Brain-derived peptides increase the expression of a blood-brain barrier GLUT1 glucose transporter reporter gene.

The brain-derived peptide preparation Cerebrolysin (C1; EBEWE, Austria) increases the stability of blood-brain barrier (BBB)-GLUT1 transcript. To determine if the increase in BBB-GLUT1 mRNA stability is associated with an augmentation of gene expression, the present investigation studied the effect of C1 on the expression of a BBB-GLUT1-luciferase reporter gene in brain endothelial cultured (ECL) cells. Dose response studies showed that C1 markedly increased the expression of luciferase when the BBB-GLUT1-reporter gene was used. On the contrary, C1 produced no changes in the expression pattern of the control reporter gene, which lacks the GLUT1 regulatory sequence. Desensitization of the protein kinase C (PKC) receptor with the phorbol ester TPA, or inhibition with either 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H7) or staurosporine, had no effect on the increased levels of luciferase induced by C1. Transfection efficiency was determined by measuring intracellular levels of the expression vector using a quantitative polymerase chain reaction (PCR) assay. The data presented here demonstrate that C1 increases BBB-GLUT1 gene expression in ECL cells through a mechanism that appears to be independent of activation of PKC.