Regulation of large calcium-activated potassium channels by protein phosphatase 2A

Steven C. Sansom, James D. Stockand, David Hall, Bruce Williams

Research output: Contribution to journalArticle

48 Citations (Scopus)

Abstract

Vasodilating agents induce relaxation of mesangial cells, in part through cGMP-mediated activation of large calcium-activated potassium channels (BK(Ca)). Normally quiescent in cell-attached patches, the response of BK(Ca) to nitric oxide, atrial natriuretic peptide, and dibutyryl cGMP (Bt2cGMP) is characterized by a biphasic increase and then decrease ('rundown') in open probability. Using the patch-clamp method in conjunction with phosphatase inhibitors, we investigated whether the run-down phase was the result of dephosphorylation by an endogenous protein phosphatase. In cell-attached patches, cantharidic acid (500 nM), okadaic acid (100 nM), and calyculin A (100 nM), nondiscriminant inhibitors of protein phosphatases 1 (PP1) and 2A (PP2A) at these concentrations, caused a significantly greater and sustained response of BK(Ca) to Bt2cGMP. Within 2 min, the response of BK(Ca) to the combination of cantharidic acid and Bt2cGMP was greater than the response to these agents added separately. Incubation of mesangial cells with okadaic acid for 20 min at a concentration (5 nM) specific for PP2A increased the basal open probability of BK(Ca) and completely inhibited rundown after activation by Bt2cGMP. Incubation with calyculin A (10 nM), a more potent inhibitor of PP1, did not affect BK(Ca) activity. In inside-out patches, Bt2cGMP plus MgATP caused a sustained activation of BK(Ca) that was inhibited by exogenous PP2A but not PP1. It is concluded that either BK(Ca) or a tightly associated regulator of BK(Ca) is a common substrate for endogenous cGMP-activated protein kinase, which activates BK(Ca), and PP2A, which inactivates BK(Ca), in human mesangial cells.

Original languageEnglish (US)
Pages (from-to)9902-9906
Number of pages5
JournalJournal of Biological Chemistry
Volume272
Issue number15
DOIs
StatePublished - Apr 11 1997

Fingerprint

Calcium-Activated Potassium Channels
Protein Phosphatase 2
Mesangial Cells
Okadaic Acid
Chemical activation
Protein Phosphatase 1
Acids
Phosphoprotein Phosphatases
Clamping devices
Atrial Natriuretic Factor
Phosphoric Monoester Hydrolases
Protein Kinases
Nitric Oxide
Adenosine Triphosphate
Substrates
calyculin A

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Regulation of large calcium-activated potassium channels by protein phosphatase 2A. / Sansom, Steven C.; Stockand, James D.; Hall, David; Williams, Bruce.

In: Journal of Biological Chemistry, Vol. 272, No. 15, 11.04.1997, p. 9902-9906.

Research output: Contribution to journalArticle

Sansom, Steven C. ; Stockand, James D. ; Hall, David ; Williams, Bruce. / Regulation of large calcium-activated potassium channels by protein phosphatase 2A. In: Journal of Biological Chemistry. 1997 ; Vol. 272, No. 15. pp. 9902-9906.
@article{e261c237d84e406b95a83a6c0ad30235,
title = "Regulation of large calcium-activated potassium channels by protein phosphatase 2A",
abstract = "Vasodilating agents induce relaxation of mesangial cells, in part through cGMP-mediated activation of large calcium-activated potassium channels (BK(Ca)). Normally quiescent in cell-attached patches, the response of BK(Ca) to nitric oxide, atrial natriuretic peptide, and dibutyryl cGMP (Bt2cGMP) is characterized by a biphasic increase and then decrease ('rundown') in open probability. Using the patch-clamp method in conjunction with phosphatase inhibitors, we investigated whether the run-down phase was the result of dephosphorylation by an endogenous protein phosphatase. In cell-attached patches, cantharidic acid (500 nM), okadaic acid (100 nM), and calyculin A (100 nM), nondiscriminant inhibitors of protein phosphatases 1 (PP1) and 2A (PP2A) at these concentrations, caused a significantly greater and sustained response of BK(Ca) to Bt2cGMP. Within 2 min, the response of BK(Ca) to the combination of cantharidic acid and Bt2cGMP was greater than the response to these agents added separately. Incubation of mesangial cells with okadaic acid for 20 min at a concentration (5 nM) specific for PP2A increased the basal open probability of BK(Ca) and completely inhibited rundown after activation by Bt2cGMP. Incubation with calyculin A (10 nM), a more potent inhibitor of PP1, did not affect BK(Ca) activity. In inside-out patches, Bt2cGMP plus MgATP caused a sustained activation of BK(Ca) that was inhibited by exogenous PP2A but not PP1. It is concluded that either BK(Ca) or a tightly associated regulator of BK(Ca) is a common substrate for endogenous cGMP-activated protein kinase, which activates BK(Ca), and PP2A, which inactivates BK(Ca), in human mesangial cells.",
author = "Sansom, {Steven C.} and Stockand, {James D.} and David Hall and Bruce Williams",
year = "1997",
month = "4",
day = "11",
doi = "10.1074/jbc.272.15.9902",
language = "English (US)",
volume = "272",
pages = "9902--9906",
journal = "Journal of Biological Chemistry",
issn = "0021-9258",
publisher = "American Society for Biochemistry and Molecular Biology Inc.",
number = "15",

