Decrease in cell-surface laminin receptor and cellular prion protein by cAMP attenuates amyloid-β uptake and amyloid-β-induced neuronal cell death

Previous studies have shown that amyloid-β oligomers (AβO) bind with high affinity to cellular prion protein (PrP C ). The AβO-PrP C complex binds to cell-surface co-receptors, including the laminin receptor (67LR). Our current studies revealed that in Neuroscreen-1 cells, 67LR is the major co-receptor involved in the cellular uptake of AβO and AβO-induced cell death. Both pharmacological (dibutyryl-cAMP, forskolin, rolipram) and physiological (pituitary adenylate cyclase-activating polypeptide) cAMP-elevating agents decreased cell-surface PrP C and 67LR, thereby attenuating the uptake of AβO and the resultant neuronal cell death. These cAMP protective effects are dependent on protein kinase A, but not dependent on the exchange protein directly activated by cAMP. Conceivably, cAMP protects neuronal cells from AβO-induced cytotoxicity by decreasing cell-surface associated PrP C and 67LR.