Huntingtin aggregation impairs autophagy leading to Argonaute-2 accumulation and global microRNA dysregulation
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ABSTRACT:
ORGANISM(S): Mus musculus Homo sapiens
PROVIDER: GSE78928 | GEO | 2018/08/07
REPOSITORIES: GEO
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2021-12-20 | PXD029689 | Pride
Project description:In this study the generic impact of protein aggregation (aggregation of proteins not associated with neurodegenerative disease) on gene expression in cultured cells was investigated by DNA microarray technology. The survey of gene expression showed that the Hsp40, Hsp70 and Hsp105 genes, all of which have documented aggregation suppression activity, were up-regulated. Unexpectedly, the survey also showed increased expression of the MEK5 gene with concomitant silencing of the MEK3 gene. The expression pattern of MEK5 at the mRNA and protein levels aligns with the kinetics of aggregate formation and dissolution. Cell viability was unaffected by protein aggregates. These findings are of particular importance for chronic neurodegenerative diseases where the intraneuronal accumulation of aggregate-prone proteins are a major characteristic of the diseases. The identification of changes in MEK5 gene expression have been observed in Alzheimer-related diseases which provides new diagnostic and therapeutic avenues in these diseases. The molecular neuropathological findings would not have occurred without the generic microarray analyses.
2005-07-20 | E-MEXP-389 | biostudies-arrayexpress
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Project description:Specific insoluble protein aggregates are the hallmarks of many neurodegenerative diseases. For example, cytoplasmic aggregates of the RNA-binding protein TDP-43 are observed in 97% of cases of Amyotrophic Lateral Sclerosis (ALS). However, whether the protein aggregates themselves or other forms of the proteins are toxic to cells is still a very open question for many of these diseases. Here we address this question for TDP-43 by systematically mutating the protein and quantifying the effects on cellular toxicity. In a dataset of >50,000 mutations in the intrinsically disordered prion-like domain (PRD), changes in hydrophobicity and aggregation potential are highly predictive of changes in toxicity. Surprisingly, however, increased hydrophobicity and cytoplasmic aggregation reduce toxicity. Mutations have their strongest effects in a central region of the PRD, with variants that increase toxicity promoting the formation of more dynamic liquid-like condensates. Moreover, the genetic interactions in double mutants indicate that specific secondary structures form in this region and have detectable effects on aggregation and toxicity in vivo. Our results demonstrate that deep mutagenesis is a powerful approach for probing the sequence-function relationships of intrinsically disordered proteins, as well as their in vivo structural conformations. Moreover, they reveal that aggregation of TDP-43 is not toxic but actually protects cells, most likely by titrating the protein away from a toxic liquid-like phase.
2019-08-14 | GSE128165 | GEO
Project description:INTRODUCTION: The pathogenicity at differing points along the aggregation pathway of many fibril-forming proteins associated with neurodegenerative diseases is unclear. Understanding the effect of different aggregation states of these proteins on cellular processes is essential to enhance understanding of diseases and provide future options for diagnosis and therapeutic intervention.</br>OBJECTIVES:To establish a robust method to probe the metabolic changes of neuronal cells and use it to monitor cellular response to challenge with three amyloidogenic proteins associated with neurodegenerative diseases in different aggregation states.</br>METHOD: Neuroblastoma SH-SY5Y cells were employed to design a robust routine system to perform a statistically rigorous NMR metabolomics study into cellular effects of sub-toxic levels of alpha-synuclein, amyloid-beta 40 and amyloid-beta 42 in monomeric, oligomeric and fibrillar conformations.</br>RESULTS: This investigation developed a rigorous model to monitor intracellular metabolic profiles of neuronal cells through combination of existing methods. This model revealed eight key metabolites that are altered when neuroblastoma cells are challenged with proteins in different aggregation states. Metabolic pathways associated with lipid metabolism, neurotransmission and adaptation to oxidative stress and inflammation are the predominant contributors to the cellular variance and intracellular metabolite levels. The observed metabolite changes for monomer and oligomer challenge may represent cellular effort to counteract the pathogenicity of the challenge, whereas fibrillar challenge is indicative of system shutdown. This implies that although markers of stress are more prevalent under oligomeric challenge the fibrillar response suggests a more toxic environment.</br>CONCLUSION: This approach is applicable to any cell type that can be cultured in a laboratory (primary or cell line) as a method of investigating how protein challenge affects signalling pathways, providing additional understanding as to the role of protein aggregation in neurodegenerative disease initiation and progression.
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Project description:During adult neurogenesis, newly formed olfactory bulb (OB) interneurons migrate radially to integrate into specific layers of the OB. Despite the importance of this process, the intracellular mechanisms that regulate radial migration remain poorly understood. Here we find that microRNA (miRNA) let-7 regulates radial migration by modulating autophagy in new-born neurons. Using Argonaute2-immunoprecipitation, we performed global profiling of miRNAs in adult-born OB neurons and identified let-7 as a highly abundant miRNA family. Knockdown of let-7 in migrating neuroblasts prevented radial migration and led to an immature morphology of newly formed interneurons. This phenotype was accompanied by a decrease in autophagic activity. Overexpression of Beclin-1 or TFEB in new-born neurons lacking let-7 resulted in re-activation of autophagy and restored radial migration. Thus, these results reveal a miRNA-dependent link between autophagy and adult neurogenesis with implications for neurodegenerative diseases where these processes are impaired.
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Project description:Protein aggregation is a hallmark of many neurodegenerative diseases. In order to cope with misfolding and aggregation, cells have evolved an elaborate network of molecular chaperones, composed of different families. But while chaperoning mechanisms for different families are well established, functional and regulatory diversification within chaperone families is still largely a mystery. Here we decided to explore chaperone functional diversity, through the lens of pathological aggregation. We revealed that different naturally-occurring isoforms of DNAJ chaperones showed differential effects on different types of aggregates. We performed a chaperone screen for modulators of two neurodegeneration-related aggregating proteins, the Huntington’s disease-related HTT-polyQ, and the ALS-related mutant FUS (mutFUS). The screen identified known modulators of HTT-polyQ aggregation, confirming the validity of our approach. Surprisingly, modulators of mutFUS aggregation were completely different than those of HTT-polyQ. Interestingly, different naturally-occurring isoforms of DNAJ chaperones had opposing effects on HTT-polyQ vs. mutFUS aggregation. We identified a complex of the full length (FL) DNAJB14 and DNAJB12 isoforms which substantially alleviated mutFUS aggregation, in an HSP70-dependent manner. Their naturally occurring short isoforms were unable to form the complex, nor to interact with HSP70, and lost their ability to reduce mutFUS aggregation. In contrast, the short isoform of DNAJB12 significantly alleviated HTT-polyQ aggregation, while DNAJB12-FL aggravated HTT-polyQ aggregation. Finally, we demonstrated that full-length DNAJB14 ameliorated mutFUS aggregation compared to DNAJB14-short in primary neurons. Together, our data unraveled distinct molecular properties required for aggregation protection in different neurodegenerative diseases, and revealed a new layer of complexity of the chaperone network elicited by naturally occurring J-protein isoforms, highlighting functional diversity among the DNAJ family.
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