Oxysterol and Diabetes Activate STAT3 and Control Endothelial Expression of Profilin-1 via OSBP1

Endothelial dysfunction plays a central role in diabetic vascular disease, but its molecular bases are not completely defined. We showed previously that the actin-binding protein proflin-1 was increased in the diabetic endothelium and that attenuated expression of profilin-1 protected against atherosclerosis. Also 7-ketocholesterol up-regulated profilin-1 in endothelial cells via transcriptional mechanisms. The present study addressed the pathways responsible for profilin-1 gene expression in 7-ketocholesterol-stimulated endothelial cells and in the diabetic aorta. In luciferase reporter assays, the response to 7-ketocholesterol within the 5′-flanking region of profilin-1 was dependent on a single STAT response element. In aortic endothelial cells, 7-ketocholesterol enhanced STAT3 activation, which required JAK2 and tyrosine 394 phosphorylation of oxysterol-binding protein-1. These changes were recapitulated in the aorta of diabetic rats. Also 7-ketocholesterol in cultured endothelial cells and diabetes in the aorta elicited the recruitment of STAT3 and relevant coregulatory factors to the oxysterol-responsive region of the profilin-1 promoter. These events were required for profilin-1 up-regulation. These studies identify a previously unrecognized oxysterol-binding protein-mediated mode of activation of STAT3 that controls the expression of the proatherogenic protein profilin-1 in response to 7-ketocholesterol and the diabetic milieu. Endothelial dysfunction plays a central role in diabetic vascular disease, but its molecular bases are not completely defined. We showed previously that the actin-binding protein proflin-1 was increased in the diabetic endothelium and that attenuated expression of profilin-1 protected against atherosclerosis. Also 7-ketocholesterol up-regulated profilin-1 in endothelial cells via transcriptional mechanisms. The present study addressed the pathways responsible for profilin-1 gene expression in 7-ketocholesterol-stimulated endothelial cells and in the diabetic aorta. In luciferase reporter assays, the response to 7-ketocholesterol within the 5′-flanking region of profilin-1 was dependent on a single STAT response element. In aortic endothelial cells, 7-ketocholesterol enhanced STAT3 activation, which required JAK2 and tyrosine 394 phosphorylation of oxysterol-binding protein-1. These changes were recapitulated in the aorta of diabetic rats. Also 7-ketocholesterol in cultured endothelial cells and diabetes in the aorta elicited the recruitment of STAT3 and relevant coregulatory factors to the oxysterol-responsive region of the profilin-1 promoter. These events were required for profilin-1 up-regulation. These studies identify a previously unrecognized oxysterol-binding protein-mediated mode of activation of STAT3 that controls the expression of the proatherogenic protein profilin-1 in response to 7-ketocholesterol and the diabetic milieu. Dysfunction of the vascular endothelium precedes, and may contribute to, atheroma formation in response to a plethora of cardiovascular noxae, including diabetes (1Johnstone M.T. Creager S.J. Scales K.M. Cusco J.A. Lee B.K. Creager M.A. Circulation. 1993; 88: 2510-2516Crossref PubMed Scopus (1009) Google Scholar, 2Tesfamariam B. Brown M.L. Deykin D. Cohen R.A. J. Clin. Investig. 1990; 85: 929-932Crossref PubMed Scopus (321) Google Scholar), hyperlipidemia (3Chikani G. Zhu W. Smart E.J. Am. J. Physiol. 2004; 287: E386-E389Crossref PubMed Scopus (26) Google Scholar, 4Steinberg H.O. Bayazeed B. Hook G. Johnson A. Cronin J. Baron A.D. Circulation. 1997; 96: 3287-3293Crossref PubMed Scopus (165) Google Scholar), and systemic as well as local inflammatory mediators (5Libby P. Nature. 2002; 420: 868-874Crossref PubMed Scopus (7017) Google Scholar). Although several markers of endothelial dysfunction have already garnered interest in the clinical arena (6Ridker P.M. Hennekens C.H. Roitman-Johnson B. Stampfer M.J. Allen J. Lancet. 1998; 351: 88-92Abstract Full Text Full Text PDF PubMed Scopus (1123) Google Scholar, 7Schächinger V. Britten M.B. Zeiher A.M. Circulation. 