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The article explores the relationship between ageing and the decline in mitochondrial oxidative capacity in skeletal muscle. Mitochondria are crucial for ATP production, and their dysfunction can lead to various health issues. Studies suggest that reduced oxidative capacity is a fundamental aspect of ageing skeletal muscle, impacting physical function and overall health. The decline in mitochondrial function with age is independent of reduced physical activity, highlighting the complex interplay of factors affecting mitochondrial health in older adults. [Extracted from the article]

Investigating amyloid–β (Aβ) peptides in solution is essential during the initial stages of developing lead compounds that can influence Aβ fibrillation while the peptide is still in a soluble state. The tendency of the Aβ(1–42) peptide to misfold in solution, correlated to the aetiology of Alzheimer's disease (AD), is one of the main hindrances to characterising its aggregation kinetics in a cell-mimetic environment. Moreover, the Aβ(1–42) aggregation triggers the unfolded protein response (UPR) in the endoplasmic reticulum (ER), leading to cellular dysfunction and multiple cell death modalities, exacerbated by reactive oxygen species (ROS), which damage cellular components and trigger inflammation. Antioxidants like curcumin, a derivative of Curcuma longa, help mitigate ER stress by scavenging ROS and enhancing antioxidant enzymes. Furthermore, evidence in the literature highlights the effect of curcumin on the secondary structure of Aβ(1–42). This explorative study investigates the Aβ(1–42) peptide conformational behaviour in the presence of curcumin and six derivatives using circular dichroism (CD) to explore their interactions with lipid bilayers, potentially preventing aggregate formation. The results suggest that the synthetic tetrahydrocurcumin (THC) derivative interacts with the amyloid peptide in all the systems presented, while cyclocurcumin (CYC) and bisdemethoxycurcumin (BMDC) only interact when the peptide is in a less stable conformation. Molecular dynamics simulations helped visualise the curcuminoids' effect in an aqueous system and hypothesise the importance of the peptide surface exposition to the solvent, differently modulated by the curcumin derivatives. [ABSTRACT FROM AUTHOR]

Endoplasmic reticulum (ER) stress is a crucial factor in the progression of obesity-related type 2 diabetes (diabesity), contributing to skeletal muscle (SKM) dysfunction, calcium imbalance, metabolic inflexibility, and muscle atrophy. The ER and mitochondria together regulate intracellular calcium levels, and melatonin, a natural compound with antioxidant properties, may alleviate these challenges. Our previous research showed that melatonin raises intracellular calcium and preserves muscle structure by enhancing mitochondrial function in obese diabetic rats. This study further explores melatonin's potential to reduce ER stress in the vastus lateralis (VL) muscle by modulating the unfolded protein response (UPR) and restoring calcium levels disrupted by diabesity. Five-week-old Zücker diabetic fatty (ZDF) rats and lean littermates of both sexes were divided into control and melatonin-treated groups (10 mg/kg/day for 12 weeks). Flame atomic absorption spectrometry results showed that melatonin restored VL intraorganellar calcium homeostasis, increasing calcium levels in mitochondria and reducing them in the ER by raising the activity and expression of calcium transporters in both sexes of ZDF rats. Melatonin also decreased ER stress markers (GRP78, ATF6, IRE1α, and PERK) and reduced pro-apoptosis markers (Bax, Bak, P-JNK, cleaved caspase 3 and 9) while increasing Bcl2 levels and melatonin receptor 2 (MT2) expression. These findings suggest that melatonin may protect against muscle atrophy in obese and diabetic conditions by mitigating ER stress and calcium imbalance, highlighting its therapeutic potential. [ABSTRACT FROM AUTHOR]

Nitrogen bisphosphonates, such as zoledronic acid, target the enzyme farnesyl diphosphate synthase (FDPS) in the isoprenoid biosynthetic pathway (IBP), and are the frontline treatment for osteolytic bone diseases. A strong affinity of these agents for bone limits their distribution out of the skeleton. Geranylgeranyl diphosphate synthase (GGDPS) is directly downstream to FDPS in the IBP and novel GGDPS inhibitors such as RAM2061 have been shown to have key drug-like features including prolonged half-life, metabolic stability, and systemic distribution. Furthermore, RAM2061 exerts anti-neoplastic benefits in mouse models of multiple myeloma and Ewing sarcoma. Therefore, we are interested in determining the potential impact of RAM2061 on osteoclast biology and bone remodeling. Studies utilizing undifferentiated RAW264.7 cells demonstrated that treatment with RAM2061 depletes cells of geranylgeranyl diphosphate, impairs protein geranylgeranylation, and induces markers of the unfolded protein response pathway and apoptosis. Differentiation of RAW264.7 cells to mature osteoclasts is disrupted by RAM2061, resulting in decreased numbers of mature osteoclasts, altered morphology, and decreased tartrate-resistant acid phosphatase activity. Treatment of fully differentiated RAW264.7 cells with RAM2061 led to decreased resorptive activity. Confocal microscopy studies revealed that RAM2061 disrupts Cdc42 localization, inhibiting proper actin ring formation in osteoclasts. No significant impact on bone turnover markers or bone histomorphology was observed following a 3-week treatment of CD-1 mice with RAM2061, although decreased numbers of osteoclasts were observed. Liquid chromatography-tandem mass spectrometry studies confirmed accumulation of RAM2061 in bone from the in vivo studies as well as hydroxyapatite binding in vitro. In conclusion, these studies are the first to demonstrate the anti-osteoclastic activity of GGDPS inhibitor treatment and support future studies exploring the therapeutic benefit of this novel therapy in the setting of pathological bone remodeling. [ABSTRACT FROM AUTHOR]

