Breaking the Balance: Cellular Stress, Proteostasis, Aggregates and Neurodegeneration

A special issue of Cells (ISSN 2073-4409).

Deadline for manuscript submissions: 25 September 2026 | Viewed by 1051

Editor

Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
Interests: proteastasis; neurodegeneration; aging

Special Issue Information

Dear Colleagues,

Neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and Huntington's disease are characterized by progressive neuronal dysfunction and loss, often associated with the accumulation of misfolded proteins and intracellular aggregates. At the heart of these conditions lies a fundamental breakdown in cellular proteostasis—the ability of cells to maintain a functional proteome through finely tuned networks of protein synthesis, folding, trafficking, and degradation. Cellular stress, whether due to aging, oxidative damage, metabolic dysfunction, or environmental factors, places an increasing burden on these proteostasis mechanisms. As these systems fail, toxic aggregates form, triggering inflammation, impairing organelle function, and disrupting neural connectivity. This Special Issue will explore how various forms of cellular stress compromise proteostasis and drive the formation of protein aggregates in the nervous system. We welcome contributions investigating molecular mechanisms, stress–response pathways, protein quality control systems, and emerging therapeutic approaches for restoring proteostasis or preventing aggregate toxicity. Studies using in vitro models, in vivo systems, or human patient data are all encouraged. By bringing together diverse perspectives on the collapse of proteostasis and its link to neurodegeneration, we will highlight shared mechanisms and novel insights that could inform future interventions.

Dr. Zhaoyu Li
Guest Editor

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Keywords

  • proteostasis
  • cellular stress
  • protein aggregation
  • neurodegeneration
  • autophagy
  • unfolded protein response
  • oxidative stress
  • aging
  • molecular chaperones
  • protein quality control

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Published Papers (2 papers)

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Research

24 pages, 9647 KB  
Article
Neurodegenerative NMNAT2 Deficiency Promotes APP Processing in a SARM1-Dependent Manner
by Andrea Enriquez, Sen Yang, Karen Ling, Paymaan Jafar-Nejad and Hui-Chen Lu
Cells 2026, 15(12), 1100; https://doi.org/10.3390/cells15121100 - 17 Jun 2026
Viewed by 163
Abstract
Metabolic dysfunction and proteinopathy are hallmarks of neurodegenerative disease, yet their mechanistic interplay remains poorly understood. Here, we show that loss of the neuronal NAD+-synthesizing enzyme Nicotinamide mononucleotide adenylyltransferase 2 (NMNAT2) disrupts amyloid precursor protein (APP) processing in cortical neurons, leading [...] Read more.
Metabolic dysfunction and proteinopathy are hallmarks of neurodegenerative disease, yet their mechanistic interplay remains poorly understood. Here, we show that loss of the neuronal NAD+-synthesizing enzyme Nicotinamide mononucleotide adenylyltransferase 2 (NMNAT2) disrupts amyloid precursor protein (APP) processing in cortical neurons, leading to accumulation of APP C-terminal fragments (APP-CTFs). NMNAT2 deficiency lowers the NAD+/NADH redox ratio coincident with APP-CTF buildup. Temporal profiling reveals a biphasic increase in APP-CTFs, with an initial gradual rise followed by rapid accumulation, paralleling the expansion of differentially expressed proteins. Pathway analysis indicates early activation of JNK/MAPK signaling, followed by late-stage suppression of mitochondrial pathways and induction of endoplasmic reticulum stress and unfolded protein response programs. Seahorse analyses reveal early glycolytic impairment followed by deficits in mitochondrial respiration. Knockdown of the NAD+ hydrolase sterile alpha and TIR motif-containing protein 1 (SARM1) restores mitochondrial function and normalizes APP-CTF levels in NMNAT2 knockout neurons, whereas NAD+ supplementation provides only modest rescue. Together, these data demonstrate that neuronal NAD+ depletion drives progressive, SARM1-dependent disruption of glucose metabolism and proteostasis, impairing APP processing. The NMNAT2–SARM1 axis thus links metabolic stress to proteinopathy and highlights SARM1 as a central mediator of neurodegenerative dysfunction. Full article
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16 pages, 2351 KB  
Article
Suppression of Tau Phosphorylation Induces Neurotoxicity, Causing Developmental Defects and Degeneration in C. elegans
by Man Pok Lu, Yi Rong, Jingyi Wang, Xiaochun Yu, Hongjiang Liu, Yingjie Wu, Minxing Zhang, Yining Chen, Yidong Li, Yuner Yan, Aiden Liu and Zhaoyu Li
Cells 2026, 15(9), 793; https://doi.org/10.3390/cells15090793 - 27 Apr 2026
Viewed by 480
Abstract
Tau hyperphosphorylation is a hallmark of tauopathies and is closely associated with neurodegeneration. While targeting kinases and phosphatases to suppress tau phosphorylation has become an increasingly attractive therapeutic approach, the functional significance of tau phosphorylation and the potential risks of suppressing this process [...] Read more.
Tau hyperphosphorylation is a hallmark of tauopathies and is closely associated with neurodegeneration. While targeting kinases and phosphatases to suppress tau phosphorylation has become an increasingly attractive therapeutic approach, the functional significance of tau phosphorylation and the potential risks of suppressing this process are not fully understood. Using C. elegans, we introduced non-phosphorylatable tau mutations (hTauAP) to model the suppression of tau phosphorylation. Unexpectedly, we found that hTauAP induced severe neurotoxicity, resulting in behavioural deficits and severe neurite abnormalities. This neurotoxicity is associated with excessive accumulation of hTauAP on microtubules, leading to both neurite developmental defects and adult neurite degeneration. The neurotoxic effects of hTauAP require its microtubule-binding domain (MTB) and are primarily driven by the loss of phosphorylation in the C-terminal region (CTR). Removing either domain reduces microtubule association and suppresses toxicity. Within CTR, suppressing phosphorylation at S396 or S404 is critical for neurotoxicity. These findings highlight the essential role of tau phosphorylation in neuronal function and underscore the potential risks of broadly suppressing tau phosphorylation as a therapeutic strategy. Full article
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