title: Protein kinase A-phosphorylated KV1 channels in PSD95 signaling complex contribute to the resting membrane potential and diameter of cerebral arteries.
abstract: BACKGROUND
  Postsynaptic density-95 (PSD95) is a scaffolding protein that associates with voltage-gated, Shaker-type K(+) (KV1) channels and promotes the expression of KV1 channels in vascular smooth muscle cells of the cerebral (cVSMCs) circulation. However, the physiological role of PSD95 in mediating molecular signaling in cVSMCs is unknown.
  
  
  OBJECTIVE
  We explored whether a specific interaction between PSD95 and KV1 channels enables protein kinase A phosphorylation of KV1 channels in cVSMCs to promote vasodilation.
  
  
  RESULTS
  Rat cerebral arteries were used for analyses. A membrane-permeable peptide (KV1-C peptide) corresponding to the postsynaptic density-95, discs large, zonula occludens-1 binding motif in the C terminus of KV1.2α was designed as a dominant-negative peptide to disrupt the association of KV1 channels with PSD95. Application of KV1-C peptide to cannulated, pressurized cerebral arteries rapidly induced vasoconstriction and depolarized cVSMCs. These events corresponded to reduced coimmunoprecipitation of the PSD95 and KV1 proteins without altering surface expression. Middle cerebral arterioles imaged in situ through cranial window also constricted rapidly in response to local application of KV1-C peptide. Patch-clamp recordings confirmed that KV1-C peptide attenuates KV1 channel blocker (5-(4-phenylalkoxypsoralen))-sensitive current in cVSMCs. Western blots using a phospho-protein kinase A substrate antibody revealed that cerebral arteries exposed to KV1-C peptide showed markedly less phosphorylation of KV1.2α subunits. Finally, phosphatase inhibitors blunted both KV1-C peptide-mediated and protein kinase A inhibitor peptide-mediated vasoconstriction.
  
  
  CONCLUSIONS
  These findings provide initial evidence that protein kinase A phosphorylation of KV1 channels is enabled by a dynamic association with PSD95 in cerebral arteries and suggest that a disruption of such association may compromise cerebral vasodilation and blood flow.
authors.affiliation: From the Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock (C.L.M., P.L.N., N.J.R., S.W.R.); and University of Kansas Cancer Center, University of Kansas Medical Center, Kansas City (N.K.P.).
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Moore
authors.forename: Piper L
authors.initials: PL
authors.lastname: Nelson
authors.forename: Nikhil K
authors.initials: NK
authors.lastname: Parelkar
authors.forename: Nancy J
authors.initials: NJ
authors.lastname: Rusch
authors.forename: Sung W
authors.initials: SW
authors.lastname: Rhee
mesh_terms: D000818:Animals; D002536:Cerebral Arteries / Q000502:physiology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000502:physiology*; D000076122:Disks Large Homolog 4 Protein; D004791:Enzyme Inhibitors / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins / Q000502:physiology*; D008297:Male; D008564:Membrane Potentials / Q000502:physiology*; D008565:Membrane Proteins / Q000502:physiology*; D023421:Models, Animal; D018408:Patch-Clamp Techniques; D010766:Phosphorylation / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology; D051637:Shaker Superfamily of Potassium Channels / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*; D014661:Vasoconstriction / Q000502:physiology; D014664:Vasodilation / Q000502:physiology
chemical_list: D000076122:Disks Large Homolog 4 Protein; C501449:Dlg4 protein, rat; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D051637:Shaker Superfamily of Potassium Channels; D017868:Cyclic AMP-Dependent Protein Kinases
keywords: PDZ domains; cerebral arteries; muscle, smooth, vascular; potassium channels