Elevation of β-Amyloid Peptide 2–42 in Sporadic and Familial Alzheimer's Disease and Its Generation in PS1 Knockout Cells

Abstract

show a decrease of all secreted A␤ peptide species, as expected, because this mutant is processed mainly by ␣-secretase. This drop is even more pronounced for the APP-KK construct (APP mutant carrying an endoplasmic reticulum retention motif). Surprisingly, A␤2-42 is significantly less affected in PS1؊/؊ neurons and in neurons transfected with the endocytosis-deficient APP-⌬ct construct. Our data confirm that PS1 is closely involved in the production of A␤1-40/42 and the carboxyl-terminal-truncated A␤1-37, A␤1-38, and A␤1-39, but the amino-terminaltruncated and carboxyl-terminal-elongated A␤2-42 seems to be less affected by PS1 deficiency. Moreover, our results indicate that the latter A␤ peptide species could be generated by a ␤ Asp/Ala -secretase activity.

CSF amyloid-β-peptides in Alzheimer's disease, dementia with Lewy bodies and Parkinson's disease dementia

“…The introduction of ratios of Aβ1–42 to Aβ1–37, 1–38, 1–39 and 1–40, respectively, improved the diagnostic test accuracy for each differential diagnostic question relative to the Aβ1–42 levels alone. First, this may be due to disease-specific interactions of each ongoing neurodegenerative dementia process with APP metabolism, which cannot be adequately represented by the sole measurement of absolute Aβ1–42 levels (Wiltfang et al ., 2001). Second, the percentage abundance of each Aβ peptide species displayed a lower inter-individual variance of values than its absolute levels (Wiltfang et al ., 2003).…”

Baculoviruses expressing the human familial Alzheimer's disease presenilin 1 mutation lacking exon 9 increase levels of an amyloid beta-like protein in Sf9 cells

“…12 To achieve better separation between the Ab 40 and Ab 42 species, supernatants were subjected to electrophoresis using a 15% bis-bicine SDS-PAGE gel. 25,26 In this method, the immunoprecipitates were resuspended in 0.36 M Bis-Tris, containing 0.16 M Bicine, 1% (w/v) SDS, 15% (w/v) sucrose, 2.5% (v/v) b-mercaptoethanol and 0.004% bromophenol blue, and loaded onto a 15% bis-bicine SDS-PAGE gel. Electrophoresis was performed at 12 mA/gel constant current for 30 min and 24 mA/gel for 3-4 h in cathode buffer consisting of 0.2 M bicine, 0.25% SDS and 0.1 M NaOH and an anode buffer consisting of 1.6 M Tris and 0.4 M H 2 SO 4 .…”

Magnesium in the Central Nervous System

“…All these different aspects will be elucidated in the present review to provide a framework as comprehensive as possible to correlate changes in cellular Mg 2+ homeostasis and content with variations in the function of specific enzymes, which ultimately affect the modus operandi of different cellular organelles and cell types. Cellular Mg 2+ distribution Direct and indirect measurement of total cellular Mg 2+ content by various techniques consistently indicates that total Mg 2+ concentration ranges between 17 to 20mM in the majority of mammalian cell types examined Wolf et al, 2003). Determinations of total and free Mg 2+ concentrations by electron probe X--rays microanalysis (EPXMA), 31 P--NMR, selective Mg 2+ --electrode, 13 C--NMR citrate/iso--citrate ratio or fluorescent indicators (Table I in in Wolf andCittadini, 2003) localize major amounts of Mg 2+ within mitochondria, nucleus, and endo--(sarco)--plasmic reticulum, with total concentrations ranging between 15 to 18 mM in each of these organelles.…”

“…Cellular Mg 2+ distribution Direct and indirect measurement of total cellular Mg 2+ content by various techniques consistently indicates that total Mg 2+ concentration ranges between 17 to 20mM in the majority of mammalian cell types examined Wolf et al, 2003). Determinations of total and free Mg 2+ concentrations by electron probe X--rays microanalysis (EPXMA), 31 P--NMR, selective Mg 2+ --electrode, 13 C--NMR citrate/iso--citrate ratio or fluorescent indicators (Table I in in Wolf andCittadini, 2003) localize major amounts of Mg 2+ within mitochondria, nucleus, and endo--(sarco)--plasmic reticulum, with total concentrations ranging between 15 to 18 mM in each of these organelles. Binding of Mg 2+ by phospholipids, proteins, nucleic acids, chromatin and nucleotides has been invoked to explain the persistence of such a high Mg 2+ concentration within these organelles.…”

“…Mg 2+ transport mechanisms Eukaryotes retain their cellular Mg 2+ content virtually unaltered under resting conditions even when exposed to a significant gradient across the cell membrane (e.g. culturing in virtually zero extracellular Mg 2+ content) (Wolf et al, 2003;Romani, 2007). Atomic absorbance spectro--photometry determinations and radioisotopic equilibrium indicate Mg 2+ turnover rates ranging from 1 hour (adipocytes) to several days (lymph--ocytes) as a result of structural and functional specificity of different tissues and cells (Romani, 2007).…”