Fluid flow activates a regulator of translation, p70/p85 S6 kinase, in human endothelial cells.
Cellular phenotype is determined not only by genetic transcription but also by subsequent translation of mRNA into protein. Extracellular signals trigger intracellular pathways that distinctly activate translation. The 70/85-kDa S6 kinase (pp70(S6k)) is a central enzyme in the signal-dependent control of translation, but its regulation in endothelial cells is largely unknown. Here we show that fluid flow (in the absence of an exogenous mitogen) as well as humoral agonists activate endothelial pp70(S6k). Rapamycin, an inhibitor of the mammalian target of rapamycin (mTOR), and wortmannin, a phosphatidylinositol 3-kinase inhibitor, blocked flow-induced pp70(S6k) activation; FK-506, a rapamycin analog with minimal mTOR inhibitory activity, and PD-98059, an inhibitor of the flow-sensitive mitogen-activated protein kinase pathway, had no effect. Synthesis of Bcl-3, a protein whose translation is controlled by an mTOR-dependent pathway, was induced by flow and inhibited by rapamycin and wortmannin. Transcriptional blockade did not abolish the flow-induced upregulation of Bcl-3. Fluid forces may therefore modify endothelial phenotype by specifically regulating translation of certain mRNA transcripts into protein.
Kraiss
L W
LW
Division of Vascular Surgery, Department of Surgery, Eccles Institute of Human Genetics, University of Utah, Salt Lake City, Utah 84112, USA. larry.kraiss@hmbg.utah.edu
Weyrich
A S
AS
Alto
N M
NM
Dixon
D A
DA
Ennis
T M
TM
Modur
V
V
McIntyre
T M
TM
Prescott
S M
SM
Zimmerman
G A
GA
D016475:3T3 Cells; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D000081242:B-Cell Lymphoma 3 Protein; D001783:Blood Flow Velocity / Q000502:physiology*; D015153:Blotting, Western; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D004789:Enzyme Activation / Q000187:drug effects / Q000235:genetics; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology; D051379:Mice; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors; D020033:Protein Isoforms / Q000378:metabolism; D011494:Protein Kinases; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis; D019893:Ribosomal Protein S6 Kinases / Q000235:genetics / Q000378:metabolism*; D020123:Sirolimus / Q000494:pharmacology; D013314:Stress, Mechanical; D058570:TOR Serine-Threonine Kinases; D016559:Tacrolimus / Q000494:pharmacology; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic / Q000502:physiology; D014783:Viscosity; D000077191:Wortmannin
D000730:Androstadienes; D000081242:B-Cell Lymphoma 3 Protein; C000631344:BCL3 protein, human; C000631345:Bcl3 protein, mouse; D007166:Immunosuppressive Agents; D000081082:Phosphoinositide-3 Kinase Inhibitors; D020033:Protein Isoforms; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D011494:Protein Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); C546842:MTOR protein, human; C546843:mTOR protein, mouse; D019893:Ribosomal Protein S6 Kinases; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus; D016559:Tacrolimus; D000077191:Wortmannin