Human ether-a-go-go-related gene 1 channels are physically linked to beta1 integrins and modulate adhesion-dependent signaling.
Adhesive receptors of the integrin family are primarily involved in cell-extracellular matrix adhesion. Additionally, integrins trigger multiple signaling pathways that are involved in cell migration, proliferation, survival, and differentiation. We previously demonstrated that the activation of integrins containing the beta(1) subunit leads to a selective increase in potassium currents carried by the human ether-a-go-go-related gene (hERG) channels in neuroblastoma and leukemia cells; this current activation modulates adhesion-dependent differentiation in these cells. We hypothesized that the cross-talk between integrins and hERG channels could be traced back to the assembly of a macromolecular signaling complex comprising the two proteins. We tested this hypothesis in both SH-SY5Y neuroblastoma cells and in human embryonic kidney 293 cells stably transfected with hERG1 and, therefore, expressing only the full-length hERG1 protein on the plasma membrane. The beta(1) integrin and hERG1 coprecipitate in these cells and colocalize in both intracellular and surface membrane compartments. The two proteins also coprecipitate with caveolin-1, suggesting the localization of the complex in lipid rafts/caveolae. hERG1-transfected cells undergo an activation of hERG currents after beta(1) integrin-mediated adhesion to fibronectin; concomitant with this activation, the focal adhesion kinase associates with the hERG1 protein and becomes tyrosine phosphorylated. Using hERG1-specific inhibitors, we show that the tyrosine phosphorylation of focal adhesion kinase is strictly dependent on hERG channel activity. Similarly, the activity of the small GTPase Rac1 turned out to be dependent on hERG currents. On the whole, these data indicate that the hERG1 protein associates with beta(1) integrins and modulates adhesion receptor signaling.
Cherubini
Alessia
A
Department of Experimental Pathology and Oncology, University of Firenze, 50134 Firenze, Italy.
Hofmann
Giovanna
G
Pillozzi
Serena
S
Guasti
Leonardo
L
Crociani
Olivia
O
Cilia
Emanuele
E
Di Stefano
Paola
P
Degani
Simona
S
Balzi
Manuela
M
Olivotto
Massimo
M
Wanke
Enzo
E
Becchetti
Andrea
A
Defilippi
Paola
P
Wymore
Randy
R
Arcangeli
Annarosa
A
D002448:Cell Adhesion; D018929:Cell Culture Techniques; D002460:Cell Line; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels / Q000378:metabolism*; D005353:Fibronectins / Q000378:metabolism; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006801:Humans; D039641:Integrin beta Chains / Q000032:analysis / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism; D007668:Kidney / Q000166:cytology / Q000196:embryology; D008954:Models, Biological; D009447:Neuroblastoma / Q000473:pathology; D018408:Patch-Clamp Techniques; D010766:Phosphorylation; D011233:Precipitin Tests; D015398:Signal Transduction; D014162:Transfection; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels; D005353:Fibronectins; D039641:Integrin beta Chains; C000606913:KCNH2 protein, human; D020830:rac1 GTP-Binding Protein