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TDP-43 skein-like inclusions formed by BAG3/HSP70 guided co-aggregation with actin binding proteins attached to actin filaments

ABSTRACT: In multiple neurodegenerative diseases, the RNA binding protein TDP-43 forms cytoplasmic aggregates of distinct morphologies, including skein-like, spherical, diffuse, and granular inclusions. While the N-terminal self-oligomerization domain (NTD) regulates TDP-43 de-mixing into cytoplasmic droplets, inhibition of NTD-mediated oligomerization is shown here to promote the formation of skein-like inclusions. Utilizing proximity labeling/mass spectrometry, cellular stresses are shown to induce TDP-43 association with actin-binding proteins that include filamins and beta actinin. Small interfering RNA-mediated reduction of filamin in Drosophila ameliorates cell loss from cytoplasmic TDP-43, consistent with filamin/TDP-43 interaction enhancing cytotoxicity. TDP-43s association with actin-binding proteins is mediated by BAG3, a HSP70 family nucleotide exchange factor (NEF) that regulates proteostasis of actin-binding proteins. BAG2, another HSP70 NEF facilitates the formation of small, rounded TDP-43 inclusions. Our evidence demonstrates that both TDP-43 self-oligomerization and its binding partners, including HSP70 and the co-chaperones BAG2 and BAG3, drive formation of different types of TDP-43 inclusions.

INSTRUMENT(S): Orbitrap Fusion Lumos

ORGANISM(S): Homo Sapiens (ncbitaxon:9606)

SUBMITTER: Don W. Cleveland

PROVIDER: MSV000098098 | MassIVE | Sun Jun 08 17:39:00 BST 2025

REPOSITORIES: MassIVE

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