Abstract
Purpose: :
Diacylglycerol (DG) activates protein kinase C (PKC), which plays important roles in the pathogenesis of diabetic retinopathy. In the previous report (Sato S et al: ARVO meeting in 2005), we reported that diacylglycerol kinase α (DGKα) expression is induced by high glucose stimulation and may be related to the production of vascular endothelial growth factor (VEGF). The aim of this study is to investigate the molecular mechanisms by which high glucose stimulation induces DGKα gene expression to develop the new therapeutic agent for diabetic retinopathy.
Methods: :
We used 2 retinoblastoma cell lines (WERI–Rb–1 & Y–79: RB cells) as retina–derived cells. The expression of DGKα and VEGF was observed after the high glucose stimulation (22.0mM of glucose = HG), and compared with the normal glucose condition (5.5mMNG). The expression of DGKα and VEGF was investigated by RT–PCR under HG or NG. To investigate whether HG induces DGKα gene transcription, we used luciferase–promoter assay. Luciferase reporter plasmid containing human DGKα gene promoter region (–601 to 0) was made. RB cells were transfected and treated with HG or NG for 2days, and luciferase activity was assayed.
Results: :
HG increased the DGKα expression in Y–79, not in WERI. HG increased the expression of VEGF in both cell lines. Only Y79 RB cells transfected with DGKα promoter responded to HG stimulation, not WERI.
Conclusions: :
The high glucose stimulation induced DGKα gene transcription. The effects of glucose–induced transcription were different in the cell lines, which suggests the complicated molecular mechanisms of DGKα gene transcription regulation.
Keywords: diabetic retinopathy • pathology: experimental • retinoblastoma