Disruption of cytoskeletal integrity impairs Gi-mediated signaling due to displacement of Gi proteins.
beta1 integrins play a crucial role as cytoskeletal anchorage proteins. In this study, the coupling of the cytoskeleton and intracellular signaling pathways was investigated in beta1 integrin deficient (-/-) embryonic stem cells. Muscarinic inhibition of the L-type Ca2+ current (ICa) and activation of the acetylcholine-activated K+ current (IK,ACh) was found to be absent in beta1 integrin-/- cardiomyocytes. Conversely, beta adrenoceptor-mediated modulation of ICa was unaffected by the absence of beta1 integrins. This defect in muscarinic signaling was due to defective G protein coupling. This was supported by deconvolution microscopy, which demonstrated that Gi exhibited an atypical subcellular distribution in the beta1 integrin-/- cardiomyocytes. A critical role of the cytoskeleton was further demonstrated using cytochalasin D, which displaced Gi and impaired muscarinic signaling. We conclude that cytoskeletal integrity is required for correct localization and function of Gi-associated signaling microdomains.
Bloch
W
W
Institute of Anatomy I, University of Cologne, Germany.
Fan
Y
Y
Han
J
J
Xue
S
S
Schöneberg
T
T
Ji
G
G
Lu
Z J
ZJ
Walther
M
M
Fässler
R
R
Hescheler
J
J
Addicks
K
K
Fleischmann
B K
BK
D000109:Acetylcholine / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology; D020746:Calcium Channels, L-Type / Q000378:metabolism; D002451:Cell Compartmentation; D002478:Cells, Cultured; D015638:Cytochalasin D / Q000494:pharmacology; D003599:Cytoskeleton / Q000378:metabolism*; D022001:Focal Adhesions; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism*; D019012:Integrin beta1 / Q000235:genetics / Q000378:metabolism*; D007545:Isoproterenol / Q000494:pharmacology; D051379:Mice; D018727:Muscarinic Antagonists / Q000494:pharmacology; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D009569:Nitric Oxide / Q000494:pharmacology; D015221:Potassium Channels / Q000378:metabolism; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D011976:Receptors, Muscarinic / Q000378:metabolism*; D015398:Signal Transduction
D000318:Adrenergic beta-Agonists; D020746:Calcium Channels, L-Type; D019012:Integrin beta1; D018727:Muscarinic Antagonists; D015221:Potassium Channels; D011943:Receptors, Adrenergic, beta; D011976:Receptors, Muscarinic; D015638:Cytochalasin D; D009569:Nitric Oxide; D009320:Atrial Natriuretic Factor; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D007545:Isoproterenol; D000109:Acetylcholine