Biology subjects

Winter, R.

Publications and source records attributed to Winter, R..

3 recordsLinked to original sources

bioRxiv2025

Protein-Independent Liquid - Liquid Phase Separation of Adenosine Triphosphate under Crowded Conditions

Adenosine triphosphate (ATP), a common constituent of protein-rich biomolecular condensates, itself undergoes liquid-liquid phase separation (LLPS) even in the absence of polypeptides. Using polyethylene glycol as macromolecular crowding agent, we observed robust ATP droplet formation at pH 2-11. Moderate NaCl and lower temperatures promote LLPS by lowering critical ATP and crowder concentrations. Very high salt reverses this trend through anomalous underscreening, but ATP droplets still survive in hypersaline environments. Most importantly, physiological millimolar ATP concentrations are sufficient for phase separation in the presence of millimolar Mg2+ and crowders, mimicking intracellular conditions. pH tunes intermolecular interactions, evidenced by inversion of the adenosine circular dichroism Cotton effect. These results reveal intrinsic, protein-independent LLPS of ATP with potential roles in cellular compartmentalization and pathological phase transitions.

biophysics↗

bioRxiv2024

Topological confinement by a membrane anchor suppresses phase separation into protein aggregates: implications for prion diseases

Protein misfolding and aggregation are a hallmark of various neurodegenerative disorders. However, the underlying mechanisms driving protein misfolding in the cellular context are incompletely understood. Here we show that the restriction of conformational degrees of freedom by a membrane anchor stabilizes the native protein conformation and suppresses liquid-liquid phase separation and protein aggregation. Inherited prion diseases in humans and neurodegeneration in transgenic mice are linked to the expression of anchorless prion protein (PrP), suggesting that the C-terminal glycosylphosphatidylinositol (GPI) anchor of native PrP impedes spontaneous formation of neurotoxic and infectious PrP species. Combining novel in vitro and in vivo approaches, we show that anchoring to membranes prevents spontaneous aggregation of PrP. Upon release from the membrane, PrP undergoes a rapid conformational transition to detergent-insoluble aggregates. Our study supports an essential role of the GPI anchor in preventing spontaneous misfolding of PrPC.

molecular biology↗

bioRxiv2020

Comparison of manual and automated ventricle segmentation in the maternal immune stimulation rat model of schizophrenia

Maternal immune stimulation (MIS) is strongly implicated in the etiology of neuropsychiatric disorders. Magnetic resonance imaging (MRI) studies provide evidence for brain structural abnormalities in rodents following prenatal exposure to MIS. Reported volumetric changes in adult MIS offspring comprise among others larger ventricular volumes, consistent with alterations found in patients with schizophrenia. Linking rodent models of MIS with non-invasive small animal neuroimaging modalities thus represents a powerful tool for the investigation of structural endophenotypes. Traditionally manual segmentation of regions-of-interest, which is laborious and prone to low intra- and inter-rater reliability, was employed for data analysis. Recently automated analysis platforms in rodent disease models are emerging. However, none of these has been found to reliably detect ventricular volume changes in MIS nor directly compared manual and automated data analysis strategies. The present study was thus conducted to establish an automated, structural analysis method focused on lateral ventricle segmentation. It was applied to ex-vivo rat brain MRI scans. Performance was validated for phenotype induction following MIS and preventive treatment data and compared to manual segmentation. In conclusion, we present an automated analysis platform to investigate ventricular volume alterations in rodent models thereby encouraging their preclinical use in the search for new urgently needed treatments.

neuroscience↗