Patel Niketa A, Yamamoto Mayumi, Illingworth Philip, Mancu Daniel, Mebert Konrad, Chappell David S, Watson James E, Cooper Denise R
Department of Biochemistry, College of Medicine, University of South Florida, Tampa, USA.
Arch Biochem Biophys. 2002 Jul 1;403(1):111-20. doi: 10.1016/S0003-9861(02)00208-4.
High-glucose exposure down-regulates protein kinaseC beta II posttranscriptionally in rat and human vascular smooth muscle cells and contributes to increased cell proliferation. High-glucose-induced mRNA destabilization is specific for PKC beta II mRNA, while PKC beta I and other PKC mRNA are not affected. This study focused on whether glucose metabolism was required. The effect was blocked by cytochalasin B, suggesting a requirement for glucose uptake. Glucosamine did not mimic the effect, indicating that metabolism via hexosamine pathway was not involved. The effect was hexokinase-independent since 3-O-methylglucose, in a dose-dependent manner, mimicked high-glucose effects. Cycloheximide did not block the effect excluding dependency on new protein synthesis. Wortmannin and LY294002, phosphoinositide 3-kinase (PI3-kinase) inhibitors, blocked glucose effects in the presence of 5,6-dichloro-1-beta-d-ribofuranosylbenzimidazole. Glucose and 3-O-methylglucose activated PI3-kinase, and LY294002 blocked glucose effects on Akt phosphorylation. In these cells, high-glucose concentrations activated a metabolically linked signaling pathway independent of glucose metabolism to regulate mRNA processing.
高糖暴露在转录后水平下调大鼠和人血管平滑肌细胞中的蛋白激酶CβII，并导致细胞增殖增加。高糖诱导的mRNA不稳定是PKCβII mRNA特有的，而PKCβI和其他PKC mRNA不受影响。本研究聚焦于是否需要葡萄糖代谢。细胞松弛素B可阻断该效应，提示需要葡萄糖摄取。氨基葡萄糖不能模拟该效应，表明不涉及通过己糖胺途径的代谢。该效应不依赖己糖激酶，因为3 - O -甲基葡萄糖以剂量依赖方式模拟了高糖效应。放线菌酮不能阻断该效应，排除了对新蛋白质合成的依赖性。渥曼青霉素和LY294002，即磷酸肌醇3激酶（PI3激酶）抑制剂，在存在5,6 -二氯 - 1 -β - D -呋喃核糖基苯并咪唑的情况下可阻断葡萄糖效应。葡萄糖和3 - O -甲基葡萄糖激活PI3激酶，且LY294002可阻断葡萄糖对Akt磷酸化的影响。在这些细胞中，高糖浓度激活了一条与代谢相关的信号通路，该通路独立于葡萄糖代谢来调节mRNA加工。