The placenta is a temporary organ that forms during pregnancy and is essential for fetal development and maternal health. As an endocrine organ, proper placental function requires continual production, folding, and transport of proteins and lipids. Central to these processes is the endoplasmic reticulum (ER), a dynamic organelle responsible for maintaining cellular protein and lipid synthesis and processing. ER stress occurs when there is an accumulation of unfolded or misfolded proteins, which triggers the activation of cellular pathways collectively called the unfolded protein response. Unfolded protein response pathways act to alleviate the misfolded protein burden and restore ER homeostasis, or if unresolved, initiate cell death. While prolonged ER stress has been linked to deficient placental function and adverse pregnancy outcomes, basal activation of unfolded protein response pathways is required for placental development and function. This review explores the importance of ER homeostasis in placental development and function, examining how disruptions in ER stress responses may contribute to adverse pregnancy outcomes. [ABSTRACT FROM AUTHOR]

ABSTRACT: Endoplasmic reticulum (ER) is a crucial organelle associated with cellular homeostasis. Accumulation of improperly folded proteins results in ER stress, accompanied by the reaction involving triggering unfolded protein response (UPR). The UPR is mediated through ER membrane-associated sensors, such as protein kinase-like ER kinase (PERK), inositol-requiring transmembrane kinase/endoribonuclease 1α, and activating transcription factor 6 (ATF6). Prolonged stress triggers cell apoptotic reaction, resulting in cell death. Neuronal cells are especially susceptible to protein misfolding. Notably, ER and UPR malfunctions are linked to many neurodegenerative diseases, such as Alzheimer's disease (AD) and Parkinson's disease (PD), delineated by accumulation of misfolded proteins. Notably, ATF family members play key roles in AD and PD pathogenesis. However, the connection between ER stress, UPR, and neuropathology is not yet fully understood. Here, we discuss our present knowledge of the association between ER stress, the UPR, and neurodegeneration in AD and PD. We also discuss the roles of ATF family members in AD and PD pathogenesis. Moreover, we provide a mechanistic clarification of how disease-related molecules affect ER protein homeostasis and explore recent findings that connect the UPR to neuronal plasticity. [ABSTRACT FROM AUTHOR]

All viruses are obligate intracellular parasites that use host machinery to synthesize viral proteins. In infected eukaryotes, viral secreted and transmembrane proteins are synthesized at the endoplasmic reticulum (ER). Many viruses refashion ER membranes into bespoke factories where viral products accumulate while evading host pattern recognition receptors. ER processes are tightly regulated to maintain cellular homeostasis, so viruses must either conform to ER regulatory mechanisms or subvert them to ensure efficient viral replication. Reticulophagy is a catabolic process that directs lysosomal degradation of ER components. There is accumulating evidence that reticulophagy serves as a form of antiviral defense; we call this defense "xERophagy" to acknowledge its relationship to xenophagy, the catabolic degradation of microorganisms by macroautophagy/autophagy. In turn, viruses can subvert reticulophagy to suppress host antiviral responses and support efficient viral replication. Here, we review the evidence for functional interplay between viruses and the host reticulophagy machinery. Abbreviations: AMFR: autocrine motility factor receptor; ARF4: ADP-ribosylation factor 4; ARL6IP1: ADP-ribosylation factor-like 6 interacting protein 1; ATL3: atlastin GTPase 3; ATF4: activating transcription factor 4; ATF6: activating transcription factor 6; BPIFB3: BPI fold containing family B, member 3; CALCOCO1: calcium binding and coiled coil domain 1; CAMK2B: calcium/calmodulin-dependent protein kinase II, beta; CANX: calnexin; CDV: canine distemper virus; CCPG1: cell cycle progression 1; CDK5RAP3/C53: CDK5 regulatory subunit associated protein 3; CIR: cargo-interacting region; CoV: coronavirus; CSNK2/CK2: casein kinase 2; CVB3: coxsackievirus B3; DAPK1: death associated protein kinase 1; DENV: dengue virus; DMV: double-membrane vesicles; EBOV: Ebola virus; EBV: Epstein-Barr Virus; EIF2AK3/PERK: eukaryotic translation initiation factor 2 alpha kinase 3; EMCV: encephalomyocarditis virus; EMV: extracellular microvesicle; ER: endoplasmic reticulum; ERAD: ER-associated degradation; ERN1/IRE1: endoplasmic reticulum to nucleus signalling 1; EV: extracellular vesicle; EV71: enterovirus 71; FIR: RB1CC1/FIP200-interacting region; FMDV: foot-and-mouth disease virus; HCMV: human cytomegalovirus; HCV: hepatitis C virus; HMGB1: high mobility group box 1; HSPA5/BiP: heat shock protein 5; IFN: interferon; IFNG/IFN-γ: interferon gamma; KSHV: Kaposi's sarcoma-associated herpesvirus; LIR: MAP1LC3/LC3-interacting region; LNP: lunapark, ER junction formation factor; MAP1LC3: microtubule-associated protein 1 light chain 3; MAP3K5/ASK1: mitogen-activated protein kinase kinase kinase 5; MAPK/JNK: mitogen-activated protein kinase; MeV: measles virus; MHV: murine hepatitis virus; NS: non-structural; PDIA3: protein disulfide isomerase associated 3; PRR: pattern recognition receptor; PRRSV: porcine reproductive and respiratory syndrome virus; RB1CC1/FIP200: RB1-inducible coiled-coil 1; RETREG1/FAM134B: reticulophagy regulator 1; RHD: reticulon homology domain; RTN3: reticulon 3; RTN3L: reticulon 3 long; sAIMs: shuffled Atg8-interacting motifs; SARS-CoV: severe acute respiratory syndrome coronavirus; SINV: Sindbis virus; STING1: stimulator of interferon response cGAMP interactor 1; SVV: Seneca Valley virus; SV40: simian virus 40; TEX264: testis expressed gene 264 ER-phagy receptor; TFEB: transcription factor EB; TRAF2: TNF receptor-associated factor 2; UIM: ubiquitin-interacting motif; UFM1: ubiquitin-fold modifier 1; UPR: unfolded protein response; VAPA: vesicle-associated membrane protein, associated protein A; VAPB: vesicle-associated membrane protein, associated protein B and C; VZV: varicella zoster virus; WNV: West Nile virus; XBP1: X-box binding protein 1; XBP1s: XBP1 spliced; xERophagy: xenophagy involving reticulophagy; ZIKV: Zika virus [ABSTRACT FROM AUTHOR]

