Cytoplasmic translocation of high-mobility group box-1 protein is induced by diabetes and high glucose in retinal pericytes

The aim of the present study was to assess the involvement of the high-mobility group box-1 (HMGB1) protein, receptor for advanced glycation end products (RAGE) and nuclear factor (NF)-B signaling pathway in the development of diabetic retinopathy. Rat primary retinal pericytes were exposed to 25 mmol/l D-glucose for 48 h. Diabetic retinal vessels were prepared from streptozotocin-induced diabetic rats 12 weeks following the induction of diabetes. The expression of HMGB1 was detected using immunofluorescence staining. The expression of RAGE and the activity of NF-B were analyzed using western blot and electrophoretic mobility shift assays, respectively. The results showed that HMGB1 was translocated to the cytoplasm of the high glucose-treated pericytes and diabetic retinal pericytes, whereas, in the control cells and the normal retinas, HMGB1 was expressed in the cell nuclei only. The expression of RAGE, a potential receptor for HMGB1, and the activity of NF-B were also increased in the high glucose-treated pericytes, compared with the normal control cells. In addition, high glucose increased the binding of NF-B to the RAGE promoter. These findings suggested that the cytoplasmic translocation of HMGB1 may be caused by diabetes and high glucose in retinal pericytes, and that the pathogenic role of HMGB1 may be dependent on the expression of RAGE and activation of NF-kappa B.