Ehsani, K. | bioRxiv Science

bioRxiv2026

Negative association between nodular stromal fibrosis and large lipid droplets in human choroid plexus epithelial cells

Fibrosis is an age-related change within the human choroid plexus that is likely to affect its function negatively. We systematically analyzed nodular stromal fibrosis present in postmortem tissue from a large repository encompassing the human lifespan. Following manual annotation of sampled images from 81 specimens of choroid plexus from the atrium of the lateral ventricle, a deep learning model was trained to assess stages of fibrosis (dense, hyalinized, and mineralized) occurring in papillae across whole slide images of hematoxylin and eosin-stained sections from 204 cases. The percentage of affected papillae and the relative area of fibrosis at all three stages of severity increased with age. Affected papillae were significantly clustered across the choroid plexus, with areas of high and low fibrotic density. Choroid plexus epithelial cells (CPECs) associated with fibrotic papillae were less likely to contain large lipid droplets than were non-fibrotic papillae, as assessed by another deep learning model. Across papillae within a case, the area of each stage of fibrosis was negatively correlated with the prevalence of CPECs containing large lipid droplets. Finally, individuals displaying more nodular fibrosis had significantly fewer CPECs containing large lipid droplets. Thus, age-related nodular stromal fibrosis may negatively impact lipid storage and homeostasis for the choroid plexus and brain.

pathology↗

bioRxiv2025

The Hsp40 co-chaperone DNAJC7 modifies polyglutamine but not polyglycine aggregation

Protein-encoding nucleotide repeat expansion diseases, including polyglutamine (polyQ) and polyglycine (polyG) diseases, are characterized by the accumulation of aggregation-prone proteins. In the polyQ diseases, including Huntingtons disease and several spinocerebellar ataxias, substantial prior evidence supports a pathogenic role for mutant polyQ-expanded protein misfolding and aggregation, with molecular chaperones showing promise in suppressing disease phenotypes in cellular and animal models. The goal of this study is to establish a scalable cell-based model to systematically evaluate genetic modifiers of protein aggregation in both polyQ and polyG diseases. We developed FRET-based reporter systems that model polyQ and polyG aggregation in human cells and used them to perform high-throughput CRISPR interference screens targeting all known molecular chaperones. In the polyQ model, the screen identified multiple Hsp70 chaperones and Hsp40 co-chaperones previously implicated in polyQ aggregation and additionally revealed the Hsp40 co-chaperone DNAJC7 as a potent and previously unrecognized suppressor of polyQ aggregation. In contrast, in a FRET-based polyG aggregation model of neuronal intranuclear inclusion disease, CRISPRi screening showed minimal overlap of chaperone modifiers of the polyQ screen. Direct knockdown of DNAJC7 also did not affect polyG aggregation, yet overexpressed DNAJC7 co-localized with both polyQ and polyG aggregates in cells and reduced their aggregation. In addition to establishing new inducible, scalable cellular models for polyQ and polyG aggregation, this work expands the role of DNAJC7 in regulating folding of disease-associated proteins.

neuroscience↗