Sensorineural hearing loss (SNHL) is characterized by a compromised cochlear perception of sound waves. Major risk factors for SNHL include genetic mutations, exposure to noise, ototoxic medications, and the aging process. Previous research has demonstrated that inflammation, oxidative stress, apoptosis, and autophagy, which are detrimental to inner ear cells, contribute to the pathogenesis of SNHL; however, the precise mechanisms remain inadequately understood. The endoplasmic reticulum (ER) plays a key role in various cellular processes, including protein synthesis, folding, lipid synthesis, cellular calcium and redox homeostasis, and its homeostatic balance is essential to maintain normal cellular function. Accumulation of unfolded or misfolded proteins in the ER leads to endoplasmic reticulum stress (ERS) and activates the unfolded protein response (UPR) signaling pathway. The adaptive UPR has the potential to reestablish protein homeostasis, whereas the maladaptive UPR, associated with inflammation, oxidative stress, apoptosis, and autophagy, can lead to cellular damage and death. Recent evidence increasingly supports the notion that ERS-mediated cellular damage responses play a crucial role in the initiation and progression of various SNHLs. This article reviews the research advancements on ERS in SNHL, with the aim of elucidating molecular biological mechanisms underlying ERS in SNHL and providing novel insights for the treatment. [ABSTRACT FROM AUTHOR]

Human lungs consist of a distinctive array of cell types, which are subjected to persistent challenges from chemical, mechanical, biological, immunological, and xenobiotic stress throughout life. The disruption of endoplasmic reticulum (ER) homeostatic function, triggered by various factors, can induce ER stress. To overcome the elevated ER stress, an adaptive mechanism known as the unfolded protein response (UPR) is activated in cells. However, persistent ER stress and maladaptive UPR can lead to defects in proteostasis at the cellular level and are typical features of the lung aging. The aging lung and associated lung diseases exhibit signs of ER stress-related disruption in cellular homeostasis. Dysfunction resulting from ER stress and maladaptive UPR can compromise various cellular and molecular processes associated with aging. Hence, comprehending the mechanisms of ER stress and UPR components implicated in aging and associated lung diseases could enable to develop appropriate therapeutic strategies for the vulnerable population. [ABSTRACT FROM AUTHOR]

The pathogenesis of alcohol‐related liver disease (ALD) is closely linked to mitochondrial dysfunction and impaired cellular energy metabolism. In this study, we explored how ethanol triggers inflammation, oxidative stress, and mitochondrial dysfunction in Kupffer cells, i.e.hepatic resident macrophages, primarily focusing on the mitochondrial unfolded protein response (UPRmt) using immortalized mouse Kupffer cells (ImKCs) and mouse primary KCs. The UPRmt is a cellular defense mechanism activated in response to the perturbation of mitochondrial proteostasis to maintain mitochondrial integrity and function by upregulating the expression of mitochondrial chaperones and proteases. We also determined whether nicotinamide riboside (NR), a NAD+ precursor, could mitigate ethanol‐triggered cellular damage. When ImKCs were exposed to 80 mm ethanol for 72 h, they displayed inflammation, oxidative stress, and impaired mitochondrial function with decreased mitochondrial content and deformed mitochondrial crista structure. NR, however, counteracted the effects of ethanol. Furthermore, ethanol increased mRNA and protein levels of UPRmt genes, such as mitochondrial chaperones and proteases, which were attenuated by NR. Notably, the ethanol‐induced shift in the entry of activating transcription factor 5 (ATF5), a putative transcriptional regulator of UPRmt, to the nucleus from the mitochondria was abolished by NR. The induction of UPRmt genes by ethanol was significantly repressed when Atf5 was knocked down, indicating the role of ATF5 in the induction of UPRmt genes in ImKCs exposed to ethanol. We also confirmed the induction of UPRmt gene expression in mouse and human livers exposed to alcohol. Our findings demonstrate the ability of NR to alleviate ethanol‐induced oxidative stress, inflammation, and mitochondrial dysfunction, partly by modulating the ATF5‐dependent UPRmt pathway in ImKCs, suggesting its potential for ALD therapy. © 2024 The Pathological Society of Great Britain and Ireland. [ABSTRACT FROM AUTHOR]

Spinocerebellar ataxia type 22 (SCA22) caused by KCND3 mutations is an autosomal dominant disorder. We established a mouse model carrying the Kcnd3 F227del mutation to study the molecular pathogenesis. Four findings were pinpointed. First, the heterozygous mice exhibited an early onset of defects in motor coordination and balance which mirror those of SCA22 patients. The degeneration and a minor loss of Purkinje cells, together with the concurrent presence of neuroinflammation, as well as the previous finding on electrophysiological changes, may all contribute to the development of the SCA22 ataxia phenotype in mice carrying the Kcnd3 F227del mutant protein. Second, the mutant protein is retained by the endoplasmic reticulum and Golgi, leading to activation of the unfolded protein response and a severe trafficking defect that affects its membrane destination. Intriguingly, profound damage of the Golgi is the earliest manifestation. Third, analysis of the transcriptome revealed that the Kcnd3 F227del mutation down‐regulates a panel of genes involved in the functioning of synapses and neurogenesis which are tightly linked to the functioning of Purkinje cells. Finally, no ataxia phenotypes were detectable in knockout mice carrying a loss‐of‐function Kcnd3 mutation. Thus, Kcnd3 F227del is a dominant‐negative mutation. This mouse model may serve as a preclinical model for exploring therapeutic strategies to treat patients. © 2024 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland. [ABSTRACT FROM AUTHOR]

