| 1. |
- Guzman, Erika Avendano, et al.
(author)
-
Abundance of A beta(5-x) x like immunoreactivity in transgenic 5XFAD, APP/PS1KI and 3xTG mice, sporadic and familial Alzheimer's disease
- 2014
-
In: Molecular Neurodegeneration. - : Springer Science and Business Media LLC. - 1750-1326. ; 9, s. 13-
-
Journal article (peer-reviewed)abstract
- Background: According to the modified amyloid hypothesis the main event in the pathogenesis of Alzheimer's disease (AD) is the deposition of neurotoxic amyloid beta-peptide (A beta) within neurons. Additionally to full-length peptides, a great diversity of N-truncated A beta variants is derived from the larger amyloid precursor protein (APP). Vast evidence suggests that A beta(x-42) isoforms play an important role triggering neurodegeneration due to its high abundance, amyloidogenic propensity and toxicity. Although N-truncated and A beta(x-42) species have been pointed as crucial players in AD etiology, the A beta(5-x) isoforms have not received much attention. Results: The present study is the first to show immunohistochemical evidence of A beta(5-x) in familial cases of AD (FAD) and its distribution in APP/PS1KI, 5XFAD and 3xTG transgenic mouse models. In order to probe A beta(5-x) peptides we generated the AB5-3 antibody. Positive plaques and congophilic amyloid angiopathy (CAA) were observed among all the FAD cases tested carrying either APP or presenilin 1 (PS1) mutations and most of the sporadic cases of AD (SAD). Different patterns of A beta(5-x) distribution were found in the mouse models carrying different combinations of autosomal mutations in the APP, PS1 and Tau genes. All of them showed extracellular A beta deposits but none CAA. Additionally, they were all affected by a severe amyloid pathology in the hippocampus among other areas. Interestingly, neither 5XFAD nor APP/PS1KI showed any evidence for intraneuronal A beta(5-x). Conclusions: Different degrees of A beta(5-x) accumulations can be found in the transgenic AD mouse models and human cases expressing the sporadic or the familial form of the disease. Due to the lack of intracellular A beta(5-x), these isoforms might not be contributing to early mechanisms in the cascade of events triggering AD pathology. Brain sections obtained from SAD cases showed higher A beta(5-x)-immunoreactivity in vascular deposits than in extracellular plaques, while both are equally important in the FAD cases. The difference may rely on alternative mechanisms involving A beta(5-x) peptides and operating in a divergent way in the late and early onset forms of the disease.
|
|
| 2. |
- Reinert, Jochim, et al.
(author)
-
A beta(38) in the Brains of Patients with Sporadic and Familial Alzheimer's Disease and Transgenic Mouse Models
- 2014
-
In: Journal of Alzheimer's Disease. - 1387-2877 .- 1875-8908. ; 39:4, s. 871-881
-
Journal article (peer-reviewed)abstract
- The pathogenesis of Alzheimer's disease (AD) is believed to be closely dependent on deposits of neurotoxic amyloid-beta peptides (A beta), which become abundantly present throughout the central nervous system in advanced stages of the disease. The different A beta peptides existing are generated by subsequent cleavage of the amyloid-beta protein precursor (A beta PP) and may vary in length and differ at their C-terminus. Despite extensive studies on the most prevalent species A beta(40) and A beta(42), A beta peptides with other C-termini such as A beta(38) have not received much attention. In the present study, we used a highly specific and sensitive antibody against A beta(38) to analyze the distribution of this A beta species in cases of sporadic and familial AD, as well as in the brains of a series of established transgenic AD mouse models. We found A beta(38) to be present as vascular deposits in the brains of the majority of sporadic AD cases, whereas it is largely absent in non-demented control cases. A beta(38)-positive extracellular plaques were virtually limited to familial cases. Interestingly we observed A beta(38)-positive plaques not only among familial cases due to A beta PP mutations, but also in cases of familial AD caused by presenilin (PSEN) mutations. Furthermore we demonstrate that A beta(38) deposits in the form of extracellular plaques are common in several AD transgenic mouse models carrying either only A beta PP, or combinations of A beta PP, PSEN1, and tau transgenes.
|
|
