The intracellular accumulation of polymeric neuroserpin explains the severity of the dementia FENIB

Miranda, Elena; Ian, MacLeod; Davies, Mark; Pérez, Juan; Römisch, Karin; Crowther, Damian C.; Lomas, David A.

doi:10.1093/hmg/ddn041

Cited by 90 publications

(178 citation statements)

References 43 publications

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“…1A). Notably, G392E neuroserpin, which is associated with the most severe form of FENIB (7), formed the most aggregates, consistent with previous findings that this mutant easily forms accumulated "polymers" (21). The quantitative data are shown in Fig.…”

Section: Regulation Of Aggregate Formation and Cellular Turnover Of Msupporting

confidence: 88%

The Endoplasmic Reticulum (ER)-associated Degradation System Regulates Aggregation and Degradation of Mutant Neuroserpin

Ying

Wang

Fan

et al. 2011

Journal of Biological Chemistry

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Familial encephalopathy with neuroserpin inclusion bodies is a neurodegenerative disorder characterized by the accumulation of neuroserpin polymers in the endoplasmic reticulum (ER) of cortical and subcortical neurons in the CNS because of neuroserpin point mutations. ER-associated degradation (ERAD) is involved in mutant neuroserpin degradation. In this study, we demonstrate that two ER-associated E3 ligases, Hrd1 and gp78, are involved in the ubiquitination and degradation of mutant neuroserpin. Overexpression of Hrd1 and gp78 decreases the mutant neuroserpin protein level, whereas Hrd1 and gp78 knockdown increases mutant neuroserpin stability. Moreover, ERAD impairment by mutant valosin-containing protein increases the mutant neuroserpin protein level and aggregate formation. Thus, these findings identify mutant neuroserpin as an ERAD target and show that Hrd1 and gp78 mediate mutant neuroserpin turnover through the ERAD pathway.Misfolding of specific proteins can lead to the formation of aggregates, which is associated with most neurodegenerative disorders. Protein aggregates are extracellular in Alzheimer's disease, cytosolic in Parkinson's disease and amyotrophic lateral sclerosis, both cytosolic and intranuclear in polyglutamine (polyQ) 3 diseases, and localize to the endoplasmic reticulum (ER) in familial encephalopathy with neuroserpin inclusion bodies (FENIB), which is caused by neuroserpin mutations (1). Although the role of the protein aggregates in the pathogenesis of these diseases is still poorly understood, a common feature of these aggregates is that they are all marked by ubiquitin. Neurodegenerative protein aggregation is closely related to the ubiquitin-proteasome system, a major cellular turnover system (2). Mutant neuroserpin aggregates have been observed in brain and cultured cells (3, 4). Neuroserpin is a secretory glycoprotein (5) that is a member of the serine protease inhibitor serpin family, and it is mainly expressed in the CNS (6). Mutations in neuroserpin result in its misfolding and accumulation in the ER (3, 4, 7). To date, four mutants of neuroserpin, S49P, S52R, H338R, and G392E, have been identified in association with FENIB (8). In FENIB-diseased brains, G392E, the most disruptive mutant, forms more inclusion bodies and at an earlier age of onset (13 years) than the other neuroserpin mutants (9). Because the earlier onset of FENIB is strongly correlated with the level of intracellular neuroserpin accumulation, neuroserpin accumulation appears to play a central role in FENIB pathology.Many accumulated proteins that are caused by mutations or ER stress are targeted by a protein quality control system, termed ER-associated degradation (ERAD). ERAD is a degradation system in which proteins that are misfolded in the ER are exported to the cytosol for proteasomal degradation (10, 11). ER-associated E3 ubiquitin ligases, together with the VCPUfd1-Npl4 complex, are key components of the ERAD machinery. During the ERAD process, selected proteins are ubiquitinated by E3 ubiquitin lig...

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Section: Regulation Of Aggregate Formation and Cellular Turnover Of Msupporting

confidence: 88%

The Endoplasmic Reticulum (ER)-associated Degradation System Regulates Aggregation and Degradation of Mutant Neuroserpin

Ying

Wang

Fan

et al. 2011

Journal of Biological Chemistry

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“…Western blotting was performed under denaturing and nondenaturing (Miranda et al 2004) conditions using antibodies against GFP (Clonetch), a-tubulin (Sigma-Aldrich), ATF6 (Imgenex), eIF2a/eIF2aP (Cell Signaling), neuroserpin (Miranda et al 2008), LC3-I/-II (Thelen et al 2012), and actin (Sigma-Aldrich). Visualization and quantification was done with either Imager Gel Doc System and Quantity One software (Bio-Rad) or Typhoon Trio scanner with ImageQuant software (GE Healthcare).…”

Section: Sds-page and Immunoblottingmentioning

confidence: 99%

“…The ELISA was performed according to published protocols (Miranda et al 2008). Three mice per genotype and timepoint were analyzed.…”