Over the past few decades, microtubules have been targeted by various anticancer drugs, including paclitaxel and eribulin. Despite their promising effects, the development of drug resistance remains a challenge. We aimed to define a novel cell death mechanism that targets microtubules using eribulin and to assess its potential in overcoming eribulin resistance. Notably, treating non-resistant breast cancer cells with eribulin led to increased microtubule acetylation around the nucleus and cell death. Conversely, eribulin-resistant (EriR) cells did not exhibit a similar increase in acetylation, even at half-maximal inhibitory concentrations. Interestingly, silencing the ATAT1 gene, which encodes the α-tubulin N-acetyltransferase 1 (the enzyme responsible for microtubule acetylation), induces eribulin resistance, mirroring the phenotype of EriR cells. Moreover, eribulin-induced acetylation of microtubules facilitates the transport of Ca2+ from the ER to the mitochondria, releasing cytochrome c and subsequent cell death. Transcriptome analysis of EriR cells revealed a significant downregulation of ER stress-induced apoptotic signals, particularly the activity of protein kinase RNA-like ER kinase (PERK), within the unfolded protein response signaling system. Pharmacological induction of microtubule acetylation through a histone deacetylase 6 inhibitor combined with the activation of PERK signaling using the PERK activator CCT020312 in EriR cells enhanced mitochondrial Ca2+ accumulation and subsequent cell death. These findings reveal a novel mechanism by which eribulin-induced microtubule acetylation and increased PERK activity lead to Ca2+ overload from the ER to the mitochondria, ultimately triggering cell death. This study offers new insights into strategies for overcoming resistance to microtubule-targeting agents. [ABSTRACT FROM AUTHOR]

Background: Clear cell renal cell carcinoma (ccRCC) is a type of cancer characterized by a vast intracellular accumulation of lipids that are critical to sustain growth and viability of the cells in the tumour microenvironment. Stearoyl-CoA 9-desaturase 1 (SCD-1) is an essential enzyme for the synthesis of monounsaturated fatty acids and consistently overexpressed in all stages of ccRCC growth. Methods: Human clear cell renal cell carcinoma lines were treated with small-molecule inhibitors of protein kinase CK2. Effects on the expression levels of SCD-1 were investigated by RNA-sequencing, RT-qPCR, Western blot, and in vivo studies in mice. Phase-contrast microscopy, fluorescence microscopy, flow cytometry, and MALDI-mass spectrometry analysis were carried out to study the effects on endogenous lipid accumulation, induction of endoplasmic reticulum stress, rescue effects induced by exogenous MUFAs, and the identity of lipid populations. Cell proliferation and survival were investigated in real time employing the Incucyte® live-cell analysis system. Statistical significance was determined by applying the two-tailed Student's t test when comparing two groups of data whereas the two-way ANOVA, multiple Tukey's test was employed for multiple comparisons. Results: Here, we show that protein kinase CK2 is critical for preserving the expression of SCD-1 in ccRCC lines maintained in culture and heterotransplanted into nude mice. Consistent with this, pharmacological inhibition of CK2 leads to induction of endoplasmic reticulum stress linked to unfolded protein response activation and decreased proliferation of the cells. Both effects could be reversed by supplementing the growth medium with oleic acid indicating that these effects are specifically caused by reduced expression of SCD-1. Analysis of lipid composition by MALDI-mass spectrometry revealed that inhibition of CK2 results in a significant accumulation of the saturated palmitic- and stearic acids. Conclusions: Collectively, our results revealed a previously unidentified molecular mechanism regulating the synthesis of monounsaturated fatty acids corroborating the notion that novel therapeutic approaches that include CK2 targeting, may offer a greater synergistic anti-tumour effect for cancers that are highly dependent on fatty acid metabolism. [ABSTRACT FROM AUTHOR]

A positive association has been demonstrated between consumption of sucrose-sweetened beverages and the prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD). Since the administration of 30 % sucrose in the drinking water (sucrose-rich diet (SRD)) to rats has proven to be a good model of systemic insulin resistance, the aim of our study was to analyse the effect of caloric restriction applied on SRD-treated rats by switching back to a standard diet, on liver morphology, function and metabolism. Consumption of an SRD causes a metabolic shift towards gluconeogenesis and fatty acid synthesis leading to an increase in TAG levels in plasma and in the liver that were associated with a decrease in insulin sensitivity. Moreover, our results show that animals fed an SRD develop steatohepatitis characterised by the generation of oxidative stress, endoplasmic reticulum (ER) stress, inflammation and apoptosis. Although no histological changes were observed after a 2-week caloric restriction, key pathways associated with the progression of MASLD as inflammation, ER stress and apoptosis were slowed down. Notably, this 2-week intervention also increased liver insulin sensitivity (evaluated by AKT activity in this tissue) and drove the lipid metabolic profile towards oxidation, thus lowering circulating TAG levels. In summary, the present study uncovers underlying mechanisms affected, and their metabolic consequences, during the first stages of the phenotypic reversal of steatohepatitis by switching back to a standard diet after receiving sucrose-sweetened water for several weeks. [ABSTRACT FROM AUTHOR]

ABSTRACT The endoplasmic reticulum (ER) serves as the primary site for protein biosynthesis and processing, with ER homeostasis being essential for the survival of plant cells. Numerous studies have underscored the pivotal role of the ER as a battleground for host–pathogen interactions. Pathogens secrete effectors to subvert the host ER and manipulate ER‐mediated defense responses, fostering an infection‐permissive environment for their proliferation. Plants respond to these challenges by triggering ER stress responses, including the unfolded protein response (UPR), autophagy, and cell death pathways, to combat pathogens and ensure survival. Consequently, plants are faced with a life‐or‐death decision, directly influencing the outcomes of pathogen infection. In this review, recent advances in manipulating host ER homeostasis by pathogens are introduced, further key counteracting strategies employed by host plants to maintain ER homeostasis during infection are summarized, and finally, several pending questions the studies involving both parties in this evolving field are proposed. [ABSTRACT FROM AUTHOR]

