bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/655340

Amyloid-β induced membrane damage instigates tunnelling nanotubes and direct cell-to-cell transfer

Ollinger, K.·Kagedal, K.·Nath, S.
View original source ↗Export metadata ↓

Abstract

Alzheimers disease (AD) pathology progresses gradually via anatomically connected brain regions. Earlier studies have shown that amyloid-{beta}1-42 oligomers (oA{beta}) can be directly transferred between connected neurons. However, the mechanism of transfer is not fully revealed. We observed formation of oA{beta} induced tunneling nanotubes (TNTs), nanoscaled f-actin containing membrane conduit, in differentially differentiated SH-SY5Y neuronal models. Time-lapse images showed that TNTs propagate oligomers from one cell to another. Preceding the TNT-formation, we detected oA{beta} induced plasma membrane (PM) damage and calcium-dependent repair through lysosomal-exocytosis and significant membrane surface expansion, followed by massive endocytosis to re-establish the PM. Massive endocytosis was monitored by an influx of the membrane-impermeable dye TMA-DPH and PM damage was quantified by propidium iodide influx in the absence of calcium. The massive endocytosis eventually caused accumulation of internalized oA{beta} in Lamp1 positive multi vesicular bodies/lysosomes via the actin cytoskeleton remodulating p21-activated kinase1 (PAK1) dependent endocytic pathway. Three dimensional quantitative and qualitative confocal imaging, structured illumination superresolution microscopy (SIM) and flowcytometry data revealed that oA{beta} induces activated phospho-PAK1, which modulates the formation of long stretched f-actin extensions between cells. Moreover, formation of TNTs can be inhibited by preventing PAK1 dependent internalization of oA{beta} using small-molecule inhibitor IPA-3, a highly selective cell permeable auto-regulatory inhibitor of PAK1. The present study gives insight that the TNTs are probably instigated as a consequence of oA{beta} induced PM damage and repair process, followed by PAK1 dependent endocytosis and actin remodeling, probably to maintain cell surface expansion and/or membrane tension in equilibrium.

Explore related subjects

cell biologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Ollinger, K., Kagedal, K., Nath, S.. 2019-05-31. Amyloid-β induced membrane damage instigates tunnelling nanotubes and direct cell-to-cell transfer. https://doi.org/10.1101/655340

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Platycodin D2 Targets Vimentin to Suppress Fibroblast-Myofibroblast Transition: A Novel Therapeutic Strategy Against Pulmonary Fibrosis

Background Pulmonary fibrosis is a progressive lung disease characterized by excessive extracellular matrix deposition and irreversible decline in lung function with limited effective therapeutic targets. Vimentin, a type III intermediate filament protein, plays a critical role in fibroblast activation and fibrogenesis, representing a promising drug target. Methods Novel vimentin ligands were screened via virtual screening. SPR assay verified compound-vimentin binding affinity. CETSA and CD spectroscopy analyzed protein structural changes after compound binding. In vitro FMT model and in vivo bleomycin-induced pulmonary fibrosis model were used to assess antifibrotic effects, and mutagenesis assays identified key binding amino acid residues. Results Platycodin D2 (PD2) from Platycodon grandiflorus was identified as a novel high-affinity vimentin ligand (Kd = 392.8 nM). PD2 binds vimentin directly, alters its secondary structure and induces insoluble aggregation. It effectively inhibits TGF-{beta}1-induced FMT in vitro and mitigates bleomycin-induced pulmonary fibrosis in vivo, reducing collagen deposition and improving animal survival. Critically, mutagenesis validation confirmed that key residues (Glu138 in chain A, Glu132 and Glu143 in chain B, as well as Glu50 and Arg54 in chain C) are essential for this interaction. Conclusions Our findings establish PD2 as a novel pharmacological inducer of aberrant vimentin aggregation, presenting a distinct target-driven strategy for antifibrotic drug development.

cell biology↗
bioRxiv2026

Diversification of budding yeast polarization dynamics after compensatory experimental evolution

Essential cellular processes evolve under strong selection, yet protein networks underlying conserved functions can vary substantially. To what extent evolution constrains the intracellular dynamics of proteins performing essential functions is currently largely unknown. Here, we characterize budding yeast polarization phenotypes along a previously established evolutionary recovery trajectory, compensating for the loss of near-essential polarity gene BEM1. Through quantitative live cell imaging, we show that loss of BEM1 weakens and destabilizes polarization. Surprisingly, in recovered evolved lineages, protein dynamics change significantly compared to the ancestor: most notably, presence of main regulator Cdc42-GTP is strongly decreased, while polarisome member Spa2 localizes more slowly into mobile foci. Although separate phenotypic characteristics are only weakly constrained, we find evidence of effective protein-independent localization modes, revealing signs of convergence along the evolutionary trajectory. Together, our results show that evolution can restore global cellular function without conserving microscopic organization, instead giving rise to novel molecular phenotypes.

cell biology↗
bioRxiv2026

Role of Very Long-Chain Fatty Acyl-Ceramides in Endocytic Uptake

Specialized endoplasmic reticulum (ER) subdomains termed ER sterol exit sites (ERSES), transiently contact endocytic sites to locally supply sterols, which in turn initiate actin polymerization and drive membrane invagination. Osh2, an oxysterol-binding protein (OSBP)-related protein (ORP), mediates the non-vesicular sterol transfer at ER-endocytic contact sites (ER-ECS). In search for additional ERSES components, we identified Fat1, a fatty acid (FA) transporter and acyl-CoA synthetase with specificity for very long-chain (VLC) FAs (C20-C26). Analysis of VLC-FA anabolic and catabolic pathways revealed a specific requirement for VLC fatty acyl-ceramides (VLCA-Cers) in the constriction of endocytic invaginations. Strikingly, the Cer synthase physically interacted with the endocytic machinery, pointing to a direct role of VLCFA-Cers in membrane remodelling. Consistent with this view, molecular dynamics and live-cell imaging of a Cer probe indicated that the ORPs Osh1 and Osh3 contribute to Cer export from at ER-ECS and and that their depletion recapitulates the endocytic defects observed in the absence of VLCFA-Cer. Our findings establish that local transport of VLCA-Cers is required for endocytic budding and reveal ERSES as hubs where Cer and sterol biosynthesis and transport converge

cell biology↗