Pyroglutamate-Aβ 3 and 11 colocalize in amyloid plaques in Alzheimer's disease cerebral cortex with pyroglutamate-Aβ 11 forming the central core

Abstract

N-terminal truncated amyloid beta (Aβ) derivatives, especially the forms having pyroglutamate at the 3 position (AβpE3) or at the 11 position (AβpE11) have become the topic of considerable study. AβpE3 is known to make up a substantial portion of the Aβ species in senile plaques while AβpE11 has received less attention. We have generated very specific polyclonal antibodies against both species. Each antibody recognizes only the antigen against which it was generated on Western blots and neither recognizes full length Aβ. Both anti-AβpE3 and anti-AβpE11 stain senile plaques specifically in Alzheimer’s disease cerebral cortex and colocalize with Aβ, as shown by confocal microscopy. In a majority of plaques examined, AβpE11 was observed to be the dominant form in the innermost core. These data suggest that AβpE11 may serve as a generating site for senile plaque formation.

Amyloid-β Peptide Aβ3pE-42 Induces Lipid Peroxidation, Membrane Permeabilization, and Calcium Influx in Neurons

“…The predominance of pE-A␤ in the central core of plaques suggests an early involvement in amyloid deposition in the AD brain (52), whereas correlation between pE-A␤ and a decline in Mini Mental State Examination scores implicate pE-A␤ cytotoxicity in AD neurodegeneration (53,54). In parallel, markers of oxidative stress are among the earliest detectable pathological changes in transgenic AD mouse models (55) and the human AD brain (36,56,57), with numerous lines of evidence implicating A␤ as a central contributor to oxidative stress in AD (58,59).…”

“…This does not exclude the possibility that pE-A␤ may affect the clearance of full-length A␤ when the peptides are aggregated, which will require further investigation. The capacity for A␤3pE-42 to resist proteolytic degradation in both neurons and astrocytes is highly relevant given that pE-A␤ peptides are found in the cores of amyloid plaques in the AD brain (52), suggesting that pE-A␤ peptides, once formed, are long-lived neurotoxins. Dityrosine is another post-translational protein modification that confers resistance to cellular catabolism.…”

“…This observation can likely be attributed to increased hydrophobicity and the propensity to oligomerize; dityrosine formation is dependent on both the production of A␤-tyrosyl radicals and the close proximity of A␤ molecules to allow tyrosine-tyrosine coupling (33). It is reasonable to speculate that the capacity for amyloid plaques to resist solubilization and clearance is due to the contribution of both the pE and dityrosine modifications to A␤, which may account for the abundance of pE-A␤ in plaque cores (52).…”

CuII Binding to Various Forms of Amyloid‐β Peptides: Are They Friends or Foes?

“…The formation of pyroglutamate at the 11-position (see above) is also possible, but its effect has been less studied. [124,132,133] …”

Phosphorylated low-density lipoprotein receptor-related protein 6 is prevalent in hippocampal progenitor cells and circuits of aged human hippocampus

“…For brightfield microscopy, detection of pLrp6-bound primary antibodies was carried out with horse radish peroxidase (HRP)-conjugated secondary antibodies, exposed by enzymatic processing of diaminobenzidine (DAB). Fluorescence confocal microscopy (Leica SP5) was used as previously described [12] to assess colocalization of pLrp6 with primary antibodies bound to NeuN, Sox2, and GFAP (Santa Cruz Biotechnology). Secondary antibodies conjugated with Alexafluor 488, 555 or 633 dyes (Life Technologies) were used to detect bound primary antibodies for fluorescence imaging.…”