Showing papers on "Proteotoxicity published in 2023"

Cell surface protein aggregation triggers endocytosis to maintain plasma membrane proteostasis

Abstract: Abstract The ability of cells to manage consequences of exogenous proteotoxicity is key to cellular homeostasis. While a plethora of well-characterised machinery aids intracellular proteostasis, mechanisms involved in the response to denaturation of extracellular proteins remain elusive. Here we show that aggregation of protein ectodomains triggers their endocytosis via a macroendocytic route, and subsequent lysosomal degradation. Using ERBB2/HER2-specific antibodies we reveal that their cross-linking ability triggers specific and fast endocytosis of the receptor, independent of clathrin and dynamin. Upon aggregation, canonical clathrin-dependent cargoes are redirected into the aggregation-dependent endocytosis (ADE) pathway. ADE is an actin-driven process, which morphologically resembles macropinocytosis. Physical and chemical stress-induced aggregation of surface proteins also triggers ADE, facilitating their degradation in the lysosome. This study pinpoints aggregation of extracellular domains as a trigger for rapid uptake and lysosomal clearance which besides its proteostatic function has potential implications for the uptake of pathological protein aggregates and antibody-based therapies.

The functional role of Ire1 in regulating autophagy and proteasomal degradation under prolonged proteotoxic stress

Abstract: Inhibition of endoribonuclease/kinase Ire1 has shown beneficial effects in many proteotoxicity‐induced pathology models. The mechanism by which this occurs has not been elucidated completely. Using a proteotoxic yeast model of Huntington's disease, we show that the deletion of Ire1 led to lower protein aggregation at longer time points. The rate of protein degradation was higher in ΔIre1 cells. We monitored the two major protein degradation mechanisms in the cell. The increase in expression of Rpn4, coding for the transcription factor controlling proteasome biogenesis, was higher in ΔIre1 cells. The chymotrypsin‐like proteasomal activity was also significantly enhanced in these cells at later time points of aggregation. The gene and protein expression levels of the autophagy gene Atg8 were higher in ΔIre1 than in wild‐type cells. Significant increase in autophagy flux was also seen in ΔIre1 cells at later time points of aggregation. The results suggest that the deletion of Ire1 activates UPR‐independent arms of the proteostasis network, especially under conditions of aggravated stress. Thus, the inhibition of Ire1 may regulate UPR‐independent cellular stress‐response pathways under prolonged stress.

Preclinical mouse model of a misfolded PNLIP variant develops chronic pancreatitis

Abstract: Objective Increasing evidence implicates mutation-induced protein misfolding and endoplasm reticulum (ER) stress in the pathophysiology of chronic pancreatitis (CP). The paucity of animal models harbouring genetic risk variants has hampered our understanding of how misfolded proteins trigger CP. We previously showed that pancreatic triglyceride lipase (PNLIP) p.T221M, a variant associated with steatorrhoea and possibly CP in humans, misfolds and elicits ER stress in vitro suggesting proteotoxicity as a potential disease mechanism. Our objective was to create a mouse model to determine if PNLIP p.T221M causes CP and to define the mechanism. Design We created a mouse model of Pnlip p.T221M and characterised the structural and biochemical changes in the pancreas aged 1–12 months. We used multiple methods including histochemistry, immunostaining, transmission electron microscopy, biochemical assays, immunoblotting and qPCR. Results We demonstrated the hallmarks of human CP in Pnlip p.T221M homozygous mice including progressive pancreatic atrophy, acinar cell loss, fibrosis, fatty change, immune cell infiltration and reduced exocrine function. Heterozygotes also developed CP although at a slower rate. Immunoblot showed that pancreatic PNLIP T221M misfolded as insoluble aggregates. The level of aggregates in homozygotes declined with age and was much lower in heterozygotes at all ages. The Pnlip p.T221M pancreas had increased ER stress evidenced by dilated ER, increased Hspa5 (BiP) mRNA abundance and a maladaptive unfolded protein response leading to upregulation of Ddit3 (CHOP), nuclear factor-κB and cell death. Conclusion Expression of PNLIP p.T221M in a preclinical mouse model results in CP caused by ER stress and proteotoxicity of misfolded mutant PNLIP.

