Stat6 activation is essential for interleukin-4 induction of P-selectin transcription in human umbilical vein endothelial cells.
Chronic upregulation of P-selectin expression on the surface of the endothelium has been observed in and likely contributes to a number of chronic inflammatory diseases, including atherosclerosis. Agonists of P-selectin expression fall into 2 categories: those that induce a very rapid, transient increase, lasting only hours, and those that induce prolonged upregulation lasting days. It is the latter group, which includes interleukin-4 (IL-4), that is likely to be a mediator of chronic P-selectin upregulation. The increase in P-selectin expression induced by IL-4 results from increased transcriptional activation of the P-selectin gene. The aim of this study was to deduce the postreceptor signaling pathway(s) giving rise to the prolonged increase in P-selectin expression induced by IL-4. We demonstrate the existence of 2 functional signal transducer and activator of transcription 6 (Stat6) binding sites on the P-selectin promoter and further demonstrate, by functional analysis of the P-selectin promoter, that binding of activated Stat6 to at least 1 site is essential for IL-4-induction of P-selectin transcription. Site 1 (nucleotide[nt] -142) bound Stat6 with a higher affinity than did site 2 (nt -229), and this difference was reflected functionally as constructs in which only site 1 was functional showed full IL-4 inducibility, whereas constructs in which only site 2 was functional showed only 40% of maximal IL-4 inducibility. IL-4 also induced prolonged activation of Stat6, which was contingent on the continuous presence of IL-4. The sustained activation of Stat6 induced by IL-4 is likely to be a key factor leading to the prolonged activation of the P-selectin promoter, thereby resulting in prolonged P-selectin upregulation.
Khew-Goodall
Y
Y
Hanson Centre for Cancer Research, Division of Human Immunology, Institute of Medical and Veterinary Science, Adelaide, Australia. yeesim.khew-goodall@imvs.sa.gov.au
Wadham
C
C
Stein
B N
BN
Gamble
J R
JR
Vadas
M A
MA
D001483:Base Sequence; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000502:physiology; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000378:metabolism*; D006801:Humans; D007377:Interleukin-3 / Q000494:pharmacology; D015847:Interleukin-4 / Q000494:pharmacology*; D008969:Molecular Sequence Data; D053683:Oncostatin M; D019007:P-Selectin / Q000235:genetics*; D010455:Peptides / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D050800:STAT6 Transcription Factor; D015534:Trans-Activators / Q000502:physiology*; D014158:Transcription, Genetic / Q000187:drug effects*; D019010:Vascular Cell Adhesion Molecule-1 / Q000235:genetics
D007377:Interleukin-3; C508351:OSM protein, human; D019007:P-Selectin; D010455:Peptides; D050800:STAT6 Transcription Factor; C494101:STAT6 protein, human; D015534:Trans-Activators; D019010:Vascular Cell Adhesion Molecule-1; D053683:Oncostatin M; D015847:Interleukin-4; D017871:Calcium-Calmodulin-Dependent Protein Kinases