Branzell, N. | Search bioRxiv

bioRxiv2026

Spatial organization and mitigation of autofluorescence in multiplexed spatial proteomics of aged fresh-frozen human brain

Multiplexed imaging technologies are transforming the study of human tissue biology, but their application to the aged brain is hindered by autofluorescence, particularly in fresh-frozen specimens. Here, we characterized autofluorescence across four brain regions from 21 donors and found broad spectral emission, regional and gray-white matter differences, and an association with donor age. Photobleaching conditions adopted from formalin-fixed paraffin-embedded tissue caused marked region- and compartment-dependent damage in fresh-frozen sections. We therefore developed a Tris-EDTA-supplemented photobleaching workflow that reduced autofluorescence by 58-70% while preserving tissue architecture and cellular content. We established a custom 28-plex DNA-barcoded antibody panel targeting neuronal, glial, immune, and vascular markers, providing a resource for fresh-frozen human brain. Integration of the optimized photobleaching workflow with this panel enabled spatial proteomic analysis across fresh-frozen brain regions. By co-registering pre-photobleaching autofluorescence with multiplexed protein maps, we further established a cellular-resolution framework for spatial characterization of autofluorescence. This revealed region-dependent protein marker relationships and preferential enrichment of autofluorescent particles near nuclei and within microglial and CD68-positive regions. Together, this work establishes a practical workflow for multiplexed spatial proteomics in fresh-frozen brain and characterizes autofluorescence as both a technical confound and a spatially structured feature of the aged human brain.

neuroscience↗

bioRxiv2024

The CHCHD2-CHCHD10 protein complex is modulated by mitochondrial dysfunction and alters lipid homeostasis in the mouse brain.

The highly conserved CHCHD2 and CHCHD10 are small mitochondrial proteins residing in the intermembrane space. Recently, mutations in the CHCHD2 and CHCHD10 genes have been linked to severe disorders, including Parkinsons disease and amyotrophic lateral sclerosis. In cultured cells, a small fraction of CHCHD2 and CHCHD10 oligomerize to form a high molecular weight complex of unknown function. Here, we generated a whole-body Chchd2 knockout mouse to investigate the in vivo role of CHCHD2 and its protein complex. We show that CHCHD2 is crucial for sustaining full motor capacity, normal striatal dopamine levels, and lipid homeostasis in the brain of adult male mice. We also demonstrate that in mouse tissues, CHCHD2 and CHCHD10 exist exclusively as a high molecular weight complex, whose levels are finely tuned under physiological conditions. In response to mitochondrial dysfunction, the abundance and size of the CHCHD2-CHCHD10 complex increases, a mechanism conserved across different tissues. Although the loss of CHCHD2 does not abolish CHCHD10 oligomerization, it enhances cell vulnerability to mitochondrial stress, suggesting that CHCHD2 is protective against mitochondrial damage. Our findings uncover the role of CHCHD2 in preserving tissue homeostasis and provide important insights into the involvement of the CHCHD2-CHCHD10 complex in human diseases.

neuroscience↗