2000; 101: 1899-1906Crossref PubMed Scopus (2361) Google Scholar), the molecular bases of endothelial injury are still not fully understood. A growing body of evidence indicates that cytoskeletal dynamics regulate essential antiadhesive, anti-inflammatory, and antiatherogenic properties in endothelial cells (EC) 2The abbreviations used are:ECendothelial cellsRAECrat aortic endothelial cellsPfnprofilin-1JAK2Janus-activated kinase-2STATsignal transducers and activators of transcriptionOSBPoxysterol-binding proteinPHpleckstrin homologyChIPchromatin immunoprecipitationshshort hairpinSH2Src homology 2STZstreptozotocinD.U.densitometric unit(s)GAPGTPase-activating proteinIL-6interleukin-6IL-6Rinterleukin-6 receptorWTwild-typeHDAChistone deacetylaseDM5-month STZ diabeticCBPcAMP-responsive element-binding protein (CREB)-binding proteinSRC1steroid receptor coactivator 1H3histone 3AcH3acetylated H3BRG1Brahma-related gene 1. (8Fledderus J.O. van Thienen J.V. Boon R.A. Dekker R.J. Rohlena J. Volger O.L. Bijnens A.P. Daemen M.J. Kuiper J. van Berkel T.J. Pannekoek H. Horrevoets A.J. Blood. 2007; 109: 4249-4257Crossref PubMed Scopus (122) Google Scholar, 9Ingber D.E. Circ. Res. 2003; 91: 877-887Crossref Scopus (534) Google Scholar). endothelial cells rat aortic endothelial cells profilin-1 Janus-activated kinase-2 signal transducers and activators of transcription oxysterol-binding protein pleckstrin homology chromatin immunoprecipitation short hairpin Src homology 2 streptozotocin densitometric unit(s) GTPase-activating protein interleukin-6 interleukin-6 receptor wild-type histone deacetylase 5-month STZ diabetic cAMP-responsive element-binding protein (CREB)-binding protein steroid receptor coactivator 1 histone 3 acetylated H3 Brahma-related gene 1. Our laboratory demonstrated that the actin-binding protein profilin-1 (Pfn) plays a role in endothelial dysfunction and atherosclerosis. Pfn is a well characterized regulator of cytoskeletal architecture because of its multifaceted function in actin filament assembly (10Kang F. Purich D.L. Southwick F.S. J. Biol. Chem. 1999; 274: 36963-36972Abstract Full Text Full Text PDF PubMed Scopus (145) Google Scholar) and depolymerization (11Didry D. Carlier M.F. Pantaloni D. J. Biol. Chem. 1998; 273: 25602-25611Abstract Full Text Full Text PDF PubMed Scopus (164) Google Scholar). Of note, little is known regarding the transcriptional regulation of Pfn in mammalian cells either constitutively or in response to factors promoting vascular disease. We showed previously that Pfn protein levels were increased in the diabetic endothelium and within atherosclerotic plaques (12Romeo G. Frangioni J.V. Kazlauskas A. FASEB J. 2004; 18: 725-727Crossref PubMed Scopus (32) Google Scholar). Also attenuation of Pfn levels protected against atherosclerosis and endothelial dysfunction upon high fat feeding (13Romeo G.R. Moulton K.S. Kazlauskas A. Circ. Res. 2007; 101: 357-367Crossref PubMed Scopus (51) Google Scholar). Finally 7-ketocholesterol (oxysterol), but not high glucose concentrations, elevated Pfn expression in EC in part via transcriptional mechanisms (12Romeo G. Frangioni J.V. Kazlauskas A. FASEB J. 2004; 18: 725-727Crossref PubMed Scopus (32) Google Scholar). Collectively these studies suggest that Pfn levels are regulated by oxidized lipids and contribute to vascular injury associated to diabetes and a high fat diet. Oxysterols are naturally occurring oxygenated products of cholesterol that play a major role in cholesterol homeostasis (14Massey J.B. Curr. Opin. Lipidol. 2006; 17: 296-301Crossref PubMed Scopus (71) Google Scholar) and are enriched in foam cells and atherosclerotic plaques (15Brown A.J. Leong S.L. Dean R.T. Jessup W. J. Lipid Res. 1997; 38: 1730-1745Abstract Full Text PDF PubMed Google Scholar). In addition to interacting and regulating the activity of members of the liver X receptor family of transcription factors (for a review, see Ref. 16Zelcer N. Tontonoz P. J. Clin. Investig. 2006; 116: 607-614Crossref PubMed Scopus (775) Google Scholar), oxysterols bind with varying affinity to the cytosolic protein oxysterol-binding protein-1 (OSBP1), which was first identified by Taylor et al. (17Taylor F.R. Saucier S.E. Shown E.P. Parish E.J. Kandutsch A.A. J. Biol. Chem. 1984; 259: 12382-12387Abstract Full Text PDF PubMed Google Scholar), and a growing list of OSBP1-related proteins (18Olkkonen V.M. Levine T.P. Biochem. Cell Biol. 2004; 82: 87-98Crossref PubMed Scopus (101) Google Scholar). Oxysterol binding to the sterol-binding domain of OSBP1 elicits its translocation and tethering to the Golgi, which is mediated by the PH domain located in the N-terminal region of the protein (19Ridgway N.D. Dawson P.A. Ho Y.K. Brown M.S. Goldstein J.L. J. Cell Biol. 1992; 116: 307-319Crossref PubMed Scopus (241) Google Scholar). Recently OSBP1 was identified as an essential component of a multiprotein complex that regulates p44/42 mitogen-activated protein kinase activity in response to cholesterol and oxysterol (20Wang P.Y. Weng J. Anderson R.G. Science. 