ABSTRACT Climate change is leading to more frequent and severe extreme temperature events, negatively impacting agricultural productivity and threatening global food security. Plant reproduction, the process fundamental to crop yield, is highly susceptible to heatwaves, which disrupt pollen development and ultimately affect seed‐set and crop yields. Recent research has increasingly focused on understanding how pollen grains from various crops react to heat stress at the molecular and cellular levels. This surge in interest over the last decade has been driven by advances in genomic technologies, such as single‐cell RNA sequencing, which holds significant potential for revealing the underlying regulatory reprogramming triggered by heat stress throughout the various stages of pollen development. This review focuses on how heat stress affects gene regulatory networks, including the heat stress response, the unfolded protein response, and autophagy, and discusses the impact of these changes on various stages of pollen development. It highlights the potential of pollen selection as a key strategy for improving heat tolerance in crops by leveraging the genetic variability among pollen grains. Additionally, genome‐wide association studies and population screenings have shed light on the genetic underpinnings of traits in major crops that respond to high temperatures during male reproductive stages. Gene‐editing tools like CRISPR/Cas systems could facilitate precise genetic modifications to boost pollen heat resilience. The information covered in this review is valuable for selecting traits and employing molecular genetic approaches to develop heat‐tolerant genotypes. [ABSTRACT FROM AUTHOR]

FUS-mediated alternative splicing and METTL3-regulated RNA methylation play crucial roles in RNA processing. The purpose of this study was to investigate the interactive roles of FUS and METTL3 in gastric cancer (GC) progression. RNA sequencing data were obtained from the TCGA-STAD dataset. Differentially expressed genes (DEGs) were analyzed across groups stratified by the medians of FUS, METTL3, and NEAT1, respectively. Endoplasmic reticulum (ER) stress markers PERK, IRE1, pIRE1, Bip, and CHOP, as well as related apoptosis stress markers PARP, cleaved-PARP, (Cleaved) Caspase 7, and (Cleaved) Caspase 3, were assessed through western blotting. Alternative splicing and N6-methyladenosine (m(6)A) methylation of specific genes were detected with MeRIP-PCR. Finally, in vivo experiments were conducted using nude mice bearing sh-FUS-transfected HGC27 xenograft tumors. FUS and METTL3 expression levels were elevated in GC tissues. A significant overlap of DEGs was observed between the FUS- and METTL3-stratified groups. These overlapping DEGs were predominantly enriched in mRNA processing and protein processing in the ER. ER stress and apoptosis were induced by sh-FUS or sh-METTL3, which was further enhanced by ER stress inducer tunicamycin in both MKN45 and HGC27 cells. Similarly, DEGs for NEAT1 high- and low-expressed groups were enriched in protein processing in the ER and spliceosome. To a lesser extent, ER stress was also induced by sh-NEAT1 and enhanced by tunicamycin in HGC27 cells. Furthermore, sh-FUS or sh-METTL3 influenced alternative splicing and methylation of specific mRNAs, including FUS, NEAT1, PCNA, MCM2, and BIRC5. Tumor progression was inhibited by sh-FUS in mice, and ER stress and apoptosis were induced, which were further enhanced by tunicamycin. FUS and METTL3 collaborate to facilitate RNA maturation. Inhibiting FUS or METTL3 promoted ER stress and apoptosis and inhibited progression in GC. Aberrant levels of FUS and METTL3 can evoke endoplasmic reticulum (ER) stress and apoptosis by generating splicing and methylation variants of mRNAs in gastric cancer, supporting the therapeutic potential of inducing ER stress [ABSTRACT FROM AUTHOR]

Background: the protein phosphatase 3 catalytic subunit alpha (PPP3CA) gene encodes for the alpha isoform of the calcineurin catalytic subunit, which controls the phosphorylation status of many targets. Currently, 23 pathogenic variants of PPP3CA are known, with clinical manifestations varying by mutation type and domain. Results: through whole exome sequencing, we found two de novo variants in PPP3CA: a frameshift variant predicted leading to a truncated protein in Pt.1 and a splicing variant in Pt.2 associated with mild phenotype. PPP3CA is ubiquitously expressed with tissue-specificity of; namely, splicing isoform 1 prevailing over isoform 2 in the central nervous system. By analyzing isoform distribution in patient-derived cell lines, we highlight a skewed expression of both isoforms in Pt.1, whereas only isoform 2 shows a moderate reduction in Pt.2. In contrast, we did not observe significant abundance changes at the protein level. Cell lines derived from Pt.1 showed a reduced proliferation, associated with an increase in cell death and the upregulation of the unfolded protein response (UPR) pathway. Conclusion: data suggest that an aberrant PPP3CA protein in Pt.1 could lead to UPR activation resulting in increased cell death. In Pt.2 an imbalance between the two main isoforms possibly explains the peculiar pathological manifestations, such as a moderate developmental delay. [ABSTRACT FROM AUTHOR]

The eLife article from December 18, 2024, details a proteomics study on circulating extracellular vesicles for biomarker discovery in pancreatic cancer. Researchers analyzed plasma samples from 124 individuals with various pancreatic diseases and controls, identifying a seven-protein signature that accurately diagnosed pancreatic cancer with an 89% prediction accuracy. The study underscores the significance of early detection in improving patient outcomes and offers valuable insights into potential biomarkers for pancreatic cancer diagnosis and prognosis. Conducted ethically with the approval of the Harvard Cancer Center Institutional Review Board, the research highlights the potential of extracellular vesicle proteins as biomarkers for pancreatic cancer. [Extracted from the article]

