Biology subjects

Allerton, S. C.

Publications and source records attributed to Allerton, S. C..

3 recordsLinked to original sources

bioRxiv2025

Tracking gene expression of single mitochondria in live neurons using nanotweezers

Neurons are highly polarised cells that depend on mitochondria for energy and signalling homeostasis. Importantly, energy and signalling requirements vary considerably across individual neurons both spatially and temporally. Therefore, to fully understand neuronal mitochondria, methods are needed to analyse mitochondria in live cells over time. The nanotweezer, a minimally invasive single-cell sampling technique, enables precise extraction a individual mitochondria from defined subcellular locations. Here, we combine single-mitochondrial extraction from live neurons with mitochondrial gene expression tracking and mtDNA profiling. By tracking mitochondrial gene expression in the same neurons over time, we reveal a downregulation of mitochondrial genes MT-ND1 and MT-ATP6 following exposure to -synuclein aggregates, independent of the proximity of the aggregates to the sampled mitochondria. Our approach provides precise, dynamic measurements of mitochondrial composition and gene expression in vivo at single-organelle resolution, enabling mechanistic studies of neuronal mitochondrial heterogeneity and its perturbation in models of neurodegeneration.

neuroscience↗

bioRxiv2024

Molecular rotors provide insight into the mechanism of formation and conversion of α-synuclein aggregates

-Synuclein is an intrinsically disordered protein that forms amyloids in Parkinsons disease. Currently, detection methods predominantly report on the formation of mature amyloids but have poor sensitivity to the early-stage, toxic oligomers. Molecular rotors are fluorophores that sense changes in the viscosity of their local environment. Here, we monitor -synuclein oligomer formation using the fluorescence lifetime of molecular rotors. We detect oligomer formation and conversion into amyloids for wild type and two -synuclein variants; the pathological mutant A30P and {Delta}P -synuclein, which lacks a master regulator region of aggregation (residues 36-42). We report that A30P -synuclein shows a similar rate of oligomer formation compared to wild type -synuclein, whereas {Delta}P -synuclein shows delayed oligomer formation. Additionally, both variants demonstrate a slower conversion of oligomers to amyloids. Our method provides a quantitative approach to unveiling the complex mechanism of -synuclein aggregation which is key to understanding the pathology of Parkinsons disease.

biochemistry↗

bioRxiv2024

The N-terminal Region of alpha-Synuclein Controls Amyloid Nucleation at the Condensate Interface

-Synuclein self-assembles into amyloid fibrils during neurodegeneration. The protein can also self-assemble via liquid-liquid phase separation to form biomolecular condensates. The link between these processes is evident, as -synuclein condensates can mature into amyloids. However, the mechanisms driving this maturation remain largely unknown, particularly when incorporating pathological post-translational modifications known to affect -synuclein self-assembly in the absence of LLPS, such as N-terminal truncation. Moreover, condensates are primarily studied as isolated entities; however, it is increasingly evident that they interact with various cellular components and surfaces. Here, we developed a microscopy-based quantitative real-time imaging protocol to investigate how N-terminal truncation influences -synuclein condensate formation, well surface wetting, and maturation. We found that increasing -synuclein truncation, which reduces N-terminal hydrophobicity, inhibits condensate sedimentation, enhances surface wettability, and accelerates maturation. Additionally, by increasing well surface hydrophobicity we decreased -synuclein condensate wettability, delaying their maturation. Thus, we propose that enhanced wettability, which increases the condensate surface-to-volume ratio, promotes -synuclein nucleation at the condensate-bulk solution interface, thereby accelerating maturation. Our results reveal distinct mechanistic roles for -synuclein N-terminal residues and indicate that condensate wetting on cellular surfaces, such as synaptic vesicles, may drive toxic aggregate formation during neurodegeneration.

biochemistry↗