High D‐glucose reduces human equilibrative nucleoside transporter 1 (hENT1)‐mediated adenosine uptake involving endothelial nitric oxide synthase (eNOS), mitogen‐activated protein (MAP) kinase kinases 1 and 2/MAP kinases p42/44 (MEK/ERKs), and protein kinase C (PKC) activation in human umbilical vein endothelium (HUVEC). Since NO represses SLC29A1 gene (hENT1) promoter activity we studied whether D‐glucose‐reduced hENT1‐adenosine transport results from lower SLC29A1 expression in HUVEC primary cultures. HUVEC incubation (24 h) with high D‐glucose (25 mM) reduced hENT1‐adenosine transport and pGL3‐hENT1−1114 construct SLC29A1 reporter activity compared with normal D‐glucose (5 mM). High D‐glucose also reduced pGL3‐hENT1−1114 reporter activity compared with cells transfected with pGL3‐hENT1−795 construct. NG‐nitro‐L‐arginine methyl ester (L‐NAME, NOS inhibitor), PD‐98059 (MEK1/2 inhibitor), and/or calphostin C (PKC inhibitor) blocked D‐glucose effects. Insulin (1 nM) and phorbol 12‐myristate 13‐acetate (PMA, 100 nM, PKC activator), but not 4α‐phorbol 12,13‐didecanoate (4αPDD, 100 nM, PMA less active analogue) reduced hENT1‐adenosine transport. L‐NAME and PD‐98059 blocked insulin effects. L‐NAME, PD‐98059, and calphostin C increased hENT1 expression without altering protein or mRNA stability. High D‐glucose increased Sp1 transcription factor protein abundance and binding to SLC29A1 promoter, phenomena blocked by L‐NAME, PD‐98059, and calphostin C. Sp1 overexpression reduced SLC29A1 promoter activity in normal D‐glucose, an effect reversed by L‐NAME and further reduced by S‐nitroso‐N‐acetyl‐L,D‐penicillamine (SNAP, NO donor) in high D‐glucose. Thus, reduced hENT1‐mediated adenosine transport in high D‐glucose may result from increased Sp1 binding to SLC29A1 promoter down‐regulating hENT1 expression. This phenomenon depends on eNOS, MEK/ERKs, and PKC activity, suggesting potential roles for these molecules in hyperglycemia‐associated endothelial dysfunction. J. Cell. Physiol. 215: 645–656, 2008. © 2007 Wiley‐Liss, Inc.

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   |wiki=    Sante
   |area=    MersV1
   |flux=    Main
   |étape=   Exploration
   |type=    RBID
   |clé=     ISTEX:7A8E46B18F42530AF3E771E482066C4C2C2CB025
   |texte=   High D‐glucose reduces SLC29A1 promoter activity and adenosine transport involving specific protein 1 in human umbilical vein endothelium
}}