2005; 307: 1472-1476Crossref PubMed Scopus (247) Google Scholar), thus defining an unexpected role for OSBP1 as a scaffolding for the assembly of signaling modules. Based on our previous findings, we reasoned that elucidating the mechanisms for oxysterol- and diabetes-dependent up-regulation of Pfn would shed new light on the pathophysiology of vascular injury associated with the metabolic syndrome. Here we show that OSBP1 is required for oxysterol-dependent nucleation and activation of the JAK2/STAT3 pathway, which in turn regulates Pfn gene expression in EC. Similarly diabetes increases the activation of STAT3 and its recruitment to the Pfn promoter in large vessels in vivo. Reagents—7-Ketocholesterol (hereafter, oxysterol) and 25-hydroxycholesterol (Steraloids, Inc.) were the oxidized cholesterol derivatives used for cell stimulation. Other reagents were purchased from Sigma-Aldrich unless otherwise specified. Cells—Rat aortic endothelial cells (RAEC) were isolated and cultured as described previously (12Romeo G. Frangioni J.V. Kazlauskas A. FASEB J. 2004; 18: 725-727Crossref PubMed Scopus (32) Google Scholar). Stimulation with oxysterols was performed at a final concentration of 10 μg/ml (∼25 μm) in ethanol. Cell viability (trypan blue exclusion test) and apoptosis, assessed by photometric detection of mono- and oligonucleosomes (Cell Death Detection ELISAPLUS, Roche were in and cells the short of our Stimulation with rat and rat was performed in with and and of diabetes by streptozotocin of body in and for and aorta were described previously (12Romeo G. Frangioni J.V. Kazlauskas A. FASEB J. 2004; 18: 725-727Crossref PubMed Scopus (32) Google Scholar). was to the of in diabetic in the aorta was either used for of protein from the endothelium (12Romeo G. Frangioni J.V. Kazlauskas A. FASEB J. 2004; 18: 725-727Crossref PubMed Scopus (32) Google Scholar) or for chromatin immunoprecipitation in and cells were performed as described in the with several was with to a final concentration for or 10 for enhanced the of the STAT3 and steroid receptor coactivator 1 immunoprecipitation addition of for at and in cells were in and were to the at for the was in 1 of 2 and for 10 at and to with a B. for the was and the was in of 10 and was performed on of by a of in a to of at for in a the was with and and used for A was to the were for 3 at the and either or with The and for immunoprecipitation to the as in 1. the complex was from the by with of and was at a final concentration of μg/ml for 1 at by at for to Finally proteins were for 2 at with μg/ml in and 10 by the promoter were by the to and to a The in the aorta was several of the in and diabetic were first with and with The aorta was and from were for and to with a B. were in by of by a of in a from were for and used in in a new was with and 1 and and cells were in with 2 μg/ml 10 1 and 1 and a short in A and was performed in A for on by with a B. were by at for the was used as The was in of and and of high and were of with a were for 1 at at for the was used as the were in a final and cell were in and for immunoprecipitation or as described previously (12Romeo G. Frangioni J.V. Kazlauskas A. FASEB J. 2004; 18: 725-727Crossref PubMed Scopus (32) Google Scholar). from the aortic endothelium of and diabetic were as previously (12Romeo G. Frangioni J.V. Kazlauskas A. FASEB J. 2004; 18: 725-727Crossref PubMed Scopus (32) Google Scholar). for OSBP1 in rat aorta was performed 1 of from the endothelium of and aorta (12Romeo G. Frangioni J.V. Kazlauskas A. FASEB J. 2004; 18: 725-727Crossref PubMed Scopus (32) Google Scholar). immunoprecipitation were performed of or aorta was performed with the and or A list of used for and the molecular of the is in were for used as a (12Romeo G. Frangioni J.V. Kazlauskas A. FASEB J. 2004; 18: 725-727Crossref PubMed Scopus (32) Google Scholar, G.R. Moulton K.S. Kazlauskas A. Circ. Res. 2007; 101: 357-367Crossref PubMed Scopus (51) Google used for molecular laboratory in a new and expression of OSBP1 and a the was with from and by of and of the The for was the The for was to of of to is were by of and cells A. PubMed Scopus Google Scholar), the was for at and used to as described previously (12Romeo G. Frangioni J.V. Kazlauskas A. FASEB J. 2004; 18: 725-727Crossref PubMed Scopus (32) Google Scholar). with expression of OSBP1 was levels were with to STAT3 were with the rat STAT3 expression or the a of and hairpin of OSBP1 was the described previously by et al. (20Wang P.Y. Weng J. Anderson R.G. Science. 