Background: Alzheimer's disease (AD) is characterized by the presence of neurofibrillary tangles made of hyperphosphorylated tau and senile plaques composed of beta-amyloid. These pathognomonic deposits have been implicated in the pathogenesis, although the molecular mechanisms and consequences remain undetermined. UFM1 is an important, but understudied ubiquitin-like protein that is covalently attached to substrates. UFMylation has recently been identified as major modifier of tau aggregation upon seeding in experimental models. However, potential alterations of the UFM1 pathway in human AD brain have not been investigated yet. Methods: Here we used frontal and temporal cortex samples from individuals with or without AD to measure the protein levels of the UFMylation pathway in human brain. We used multivariable regression analyses followed by Bonferroni correction for multiple testing to analyze associations of the UFMylation pathway with neuropathological characteristics, primary biochemical measurements of tau and additional biochemical markers from the same cases. We further studied associations of the UFMylation cascade with cellular stress pathways using Spearman correlations with bulk RNAseq expression data and functionally validated these interactions using gene-edited neurons that were generated by CRISPR-Cas9. Results: Compared to controls, human AD brain had increased protein levels of UFM1. Our data further indicates that this increase mainly reflects conjugated UFM1 indicating hyperUFMylation in AD. UFMylation was strongly correlated with pathological tau in both AD-affected brain regions. In addition, we found that the levels of conjugated UFM1 were negatively correlated with soluble levels of the deUFMylation enzyme UFSP2. Functional analysis of UFM1 and/or UFSP2 knockout neurons revealed that the DNA damage response as well as the unfolded protein response are perturbed by changes in neuronal UFM1 signaling. Conclusions: There are marked changes in the UFMylation pathway in human AD brain. These changes are significantly associated with pathological tau, supporting the idea that the UFMylation cascade might indeed act as a modifier of tau pathology in human brain. Our study further nominates UFSP2 as an attractive target to reduce the hyperUFMylation observed in AD brain but also underscores the critical need to identify risks and benefits of manipulating the UFMylation pathway as potential therapeutic avenue for AD. [ABSTRACT FROM AUTHOR]

Objective: Mitochondrial dysfunction is widely implicated in various diseases and pathological conditions. The mito- chondrial unfolded protein response (UPRmt) is activated to maintain mitochondrial function when misfolded proteins accumulate. Recent findings have unveiled several factors that activate UPRmt. However, the precise mechanism underlying UPR activation by microbes, re- mains incompletely understood. To identify bacterial modifiers of host mitochondrial unfolded protein response. Methods: We developed an in vivo high-throughput screening assay to assess the impact of microbes on host mitochondrial unfolded protein response. We screened 3985 Escherichia coli single-gene deleted mutants. Results: Through first screening and further validation, we identified 88 E. coli single-gene deleted mutants and Agrococcus R98 that regulate UPRmt in C. elegans. 88 E. coli genes are involved in various cellular processes, including signal transduction, RNA modification, and transport. Notably, 40% of these genes are related to bacterial metabolism. fep G encodes a ferric enterobactin ABC transporter subunit, essential for retrieving insoluble Fe(III) from environments. We supplemented C. elegans fed Δ fepG and other mutants with the iron and observed a repression of host UPRmt, suggesting that bacteria act through iron to trigger C. elegans mitochondrial unfolded protein response. However, iron supplementation did not inhibit the host UPR induced by Agrococcus R98, demonstrating that different species of bacteria stimulate the host UPRmt by different mechanisms. Conclusions: Our study sheds light on a systems-level understanding of how microbial metabolites regulate host mitochondrial unfolded protein response, laying a foundation for similar investigations in higher organisms. [ABSTRACT FROM AUTHOR]

SUMMARY: Plants have an amazing capacity to outcompete neighboring organisms for space and resources. Toxic metabolites are major players in these interactions, which can have a broad range of effectiveness by targeting conserved molecular mechanisms, such as protein biosynthesis. However, lack of knowledge about defensive metabolite pathways, their mechanisms of action, and resistance mechanisms limits our ability to manipulate these pathways for enhanced crop resilience. Nonproteogenic amino acids (NPAAs) are a structurally diverse class of metabolites with a variety of functions but are typically not incorporated during protein biosynthesis. Here, we investigate the mechanism of action of the NPAA azetidine‐2‐carboxylic acid (Aze), an analog of the amino acid proline (Pro). Using a combination of plate‐based assays, metabolite feeding, metabolomics, and proteomics, we show that Aze inhibits the root growth of Arabidopsis and other plants. Aze‐induced growth reduction was restored by supplementing L‐, but not D‐Pro, and nontargeted proteomics confirm that Aze is misincorporated for Pro during protein biosynthesis, specifically on cytosolically translated proteins. Gene expression analysis, free amino acid profiling, and proteomics show that the unfolded protein response is upregulated during Aze treatment implicating that Aze misincorporation results in accumulation of misfolded proteins triggering a global stress response. This study demonstrates the mechanism of action of Aze in plants and provides a foundation for understanding the biological functions of proteotoxic metabolites. [ABSTRACT FROM AUTHOR]

Stiffening of the brain extracellular matrix (ECM) in glioblastoma promotes tumor progression. Previously, we discovered that protein kinase R (PKR)‐like endoplasmic reticulum kinase (PERK) plays a role in glioblastoma stem cell (GSC) adaptation to matrix stiffness through PERK/FLNA‐dependent F‐actin remodeling. Here, we examined the involvement of PERK in detecting stiffness changes via focal adhesion complex (FAC) formation. Compared to control GSCs, PERK‐deficient GSCs show decreased vinculin and tensin expression, while talin and integrin‐β1 remain constant. Furthermore, vimentin was also reduced while tubulin increased, and a stiffness‐dependent increase of the differentiation marker GFAP expression was absent in PERK‐deficient GSCs. In conclusion, our study reveals a novel role for PERK in FAC formation during matrix stiffening, which is likely linked to its regulation of F‐actin remodeling. [ABSTRACT FROM AUTHOR]

