Biology subjects

Harrington, C. R.

Publications and source records attributed to Harrington, C. R..

4 recordsLinked to original sources

bioRxiv2026

Targeted Analysis of >1500 Plasma Proteoforms via Individual Ion Mass Spectrometry

Plasma proteomics has long sought to accessibly sense human biology, precisely detect disease states, and advance diagnostics through clinical translation. In recent years, companies with defined panels such as Olink and Somascan have entered the field to complement bottom-up mass spectrometry (BUP). This study leverages a novel mass spectrometry platform to capture targeted proteoform information lost by mainline antibody-, aptamer-, and BUP-driven workflows. The Plasma Proteoform Assay (PPA) uses Individual Ion Mass Spectrometry (I{superscript 2}MS) to resolve mixtures of intact proteins presented by direct injection. Two proteoform panels, PPA 526 and PPA 1514, were defined from human plasma samples obtained from 81 individuals. The panels quantify 526 proteoforms derived from 59 genes and 1,514 proteoforms from 155 genes, respectively. Reproducibility for both panels showed coefficients of variation below 20% for most proteoforms (59-80%). PPA was benchmarked in studies including subjects with hepatic cirrhosis (N=30) and resilient agers carrying a SERPINE1 (PAI 1) mutation (N=27). PPA signatures distinguished SERPINE1 mutation carriers from affected individuals and provided sufficient resolution to discriminate among cirrhosis disease stages. In summary, we present PPA 526 and PPA 1514, the first scalable plasma proteoform panels capable of tracking hundreds to thousands of targets in a few minutes per sample.

biochemistry↗

bioRxiv2025

The Icelandic mutation APPA673T on amyloid-β plaque burden in the 5xFAD Alzheimer model

The protective Icelandic mutation in the amyloid precursor protein (APP) gene, APPA673T, identified in Icelandic and other Nordic populations is associated with a significantly lower risk of developing Alzheimers disease (AD). Conflicting results have been reported for the APPA673T mutation in various knock-in models of AD, but its effect in 5x familial AD (5xFAD) mice has never been investigated. We have crossed C57Bl6/J mice expressing a single point mutation edited into the murine APP gene via CRISPR-Cas gene editing, termed APPA673T, with 5xFAD mice that overexpress human APP carrying the Swedish (K670N/M671L), Florida (I716V), and London (V717I) mutations as well as human presenilin-1 (PS1) with two mutations (M146L and L286V); the resulting mice were termed 5xFADxAPPA673T. We have investigated amyloid beta (A{beta}) pathology in 5xFADxAPPA673T, 5xFAD and their respective controls, APPA673T and C57Bl6/J wild types, at 6-months of age using immunohistochemistry, immunoblotting, and ELISAs. We found a moderate yet significant reduction for A{beta} plaque size in male 5xFADxAPPA673T compared to 5xFAD. No differences were observed for soluble/insoluble A{beta}40 and A{beta}42 levels per se, but lower plaque count/area was found in 5xFADxAPPA673T when A{beta}42/A{beta}40 ratios were low, suggesting a genotype-dependent sensitivity to A{beta} aggregation and accumulation. Therefore, the APPA673T mutation has the potential to modify A{beta} pathology in 5xFAD mice at the age of 6 months.

neuroscience↗

bioRxiv2025

The effect of the Icelandic mutation APPA673T in the line 66 model of tauopathy

The Icelandic mutation in the amyloid precursor protein (APP), APPA673T, has been identified in Icelandic and Scandinavian populations and is associated with a significantly lower risk of developing Alzheimers disease (AD). Although this mutation led to reduction in amyloid {beta}-protein (A{beta}) production, its effect on tau pathology is not well studied. We have crossed line 66 (L66) tau transgenic mice that overexpress the P301S aggregation-prone form of tau with C57Bl6/J mice expressing a single point mutation edited into the murine APP gene via CRISPR-Cas gene editing, termed APPA673T. We have performed ELISA, histopathological and behavioural analyses of heterozygous male/female L66 and L66xAPPA673T crosses at the age of 6 months to investigate the effect of the A673T mutation on tau brain pathology and behavioural deficits in these mice. Using immunohistochemistry, we found only a moderate, yet significant, reduction of mAb 7/51-reactive tau in prefrontal cortex for L66xAPPA673T compared to L66 mice. Quantification of tau in soluble/insoluble brain homogenate fractions by ELISA confirmed the lack of overt differences between genotypes, as did our extensive behavioural phenotyping using six different paradigms accessing motor function, olfaction, depression/apathy-like behaviour, as well as exploration and sociability. Therefore, the APPA673T mutation does not appear to modulate tau pathology or motor and neuropsychiatric behaviour in L66 tau transgenic mice.

neuroscience↗

bioRxiv2022

Solid-state NMR of paired helical filaments formed by the core tau fragment tau(297-391)

Aggregation of the tau protein into fibrillar cross-{beta} aggregates is a hallmark of Alzheimers diseases (AD) and many other neurodegenerative tauopathies. Recently, several core structures of patient-derived tau paired helical filaments (PHFs) have been solved revealing a structural variability that often correlates with a specific tauopathy. To further characterize the dynamics of these fibril cores, to screen for strain-specific small molecules as potential biomarkers and therapeutics, and to develop strain-specific antibodies, recombinant in-vitro models of tau filaments are needed. We recently showed that a 95-residue fragment of tau (from residue 297 to 391), termed dGAE, forms filaments in vitro in the absence of polyanionic co-factors often used for in vitro aggregation of full length tau. Tau(297-391) was identified as the proteolytic resistant core of tau PHFs and overlaps with the structures characterized by cryo-electron microscopy in ex-vivo PHFs, making it a promising model for the study of AD tau filaments in vitro. In the present study, we used solid-state NMR to characterize tau(297-391) filaments and show that such filaments assembled under non-reducing conditions are more dynamic and less ordered than those made in the presence of the reducing agent, DTT. We further report the resonance assignment of tau(297-392)+DTT filaments and compare it to existing core structures of tau.

biophysics↗