Preclinical Overview of Drugs Affecting Protein Turnover in Multiple Myeloma

Abstract: Multiple myeloma (MM) is the prototypic cancer model for proteotoxicity due to the extensive and sustained synthesis of immunoglobulin or free light chain in the face of insufficient proteasome activity. A large body of work has shown that the baseline ratio between load on the proteasome and proteasome activity can predict response to proteasome inhibitors (PIs), and that an increase in proteasome capacity or load can increase or reduce PI sensitivity, respectively. As the proteasome is part of an extensive network of proteins participating in maintaining protein homeostasis (or proteostasis), there has been an interest in identifying novel molecular targets for MM and other forms of lymphoma therapy within the proteostasis network. In this chapter, we will review FDA-approved and investigational agents targeting the proteostasis network, with an emphasis on the molecular mechanisms driving PI resistance and laboratory-based combination treatments to overcome it.

Novel compound inhibits glycolysis, proteotoxicity, inflammation, and impairments in animal models of Alzheimer’s, Huntington’s, and stroke: Aging as a consequence of glycolysis

Abstract: Alzheimer’s Disease (AD) and other age-related diseases are increasingly among the most devastating strains on public health systems as the population ages, yet few treatments produce clinically significant protection. Although it is widely agreed that proteotoxicity drives impairments in AD and other neurological diseases, many preclinical and case-report studies indicate that increased microglial production of pro-inflammatory cytokines such as TNF-a mediate proteotoxicity in AD and other neurological conditions. The critical importance of inflammation, especially TNF-a, in driving age-related diseases is indicated by the fact that Humira, simply a monoclonal antibody to TNF-a, has become the top-selling drug in history, even though it does not cross the blood-brain barrier. Since target-based strategies to discover drugs to treat these diseases have largely failed, we developed parallel high-throughput phenotypic screens to discover small molecules which inhibit age-related proteotoxicity in a C. elegans model of AD, AND microglia inflammation (LPS-induced TNF-a). In the initial screen of 2560 compounds to delay Abeta proteotoxicity in C. elegans, the most protective compounds were, in order, phenylbutyrate (HDAC inhibitor), methicillin (beta lactam antibiotic), and quetiapine (tricyclic antipsychotic). These classes of compounds are already robustly implicated as potentially protective in AD and other neurodegenerative diseases. In addition to quetiapine, other tricyclic antipsychotic drugs also delayed age-related Abeta proteotoxicity and microglial TNF-a. Based on these results we carried out extensive structure-activity relationship studies, leading to the synthesis of a novel congener of quetiapine, #310, which inhibits a wide range of pro-inflammatory cytokines in mouse and human myeloid cells, and delays impairments in animal models of AD, Huntington’s, and stroke. #310 is highly concentrated in brain after oral delivery with no apparent toxicity, increases lifespan, and produces molecular responses highly similar to those produced by dietary restriction. Among these molecular responses are induction of CBP and inhibition of CtBP and CSPR1, and inhibition of glycolysis, reversing gene expression profiles and elevated glycolysis associated with AD. Several lines of investigation strongly supported that the protective effects of #310 are mediated by activating the Sigma-1 receptor, whose protective mechanisms in turn also entail inhibiting glycolysis. Reduced glycolysis has also been implicated in the generally protective effects of dietary restriction, rapamycin, reduced IFG-1 activity, and ketones during aging, suggesting that aging is at least in large part a consequence of glycolysis. In particular, the age-related increase in adiposity, and subsequent pancreatic decompensation leading to diabetes, is plausibly a consequence of age-related increase in beta cell glycolysis. Consistent with these observations, the glycolytic inhibitor 2-DG inhibited microglial TNF-a and other markers of inflammation, delayed Abeta proteotoxicity, and increased lifespan. To our knowledge no other molecule exhibits all these protective effects which makes #310 a uniquely promising candidate to treat AD and other age-related diseases. Thus it is plausible that #310 or possibly even more effective congeners could displace Humira as a widely used therapy for age-related diseases. Furthermore, these studies suggest that the efficacy of tricyclic compounds to treat psychosis and depression could be due to their anti-inflammatory effects mediated by the Sigma-1 receptor, rather than the D2 receptor, and that better drugs to treat these conditions, as well as addiction, with fewer metabolic side effects could be developed by focusing on the Sigma-1 receptor rather than the D2 receptor. These results strongly support the value of phenotypic screens to discover drugs to treat AD and other age-related diseases and to elucidate mechanisms driving those diseases.