}

TY - JOUR

T1 - Regulation of large calcium-activated potassium channels by protein phosphatase 2A

AU - Sansom, Steven C.

AU - Stockand, James D.

AU - Hall, David

AU - Williams, Bruce

PY - 1997/4/11

Y1 - 1997/4/11

N2 - Vasodilating agents induce relaxation of mesangial cells, in part through cGMP-mediated activation of large calcium-activated potassium channels (BK(Ca)). Normally quiescent in cell-attached patches, the response of BK(Ca) to nitric oxide, atrial natriuretic peptide, and dibutyryl cGMP (Bt2cGMP) is characterized by a biphasic increase and then decrease ('rundown') in open probability. Using the patch-clamp method in conjunction with phosphatase inhibitors, we investigated whether the run-down phase was the result of dephosphorylation by an endogenous protein phosphatase. In cell-attached patches, cantharidic acid (500 nM), okadaic acid (100 nM), and calyculin A (100 nM), nondiscriminant inhibitors of protein phosphatases 1 (PP1) and 2A (PP2A) at these concentrations, caused a significantly greater and sustained response of BK(Ca) to Bt2cGMP. Within 2 min, the response of BK(Ca) to the combination of cantharidic acid and Bt2cGMP was greater than the response to these agents added separately. Incubation of mesangial cells with okadaic acid for 20 min at a concentration (5 nM) specific for PP2A increased the basal open probability of BK(Ca) and completely inhibited rundown after activation by Bt2cGMP. Incubation with calyculin A (10 nM), a more potent inhibitor of PP1, did not affect BK(Ca) activity. In inside-out patches, Bt2cGMP plus MgATP caused a sustained activation of BK(Ca) that was inhibited by exogenous PP2A but not PP1. It is concluded that either BK(Ca) or a tightly associated regulator of BK(Ca) is a common substrate for endogenous cGMP-activated protein kinase, which activates BK(Ca), and PP2A, which inactivates BK(Ca), in human mesangial cells.

AB - Vasodilating agents induce relaxation of mesangial cells, in part through cGMP-mediated activation of large calcium-activated potassium channels (BK(Ca)). Normally quiescent in cell-attached patches, the response of BK(Ca) to nitric oxide, atrial natriuretic peptide, and dibutyryl cGMP (Bt2cGMP) is characterized by a biphasic increase and then decrease ('rundown') in open probability. Using the patch-clamp method in conjunction with phosphatase inhibitors, we investigated whether the run-down phase was the result of dephosphorylation by an endogenous protein phosphatase. In cell-attached patches, cantharidic acid (500 nM), okadaic acid (100 nM), and calyculin A (100 nM), nondiscriminant inhibitors of protein phosphatases 1 (PP1) and 2A (PP2A) at these concentrations, caused a significantly greater and sustained response of BK(Ca) to Bt2cGMP. Within 2 min, the response of BK(Ca) to the combination of cantharidic acid and Bt2cGMP was greater than the response to these agents added separately. Incubation of mesangial cells with okadaic acid for 20 min at a concentration (5 nM) specific for PP2A increased the basal open probability of BK(Ca) and completely inhibited rundown after activation by Bt2cGMP. Incubation with calyculin A (10 nM), a more potent inhibitor of PP1, did not affect BK(Ca) activity. In inside-out patches, Bt2cGMP plus MgATP caused a sustained activation of BK(Ca) that was inhibited by exogenous PP2A but not PP1. It is concluded that either BK(Ca) or a tightly associated regulator of BK(Ca) is a common substrate for endogenous cGMP-activated protein kinase, which activates BK(Ca), and PP2A, which inactivates BK(Ca), in human mesangial cells.

UR - http://www.scopus.com/inward/record.url?scp=0030999831&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0030999831&partnerID=8YFLogxK

U2 - 10.1074/jbc.272.15.9902

DO - 10.1074/jbc.272.15.9902

M3 - Article

C2 - 9092528

AN - SCOPUS:0030999831

VL - 272

SP - 9902

EP - 9906

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 0021-9258

IS - 15

ER -