantly reduced intracellular accumulation upon PKA inhibition. Similar effects were observed upon siRNA knockdown of Nedd4-2. However, although Nedd4-2 is known to regulate Kv7.1 by ubiquitylation, biochemical analyses demonstrated that PKA did not influence the amount of Nedd4-2 bound to Kv7.1 or the ubiquitylation level of the channel. This suggests that PKA influences Nedd4-2-dependent Kv7.1 transport though a different molecular mechanism. In summary, we identify a novel mechanism whereby PKA can increase Kv7.1 current levels, namely by regulating Nedd4-2-dependent Kv7.1 transport.

U2 - 10.1152/ajpcell.00383.2014

DO - 10.1152/ajpcell.00383.2014

M3 - Journal article

C2 - 26405101

SN - 0363-6143

VL - 309

SP - C693-C706

JO - American Journal of Physiology: Cell Physiology

JF - American Journal of Physiology: Cell Physiology

IS - 10

ER -

Protein kinase A stimulates Kv7.1 surface expression by regulating Nedd4-2-dependent endocytic trafficking

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