The cytotoxic activity of carfilzomib together with nelfinavir is superior to the bortezomib/nelfinavir combination in non-small cell lung carcinoma

Abstract: Abstract Chemotherapy resistance is still a major problem in the treatment of patients with non-small-cell-lung carcinoma (NSCLC), and novel concepts for the induction of cytotoxicity in NSCLC are highly warranted. Proteotoxicity, the induction of cytotoxicity by targeting the ubiquitin proteasome system, represents an appealing innovative strategy . The combination of the proteasome inhibitor bortezomib (BTZ) and the proteotoxic stress-inducing HIV drug nelfinavir (NFV) synergistically induces proteotoxicity and shows encouraging preclinical efficacy in NSCLC. The second-generation proteasome inhibitor carfilzomib (CFZ) is superior to BTZ and overcomes BTZ resistance in multiple myeloma patients. Here, we show that CFZ together with NFV is superior to the BTZ + NFV combination in inducing endoplasmic reticulum stress and proteotoxicity through the accumulation of excess proteasomal substrate protein in NSCLC in vitro and ex vivo. Interestingly, NFV increases the intracellular availability of CFZ through inhibition of CFZ export from NSCLC cells that express multidrug resistance (MDR) protein. Combining CFZ with NFV may therefore represent a future treatment option for NSCLC, which warrants further investigation.

Caprylic acid attenuates amyloid-β proteotoxicity by supplying energy via β-oxidation in an Alzheimer’s disease model of the nematode <i>Caenorhabditis elegans</i>

Abstract: Computer-based analysis of motility was used as a measure of amyloid-β (Aβ) proteotoxicity in the transgenic strain GMC101, expressing human Aβ1-42 in body wall muscle cells. Aβ-aggregation was quantified to relate the effects of caprylic acid (CA) to the amount of the proteotoxic protein. Gene knockdowns were induced through RNA-interference (RNAi). Moreover, the estimation of adenosine triphosphate (ATP) levels, the mitochondrial membrane potential (MMP) and oxygen consumption served the evaluation of mitochondrial function. CA improved the motility of GMC101 nematodes and reduced Aβ aggregation. Whereas RNAi for orthologues encoding key enzymes for α-lipoic acid and ketone bodies synthesis did not affect motility stimulation by CA, knockdown of orthologues involved in β-oxidation of fatty acids diminished its effects. The efficient energy gain by application of CA was finally proven by the increase of ATP levels in association with increased oxygen consumption and MMP. In conclusion, CA attenuates Aβ proteotoxicity by supplying energy via FAO. Since especially glucose oxidation is disturbed in Alzheimer´s disease, CA could potentially serve as an alternative energy fuel.

Rutin and its application to amyotrophic lateral sclerosis

Abstract: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease with high mortality rates that leads to muscle paralysis due to motor neuron degeneration in the central nervous system. ALS severely compromises the quality of life and lifespan due to the lack of an effective therapeutic management strategy. Though the exact pathomechanism is yet to be thoroughly understood, several cellular insults have been identified to cause the progression of ALS. These include neuroinflammation, oxidative stress, nitrosative stress, mitochondrial dysregulation, axonal transport defects, impairment in vesicle trafficking, proteotoxicity, and endoplasmic reticulum (ER) stress. Most research studies focus on a single factor or a minor fraction of these cellular dysregulations, resulting in only negligible therapeutic effects. ALS is multifactorial, and hence, a multitargeted therapeutic approach is essential to overcome clinical manifestations and improve the survival of individuals affected by ALS. Small molecules such as flavonoids have attracted attention in recent decades due to their superior antioxidant, antiinflammatory, and antiapoptotic properties. Rutin is one such potent flavonoid antioxidant that exhibits beneficial effects against various neurodegenerative diseases by overcoming multiple cellular insults. This chapter provides comprehensive insights on ALS and the relationship between rutin and its mitigating effects on the signaling pathways implicated in ALS.

