PRNP and Alzheimer disease: A separate study implicated group I mGluR signaling in the regulation of Aβ42 toxicity in neurons and in AD mouse models, and Aβ42 oligomers interact with PrPC to increase metabotropic glutamate receptor 5 (mGluR5)-dependent long-term depression (LTD) and LTP (Hu et al., 2014).