A proteomics analysis of 5xFAD mouse brain regions reveals the lysosome-associated protein Arl8b as a candidate biomarker for Alzheimer’s disease

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  • Annett Boeddrich
  • Christian Haenig
  • Nancy Neuendorf
  • Eric Blanc
  • Andranik Ivanov
  • Marieluise Kirchner
  • Philipp Schleumann
  • Irem Bayraktaroğlu
  • Matthias Richter
  • Christine Mirjam Molenda
  • Anje Sporbert
  • Martina Zenkner
  • Sigrid Schnoegl
  • Christin Suenkel
  • Luisa Sophie Schneider
  • Agnieszka Rybak-Wolf
  • Bianca Kochnowsky
  • Lauren M. Byrne
  • Edward J. Wild
  • Gunnar Dittmar
  • Oliver Peters
  • Dieter Beule
  • Erich E. Wanker

Background: Alzheimer’s disease (AD) is characterized by the intra- and extracellular accumulation of amyloid-β (Aβ) peptides. How Aβ aggregates perturb the proteome in brains of patients and AD transgenic mouse models, remains largely unclear. State-of-the-art mass spectrometry (MS) methods can comprehensively detect proteomic alterations, providing relevant insights unobtainable with transcriptomics investigations. Analyses of the relationship between progressive Aβ aggregation and protein abundance changes in brains of 5xFAD transgenic mice have not been reported previously. Methods: We quantified progressive Aβ aggregation in hippocampus and cortex of 5xFAD mice and controls with immunohistochemistry and membrane filter assays. Protein changes in different mouse tissues were analyzed by MS-based proteomics using label-free quantification; resulting MS data were processed using an established pipeline. Results were contrasted with existing proteomic data sets from postmortem AD patient brains. Finally, abundance changes in the candidate marker Arl8b were validated in cerebrospinal fluid (CSF) from AD patients and controls using ELISAs. Results: Experiments revealed faster accumulation of Aβ42 peptides in hippocampus than in cortex of 5xFAD mice, with more protein abundance changes in hippocampus, indicating that Aβ42 aggregate deposition is associated with brain region-specific proteome perturbations. Generating time-resolved data sets, we defined Aβ aggregate-correlated and anticorrelated proteome changes, a fraction of which was conserved in postmortem AD patient brain tissue, suggesting that proteome changes in 5xFAD mice mimic disease-relevant changes in human AD. We detected a positive correlation between Aβ42 aggregate deposition in the hippocampus of 5xFAD mice and the abundance of the lysosome-associated small GTPase Arl8b, which accumulated together with axonal lysosomal membranes in close proximity of extracellular Aβ plaques in 5xFAD brains. Abnormal aggregation of Arl8b was observed in human AD brain tissue. Arl8b protein levels were significantly increased in CSF of AD patients. Conclusions: We report a comprehensive biochemical and proteomic investigation of hippocampal and cortical brain tissue derived from 5xFAD transgenic mice, providing a valuable resource to the neuroscientific community. We identified Arl8b, with significant abundance changes in 5xFAD and AD patient brains. Arl8b might enable the measurement of progressive lysosome accumulation in AD patients and have clinical utility as a candidate biomarker.

TidsskriftGenome Medicine
Udgave nummer1
Antal sider32
StatusUdgivet - 2023

Bibliografisk note

Funding Information:
We thank Karola Bach, Stephanie Rode, Melanie Humpenöder (MDC Berlin), and Pascal Eede (Charité Berlin) for technical support. We are grateful to the genomics core facility (MDC Berlin) for sequencing RNAs. We thank Lidia Mateo and Patrick Aloy (IRB Barcelona) for providing assistance in data analyses and Thomas Willnow und Anne-Sophie Carlo-Spiewok (MDC Berlin) for providing us breeder pairs of the 5xFAD mouse model. Human brain samples for this study were provided by the Newcastle Brain Tissue Resource which is funded in part by a grant from the UK Medical Research Council (G0400074), by NIHR Newcastle Biomedical Research Centre awarded to the Newcastle upon Tyne NHS Foundation Trust and Newcastle University, and as part of the Brains for Dementia Research Program jointly funded by Alzheimer’s Research UK and Alzheimer’s Society.

Publisher Copyright:
© 2023, The Author(s).

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