A Proteome-Centric View of Ageing, including that of the Skin and Age-Related Diseases: Considerations of a Common Cause and Common Preventative and Curative Interventions

Abstract: The proteome comprises all proteins of a cell or organism. To carry their catalytic and structure-related functions, proteins must be correctly folded into their unique native three-dimensional structures. Common oxidative protein damage affects their functionality by impairing their catalytic and interactive specificities. Oxidative damage occurs preferentially to misfolded proteins and fixes the misfolded state. This review provides an overview of the mechanism and consequences of oxidative proteome damage - specifically irreversible protein carbonylation - in relation to ageing, including that of the skin as well as to age-related degeneration and diseases (ARDD) and their mitigation. A literature review of published manuscripts, available from PubMed, focusing on proteome, proteostasis, proteotoxicity, protein carbonylation, related inflammatory diseases, ARDD and the impact of the damaged proteome on ageing. During ageing, proteome damage, especially protein carbonylation, correlates with biological age. Carbonylated proteins form aggregates which can be considered as markers and accelerators of ageing and are common markers of most ARDD. Protein carbonylation leads to general ageing of the organism and organs including the skin and potentially to diseases including Alzheimer and Parkinson disease, diabetes, psoriasis, and skin cancer. Current research is promising and may open new therapeutic approaches and perspectives by targeting proteome protection as an age and ARDD management strategy.

Ser14-RPN6 Phosphorylation Mediates the Activation of 26S Proteasomes by cAMP and Protects against Cardiac Proteotoxic Stress in Mice.

Abstract: Background A better understanding of the regulation of proteasome activities can facilitate the search for new therapeutic strategies. A cell culture study shows that cAMP-dependent protein kinase (PKA) activates the 26S proteasome by phosphorylating Ser14 of RPN6 (pS14-RPN6), but this discovery and its physiological significance remain to be established in vivo . Methods Male and female mice with Ser14 of Rpn6 mutated to Ala (S14A) or Asp (S14D) to respectively block or mimic pS14-Rpn6 were created and used along with cells derived from them. cAMP/PKA were manipulated pharmacologically. Ubiquitin-proteasome system (UPS) functioning was evaluated with the GFPdgn reporter mouse and proteasomal activity assays. Impact of S14A and S14D on proteotoxicity was tested in mice and cardiomyocytes overexpressing the misfolded protein R120G-CryAB (R120G). Results PKA activation increased pS14-Rpn6 and 26S proteasome activities in wild-type (WT) but not S14A embryonic fibroblasts (MEFs), adult cardiomyocytes (AMCMs), and mouse hearts. Basal 26S proteasome activities were significantly greater in S14D myocardium and AMCMs than in WT counterparts. S14D::GFPdgn mice displayed significantly lower myocardial GFPdgn protein but not mRNA levels than GFPdgn mice. In R120G mice, a classic model of cardiac proteotoxicity, basal myocardial pS14-Rpn6 was significantly lower compared with non- transgenic littermates, which was not always associated with reduction of other phosphorylated PKA substrates. Cultured S14D neonatal cardiomyocytes displayed significantly faster proteasomal degradation of R120G than WT neonatal cardiomyocytes. Compared with R120G mice, S14D/S14D::R120G mice showed significantly greater myocardial proteasome activities, lower levels of total and K48-linked ubiquitin conjugates and of aberrant CryAB protein aggregates, less reactivation of fetal genes and cardiac hypertrophy, and delays in cardiac malfunction. Conclusions This study establishes in animals that pS14-Rpn6 mediates the activation of 26S proteasomes by PKA and that the reduced pS14-Rpn6 is a key pathogenic factor in cardiac proteinopathy, thereby identifies a new therapeutic target to reduce cardiac proteotoxicity.

