title: Postsynaptic density-95 scaffolding of Shaker-type K⁺ channels in smooth muscle cells regulates the diameter of cerebral arteries.
abstract: Postsynaptic density-95 (PSD95) is a 95 kDa scaffolding molecule in the brain that clusters postsynaptic proteins including ion channels, receptors, enzymes and other signalling partners required for normal cognition. The voltage-gated, Shaker-type K(+) (K(V)1) channel is one key binding partner of PSD95 scaffolds in neurons. However, K(V)1 channels composed of α1.2 and α1.5 pore-forming subunits also are expressed in the vascular smooth muscle cells (cVSMCs) of the cerebral circulation, although the identity of their molecular scaffolds is unknown. Since α1.2 contains a binding motif for PSD95, we explored the possibility that cVSMCs express PSD95 as a scaffold to promote K(V)1 channel expression and cerebral vasodilatation. Cerebral arteries from Sprague-Dawley rats were isolated for analysis of PSD95 and K(V)1 channel proteins. PSD95 was detected in cVSMCs and it co-immunoprecipitated and co-localized with the pore-forming α1.2 subunit of the K(V)1 channel. Antisense-mediated knockdown of PSD95 profoundly reduced K(V)1 channel expression and suppressed K(V)1 current in patch-clamped cVSMCs. Loss of PSD95 also depolarized cVSMCs in pressurized cerebral arteries and induced a strong constriction associated with a loss of functional K(V)1 channels. Our findings provide initial evidence that PSD95 is expressed in cVSMCs, and the K(V)1 channel is one of its important binding partners. PSD95 appears to function as a critical 'dilator' scaffold in cerebral arteries by increasing the number of functional K(V)1 channels at the plasma membrane.
authors.affiliation: Department of Pharmacology and Toxicology, College of Medicine, The University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
authors.forename: Biny K
authors.initials: BK
authors.lastname: Joseph
authors.forename: Keshari M
authors.initials: KM
authors.lastname: Thakali
authors.forename: Asif R
authors.initials: AR
authors.lastname: Pathan
authors.forename: Eunju
authors.initials: E
authors.lastname: Kang
authors.forename: Nancy J
authors.initials: NJ
authors.lastname: Rusch
authors.forename: Sung W
authors.initials: SW
authors.lastname: Rhee
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002536:Cerebral Arteries / Q000502:physiology*; D000076122:Disks Large Homolog 4 Protein; D011564:Furocoumarins / Q000494:pharmacology; D055785:Gene Knockdown Techniques; D047908:Intracellular Signaling Peptides and Proteins / Q000502:physiology*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D008565:Membrane Proteins / Q000502:physiology*; D032389:Myocytes, Smooth Muscle / Q000502:physiology*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D057907:Post-Synaptic Density / Q000502:physiology*; D026902:Potassium Channel Blockers / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D060888:Real-Time Polymerase Chain Reaction; D051637:Shaker Superfamily of Potassium Channels / Q000037:antagonists & inhibitors / Q000502:physiology*; D013111:Spider Venoms / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects
chemical_list: D000076122:Disks Large Homolog 4 Protein; C501449:Dlg4 protein, rat; D011564:Furocoumarins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D016376:Oligonucleotides, Antisense; D026902:Potassium Channel Blockers; D051637:Shaker Superfamily of Potassium Channels; D013111:Spider Venoms