N-terminal pyroglutamated amyloid-beta (pGlu-Aβ)

N-terminal pyroglutamated amyloid-beta (pGlu-Aβ) is a highly neurotoxic and aggregation-prone variant of the amyloid-beta peptide, formed by the cyclization of N-terminal glutamate residues by the enzyme glutaminyl cyclase (Schilling et al., 2008, Nature Medicine). This modification typically occurs at the third amino acid position (pE3-Aβ) after initial truncation of the full-length peptide, resulting in a peptide that is more hydrophobic and resistant to degradation than standard amyloid-beta (Nussbaum et al., 2012, Nature). pGlu-Aβ is a major component of senile plaques in Alzheimer's disease and acts as a seed for the rapid accumulation of other amyloid-beta species (Perez-Garmendia & Gevorkian, 2013, Frontiers in Genetics). Because it is found almost exclusively in pathological plaques and not in physiological soluble amyloid-beta, it serves as a highly specific target for immunotherapy (Sims et al., 2023, JAMA). Therapeutic agents like donanemab are monoclonal antibodies designed to recognize this specific epitope to facilitate the clearance of established plaques via microglial phagocytosis (Mintun et al., 2021, NEJM). While targeting pGlu-Aβ has shown efficacy in slowing cognitive decline, it is associated with safety concerns such as amyloid-related imaging abnormalities (ARIA) (Withington & Turner, 2022, Neurology). Additionally, small molecule inhibitors like varoglutamstat aim to prevent the formation of this toxic species by inhibiting the glutaminyl cyclase enzyme (Lues et al., 2015, Journal of Alzheimer's Disease).

Other names

Pyroglutamate-3 amyloid-betaAβpE3pE3-AβN3pE-amyloid betaPyroglutamyl amyloid-betaAβ3(pE)-42

Monoclonal antibodies target the specific N-terminal pyroglutamate epitope to facilitate the clearance of existing amyloid plaques via microglial phagocytosis. Alternatively, small molecule inhibitors of glutaminyl cyclase prevent the enzymatic conversion of N-truncated amyloid-beta into the pyroglutamated form, thereby reducing the accumulation of toxic species.