Biology subjects

Trinkaus, V. A.

Publications and source records attributed to Trinkaus, V. A..

6 recordsLinked to original sources

bioRxiv2025

Mitochondrial proteostatic stress disrupts mitoribosome biogenesis and translation

Protein aggregation in various cellular compartments is a hallmark of proteostasis impairment linked to aging and numerous pathologies. Mitochondrial function depends on a balanced interplay of proteins imported from the cytosol as well as those synthesized on mitochondrial ribosomes (mitoribosomes). Here, we reveal an unexpected susceptibility of mitoribosome biogenesis to organellar proteostatic stress. Importing aggregation-prone proteins into yeast and human mitochondria triggered a chain of detrimental events involving extensive co-aggregation of newly-imported mitoribosome subunits and other RNA-binding proteins, as well as local disruption of mitochondrial cristae morphology. As a result, mitoribosome assembly and mitochondrial translation were severely impaired, leading to respiratory deficiency and, ultimately, loss of mitochondrial DNA. Surprisingly, dysfunction of mitochondrial HSP60 phenocopied the ribosome biogenesis defect and inhibition of translation, indicating a pronounced chaperone dependence of mitoribosome proteins. Declining mitochondrial translation likely contributes to aging and diseases associated with deficiencies in mitochondrial protein quality control machinery.

cell biology↗

bioRxiv2025

Alpha-Synuclein aggregates inhibit ESCRT-III through sequestration and collateral degradation

-Synuclein aggregation is a hallmark of Parkinsons disease and related synucleinopathies. Extracellular -synuclein fibrils enter naive cells via endocytosis, followed by transit into the cytoplasm to seed endogenous -synuclein aggregation. Intracellular aggregates sequester numerous proteins, including subunits of the ESCRT-III system for endolysosome membrane repair, but the toxic effects of these events remain poorly understood. Using cellular models and in vitro reconstitution, we found that -synuclein fibrils interact with an -helix common to ESCRT-III proteins. This interaction results in sequestration of ESCRT-III subunits and triggers their proteasomal destruction in a process of "collateral degradation." These twin mechanisms deplete the available ESCRT-III pool, initiating a toxic feedback loop. The ensuing loss of ESCRT function compromises endolysosome membranes, thereby facilitating escape of aggregate seeds into the cytoplasm, which in turn increases aggregation and ESCRT-III sequestration. We suggest that collateral degradation and triggering of self-perpetuating systems could be general mechanisms of sequestration-induced proteotoxicity. HIGHLIGHTSO_LI-Synuclein fibrils bind and sequester ESCRT-III endolysosome repair proteins C_LIO_LIAn -helical segment common to ESCRT-III mediates fibril-selective interaction C_LIO_LIFibril-bound ESCRT-III subunits undergo "collateral degradation" via the proteasome C_LIO_LIESCRT-III depletion damages endolysosomes and worsens -synuclein aggregation C_LI

biochemistry↗

bioRxiv2023

NEMO reshapes the protein aggregate interface and promotes aggrephagy by co-condensation with p62

NEMO is a ubiquitin-binding protein which regulates canonical NF-{kappa}B pathway activation in innate immune signaling, cell death regulation and host-pathogen interactions. Here we identified an NF-{kappa}B-independent function of NEMO in proteostasis regulation by promoting autophagosomal clearance of protein aggregates. NEMO-deficient cells accumulate misfolded proteins upon proteotoxic stress and are vulnerable to proteostasis challenges. Moreover, a patient with a mutation in the NEMO gene resulting in defective binding of NEMO to linear ubiquitin chains, developed a widespread mixed brain proteinopathy, including -synuclein, tau and TDP-43 pathology. NEMO amplifies linear ubiquitylation at -synuclein aggregates and promotes the local concentration of p62 into foci. In vitro, NEMO lowers the threshold concentrations required for ubiquitin-dependent phase transition of p62. In summary, NEMO reshapes the aggregate surface for efficient autophagosomal clearance by providing a mobile phase at the aggregate interphase favoring co-condensation with p62.

cell biology↗

bioRxiv2022

The AAA+ chaperone VCP disaggregates Tau fibrils and generates aggregate seeds

Amyloid-like aggregates of the microtubule-associated protein Tau are associated with several neurodegenerative disorders including Alzheimers disease. The existence of cellular machinery for the removal of such aggregates has remained unclear, as specialized disaggregase chaperones are thought to be absent in mammalian cells. Here we show in cell culture and in neurons that the AAA+ chaperone VCP is recruited to ubiquitylated Tau fibrils, resulting in their efficient disaggregation. Aggregate clearance depends on the functional cooperation of VCP with Hsp70 and the ubiquitin-proteasome machinery. Inhibition of VCP activity stabilizes large Tau aggregates, and is accompanied by a reduction in the amount of Tau species competent of prion- like aggregate seeding in recipient cells. Thus, disaggregation by VCP generates seeding-active Tau as byproduct. These findings identify VCP as a core component of the machinery for the removal of neurodegenerative disease aggregates and suggest that its activity can be associated with enhanced aggregate spreading in tauopathies.

cell biology↗

bioRxiv2021

The extracellular chaperone Clusterin enhances Tau aggregate seeding in a cellular model

Spreading of aggregate pathology across brain regions acts as a driver of disease progression in Tau-related neurodegeneration, including Alzheimers disease (AD) and frontotemporal dementia. Aggregate seeds released from affected cells are internalized by naive cells and induce the prion-like templating of soluble Tau into neurotoxic aggregates. Here we show in a cellular model system and in neurons that Clusterin, an abundant extracellular chaperone, strongly enhances Tau aggregate seeding. Upon interaction with Tau aggregates, Clusterin stabilizes highly potent, soluble seed species. Tau/Clusterin complexes enter recipient cells via endocytosis and compromise the endolysosomal compartment, allowing transfer to the cytosol where they propagate aggregation of endogenous Tau. Thus, upregulation of Clusterin, as observed in AD patients, may enhance Tau seeding and possibly accelerate the spreading of Tau pathology.

cell biology↗

bioRxiv2020

In situ architecture of neuronal alpha-Synuclein inclusions

-Synuclein (-Syn) aggregation is a hallmark of devastating neurodegenerative disorders including Parkinsons disease (PD) and multiple systems atrophy (MSA)1,2. -Syn aggregates spread throughout the brain during disease progression2, suggesting mechanisms of intercellular seeding. Formation of -Syn amyloid fibrils is observed in vitro3,4 and fibrillar -Syn has been purified from patient brains5,6, but recent reports questioned whether disease-relevant -Syn aggregates are fibrillar in structure7-9. Here we use cryo-electron tomography (cryo-ET) to image neuronal Lewy body-like -Syn inclusions in situ at molecular resolution. We show that the inclusions consist of -Syn fibrils crisscrossing a variety of cellular organelles such as the endoplasmic reticulum (ER), mitochondria and autophagic structures, without interacting with membranes directly. Neuronal inclusions seeded by recombinant or MSA patient-derived -Syn aggregates have overall similar architecture, although MSA-seeded fibrils show higher structural flexibility. Using gold-labeled seeds we find that aggregate nucleation is predominantly mediated by -Syn oligomers, with fibrils growing unidirectionally from the seed. Our results conclusively demonstrate that neuronal -Syn inclusions contain -Syn fibrils intermixed with cellular membranes, and illuminate the mechanism of aggregate nucleation.

cell biology↗