Biology subjects

Glabe, C. G.

Publications and source records attributed to Glabe, C. G..

4 recordsLinked to original sources

bioRxiv2026

The diversity of disease-associated natural human antibody specificities declines dramatically in Alzheimers disease.

Alzheimers disease (AD) is the leading cause of dementia and administration of monoclonal antibodies against A{beta} amyloid are associated with disease modifying effects leading to FDA approval for some antibodies. Naturally-occurring human antibodies (NAbs) are believed to be the front line of defense against a variety of diseases, so we investigated the specificity of NAbs in AD and cognitively normal (NC) individuals using epitomic profiling (EP). We found that the diversity of antibody-specific peptide epitope segments (ES) declines dramatically (26-fold) in the AD compared to NC populations. Many of these differentially expressed ES (DEES) map to amyloid sequences that accumulate in AD, such as A{beta}, tau, -synuclein, TDP43 and TMEM106b. NAbs that target amino terminal A{beta} epitopes are elevated in AD (residues 1-6 and 18-21) and NAbs that target different A{beta} epitopes are elevated in NC (residues 5-10 and 35-41). DEES that map to 2N4R tau are highly cross correlated in the population implying that that the antibodies may be polyspecific or that a set of antibodies are coordinately regulated. We used weighted gene correlation network analysis (WGCNA) to identify co-expressed DEES and UMAP to embed DEES in both AD and NC populations that bind to the same antibody or co-expressed set of antibodies. An average of approximately 25 DEES cluster in each WGCNA group. A major WGCNA cluster associated with AD contains 3 groups of overlapping DEES that assemble into longer linear epitopes. One of these 3 groups contain sequences that map to the amino terminus of A{beta}. DEES elevated in AD may be useful blood biomarkers for AD. The DEES clusters elevated in NC may be associated with protection against misfolded protein amyloid seeding and propagation and maintaining the resilience of neuronal populations.

neuroscience↗

bioRxiv2023

Thioflavin T In-gel Stain to Study Protein Misfolding in Frozen Tissue Specimens

There are limited options to quantify and characterize amyloid species from biological samples in a simple fashion. Thioflavin T (ThT) has now been used for decades to stain amyloid fibrils but to our knowledge we were the first to use it in-gel. Thioflavin T in-gel stain is convenient as it is fast, inexpensive, available to most labs, compatible with other fluorescent stains and downstream analyses such as mass spectrometry (MS).

biochemistry↗

bioRxiv2022

Intracellular injection of brain extracts from Alzheimer's disease patients trigger unregulated Ca2+ release from intracellular stores that hinders cellular bioenergetics

Strong evidence indicates that amyloid beta (A{beta}) inflicts its toxicity in Alzheimers disease (AD) by promoting uncontrolled elevation of cytosolic Ca2+ in neurons. We have previously shown that synthetic A{beta}42 oligomers stimulate abnormal intracellular Ca2+ release from the endoplasmic reticulum stores, suggesting that a similar mechanism of Ca2+ toxicity may be common to the endogenous A{beta}s oligomers. To investigate this possibility, we use human postmortem brain extracts from control and AD-affected patients and test their ability to trigger Ca2+ fluxes when injected intracellularly into Xenopus oocytes. Immunological characterization of samples from AD patients revealed elevated content of soluble A{beta} oligomers, detected by the conformation-dependent OC-antibody, whereas no immunoreactivity was detected in the normal samples. Intracellular injection of brain extracts from control patients failed to trigger detectable changes in intracellular Ca2+. Conversely, brain extracts from AD patients triggered Ca2+ events consisting of local and global Ca2+ fluorescent transients rising within few seconds after injection and persisting for several seconds. Pre-incubation of brain extracts with the conformation specific OC antibody completely suppressed brain extract ability to trigger cytosolic Ca2+ events. Comparison of the elementary events triggered by brain extracts and synthetic A{beta}42 oligomer showed comparable temporal evolution and amplitudes to events triggered by direct injection of IP3. Moreover, bath application of caffeine reversibly inhibited local and global Ca2+ signals in all the samples confirming the involvement of Ca2+ release from the ER. Analysis of the recorded Ca2+ fluorescence signals by computational modeling allowed quantification of the IP3 and Ca2+ generated by each sample. The model further shows that the abnormal increase of Ca2+ and IP3 may affect mitochondrial bioenergetics. These results, supports the hypothesis that endogenous amyloid oligomer contained in neurons of AD-affected brains may represent the toxic agents responsible for neurons malfunctioning and death, associated with the disruption of neuronal Ca2+ homeostasis.

cell biology↗

bioRxiv2020

Epitomic analysis of the specificity of conformation-dependent, anti-aβ amyloid monoclonal antibodies

Antibodies against A{beta} amyloid are indispensable research tools and potential therapeutics for Alzheimers Disease, but display several unusual properties, such as specificity for aggregated forms of the peptide, ability to distinguish polymorphic aggregate structures and ability to recognize generic aggregation-related epitopes formed by unrelated amyloid sequences. Understanding the mechanisms underlying these unusual properties of anti-amyloid antibodies and the structures of their corresponding epitopes is crucial for the understanding why antibodies display different therapeutic activities and for the development of more effective therapeutic agents. Here we employed a novel "epitomic" approach to map the fine structure of the epitopes of 28 monoclonal antibodies against amyloid-beta using immunoselection of random sequences from a phage display library, deep sequencing and pattern analysis to define the critical sequence elements recognized by the antibodies. Although most of the antibodies map to major linear epitopes in the amino terminal 1-14 residues of A{beta}, the antibodies display differences in the target sequence residues that are critical for binding and in their individual preferences for non-target residues, indicating that the antibodies bind to alternative conformations of the sequence by different mechanisms. Epitomic analysis also identifies more discontinuous, non-overlapping sequence A{beta} segments than peptide array approaches that may constitute the conformational epitopes that underlie the aggregation specificity of antibodies. Aggregation specific antibodies recognize sequences that display a significantly higher predicted propensity for forming amyloid than antibodies that recognize monomer, indicating that the ability of random sequences to aggregate into amyloid is a critical element of their binding mechanism.

neuroscience↗