Affiliations: [a]
Department of Biology, Boston University, Boston, MA, USA
| [b]
Department of Histology and Embryology, Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University School of Medicine, Jinan, Shandong, China
| [c]
Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA, USA
Correspondence:
[*]
Correspondence to: Heng-Ye Man, Department of Biology, 5 Cummington Mall, Boston, MA, USA. Tel.: +1 617 358 4284; E-mail: hman@bu.edu.
Abstract: As the primary mediator for synaptic transmission, AMPA receptors (AMPARs) are crucial for synaptic plasticity and higher brain functions. A downregulation of AMPAR expression has been indicated as one of the early pathological molecular alterations in Alzheimer’s disease (AD), presumably via amyloid-β (Aβ). However, the molecular mechanisms leading to the loss of AMPARs remain less clear. We report that in primary neurons, application of Aβ triggers AMPAR internalization accompanied with a decrease in cell-surface AMPAR expression. Importantly, in both Aβ-treated neurons and human brain tissue from AD patients, we observed a significant decrease in total AMPAR amount and an enhancement in AMPAR ubiquitination. Consistent with facilitated receptor degradation, AMPARs show higher turnover rates in the presence of Aβ. Furthermore, AD brain lysates and Aβ-incubated neurons show increased expression of the AMPAR E3 ligase Nedd4 and decreased expression of AMPAR deubiquitinase USP46. Changes in these enzymes are responsible for the Aβ-dependent AMPAR reduction. These findings indicate that AMPAR ubiquitination acts as the key molecular event leading to the loss of AMPARs and thus suppressed synaptic transmission in AD.
