Dynamic association of nitric oxide downstream signaling molecules with endothelial caveolin-1 in rat aorta.
Classically, nitric oxide (NO) formed by endothelial NO synthase (eNOS) freely diffuses from its generation site to smooth muscle cells where it activates soluble guanylyl cyclase (sGC), producing cGMP. Subsequently, cGMP activates both cGMP- and cAMP-dependent protein kinases [cGMP-dependent protein kinase (PKG) and cAMP-dependent protein kinase (PKA), respectively], leading to smooth muscle relaxation. In endothelial cells, eNOS has been localized to caveolae, small invaginations of the plasma membrane rich in cholesterol. Membrane cholesterol depletion impairs acetylcholine (ACh)-induced relaxation due to alteration in caveolar structure. Given the nature of NO to be more soluble in a hydrophobic environment than in water, and assuming that colocalization of components in a signal transduction cascade seems to be a critical determinant of signaling efficiency by eNOS activation, we hypothesize that sGC, PKA, and PKG activation may occur at the plasma membrane caveolae. In endothelium-intact rat aortic rings, the relaxation induced by ACh, by the sGC activator 3-(5'-hydroxymethyl-2'furyl)-1-benzyl indazole (YC-1), and by 8-bromo-cGMP was impaired in the presence of methyl-beta-cyclodextrin, a drug that disassembles caveolae by sequestering cholesterol from the membrane. sGC, PKG, and PKA were colocalized with caveolin-1 in aortic endothelium, and this colocalization was abolished by methyl-beta-cyclodextrin. Methyl-beta-cyclodextrin efficiently disassembled caveolae in endothelium. In summary, our results provide evidence of compartmentalization of sGC, PKG, and PKA in endothelial caveolae contributing to NO signaling cascade, giving new insights by which the endothelium mediates vascular smooth muscle relaxation.
Linder
A Elizabeth
AE
Medical College of Georgia, Department of Physiology (CA-3101), 1120 Fifteenth St., Augusta, GA 30912-3000, USA. elinder@mcg.edu
McCluskey
Lynnette P
LP
Cole
Kenneth R
KR
Lanning
Katherine M
KM
Webb
R Clinton
RC
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D021941:Caveolae / Q000201:enzymology / Q000502:physiology*; D051242:Caveolin 1; D022461:Caveolins / Q000502:physiology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000494:pharmacology; D017869:Cyclic GMP-Dependent Protein Kinases / Q000378:metabolism; D004730:Endothelium, Vascular / Q000201:enzymology / Q000502:physiology*; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D006162:Guanylate Cyclase / Q000378:metabolism; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D007191:Indazoles / Q000494:pharmacology; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D008854:Microscopy, Electron; D009126:Muscle Relaxation / Q000187:drug effects / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000502:physiology; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000502:physiology; D052250:Nitric Oxide Synthase Type III; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000502:physiology*; D014665:Vasodilator Agents / Q000494:pharmacology; D047392:beta-Cyclodextrins / Q000494:pharmacology
C495537:Cav1 protein, rat; D051242:Caveolin 1; D022461:Caveolins; D007191:Indazoles; D014665:Vasodilator Agents; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; C090937:3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole; C016276:8-bromocyclic GMP; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D017868:Cyclic AMP-Dependent Protein Kinases; D017869:Cyclic GMP-Dependent Protein Kinases; D006162:Guanylate Cyclase; D006152:Cyclic GMP; D000109:Acetylcholine