PKCβII/HuR/VEGF:: A new molecular cascade in retinal pericytes for the regulation of VEGF gene expression

Vascular endothelial growth factor (VEGF)-induced new vessels formation is a key event in diabetic retinopathy, a severe progressive multistage pathology. Literature data indicate that protein kinase C (PKC) is involved in the control of VEGF expression, but, so far, no data are available on the molecular pathway underlying this process. Within this context, we suggest the existence of a new molecular cascade, operating in retinal bovine pericytes and involving PKC beta II, the mRNA-stabilizing protein HuR, and VEGF. In particular we show that PKC beta II activation is responsible, through the RNA-binding protein HuR, for the increase of VEGF protein content and its release in the medium. The specificity of the PKC beta II involvement is confirmed by experiments performed with the LY379196 compound, a selective PKC beta II inhibitor. Following acute high-glucose insult this pathway seems still functioning, suggesting that a brief exposure to glucose does not compromise this molecular cascade in pericytes. A better understanding on this new pathway could open novel opportunities for the development of innovative pharmacological therapies useful in pathologies where VEGF plays a key role such as in diabetic retinopathy. (C) 2007 Elsevier Ltd. All rights reserved.