2005; 307: 1472-1476Crossref PubMed Scopus (247) Google Scholar) that were and the of to the were with as for the or and with was used to of the of the rat gene of the transcription the from was used as a for were to the of the promoter region The of a and the of the a to for the of The at was from to in the of the the were by was in cultured in a of and was as a for and cells were to for with oxysterol as described previously (12Romeo G. Frangioni J.V. Kazlauskas A. FASEB J. 2004; 18: 725-727Crossref PubMed Scopus (32) Google Scholar), cell were for luciferase activity a and for activity in a at activity was against activity and as light for of Pfn region to to to to to to in a new are as the were performed for were performed of by A of was Oxysterol via 7-ketocholesterol increases Pfn levels at in part by transcriptional mechanisms (12Romeo G. Frangioni J.V. Kazlauskas A. FASEB J. 2004; 18: 725-727Crossref PubMed Scopus (32) Google Scholar), its on promoter activity of of the 5′-flanking region of the rat gene were assessed a luciferase reporter promoter were in with as an for the reporter activity of of to the transcription was not by oxysterol promoter activity of the from to was increased in with cells for of transcription response within a single P. J. A. PubMed Scopus Google Scholar), at of response of the to activity of was elevated by with a rat STAT3 expression which in a in STAT3 protein levels by a in STAT3 activation not The of STAT3 were in thus that STAT3 levels was not to promoter expression of STAT3 not promoter activity of the Although 7-ketocholesterol was the of oxidized cholesterol used for these to 25-hydroxycholesterol in a of promoter activity with from with 7-ketocholesterol not Finally with for the liver X receptor family of transcription N. Tontonoz P. J. Clin. Investig. 2006; 116: 607-614Crossref PubMed Scopus (775) Google Scholar) and J.L. A.M. M.A. E.J. J. Chem. 2002; PubMed Scopus Google Scholar) used at final not luciferase activity of not in with of liver X receptor response R.A. PubMed Scopus Google Scholar). these studies that oxysterol regulated promoter within the of the 5′-flanking via a single located at Although transcription factors may play a role in transcriptional we the mechanisms for STAT activation and its function in Pfn regulation in response to oxysterol and to diabetes in vivo. and Oxysterol STAT3 in are transcription that in the in a and by phosphorylation in response to a plethora of Science. 1997; Scopus Google Scholar), thus as and B. 2003; PubMed Scopus Google Scholar) that may play a role in endothelial and translocation of members of the STAT family were assessed upon oxysterol and in were to oxysterol for with or the STAT3 phosphorylation at of activation, was increased at and to the by at at of JAK2 STAT3 the activation of STAT3 STAT3 or JAK2 an essential role for JAK2 in STAT3 with 25-hydroxycholesterol in a of STAT3 activation not tyrosine STAT the of Src homology 2 domain with domain to either thus to STAT translocation to the and regulation of D.E. Cell Biol. 2002; PubMed Scopus Google Scholar). from to oxysterol showed a in STAT3 activation upon oxysterol oxysterol not either or phosphorylation in with previous evidence in M.L. G.R. Biol. 2002; PubMed Scopus Google Scholar) The activation of STAT3 by oxysterol in to recapitulated in which is associated with enhanced N. F. A. 2004; PubMed Scopus Google Scholar, J. Clin. Investig. PubMed Scopus Google Scholar). STAT3 was increased in the aortic endothelium of 5-month streptozotocin diabetic with densitometric The in STAT3 activation was a of diabetes but not not Collectively these studies demonstrated that oxidized cholesterol and the JAK2/STAT3 in aortic EC and that in the diabetic and