Plasma membrane cholesterol is a key molecule in shear stress-dependent activation of extracellular signal-regulated kinase.
Shear stress, the dragging force generated by fluid flow, differentially activates extracellular signal-regulated kinase (ERK) and c-Jun NH2-terminal kinase (JNK) in bovine aortic endothelial cells (BAEC) (Jo, H., Sipos, K., Go, Y. M., Law, R., Rong, J., and McDonald, J. M. (1997) J. Biol. Chem. 272, 1395-1401). Here, we examine whether cholesterol-enriched compartments in the plasma membrane are responsible for such differential regulation. Pretreatment of BAEC with a cholesterol-binding antibiotic, filipin, did not inhibit shear-dependent activation of JNK. In contrast, filipin and other membrane-permeable cholesterol-binding agents (digitonin and nystatin), but not the lipid-binding agent xylazine, inhibited shear-dependent activation of ERK. The effect of cholesterol-binding drugs did not appear to be due to membrane permeabilization, since treatment of BAEC with a detergent, Triton X-100 which also permeabilizes membranes, did not inhibit shear-dependent activation of ERK. Furthermore, shear-dependent activation of ERK, but not JNK, was inhibited by cyclodextrin, a membrane-impermeable cholesterol-binding agent, which removes cell-surface cholesterol. Moreover, the effects of cyclodextrin were prevented by adding cholesterol during the incubation. These results indicate that cholesterol or cholesterol-sensitive compartments in the plasma membrane play a selective and essential role in activation of ERK, but not JNK, by shear stress. Although exposure to shear stress (1 h) increased the number of caveolae by 3-fold, treatment with filipin had no effect in either control or shear-exposed cells suggesting that caveolae density per se is not a crucial determinant in shear-dependent ERK activation. In summary, the current study suggests that cholesterol-sensitive microdomains in the plasma membrane, such as caveolae-like domains, play a critical role in differential activation of ERK and JNK by shear stress.
Park
H
H
Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
Go
Y M
YM
St John
P L
PL
Maland
M C
MC
Lisanti
M P
MP
Abrahamson
D R
DR
Jo
H
H
D000818:Animals; D001013:Aorta, Thoracic; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002417:Cattle; D002462:Cell Membrane / Q000502:physiology*; D002478:Cells, Cultured; D002784:Cholesterol / Q000502:physiology*; D004072:Digitonin / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000166:cytology / Q000502:physiology*; D004789:Enzyme Activation / Q000187:drug effects; D005372:Filipin / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases; D007700:Kinetics; D008563:Membrane Lipids / Q000502:physiology*; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D009761:Nystatin / Q000494:pharmacology; D013314:Stress, Mechanical; D014991:Xylazine / Q000494:pharmacology
D008563:Membrane Lipids; D009761:Nystatin; D014991:Xylazine; D005372:Filipin; D002784:Cholesterol; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D004072:Digitonin