Biology subjects

Abraham, K.

Publications and source records attributed to Abraham, K..

4 recordsLinked to original sources

bioRxiv2026

An atlas of the aging glycoproteome reveals how glycosylation modulates autoantibody binding in the brain

N-glycosylation generates substantial molecular diversity, yet how glycan composition varies throughout aging remains poorly understood. We mapped the N-glycoproteome of brain, liver, spleen, kidney, and plasma across nine ages spanning the mouse lifespan, identifying 80,618 unique N-glycopeptides at 9,211 glycosites on 4,391 glycoproteins, together with matched proteomic trajectories (glycoproteinatlas.org). Organ identity was the dominant determinant of glycan composition, but numerous glycosites nevertheless underwent remodeling with age. The brain showed a prominent age-associated increase in short paucimannose glycans, driven in part by the age-associated increase in the glycan-processing enzyme HEXB. In white matter, a hotspot for this change, aging increased the paucimannosylation of Myelin oligodendrocyte glycoprotein (MOG), a major target of central nervous system autoimmunity. We identified MOG-reactive autoantibodies in aged individuals and patients with MOG antibody-associated disease (MOGAD) and showed that the glycan at MOG N60 modulates autoantibody binding. Experimental autoimmune encephalomyelitis (EAE) recapitulated a subset of the age-associated glycosite changes, revealing shared glycosylation signatures between aging and autoimmune targeting of MOG. Together, these findings reveal site-specific N-glycosylation as both a marker of age and a regulator of molecular interactions.

neuroscience↗

bioRxiv2026

Domain-specific proteome remodeling defines mouse myelin aging

Myelin, once regarded as a static insulating structure, is now recognized as a dynamic component of the nervous system, capable of remodeling in response to experience. Its breakdown is linked to cognitive decline and neurodegenerative diseases, often preceding neuronal dysfunction. While the myelin proteome has been studied, the age- and sex-related changes it undergoes remain poorly understood. In this study, we purified myelin proteins from young, middle-aged, and aged male and female mice. Using mass spectrometry-based proteomics, we identified 4,095 unique proteins in males and 3,931 in females, with roughly 30% showing significant age-related changes in both sexes. We find an age-related increase in compact myelin structural proteins, such as MBP, MOBP, and CLDN11, and a selective vulnerability in non-compact myelin cytoskeletal proteins, such as SEPTIN2, SEPTIN8, and OPALIN. Notably, disease-associated proteins previously characterized in single-cell transcriptomics appear at the protein level in aged myelin. To firmly distinguish between proteins derived from oligodendrocytes and other cell types in vivo we labeled nascent oligodendrocyte proteins with bio-orthogonal non-canonical amino acid tagging (BONCAT). We discovered a dramatic age-related increase in lysosomal and vesicle-associated proteins, while translation and synaptic proteins decrease in myelin with age in both sexes. This dataset highlights molecular mechanisms underlying the loss of myelin integrity and function with age and provides a novel tool for studying oligodendrocyte-derived nascent proteins in vivo.

neuroscience↗

bioRxiv2024

Heterogeneous endocrine cell composition defines human islet functional phenotypes

Phenotyping and genotyping initiatives within the Integrated Islet Distribution Program (IIDP), the largest source of human islets for research in the U.S., provide standardized assessment of islet preparations distributed to researchers, enabling the integration of multiple data types. Data from islets of the first 299 organ donors without diabetes, analyzed using this pipeline, highlights substantial heterogeneity in islet cell composition associated with hormone secretory traits, sex, reported race and ethnicity, genetically predicted ancestry, and genetic risk for type 2 diabetes (T2D). While and {beta} cell composition influenced insulin and glucagon secretory traits, the abundance of {delta} cells showed the strongest association with insulin secretion and was also associated with the genetic risk score (GRS) for T2D. These findings have important implications for understanding mechanisms underlying diabetes heterogeneity and islet dysfunction and may provide insight into strategies for personalized medicine and {beta} cell replacement therapy.

physiology↗

bioRxiv2024

Volatile Organic Compound Specialists in the Phycosphere

Labile dissolved organic carbon (LDOC) in the oceans accounts for [~][1/4] of marine primary production and turns over with a half-life of seconds to days, fueling one of the largest engines of microbial heterotrophic production on the planet. Volatile organic compounds (VOCs) are poorly constrained components of LDOC. Here, we detected 78 m/z signals, corresponding to unique VOCs, including petroleum hydrocarbons, totaling 18.5 nM in the culture medium of a model diatom. In five cocultures with bacteria adapted to grow with this diatom, 1 to 66 VOCs were depleted. Two of the most active VOC consumers, Marinobacter and Roseibium, contained more genes encoding VOC oxidation proteins, and attached to the diatom, suggesting VOC specialism. With NanoSIMS and stable isotope labeling, we confirmed that Marinobacter incorporated carbon from benzene, one of the depleted VOCs detected in the co-culture. Diatom gross carbon production increased by up to 29% in the presence of VOC consumers, indicating that VOC consumption by heterotrophic bacteria in the phycosphere - a region of rapid organic carbon oxidation that surrounds phytoplankton cells - could impact global rates of gross primary production.

microbiology↗