Oxysterol of OSBP1 and with the of domain with of receptor and as in signaling pathways Curr. Opin. Cell Biol. PubMed Scopus Google Scholar). We oxysterol activators of the JAK2/STAT3 pathway, interleukin-6 receptor N. T.J. Science. PubMed Scopus Google Scholar) and receptor F. A.M. van B. Blood. PubMed Google Scholar). Oxysterol not tyrosine phosphorylation of the which is the of STAT3 phosphorylation Similarly receptor was not by oxysterol not In tyrosine phosphorylation of OSBP1 was in response to oxysterol with a to that of STAT3 activation we the of OSBP1 and the kinase responsible for STAT3 studies showed that oxysterol OSBP1 with JAK2 changes were in the of with an of endothelial with the aorta of 5-month diabetic showed a in phosphorylation of the of OSBP1 OSBP1 by enhanced of OSBP1 with JAK2 Of note, OSBP1 levels were in the not Based on these findings, we that oxysterol and diabetes STAT3 activation a and that OSBP1 play a role in of evidence OSBP1 as a for STAT3 OSBP1 a single which is the STAT3 H. M.A. N. R.G. J. Biol. Chem. 2004; Full Text Full Text PDF PubMed Scopus Google Scholar). (20Wang P.Y. Weng J. Anderson R.G. Science. 2005; 307: 1472-1476Crossref PubMed Scopus (247) Google Scholar), OSBP1 regulate the assembly of signaling in response to in diabetes and oxysterol in OSBP1 tyrosine phosphorylation and its with OSBP1 an of STAT3 the of in the of the within was assessed in wild-type OSBP1 or its oxysterol STAT3 activation was enhanced in cells and in cells with cells the of p44/42 phosphorylation was in cells, that not regulation of p44/42 (20Wang P.Y. Weng J. Anderson R.G. Science. 2005; 307: 1472-1476Crossref PubMed Scopus (247) Google Scholar). Also cells oxysterol-dependent translocation of OSBP1 to the and activation of STAT3 to that in cells, thus of In OSBP1 phosphorylation in response to oxysterol Collectively these that OSBP1 phosphorylation at was required for STAT3 activation and that of OSBP1 as a of the for Pfn in to of OSBP1 on STAT3 activation were in of OSBP1 at of the oxysterol cells showed of with cells These with the luciferase reporter studies in that OSBP1 would Pfn up-regulation in response to previously (12Romeo G. Frangioni J.V. Kazlauskas A. FASEB J. 2004; 18: 725-727Crossref PubMed Scopus (32) Google Scholar), oxysterol increased Pfn levels at in Pfn was in cells In with the role of OSBP1 in p44/42 activation (20Wang P.Y. Weng J. Anderson R.G. Science. 2005; 307: 1472-1476Crossref PubMed Scopus (247) Google Scholar), cells showed a in p44/42 phosphorylation and with an of the mitogen-activated protein kinase of not STAT3 activation or Pfn up-regulation in response to oxysterol not These studies that oxysterol an but that up-regulation of the proatherogenic protein STAT3 to the in a in the STAT at was required for oxysterol-dependent gene expression in luciferase reporter activation is by the of with histone histone and a growing family of factors Nature. 2000; PubMed Scopus Google Scholar). we STAT3 with relevant and on the promoter upon oxysterol and in 5-month STZ diabetic rats. immunoprecipitation studies addressed the of STAT3 with protein and histone proteins that have to bind STAT3 D.E. J. Biol. Chem. 1999; 274: Full Text Full Text PDF PubMed Scopus Google Scholar, F. H. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar). oxysterol the increased of STAT3 with and STAT3 with that with in with function as an for to the transcriptional Biol. PubMed Scopus Google Scholar). Oxysterol not and levels we the of oxysterol on gene activation and recruitment of coregulatory proteins on the promoter Oxysterol in histone 3 an associated with gene activation, of the 5′-flanking region of that the STAT response with to acetylated H3 at or showed is in with the oxysterol-dependent expression of the region in luciferase reporter studies oxysterol in STAT3 recruitment to the an that was by with The of STAT3 binding to showed with the of STAT3 phosphorylation and translocation In addition to oxysterol to recruitment of relevant histone and factors on the region The of with the region was and that of STAT3 and an to to chromatin not Also for and and and showed that was on the chromatin at thus the in STAT3 and recruitment at Finally oxysterol in a binding of the Brahma-related gene 1 which is a of the complex A. J. Cell 2004; PubMed Scopus Google Scholar). In oxysterol H3 at the