Proximity proteomics of C9orf72 dipeptide repeat proteins identifies molecular chaperones as modifiers of poly-GA aggregation

Liu, Feilin; Morderer, Dmytro; Wren, M. W. D.; Vettleson-Trutza, Sara A; Wang, Yanzhe; Rabichow, Benjamin E.; Salemi, Michelle; Phinney, Brett S.; Oskarsson, Björn; Dickson, Dennis W.; Rossoll, Wilfried

doi:10.1186/s40478-022-01322-x

Cited by 31 publications

(25 citation statements)

References 112 publications

(155 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Three neurodegenerative mechanisms are implicated in C9ORF72 -ALS/FTD pathology: loss of function due to reduced C9ORF72 transcript and proteins levels [ 2 ], a gain of function due to the formation of RNA foci [ 46 ], and a gain of toxic function, due to the generation and accumulation of five different dipeptide repeat proteins (DPRs), via repeat-associated non-AUG (RAN) translation of hexanucleotide repeat sequences from both sense and antisense strands [ 20 ]. Of the five DPR species, there is evidence for a toxic gain-of-function role for PolyGA, PolyGR, and PolyPR aggregates in promoting neurodegeneration in affected brain areas [ 30 , 36 , 40 ]. Previous studies have established that the positively charged arginine-rich PolyGR and PolyPR proteins, and the highly insoluble PolyGA aggregates are extremely toxic in neurons [ 44 ].…”

Section: Introductionmentioning

confidence: 99%

PolyGA targets the ER stress-adaptive response by impairing GRP75 function at the MAM in C9ORF72-ALS/FTD

et al. 2022

View full text Add to dashboard Cite

ER stress signaling is linked to the pathophysiological and clinical disease manifestations in amyotrophic lateral sclerosis (ALS). Here, we have investigated ER stress-induced adaptive mechanisms in C9ORF72-ALS/FTD, focusing on uncovering early endogenous neuroprotective mechanisms and the crosstalk between pathological and adaptive responses in disease onset and progression. We provide evidence for the early onset of ER stress-mediated adaptive response in C9ORF72 patient-derived motoneurons (MNs), reflected by the elevated increase in GRP75 expression. These transiently increased GRP75 levels enhance ER–mitochondrial association, boosting mitochondrial function and sustaining cellular bioenergetics during the initial stage of disease, thereby counteracting early mitochondrial deficits. In C9orf72 rodent neurons, an abrupt reduction in GRP75 expression coincided with the onset of UPR, mitochondrial dysfunction and the emergence of PolyGA aggregates, which co-localize with GRP75. Similarly, the overexpression of PolyGA in WT cortical neurons or C9ORF72 patient-derived MNs led to the sequestration of GRP75 within PolyGA inclusions, resulting in mitochondrial calcium (Ca2+) uptake impairments. Corroborating these findings, we found that PolyGA aggregate-bearing human post-mortem C9ORF72 hippocampal dentate gyrus neurons not only display reduced expression of GRP75 but also exhibit GRP75 sequestration within inclusions. Sustaining high GRP75 expression in spinal C9orf72 rodent MNs specifically prevented ER stress, normalized mitochondrial function, abrogated PolyGA accumulation in spinal MNs, and ameliorated ALS-associated behavioral phenotype. Taken together, our results are in line with the notion that neurons in C9ORF72-ALS/FTD are particularly susceptible to ER–mitochondrial dysfunction and that GRP75 serves as a critical endogenous neuroprotective factor. This neuroprotective pathway, is eventually targeted by PolyGA, leading to GRP75 sequestration, and its subsequent loss of function at the MAM, compromising mitochondrial function and promoting disease onset.

show abstract

Section: Introductionmentioning

confidence: 99%

PolyGA targets the ER stress-adaptive response by impairing GRP75 function at the MAM in C9ORF72-ALS/FTD

et al. 2022

View full text Add to dashboard Cite

show abstract

“…Another approach would be to reduce DPRs burden within motor neurons. One method involves the overexpression of heat shock protein B8 (HSPB8), which led to the increase in the autophagy-mediated degradation of DPRs, and enabled the clearance of aggregation prone proteins before they could convert into inclusions ( Liu et al, 2022 ). Furthermore, an interesting natural compound called berberine has been shown to influence TDP-43 protein aggregations boosting its degradation via autophagy ( Chang et al, 2016 ).…”

Section: Therapeutic Strategies For Targeting Alp In C9orf7...mentioning

confidence: 99%

Autophagy and neurodegeneration: Unraveling the role of C9ORF72 in the regulation of autophagy and its relationship to ALS-FTD pathology

Diab

Pilotto

Saxena

2023

Front. Cell. Neurosci.