Conditions of endoplasmic reticulum (ER) stress reduce protein synthesis by provoking translation regulation, governed by the eIF2a kinase PERK. When PERK is inhibited during ER stress, retention of a selective subset of glycoproteins occurs, a phenomenon we termed selective ER retention (sERr). sERr clients are enriched with tyrosine kinase receptors (RTKs), which form large molecular weight disulfide bonded complexes in the ER. The protein disulfide isomerase ERp44 promotes sERr and increases the size of sERr complexes. Here we show that sERr is reversible upon washout. Pulse chase analyses show that upon recovery, only a small fraction of the sERr complexes disintegrates and contributes to the matured proteins, while most are newly synthesized. Sequential inductions of sERr and washouts demonstrate an accelerated recovery that is dependent on the unfolded protein response transducer IRE1. Since IRE1 regulates the expression level PDIA6, we analyzed its contribution to sERr. We found that PDIA6 and ERp44 constitu-tively interact by disulfides and have opposite effects on resumed recovery of trafficking following removal of sERr conditions. Deletion of ERp44 accelerates, while deletion of PDIA6 slows down recovery with a minimal effect on total protein synthesis. ERp44 is a primary interactor with sERr clients. When missing, PDIA6 partitions more into sERr complexes. Deletion of the tumor suppressor PTEN, which induces RTK signaling, promoted sERr formation kinetics, and accelerated the recovery, suggesting feedback between RTKs signaling and sERr. This study suggests that sERr, should develop physiologically or pathologically, is counteracted by adaptation responses that involve IRE1 and PDIA6. [ABSTRACT FROM AUTHOR]

Introduction: Fish nucleated red blood cells (RBCs), also known as erythrocytes, play a crucial role in maintaining immune system balance by modulating protein expression in response to various stimuli, including viral attack. This study explores the intriguing behavior of rainbow trout RBCs when faced with the viral hemorrhagic septicemia virus (VHSV), focusing on the endoplasmic reticulum (ER) stress and the unfolded protein response (UPR). Methods: Rainbow trout RBCs were Ficoll-purified and exposed to ultraviolet (UV)-inactivated VHSV or live VHSV at different multiplicities of infection (MOIs). Using cryo-soft X-ray tomography (cryo-SXT), we uncovered structural and cellular modifications in RBCs exposed to UV-inactivated VHSV. Moreover, RBCs were treated with 4-phenylbutyric acid (4-PBA), an ER stress inhibitor, to investigate its effect on viral replication. Quantitative real-time PCR was also used to analyze the expression of genes related to the UPR and other related cellular pathways. Results and discussion: Beyond their antiviral response, RBCs undergo notable intracellular changes to combat the virus. Cryo-SXT highlighted a significant increase in the ER volume. This increase is associated with ER stress and the activation of the UPR pathway. Interestingly, VHSV replication levels augmented in RBCs under ER-stress inhibition by 4-PBA treatment, suggesting that rainbow trout RBCs tune up ER stress to control viral replication. Therefore, our findings suggested the induction of ER stress and subsequent activation UPR signaling in the antiviral response of RBCs to VHSV. The results open a new line of investigation to uncover additional mechanisms that may become novel cellular targets for the development of RBC-targeted antiviral strategies. [ABSTRACT FROM AUTHOR]

Regulation of endoplasmic reticulum (ER) homeostasis plays a critical role in maintaining cell survival. When ER stress occurs, a network of three pathways called the unfolded protein response (UPR) is activated to reestablish homeostasis. While it is known that there is cross-talk between these pathways, how this complex network is regulated is not entirely clear. Using human cancer and non-cancer cell lines, two different genome-wide approaches, and two different ER stress models, we searched for miRNAs that were decreased during the UPR and surprisingly found only one, miR-1244, that was found under all these conditions. We also verified that ER-stress related downregulation of miR-1244 expression occurred with 5 different ER stressors and was confirmed in another human cell line (HeLa S3). These analyses demonstrated that the outcome of this reduction during ER stress supported both IRE1 signaling and elevated BIP expression. Further analysis using inhibitors specific for IRE1, ATF6, and PERK also revealed that this miRNA is impacted by all three pathways of the UPR. This is the first example of a complex mechanism by which this miRNA serves as a regulatory check point for all 3 pathways that is switched off during UPR activation. In summary, the results indicate that ER stress reduction of miR-1244 expression contributes to the pro-survival arm of UPR. [ABSTRACT FROM AUTHOR]

The endoplasmic reticulum (ER) is crucial for maintaining cell homeostasis because it is the primary site for synthesizing secreted and transmembrane proteins and lipids. The unfolded protein response (UPR) is activated to restore the homeostasis of the ER when it is under stress; however, the relationship between lipids and the ER stress response in plants is not well understood. Arabidopsis GOLGI ANTI-APOPTOTIC PROTEINS (GAAPs) are involved in resisting ER stress, and in this study, we found that PASTICCINO2 (PAS2), which is involved in very-long-chain fatty acid (VLCFA) synthesis, interacts with GAAPs and INOSITOL REQUIRING ENZYME 1. The pas2 single-mutant and the gaap1 pas2 and gaap2 pas2 double-mutants exhibited increased seedling damage and an impaired UPR response under chronic ER stress. Site mutation combined with genetic analysis revealed that the role of PAS2 in resisting ER stress depended on its VLCFA synthesis domain. VLCFA contents were increased under ER stress, and this required GAAPs. Exogenous VLCFAs partially restored the defect in the activation of the UPR caused by mutation of PAS2 or GAAP under chronic ER stress. Our findings demonstrate that the association of PAS2 with GAAPs confers plant resistance to ER stress by regulating VLCFA synthesis and the UPR. This provides a basis for further studies on the connection between lipids and cell-fate decisions under stress. [ABSTRACT FROM AUTHOR]

Aberrant regulation of unfolded protein response (UPR)/endoplasmic reticulum (ER) stress pathway is associated with cancer development, metastasis, and relapse, and the UPR signal transducer ATF6 has been proposed as a diagnostic and prognostic marker for many cancers. However, a causal molecular link between ATF6 activation and carcinogenesis is not established. Here, it is found that tumor protein D52 (TPD52) integrates ER stress and UPR signaling with the chaperone machinery by promoting S2P‐mediated cleavage of ATF6. Although TPD52 has been generally considered as an oncogene, TPD52 is identified as a novel tumor suppressor in bladder cancer. Significantly, attenuation of the ER stress via depletion of TPD52 facilitated tumorigenesis in a subset of human carcinomas. Furthermore, the APCCdc20 E3 ligase is validated as the upstream regulator marking TPD52 for polyubiquitination‐mediated proteolysis. In addition, inactivation of Cdc20 sensitized cancer cells to treatment with the ER stress inducer in a TPD52‐dependent manner. Thus, the study suggests that TPD52 is a novel Cdc20 substrate that may modulate ER stress to prevent tumorigenesis. [ABSTRACT FROM AUTHOR]

