Biology subjects

Stowell, M.

Publications and source records attributed to Stowell, M..

4 recordsLinked to original sources

bioRxiv2026

TDP-43 is required to build and maintain sarcomeres

Skeletal muscle contractile units or sarcomeres require constant maintenance as they are subjected to continuous chemical and mechanical stress. When sarcomere maintenance is disrupted, as occurs in progressive neuromuscular diseases, muscle progressively atrophies, reducing muscle strength and motor control. Transient cytoplasmic ribonucleoprotein aggregates comprised of TDP-43 bound to mRNAs encoding sarcomeric structural proteins (myo-granules) are implicated in building muscle. Ablating TDP-43 in differentiated skeletal muscle causes phenotypes remarkably similar to those of progressive neuromuscular diseases, including muscle atrophy, loss of muscle mass, and aberrantly organized sarcomeres. When injured, differentiated muscle lacking TDP-43 is incapable of repair, failing to build sarcomeres, severely disrupting muscle morphology with fibrotic tissue replacing muscle tissue. TDP-43 is thus required to build and maintain sarcomeres, likely protecting and transporting mRNAs encoding sarcomeric structural proteins in myo-granules.

Cell Biology↗

bioRxiv2024

Post-Translational Modifications Control Phase Transitions of Tau

The self-assembly of Tau(297-391) into filaments, which mirror the structures observed in Alzheimers disease (AD) brains, raises questions about the role of AD-specific post-translational modifications (PTMs) in the formation of paired helical filaments (PHFs). To investigate this, we developed a synthetic approach to produce Tau(291-391) featuring N-acetyllysine, phosphoserine, phosphotyrosine, and N-glycosylation at positions commonly modified in post-mortem AD brains, thus facilitating the study of their roles in Tau pathology. Using transmission electron microscopy (TEM), cryo-electron microscopy (cryo-EM), and a range of optical microscopy techniques, we discovered that these modifications generally hinder the in vitro assembly of Tau into PHFs. Interestingly, while acetylations effect on Tau assembly displayed variability, either promoting or inhibiting phase transitions in the context of cofactor free aggregation, heparin-induced aggregation, and RNA-mediated liquid-liquid phase separation (LLPS), phosphorylation uniformly mitigated these processes. Our observations suggest that PTMs, particularly those situated outside the fibrils rigid core are pivotal in the nucleation of PHFs. Moreover, in scenarios involving heparin-induced aggregation leading to the formation of heterogeneous aggregates, most AD-specific PTMs, except for K311, appeared to decelerate the aggregation process. The impact of acetylation on RNA-induced LLPS was notably site-dependent, exhibiting both facilitative and inhibitory effects, whereas phosphorylation consistently reduced LLPS across all proteoforms examined. These insights underscore the complex interplay between site-specific PTMs and environmental factors in modulating Tau aggregation kinetics, enhancing our understanding of the molecular underpinnings of Tau pathology in AD and highlighting the critical role of PTMs located outside the ordered filament core in driving the self-assembly of Tau into PHF structures.

biophysics↗

bioRxiv2019

Rapid discovery of drug target engagement by isothermal shift assay

Identifying protein targets directly bound by drug molecules within living systems remains challenging. Here we present the isothermal shift assay, iTSA, for rapid identification of drug targets. Compared with thermal proteome profiling, a prevailing method for target engagement, iTSA offers a simplified workflow, 4-fold higher throughput, and multiplexed experimental designs with higher replication. We demonstrate application of iTSA to identify targets for several kinase inhibitors in lysates and living cells.

pharmacology and toxicology↗

bioRxiv2017

Unexpected Early Proteomic Changes in Alzheimer’s Disease Model Mice Synaptosomes

We have employed label-free quantitative proteomics of wild-type and Alzheimers disease (AD) model mice synaptosomes to investigate proteomic changes occurring during AD progression as a prelude to analysis in humans. More than 4000 proteins were analyzed using multiple analysis tools and statistical criteria. Pathway enrichment identified numerous pathways consistent with the current AD knowledge base, including dysregulation of Glutamate Receptor Signaling, Synaptic Long Term Potentiation and Depression, Rho and Rac Signaling, Calcium Signaling, and Oxidative Phosphorylation and Mitochondrial Dysfunction. Additionally, the data demonstrate that a large number of changes occur in the proteome very early relative to the onset of both traditional disease markers such as amyloid accumulation, tau phosphorylation and cognitive dysfunction. These early changes include a number of dysregulated proteins that have novel associations with AD progression. These results reinforce the importance of mechanistic investigations in early disease progression long before the classical markers of Alzheimers disease are observed.

neuroscience↗