biostudies-literatureLu SNINDS NIH HHSU.S. Department of Health & Human Services | National Institutes of Health (NIH)NIGMS NIH HHS1925-1937https://www.ebi.ac.uk/biostudies/studies/S-EPMC12782899biostudies-literatureUnknown27(11)In multiple neurodegenerative diseases, the RNA-binding protein TDP-43 forms cytoplasmic aggregates of distinct morphologies, including skein-like, small rounded granular and large spherical inclusions. Here, whereas the N-terminal self-oligomerization domain regulates TDP-43 demixing into cytoplasmic droplets, inhibition of N-terminal self-oligomerization domain-mediated oligomerization is shown to promote the formation of skein-like inclusions. Utilizing proximity labelling-mass spectrometry, cellular stresses are shown to induce TDP-43 association with actin-binding proteins that include filamins and α-actinin. Small interfering RNA-mediated reduction of filamin in Drosophila ameliorates cell loss from cytoplasmic TDP-43, consistent with the filamin-TDP-43 interaction enhancing cytotoxicity. TDP-43's association with actin-binding proteins is mediated by BAG3, a HSP70 family nucleotide exchange factor that regulates the proteostasis of actin-binding proteins. BAG2, another HSP70 nucleotide exchange factor, facilitates the formation of small, rounded TDP-43 inclusions. We demonstrate that both TDP-43 self-oligomerization and its binding partners, including HSP70 and cochaperones BAG2 and BAG3, drive the formation of the different types of TDP-43 inclusion.Nature cell biologyTDP-43 skein-like inclusions are formed by BAG3- and HSP70-guided co-aggregation with actin-binding proteins.PMC12782899P30 NS047101R01 NS121604R01 NS027036R01 NS27036P41 GM103533Oung SHan PZhang KCleveland DWArnold-Garcia ODiedrich JKZhang SYates Iii JRArogundade OALu SVazquez-Sanchez SRavits JOhkubo TfalseTDP-43 skein-like inclusions are formed by BAG3- and HSP70-guided co-aggregation with actin-binding proteins.In multiple neurodegenerative diseases, the RNA-binding protein TDP-43 forms cytoplasmic aggregates of distinct morphologies, including skein-like, small rounded granular and large spherical inclusions. Here, whereas the N-terminal self-oligomerization domain regulates TDP-43 demixing into cytoplasmic droplets, inhibition of N-terminal self-oligomerization domain-mediated oligomerization is shown to promote the formation of skein-like inclusions. Utilizing proximity labelling-mass spectrometry, cellular stresses are shown to induce TDP-43 association with actin-binding proteins that include filamins and α-actinin. Small interfering RNA-mediated reduction of filamin in Drosophila ameliorates cell loss from cytoplasmic TDP-43, consistent with the filamin-TDP-43 interaction enhancing cytotoxicity. TDP-43's association with actin-binding proteins is mediated by BAG3, a HSP70 family nucleotide exchange factor that regulates the proteostasis of actin-binding proteins. BAG2, another HSP70 nucleotide exchange factor, facilitates the formation of small, rounded TDP-43 inclusions. We demonstrate that both TDP-43 self-oligomerization and its binding partners, including HSP70 and cochaperones BAG2 and BAG3, drive the formation of the different types of TDP-43 inclusion.2025-01-01T00:00:00Z2025 Nov2026-06-06T11:44:03.741Z2026-05-30T03:07:44.996ZS-EPMC127828994117400410.1038/s41556-025-01789-5