Biology subjects

Brown-Wright, H.

Publications and source records attributed to Brown-Wright, H..

2 recordsLinked to original sources

bioRxiv2023

A transient protein folding response targets aggregation in the early phase of TDP-43-mediated disease

Understanding the mechanisms that drive TDP-43 pathology is integral to combating neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). To address this, we sought to determine the timeline of proteomic alterations across disease course in TDP-43 proteinopathy. Using longitudinal quantitative proteomics analysis of cortex samples from the cytoplasmic TDP-43 rNLS8 mouse model of ALS and FTLD, we identified several distinct protein subsets characterized by temporal alterations in protein abundance across diverse biological pathways, including protein folding, intracellular transport, myelination, and neuronal synaptic function. Remarkably, neurons in the rNLS8 cortex elicited a transitory response primarily comprising protein-folding factors prior to and in the earliest stages of disease progression. This response included increased levels of DnaJ homolog subfamily B member 5, DNAJB5, and proof-of-concept studies showed that DNAJB5 over-expression decreased TDP-43 aggregation in cell and cortical neuron cultures. Conversely, knockout of Dnajb5 exacerbated motor impairments caused by AAV-mediated cytoplasmic TDP-43 expression in the brains and spinal cords of mice. Lastly, the late disease proteomic signatures of rNLS8 mouse cortex strongly correlated with changes in human autopsy-derived TDP-43 proteinopathy tissues, indicating commonality of disease processes. Together, these findings reveal molecular mechanisms that regulate protein levels through distinct stages of ALS and FTLD progression, and suggest that protein folding factors that combat cytoplasmic TDP-43 protein aggregation could be protective in disease. HighlightsO_LIThe first longitudinal map of the cortex proteome throughout TDP-43-driven disease in a mouse model of cytoplasmic TDP-43 proteinopathy (rNLS8 mice). C_LIO_LICytoplasmic TDP-43 accumulation drives many dynamic changes to the cortex proteome, including increases in protein folding factors prior to disease onset. C_LIO_LIThe protein folding factor DNAJB5 decreases TDP-43 aggregation in HEK293 cells and primary cortical neurons and Dnajb5 knockout exacerbates cytoplasmic TDP-43-associated motor impairments in vivo. C_LIO_LIThe proteomic signature of the rNLS8 mouse cortex correlates strongly with postmortem brain tissue from human TDP-43 proteinopathies. C_LIO_LIA new webtool, TDP-map (https://shiny.rcc.uq.edu.au/TDP-map/), allows comparison of transcriptomic and proteomic datasets from mouse and human TDP-43 proteinopathy. C_LI

neuroscience↗

bioRxiv2022

Early activation of cellular stress and death pathways caused by cytoplasmic TDP-43 in the rNLS8 mouse model of ALS/FTD

TAR DNA binding protein 43 (TDP-43) pathology is a key feature of over 95% of amyotrophic lateral sclerosis (ALS) and nearly half of frontotemporal dementia (FTD) cases. The pathogenic mechanisms of TDP-43 dysfunction are poorly understood, however activation of cell stress pathways may contribute to pathogenesis. We therefore sought to identify which cell stress components are critical for driving disease onset and neurodegeneration in ALS/FTD. We studied the rNLS8 transgenic mouse model, which expresses human TDP-43 with a genetically-ablated nuclear localisation sequence within neurons of the brain and spinal cord resulting in cytoplasmic TDP-43 pathology and progressive motor dysfunction. Amongst numerous cell stress-related biological pathways profiled using qPCR arrays, several critical ISR effectors, including CCAAT/enhancer-binding homologous protein (Chop/Ddit3) and activating transcription factor 4 (Atf4), were upregulated in the cortex of rNLS8 mice prior to disease onset. This was accompanied by early up-regulation of anti-apoptotic gene Bcl2 and diverse pro-apoptotic genes including BH3-interacting domain death agonist (Bid). However, pro-apoptotic signalling predominated after onset of motor phenotypes. Notably, pro-apoptotic caspase-3 protein was elevated in the cortex of rNLS8 mice at later disease stages, suggesting that downstream activation of apoptosis drives neurodegeneration following failure of early protective responses. Unexpectedly, suppression of Chop in the brain and spinal cord using antisense oligonucleotide-mediated silencing had no effect on overall TDP-43 pathology or disease phenotypes in rNLS8 mice. Cytoplasmic TDP-43 accumulation therefore causes very early activation of ISR and both anti-and pro-apoptotic signalling that switches to predominant pro-apoptotic activation later in disease. These findings suggest that precise temporal modulation of cell stress and death pathways may be beneficial to protect against neurodegeneration in ALS and FTD. Key pointsO_LIISR genes Atf4 and Chop, anti-apoptotic Bcl2 and pro-apoptotic gene Bid, Bim, Noxa were upregulated in the cortex of rNLS8 mice prior to disease onset C_LIO_LIKnockdown of Chop had limited effects on TDP-43 pathology and did not alter motor deficits in rNLS8 mice C_LIO_LIBoth anti-and pro-apoptotic genes are upregulated prior to disease onset, and switches to activation of pro-apoptotic signalling at later disease stages C_LIO_LICaspase-3 activation likely drives neurodegeneration in the cortex of rNLS8 mice C_LI

neuroscience↗