View full text Add to dashboard Cite

The proper functioning of the cell clearance machinery is critical for neuronal health within the central nervous system (CNS). In normal physiological conditions, the cell clearance machinery is actively involved in the elimination of misfolded and toxic proteins throughout the lifetime of an organism. The highly conserved and regulated pathway of autophagy is one of the important processes involved in preventing and neutralizing pathogenic buildup of toxic proteins that could eventually lead to the development of neurodegenerative diseases (NDs) such as Alzheimer’s disease or Amyotrophic lateral sclerosis (ALS). The most common genetic cause of ALS and frontotemporal dementia (FTD) is a hexanucleotide expansion consisting of GGGGCC (G4C2) repeats in the chromosome 9 open reading frame 72 gene (C9ORF72). These abnormally expanded repeats have been implicated in leading to three main modes of disease pathology: loss of function of the C9ORF72 protein, the generation of RNA foci, and the production of dipeptide repeat proteins (DPRs). In this review, we discuss the normal physiological role of C9ORF72 in the autophagy-lysosome pathway (ALP), and present recent research deciphering how dysfunction of the ALP synergizes with C9ORF72 haploinsufficiency, which together with the gain of toxic mechanisms involving hexanucleotide repeat expansions and DPRs, drive the disease process. This review delves further into the interactions of C9ORF72 with RAB proteins involved in endosomal/lysosomal trafficking, and their role in regulating various steps in autophagy and lysosomal pathways. Lastly, the review aims to provide a framework for further investigations of neuronal autophagy in C9ORF72-linked ALS-FTD as well as other neurodegenerative diseases.

show abstract

“…Since R and D are highly charged residues, conventional immunoprecipitation/proteomics analysis, which requires cell lysis, may lead to artificial interactions during the lysis/immunoprecipitation process. To investigate the protein–protein interactions while maintaining spatial information, we performed TurboID-mediated proximity biotin labeling of the proteomes in close proximity to each R-MCD ( Figure 3 A) [ 17 , 18 ]. The visualization of biotinylated proteins using AlexaFluor488-conjugated streptavidin revealed that TurboID-(DR) 50 exclusively biotinylated proteins in nuclear speckles, and TurboID-(D 16 R 16 ) 3 biotinylated the proteins in the nucleolus, as expected ( Figure 3 B).…”

Section: Resultsmentioning

confidence: 99%

The Patterning and Proportion of Charged Residues in the Arginine-Rich Mixed-Charge Domain Determine the Membrane-Less Organelle Targeted by the Protein

Miyagi

Yamazaki

Ueda

et al. 2022

IJMS

View full text Add to dashboard Cite

Membrane-less organelles (MLOs) are formed by biomolecular liquid–liquid phase separation (LLPS). Proteins with charged low-complexity domains (LCDs) are prone to phase separation and localize to MLOs, but the mechanism underlying the distributions of such proteins to specific MLOs remains poorly understood. Recently, proteins with Arg-enriched mixed-charge domains (R-MCDs), primarily composed of R and Asp (D), were found to accumulate in nuclear speckles via LLPS. However, the process by which R-MCDs selectively incorporate into nuclear speckles is unknown. Here, we demonstrate that the patterning of charged amino acids and net charge determines the targeting of specific MLOs, including nuclear speckles and the nucleolus, by proteins. The redistribution of R and D residues from an alternately sequenced pattern to uneven blocky sequences caused a shift in R-MCD distribution from nuclear speckles to the nucleolus. In addition, the incorporation of basic residues in the R-MCDs promoted their localization to the MLOs and their apparent accumulation in the nucleolus. The R-MCD peptide with alternating amino acids did not undergo LLPS, whereas the blocky R-MCD peptide underwent LLPS with affinity to RNA, acidic poly-Glu, and the acidic nucleolar protein nucleophosmin, suggesting that the clustering of R residues helps avoid their neutralization by D residues and eventually induces R-MCD migration to the nucleolus. Therefore, the distribution of proteins to nuclear speckles requires the proximal positioning of D and R for the mutual neutralization of their charges.

show abstract

Proximity proteomics of C9orf72 dipeptide repeat proteins identifies molecular chaperones as modifiers of poly-GA aggregation

Cited by 31 publications

References 112 publications

PolyGA targets the ER stress-adaptive response by impairing GRP75 function at the MAM in C9ORF72-ALS/FTD

PolyGA targets the ER stress-adaptive response by impairing GRP75 function at the MAM in C9ORF72-ALS/FTD

Autophagy and neurodegeneration: Unraveling the role of C9ORF72 in the regulation of autophagy and its relationship to ALS-FTD pathology

The Patterning and Proportion of Charged Residues in the Arginine-Rich Mixed-Charge Domain Determine the Membrane-Less Organelle Targeted by the Protein

Contact Info

Product

Resources

About