gene chromatin in with the recruitment of STAT3 and H3 and chromatin at Pfn promoter. in to 7-ketocholesterol 10 or final with was performed by of the associated for a of the Pfn promoter the single STAT3 response at for cells were with oxysterol for and with A of the was upon oxysterol in the but not in the or indicates the of Pfn chromatin the molecular in with the μm) or by to oxysterol for the The cells to final with was performed a of by of the associated as in A. for and cells were to oxysterol for and with STAT3 recruitment on the Pfn chromatin was at and and was by indicates the of Pfn chromatin chromatin the of by for coactivator and factors in to oxysterol for the The cells to final with for and was protein showed a of to the Pfn chromatin with the recruitment of indicates the of Pfn chromatin and STAT3 on the in oxysterol in and diabetes in Pfn levels in aortic EC (12Romeo G. Frangioni J.V. Kazlauskas A. FASEB J. 2004; 18: 725-727Crossref PubMed Scopus (32) Google Scholar) in addition to STAT3 activation changes at the chromatin to that diabetes these events in the aorta in vivo. we a in the rat aorta a of at the chromatin was increased in the aorta of STZ diabetic with controls diabetes the recruitment of STAT3 on the promoter These studies that a gene for is in diabetic vessels and a the by oxysterol and the diabetic in EC. The present addressed the mechanisms that Pfn expression in EC upon with oxysterol or in diabetes in vivo. The for these from our that Pfn levels play a role in atheroma formation and vascular (13Romeo G.R. Moulton K.S. Kazlauskas A. Circ. Res. 2007; 101: 357-367Crossref PubMed Scopus (51) Google Scholar). Here we present several that pathways by oxysterol and the diabetic in EC. activation of STAT3 and its recruitment to the promoter were recapitulated in the diabetic aorta Although Pfn expression may a to the atherosclerosis in diabetic that mechanisms and of STAT3 activation in the diabetic may the by et al. P. B. M.B. Am. J. Physiol. 2007; PubMed Scopus Google Scholar), STAT3 activation in the diabetic aorta an Our studies as a of JAK2/STAT3 activation in response to STAT3 may at the and several pathways of diabetic vascular activation of STAT3 may play a role in or the that diabetes S.E. Lee J. J. Clin. Investig. 2006; 116: PubMed Scopus Google Scholar) and atherosclerosis A. R.J. G. Circulation. 2000; PubMed Scopus Google Scholar) by regulating a of gene of the in the aorta demonstrated the of the regulation of in the of diabetic vascular and to the of our the first of to the in vivo. In light of the role of STAT3 in diabetic the of its upon a we that not STAT3 recruitment to promoter a STAT3 and A. may from the of coregulatory proteins that are by oxysterol and In oxysterol regulated a of recruitment of coregulatory proteins on the promoter that not by stimulation. and A. of of these studies from the that OSBP1 is an essential of oxysterol-dependent STAT3 Although characterized as a cholesterol OSBP1 members of the OSBP1-related protein cholesterol signaling its scaffolding function as for p44/42 activation (20Wang P.Y. Weng J. Anderson R.G. Science. 2005; 307: 1472-1476Crossref PubMed Scopus (247) Google Scholar). Based on we that OSBP1 the assembly of a JAK2/STAT3 upon oxysterol We that phosphorylation of in the of the STAT3 was required for STAT3 is located within the sterol-binding domain of OSBP1 and is to oxysterol binding to OSBP1 a to JAK2 to OSBP1 as by enhanced in the diabetic aortic endothelium and in cultured EC to oxysterol Also that OSBP1 controls activation of STAT3 and p44/42 via mechanisms as of STAT3 activation was not associated with changes in p44/42 phosphorylation and not STAT3 activation not an mode of activation of STAT3 plays a role in Pfn up-regulation in EC may in the diabetic which increased Pfn These the role of OSBP1 as a signaling for pathways regulating cholesterol cell and Collectively these studies the to the of the in of diabetic vascular at phosphorylation would of the of to the of diabetic endothelial dysfunction STAT3 properties in response to J. J. J. Clin. Investig. PubMed Google Scholar). Although our on Pfn as a STAT3 these is that STAT3 activation in the diabetic aorta regulate a of gene expression relevant to diabetic vascular We for the and and and G. W. Anderson for the of with

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