Section: Elisamentioning

confidence: 99%

“…This argues for an age-dependent selective and temporally limited activation of two different ER stress pathways in Tg(NS S49P ). The availability of an ELISA specific for polymeric neuroserpin (Miranda et al 2008) allowed us to investigate the temporal distribution of polymeric neuroserpin in Tg(NS S49P ) and Tg(NS) mice. This analysis revealed a temporary decline of polymeric neuroserpin between weeks 20 and 45 and an exponential increase from week 64 onwards in Tg(NS S49P ), whereas polymeric neuroserpin could not be detected in Tg(NS) at any timepoint ( Figure 5F).…”

Section: Defects In the Upr Cause Enhanced Srp-2 Aggregation In Wormsmentioning

confidence: 99%

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A Novel Interaction Between Aging and ER Overload in a Protein Conformational Dementia

et al. 2013

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Intraneuronal deposition of aggregated proteins in tauopathies, Parkinson disease, or familial encephalopathy with neuroserpin inclusion bodies (FENIB) leads to impaired protein homeostasis (proteostasis). FENIB represents a conformational dementia, caused by intraneuronal polymerization of mutant variants of the serine protease inhibitor neuroserpin. In contrast to the aggregation process, the kinetic relationship between neuronal proteostasis and aggregation are poorly understood. To address aggregate formation dynamics, we studied FENIB in Caenorhabditis elegans and mice. Point mutations causing FENIB also result in aggregation of the neuroserpin homolog SRP-2 most likely within the ER lumen in worms, recapitulating morphological and biochemical features of the human disease. Intriguingly, we identified conserved protein quality control pathways to modulate protein aggregation both in worms and mice. Specifically, downregulation of the unfolded protein response (UPR) pathways in the worm favors mutant SRP-2 accumulation, while mice overexpressing a polymerizing mutant of neuroserpin undergo transient induction of the UPR in young but not in aged mice. Thus, we find that perturbations of proteostasis through impairment of the heat shock response or altered UPR signaling enhance neuroserpin accumulation in vivo. Moreover, accumulation of neuroserpin polymers in mice is associated with an age-related induction of the UPR suggesting a novel interaction between aging and ER overload. These data suggest that targets aimed at increasing UPR capacity in neurons are valuable tools for therapeutic intervention.

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“…S49P) are associated with a greater number and more pervasive distribution of Collins bodies and an earlier onset and more severe progression of dementia and PME (Davis et al 2002;Gooptu and Lomas 2009). Transient transfection of the mutant genes into cell lines also shows that the more destabilizing mutations result in the formation of longer polymers and a greater degree of ER retention (Miranda et al 2004(Miranda et al , 2008. Taken together, these data show that FENIB is an excellent model for conformationaldependent proteotoxicity because the disease is due to highly penetrant autosomal dominant missense mutations within a single gene; the phenotype is aging dependent, with more destabilizing mutations presenting earlier and with more severe neuronal loss; and severity is correlated with the degree of misfolded protein accumulation within the ER, which places strain directly on ER proteostasis pathways.…”

Section: Discussionmentioning

confidence: 99%

The Aggregation-Prone Intracellular Serpin SRP-2 Fails to Transit the ER inCaenorhabditis elegans

Silverman¹,

Cummings²,

O’Reilly³

et al. 2015

Genetics

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Familial encephalopathy with neuroserpin inclusions bodies (FENIB) is a serpinopathy that induces a rare form of presenile dementia. Neuroserpin contains a classical signal peptide and like all extracellular serine proteinase inhibitors (serpins) is secreted via the endoplasmic reticulum (ER)-Golgi pathway. The disease phenotype is due to gain-of-function missense mutations that cause neuroserpin to misfold and aggregate within the ER. In a previous study, nematodes expressing a homologous mutation in the endogenous Caenorhabditis elegans serpin, srp-2, were reported to model the ER proteotoxicity induced by an allele of mutant neuroserpin. Our results suggest that SRP-2 lacks a classical N-terminal signal peptide and is a member of the intracellular serpin family. Using confocal imaging and an ER colocalization marker, we confirmed that GFP-tagged wild-type SRP-2 localized to the cytosol and not the ER. Similarly, the aggregationprone SRP-2 mutant formed intracellular inclusions that localized to the cytosol. Interestingly, wild-type SRP-2, targeted to the ER by fusion to a cleavable N-terminal signal peptide, failed to be secreted and accumulated within the ER lumen. This ER retention phenotype is typical of other obligate intracellular serpins forced to translocate across the ER membrane. Neuroserpin is a secreted protein that inhibits trypsinlike proteinase. SRP-2 is a cytosolic serpin that inhibits lysosomal cysteine peptidases. We concluded that SRP-2 is neither an ortholog nor a functional homolog of neuroserpin. Furthermore, animals expressing an aggregation-prone mutation in SRP-2 do not model the ER proteotoxicity associated with FENIB.

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The intracellular accumulation of polymeric neuroserpin explains the severity of the dementia FENIB

Cited by 90 publications

References 43 publications

The Endoplasmic Reticulum (ER)-associated Degradation System Regulates Aggregation and Degradation of Mutant Neuroserpin

The Endoplasmic Reticulum (ER)-associated Degradation System Regulates Aggregation and Degradation of Mutant Neuroserpin

A Novel Interaction Between Aging and ER Overload in a Protein Conformational Dementia

The Aggregation-Prone Intracellular Serpin SRP-2 Fails to Transit the ER inCaenorhabditis elegans

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