TrkA-mediated endocytosis of p75-CTF prevents cholinergic neuron death upon γ-secretase inhibition.
Life Sci Alliance 2021;
4:4/4/e202000844. [PMID:
33536237 PMCID:
PMC7898468 DOI:
10.26508/lsa.202000844]
[Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 01/11/2021] [Accepted: 01/11/2021] [Indexed: 12/13/2022] Open
Abstract
The findings shed light into the adverse effects of GSIs observed in the Alzheimer’s field and explain, at least in part, the unexpected worsening in cognition observed in the semagacestat Phase 3 trial.
γ-secretase inhibitors (GSI) were developed to reduce the generation of Aβ peptide to find new Alzheimer’s disease treatments. Clinical trials on Alzheimer’s disease patients, however, showed several side effects that worsened the cognitive symptoms of the treated patients. The observed side effects were partially attributed to Notch signaling. However, the effect on other γ-secretase substrates, such as the p75 neurotrophin receptor (p75NTR) has not been studied in detail. p75NTR is highly expressed in the basal forebrain cholinergic neurons (BFCNs) during all life. Here, we show that GSI treatment induces the oligomerization of p75CTF leading to the cell death of BFCNs, and that this event is dependent on TrkA activity. The oligomerization of p75CTF requires an intact cholesterol recognition sequence (CRAC) and the constitutive binding of TRAF6, which activates the JNK and p38 pathways. Remarkably, TrkA rescues from cell death by a mechanism involving the endocytosis of p75CTF. These results suggest that the inhibition of γ-secretase activity in aged patients, where the expression of TrkA in the BFCNs is already reduced, could accelerate cholinergic dysfunction and promote neurodegeneration.
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