Profiling the Hsp70 Chaperone Network in Heat-Induced Proteotoxic Stress Models of Human Neurons

Abstract: Simple Summary Rising temperatures and consequent heat waves are detrimental manifestations of climate change for the population’s health. Exposure to extreme environmental heat during episodes of intense and long-lasting heat waves is a direct cause of heat-related illnesses, particularly life-threatening heat stroke. A harmful manifestation of heat stroke is damage to the central nervous system, particularly the brain, which can result in permanent disability in approximately a third of patients. Heat can damage biomolecules, particularly proteins, because of their high vulnerability to changes in cellular conditions such as temperature. Temperature-induced protein damage leads to misfolding and clumping into aggregates that are the neurotoxic agents for most neurodegenerative disorders, including heat-induced damage, with certain defining features for later. The cellular response to these processes is to increase the production of a subset of helpful proteins called heat shock proteins 70 (Hsp70). Here, we report that hyperthermia induces severe brain proteotoxic stress in different neuronal models. Likewise, we showed a differential vulnerability among neuronal cells, with more damage in mature than young cells. As part of the stress response, we report the identification, differential importance, and co-expression of Hsp70 chaperones and their interacting partners in the human neuronal models of heat-induced damage. These findings support the idea that proteotoxic stress may play a role in heat stroke-induced brain damage. This study also helps expand our knowledge about stress response during neurodegenerative damage and is essential in developing therapeutic approaches. Abstract Heat stroke is among the most hazardous hyperthermia-related illnesses and an emerging threat to humans from climate change. Acute brain injury and long-lasting brain damage are the hallmarks of this condition. Hyperthermic neurological manifestations are remarkable for their damage correlation with stress amplitude and long-term persistence. Hyperthermia-induced protein unfolding, and nonspecific aggregation accumulation have neurotoxic effects and contribute to the pathogenesis of brain damage in heat stroke. Therefore, we generated heat-induced, dose-responsive extreme and mild proteotoxic stress models in medulloblastoma [Daoy] and neuroblastoma [SH-SY5Y] and differentiated SH-SY5Y neuronal cells. We show that heat-induced protein aggregation is associated with reduced cell proliferation and viability. Higher protein aggregation in differentiated neurons than in neuroblastoma precursors suggests a differential neuronal vulnerability to heat. We characterized the neuronal heat shock response through RT-PCR array analysis of eighty-four genes involved in protein folding and protein quality control (PQC). We identify seventeen significantly expressed genes, five of which are Hsp70 chaperones, and four of their known complementing function proteins. Protein expression analysis determined the individual differential contribution of the five Hsp70 chaperones to the proteotoxic stress response and the significance of only two members under mild conditions. The co-expression analysis reveals significantly high co-expression between the Hsp70 chaperones and their interacting partners. The findings of this study lend support to the hypothesis that hyperthermia-induced proteotoxicity may underlie the brain injury of heat stroke. Additionally, this study presents a comprehensive map of the Hsp70 network in these models with potential clinical and translational implications.

Exploiting inter-tissue stress signaling mechanisms to preserve organismal proteostasis during aging

Abstract: Aging results in a decline of cellular proteostasis capacity which culminates in the accumulation of phototoxic material, causing the onset of age-related maladies and ultimately cell death. Mechanisms that regulate proteostasis such as cellular stress response pathways sense disturbances in the proteome. They are activated to increase the expression of protein quality control components that counteract cellular damage. Utilizing invertebrate model organisms such as Caenorhabditis elegans, it has become increasingly evident that the regulation of proteostasis and the activation of cellular stress responses is not a cell autonomous process. In animals, stress responses are orchestrated by signals coming from other tissues, including the nervous system, the intestine and the germline that have a profound impact on determining the aging process. Genetic pathways discovered in C. elegans that facilitate cell nonautonomous regulation of stress responses are providing an exciting feeding ground for new interventions. In this review I will discuss cell nonautonomous proteostasis mechanisms and their impact on aging as well as ongoing research and clinical trials that can increase organismal proteostasis to lengthen health- and lifespan.

Alpha-1-Antitrypsin Deficiency: A Misfolded Secretory Glycoprotein Damages the Liver by Proteotoxicity and Its Reduced Secretion Predisposes to Emphysematous Lung Disease Because of Protease-Inhibitor Imbalance

Abstract: In the classical form of α1-antitrypsin deficiency (ATD) a point mutation leads to protein misfolding such that the mutant protein accumulates in liver cells with a marked decrease in levels of this protein in the blood and body fluids. Because the major function of α1-antitrypsin is inhibition of neutrophil elastase and several other neutrophil proteases, individuals with ATD are susceptible to destructive lung disease/emphysema, now called chronic obstructive pulmonary disease (COPD), by a loss-of-function mechanism in which uninhibited neutrophil proteases destroy the connective tissue matrix of the lung. Homozygous individuals are also susceptible to liver disease by a gain-of-toxic function mechanism triggered by the intracellular accumulation of the misfolded protein. The only therapeutic strategies currently available are protein replacement therapy and lung transplantation for COPD and liver transplantation for the subgroup with progressive liver involvement. New therapeutic strategies that mitigate the intracellular accumulation/proteotoxicity have advanced to clinical trials and corrective genetic strategies are in earlier pre-clinical phases of development.

