Induction of E-selectin expression by double-stranded RNA and TNF-alpha is attenuated in murine aortic endothelial cells derived from double-stranded RNA-activated kinase (PKR)-null mice.
The adherence of leukocytes on the endothelium is mediated in part by the transient expression of the E-selectin adhesion molecule. Because we have previously shown that the dsRNA-activated kinase PKR mediates dsRNA induction of NF-kappaB, we used murine aortic endothelial (MuAE) cells isolated from wild-type and PKR-null mice to investigate the role of PKR in the induction of E-selectin expression by dsRNA (pIC) and TNF-alpha. E-selectin mRNA and protein expression was inducible by both pIC and TNF-alpha in wild-type MuAE cells, whereas induction of E-selectin expression by these agents was defective in PKR-null MuAE cells. Induction of E-selectin promoter activity and NF-kappaB DNA binding activity were substantially reduced in pIC- or TNF-alpha-treated PKR-null cells, indicating a role for PKR in both pIC and TNF-alpha induction of E-selectin via an NF-kappaB-dependent pathway. In PKR-null cells, pIC-mediated degradation of IkappaBbeta is deficient. Activation of this pathway requires the PKR-dependent degradation of the IkappaBbeta protein. Moreover, both phosphorylated and unphosphorylated activating transcription factor 2 DNA-binding activities were reduced in PKR-null aortic endothelial cells. These results indicate that the PKR is required for full activation of E-selectin expression by pIC and TNF-alpha in primary mouse aortic endothelial cells identifying activating transcription factor 2 as a new target for PKR-dependent regulation and suggest a role for PKR in leukocyte adhesion.
Bandyopadhyay
S K
SK
Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA. Bandyos@ccf.org
de La Motte
C A
CA
Williams
B R
BR
D000818:Animals; D001011:Aorta; D002478:Cells, Cultured; D017362:Cyclic AMP Response Element-Binding Protein / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D019040:E-Selectin / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D004789:Enzyme Activation / Q000276:immunology; D004790:Enzyme Induction / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology; D008156:Luciferases / Q000096:biosynthesis / Q000235:genetics; D046911:Macromolecular Substances; D051379:Mice; D018345:Mice, Knockout; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000276:immunology; D011485:Protein Binding / Q000187:drug effects / Q000276:immunology; D012330:RNA, Double-Stranded / Q000494:pharmacology*; D012333:RNA, Messenger / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D019892:eIF-2 Kinase / Q000172:deficiency* / Q000235:genetics* / Q000502:physiology
D017362:Cyclic AMP Response Element-Binding Protein; D019040:E-Selectin; D046911:Macromolecular Substances; D012330:RNA, Double-Stranded; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D008156:Luciferases; D019892:eIF-2 Kinase