cAMP‐induced decrease in cell‐surface laminin receptor and cellular prion protein 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 (PrPC). The AβO‐PrPC 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 AβΟ‐induced cell death. Both pharmacological (dibutyryl‐cAMP, forskolin and rolipram) and physiological (pituitary adenylate cyclase‐activating polypeptide) cAMP‐elevating agents decreased cell‐surface PrPC 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 PrPC and 67LR. We find that in Neuroscreen‐1 neuronal cells, 67 kDa laminin receptor (67LR) is the major co‐receptor for cellular prion protein (PrPC)‐mediated uptake of amyloid‐β oligomers (AβO) and neuronal cell death. Both pharmacological and physiological cAMP‐elevating agents acting via protein kinase A pathway decrease cell‐surface levels of 67LR and PrPC and thereby decrease uptake of AβO and neuronal cell death.