Abstract 4814: Compensatory interplay of p97 segregase and HSP70 chaperone protect cancer cells from heat-induced proteotoxicity

Abstract: Due to malignant transformation, cancer cells are characterized by elevated levels of genotoxic, replication or proteotoxic stresses, which makes them vulnerable to various external conditions, including increased temperature. Thus, hyperthermia represents a very effective therapeutic modality usually combined with standard chemotherapy or radiation. Moreover, the elevated temperature is often used in experimental studies related to protein aggregation, cellular heat shock response and other proteostasis mechanisms relevant to cancer progression and treatment. Recently, we developed a single-cell method to inflict defined, subcellular thermal damage, adopting the plasmon resonance principle. Dose-defined heat causes protein damage in subcellular compartments, rapid heat-shock chaperone recruitment, and ensuing engagement of the ubiquitin-proteasome system, providing unprecedented insights into spatiotemporal response to protein damage relevant to cancer. Using this versatile method, we discovered so-far unsuspected compensatory interplay of p97 translocase, the ubiquitin-proteasome system and heat shock protein chaperones in the processing of heat-damaged proteins. As both, p97 and heat shock proteins, represent potential cancer-relevant drug targets, these results can contribute to the development and better implementation of related therapies in cancer treatment. Citation Format: Zdenek Skrott, Katarina Chroma, Petr Muller, Ales Panacek, Jiri Bartek, Martin Mistrik. Compensatory interplay of p97 segregase and HSP70 chaperone protect cancer cells from heat-induced proteotoxicity. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4814.

Proteostasis and Ribostasis Impairment as Common Cell Death Mechanisms in Neurodegenerative Diseases

Abstract: The cellular homeostasis of proteins (proteostasis) and RNA metabolism (ribostasis) are essential for maintaining both the structure and function of the brain. However, aging, cellular stress conditions, and genetic contributions cause disturbances in proteostasis and ribostasis that lead to protein misfolding, insoluble aggregate deposition, and abnormal ribonucleoprotein granule dynamics. In addition to neurons being primarily postmitotic, nondividing cells, they are more susceptible to the persistent accumulation of abnormal aggregates. Indeed, defects associated with the failure to maintain proteostasis and ribostasis are common pathogenic components of age-related neurodegenerative diseases, including Alzheimer’s disease, Parkinson’s disease, and amyotrophic lateral sclerosis. Furthermore, the neuronal deposition of misfolded and aggregated proteins can cause both increased toxicity and impaired physiological function, which lead to neuronal dysfunction and cell death. There is recent evidence that irreversible liquid–liquid phase separation (LLPS) is responsible for the pathogenic aggregate formation of disease-related proteins, including tau, α-synuclein, and RNA-binding proteins, including transactive response DNA-binding protein 43, fused in sarcoma, and heterogeneous nuclear ribonucleoprotein A1. Investigations of LLPS and its control therefore suggest that chaperone/disaggregase, which reverse protein aggregation, are valuable therapeutic targets for effective treatments for neurological diseases. Here we review and discuss recent studies to highlight the importance of understanding the common cell death mechanisms of proteostasis and ribostasis in neurodegenerative diseases.

