Biology subjects

Trushina, N. I.

Publications and source records attributed to Trushina, N. I..

3 recordsLinked to original sources

bioRxiv2024

Redox signaling by hydrogen peroxide modulates axonal microtubule organization and induces a specific phosphorylation signature of microtubule proteins distinct from distress

Many life processes are regulated by physiological redox signals, referred to as oxidative eustress. However, excessive oxidative stress can damage biomolecules and contribute to disease. The neuronal microtubule system is critically involved in axon homeostasis, regulation of axonal transport, and neurodegenerative processes. However, whether and how physiological redox signals affect axonal microtubules is largely unknown. Using live cell imaging and super- resolution microscopy, we show that subtoxic concentrations of the central redox metabolite hydrogen peroxide increase axonal microtubule dynamics, alter the structure of the axonal microtubule array, and affect the efficiency of axonal transport. We report that the mitochondria-targeting antioxidant SkQ1 and the microtubule stabilizer EpoD abolish the increase in microtubule dynamics. We found that oxidative eustress and distress specifically modulate the phosphorylation state of the microtubule system and induce a largely non- overlapping phosphorylation pattern of MAP1B as the main target. Cell-wide phosphoproteome analysis revealed that different signaling pathways are inversely activated by oxidative eustress and distress. Signaling via casein kinase (CK2) and pyruvate dehydrogenase kinases (PDK) is activated during eustress and signaling via mammalian target of rapamycin (mTOR) and serum/glucocorticoid-regulated protein kinase (SGK) is activated during distress. The results suggest that the redox metabolite and second messenger hydrogen peroxide induces rapid and local reorganization of the microtubule array in response to mitochondrial activity or as a messenger from neighboring cells by activating specific signaling cascades.

neuroscience↗

bioRxiv2022

Quantitative live cell imaging of a tauopathy model enables the identification of a polypharmacological drug candidate that restores physiological microtubule regulation

Tauopathies such as Alzheimers disease are characterized by the aggregation and increased phosphorylation of the microtubule-associated protein tau. The pathological changes in tau are closely linked to neurodegeneration, making tau a prime candidate for intervention. However, the multiple facets of tau function and the lack of cellular tauopathy models that could support mechanism-based drug development hampers progress. Here we report the development of a live-cell imaging approach to quantitatively monitor pathological changes of human tau as it interacts with axonal microtubules. We show that a full-length aggregation-prone tau construct exhibits reduced interaction with microtubules as it increasingly aggregates. Through chemoinformatic analyses, we identified 2-phenyloxazole (PHOX) derivatives as putative polypharmacological small molecules that inhibit tau aggregation and modulate tau phosphorylation. We found that PHOX15 restores the physiological microtubule interaction of aggregation-prone tau in neurons and inhibits the first phase of tau aggregation in vitro. Furthermore, we report that PHOX15 inhibits the tau kinases GSK3{beta} and Cdk5, alters the kinome activity of model neurons, and reduces tau phosphorylation at disease-relevant sites. Molecular dynamics simulations highlight cryptic channel-like pockets crossing tau protofilaments and indicate that the binding of PHOX15 in one of the channels reduces the protofilaments ability to adopt a PHF-like conformation. The data show that our imaging approach provides a useful tool for identifying compounds that modulate tau-microtubule interaction in axons. We demonstrate that a polypharmacological approach to simultaneously treat tau aggregation and tau phosphorylation is able to restore physiological microtubule regulation, identifying PHOX15 as a promising drug candidate to counteract tau-induced neurodegeneration.

neuroscience↗

bioRxiv2022

Tau and α-synuclein shape microtubule organization and microtubule-dependent transport in neuronal dendrites

Tau and -synuclein are major players in neurodegenerative diseases, but their physiological role, particularly in dendrites, is poorly understood. Here we show that, surprisingly, lack of tau protein induces the development of a more elaborate dendritic arbor of hippocampal pyramidal cells in organotypic tissue. Using high-speed volumetric lattice light-sheet microscopy and single particle tracking, we found a more directional KIF1A-mediated transport in dendrites of Tau KO cells. Increased transport processivity correlated with longer and straighter dendritic microtubules as revealed by three-dimensional super-resolution microscopy of cultured hippocampal neurons. Unbiased mass spectrometric analysis of tissue showed highly increased expression of -synuclein in Tau KO hippocampi. Overexpression of -synuclein mimicked the transport characteristics observed in Tau KO cells. Our data indicate that tau and -synuclein shape microtubule-dependent transport in neuronal dendrites, thereby promoting dendritic arborization during maturation. Furthermore, the data demonstrate that transport efficiency and length and straightness of microtubules are correlated.

neuroscience↗