Biology subjects

Rose, K. M.

Publications and source records attributed to Rose, K. M..

3 recordsLinked to original sources

bioRxiv2026

Structural Mechanism and Cellular Restriction of Tau Seeding from Endolysosomes

The prion-like spread of tau from cell to cell in the central nervous system involves escape from the endolysosomal network, which is counteracted by the lysosomal repair activity of the ESCRT system. Here, we investigate whether other components of the lysosomal damage sensing and repair system, namely the ESCRT-recruiting Ca2+ sensor ALG-2, conjugation of ATG8s to single membranes (CASM), the phosphoinositide-initiated tethering and lipid transport (PITT) pathway, and the Parkinsons disease-related lipid transporter VPS13C are involved in tau spread. We found that the PITT pathway and VPS13C are strongly implicated in tau seeding by pre-formed fibrils (PFFs) in both neurons and astrocytes, CASM has a major role in astrocytes but not neurons, and ALG-2 has a lesser role in both. We then investigated the mechanism of damage and seeding by tau PFFs using cryo-electron tomography. Unlike the classical lysosome damage agent LLOMe, tau PFFs were not seen to directly interact with the lysosomal membrane, nor do they distort local membrane curvature. Lysosomes in PFF-treated cells were structurally intact. Extensive protein aggregates of similar character were seen in both the lysosomal lumen and in the cytosol proximal to lysosomes. The observations are consistent with the PFF-induced co-aggregation of tau with other cellular materials within lysosomes, with leakage to the cytosol attributed to reversible holes in the lysosome membrane.

cell biology↗

bioRxiv2025

Matters arising: Forced Symmetry Artifacts in a Prohibitin Complex Structure

In a recent publication, Lange et al.1 proposed an 11-spoked wheel model for the mitochondrial prohibitin complex consisting of six PHB1 and five PHB2 subunits built into low resolution density obtained from 11-fold symmetry averaging. The proposed unequal stoichiometry is inherently incompatible with symmetry. The building of an asymmetric molecular model into density obtained by 11-fold symmetry averaging is inherently self-contradictory. This contradiction alone calls the validity of the derived structure into question. Our own data revealed that the complex primarily adopts an asymmetric open conformation in situ. We show that it was the incorrect symmetry imposition on the open conformation that led to the spoked wheel density reported by Lange et al.. Further validation by re-analysis of crosslinking-mass spectrometry data, and a test of in situ template matching all support a larger prohibitin complex architecture. These findings underscore the need for great care in the imposition of symmetry cryo-ET at less than atomistic resolution.

cell biology↗

bioRxiv2024

Human ESCRT-I and ALIX function as scaffolding helical filaments in vivo

The Endosomal Sorting Complex Required for Transport (ESCRT) is an evolutionarily conserved machinery that performs reverse-topology membrane scission in cells universally required from cytokinesis to budding of enveloped viruses. Upstream acting ESCRT-I and ALIX control these events and link recruitment of viral and cellular partners to late-acting ESCRT-III CHMP4 through incompletely understood mechanisms. Using structure-function analyses combined with super-resolution imaging, we show that ESCRT-I and ALIX function as distinct helical filaments in vivo. Together, they are essential for optimal structural scaffolding of HIV-1 nascent virions, the retention of viral and human genomes through defined functional interfaces, and recruitment of CHMP4 that itself assembles into corkscrew-like filaments intertwined with ESCRT-I or ALIX helices. Disruption of filament assembly or their conformationally clustered RNA binding interfaces in human cells impaired membrane abscission, resulted in major structural instability and leaked nucleic acid from nascent virions and nuclear envelopes. Thus, ESCRT-I and ALIX function as helical filaments in vivo and serve as both nucleic acid-dependent structural scaffolds as well as ESCRT-III assembly templates. Significance statementWhen cellular membranes are dissolved or breached, ESCRT is rapidly deployed to repair membranes to restore the integrity of intracellular compartments. Membrane sealing is ensured by ESCRT-III filaments assembled on the inner face of membrane; a mechanism termed inverse topology membrane scission. This mechanism, initiated by ESCRT-I and ALIX, is universally necessary for cytokinesis, wound repair, budding of enveloped viruses, and more. We show ESCRT-I and ALIX individually oligomerize into helical filaments that cluster newly discovered nucleic acid-binding interfaces and scaffold-in genomes within nascent virions and nuclear envelopes. These oligomers additionally appear to serve as ideal templates for ESCRT-III polymerization, as helical filaments of CHMP4B were found intertwined ESCRT-I or ALIX filaments in vivo. Similarly, corkscrew-like filaments of ALIX are also interwoven with ESCRT-I, supporting a model of inverse topology membrane scission that is synergistically reinforced by inward double filament scaffolding.

cell biology↗