Nanoparticulate air pollution disrupts proteostasis in Caenorhabditis elegans

Abstract: The proteostasis network comprises the biochemical pathways that together maintain and regulate proper protein synthesis, transport, folding, and degradation. Many progressive neurodegenerative diseases, such as Huntington’s disease (HD) and Alzheimer’s disease (AD), are characterized by an age-dependent failure of the proteostasis network to sustain the health of the proteome, resulting in protein misfolding, aggregation, and, often, neurotoxicity. Although important advances have been made in recent years to identify genetic risk factors for neurodegenerative diseases, we still know relatively little about environmental risk factors such as air pollution. Exposure to nano-sized particulate air pollution, referred to herein as nanoparticulate matter (nPM), has been shown to trigger the accumulation of misfolded and oligomerized amyloid beta (Aβ) in mice. Likewise, air pollution is known to exacerbate symptoms of AD in people. We asked whether nPM contributes to the misfolded protein load, thereby overwhelming the proteostasis network and triggering proteostasis decline. To address this, we utilized C. elegans that express reporter proteins that are sensitive to changes in the protein folding environment and respond by misfolding and displaying readily scorable phenotypes, such as localized YFP fluorescence or paralysis. We found that nPM exacerbated protein aggregation in body wall muscle cells, increasing the number of large visible protein aggregates, the amount of high molecular weight protein species, and proteotoxicity. Taken together, the data point to nPM negatively impacting proteostasis. Therefore, it seems plausible that nPM exposure may exacerbate symptoms of AD and age-related dementia in a manner that is at least partially dependent on proteostasis decline.

Data from The Zinc-Finger AN1-Type Domain 2a Gene Acts as a Regulator of Cell Survival in Human Melanoma: Role of E3-Ligase cIAP2

Abstract: <div>Abstract<p>The zinc-finger AN1-type domain-2a gene, also known as AIRAP (arsenite-inducible RNA-associated protein), was initially described as an arsenite-inducible gene in <i>Caenorhabditis elegans</i> and mammalian cells. Differently from the AIRAP worm homologue, <i>aip-1</i>, a gene known to play an important role in preserving animal lifespan and buffering arsenic-induced proteotoxicity, mammals have a second, constitutively expressed, AIRAP-like gene (AIRAPL), recently implicated in myeloid transformation. We have identified human AIRAP as a canonical heat-shock gene, whose expression, differently from AIRAPL, is strictly dependent on the proteotoxic-stress regulator heat-shock factor 1 (HSF1). AIRAP function is still not well defined and there is no information on AIRAP in cancer. Herein we show that bortezomib and next-generation proteasome inhibitors ixazomib and carfilzomib markedly induce AIRAP expression in human melanoma at concentrations comparable to plasma-levels in treated patients. AIRAP-downregulation leads to bortezomib sensitization, whereas AIRAP-overexpression protects melanoma cells from the drug, identifying AIRAP as a novel HSF1-regulated marker of chemotherapy resistance. More importantly, this study unexpectedly revealed that, also in the absence of drugs, AIRAP-silencing hinders melanoma clonogenic potential and spheroid growth, promoting caspase activation and apoptotic cell death, an effect independent of AIRAPL and linked to downregulation of the antiapoptotic protein cIAP2. Interestingly, AIRAP was found to interact with cIAP2, regulating its stability in melanoma. Taken together, the results identify AIRAP as a novel HSF1-dependent regulator of prosurvival networks in melanoma cells, opening new therapeutic perspectives in chemoresistant melanoma treatment.</p>Implications:<p>The findings identify ZFAND2A/AIRAP as a novel stress-regulated survival factor implicated in the stabilization of the antiapoptotic protein cIAP2 and as a new potential therapeutic target in melanoma.</p></div>

Early life changes in histone landscape protect against age-associated amyloid toxicities through HSF-1 dependent regulation of lipid metabolism

Abstract: Abstract Recent studies revealed that early-in-life events can have highly beneficial long-term effects in animals. We now demonstrate that exposure of Caenorhabditis elegans to reactive oxygen species during development protects against amyloid-induced proteotoxicity later in life. We show that this protection is initiated by the inactivation of the redox sensitive H3K4me3 modifying COMPASS complex, and conferred by a substantial increase in the heat shock independent activity of heat shock factor 1 (HSF-1), a longevity factor known to act predominantly during C. elegans development. We show that depletion of HSF-1 leads to dramatic rearrangements of the organismal lipid landscape, and a significant decrease in mitochondrial β-oxidation. Both of these activities appear to majorly contribute to HSF-1’s protective effects against amyloid toxicity. In summary, our study reveals previously unknown links between developmental changes in the histone landscape, HSF-1 activity and lipid metabolism and the protection against age-associated amyloid toxicities later in life.