RNA interference (RNAi) is an evolutionarily conserved pathway that defends against viral infections in diverse organisms. Caenorhabditis elegans mutations that enhance RNAi have revealed pathways that may regulate antiviral defense. A genetic screen for C. elegans mutations that fail to up-regulate a defense response reporter transgene detected mutations that enhance RNAi to silence this reporter gene in the inositol polyphosphate multikinase impk-1, the synMuv B gene lin-15B, and the pathogen defense response gene pals-22. Using other assays for enhanced RNAi, we found that the impk-1 alleles and an ippk-1 gene inactivation of a later step in inositol hexaphosphate (IP6) synthesis, and the lin-15B and pals-22 alleles enhance RNAi. IP6 has been known for decades to bind and stabilize human adenosine deaminase that acts on RNA (ADAR) as well as the paralog tRNA editing ADAT. We show that the C. elegans IP6 pathway is also required for mRNA and tRNA editing. Thus, a deficiency in two axes of RNA editing enhances the already potent C. elegans RNAi antiviral defense, suggesting adenosine to inosine RNA editing may normally moderate this siRNA antiviral defense pathway. The C. elegans IP6-deficient mutants are synthetic lethal with a set of enhanced RNAi mutants that act in the polyploid hypodermis to regulate collagen secretion and signaling from that tissue, implicating IP6 signaling especially in this tissue. This enhanced antiviral RNAi response uses the C. elegans RIG-I-like receptor DRH-1 to activate the unfolded protein response (UPR). The production of primary siRNAs, rather than secondary siRNAs, contributes to this activation of the UPR through XBP-1 signaling. The gon-14 and pal-17 mutants that also emerged from this screen act in the mitochondrial defense pathway rather than by enhancing RNAi. [ABSTRACT FROM AUTHOR]

The Mitochondrial Unfolded Protein Response (UPRmt), a mitochondria-originated stress response to altered mitochondrial proteostasis, plays important roles in various pathophysiological processes. In this study, we revealed that the endoplasmic reticulum (ER)-tethered stress sensor CREBH regulates UPRmt to maintain mitochondrial homeostasis and function in the liver. CREBH is enriched in and required for hepatic Mitochondria-Associated Membrane (MAM) expansion induced by energy demands. Under a fasting challenge or during the circadian cycle, CREBH is activated to promote expression of the genes encoding the key enzymes, chaperones, and regulators of UPRmt in the liver. Activated CREBH, cooperating with peroxisome proliferator-activated receptor a (PPARα), activates expression of Activating Transcription Factor (ATF) 5 and ATF4, two major UPRmt transcriptional regulators, independent of the ER-originated UPR (UPRER) pathways. Hepatic CREBH deficiency leads to accumulation of mitochondrial unfolded proteins, decreased mitochondrial membrane potential, and elevated cellular redox state. Dysregulation of mitochondrial function caused by CREBH deficiency coincides with increased hepatic mitochondrial oxidative phosphorylation (OXPHOS) but decreased glycolysis. CREBH knockout mice display defects in fatty acid oxidation and increased reliance on carbohydrate oxidation for energy production. In summary, our studies uncover that hepatic UPRmt is activated through CREBH under physiological challenges, highlighting a molecular link between ER and mitochondria in maintaining mitochondrial proteostasis and energy homeostasis under stress conditions. [ABSTRACT FROM AUTHOR]

Proinsulin translation and folding is crucial for glucose homeostasis. However, islet β-cell control of Proinsulin translation remains incompletely understood. Here, we identify OSGEP, an enzyme responsible for t6A37 modification of tRNANNU that tunes glucose metabolism in β-cells. Global Osgep deletion causes glucose intolerance, while β-cell-specific deletion induces hyperglycemia and glucose intolerance due to impaired insulin activity. Transcriptomics and proteomics reveal activation of the unfolded protein response (UPR) and apoptosis signaling pathways in Osgep-deficient islets, linked to an increase in misfolded Proinsulin from reduced t6A37 modification. Osgep overexpression in pancreas rescues insulin secretion and mitigates diabetes in high-fat diet mice. Osgep enhances translational fidelity and alleviates UPR signaling, highlighting its potential as a therapeutic target for diabetes. Individuals carrying the C allele at rs74512655, which promotes OSGEP transcription, may show reduced susceptibility to T2DM. These findings show OSGEP is essential for islet β-cells and a potential diabetes therapy target. Pancreatic islet β cells produce insulin, so their protein quality control mechanisms are critical for human health. Here, the authors show that loss of OSGEP, an enzyme known to add the t6A modification on tRNA, disrupts proinsulin translation and causes ER stress in β cells. [ABSTRACT FROM AUTHOR]

Repetitive variations, such as oscillation, are ubiquitous in biology. In this mini review, we present a general summary of the ∼24 h circadian clock and provide a fundamental overview of another biological timekeeper that maintains ∼12 h oscillations. This ∼12 h oscillator is proposed to function independently of the circadian clock to regulate ultradian biological rhythms relevant to both protein homeostasis and liver health. Recent studies exploring these ∼12 h rhythms in humans are discussed, followed by our proposal that mammary gland physiology represents a promising area for further research. We conclude by highlighting potential translational applications in ∼12 h ultradian chronobiology. [ABSTRACT FROM AUTHOR]

Ischemic stroke (IS) is the predominant subtype of stroke and a leading contributor to global mortality. The mitochondrial-associated endoplasmic reticulum membrane (MAM) is a specialized region that facilitates communication between the endoplasmic reticulum and mitochondria, and has been extensively investigated in the context of neurodegenerative diseases. Nevertheless, its precise involvement in IS remains elusive. This literature review elucidates the intricate involvement of MAM in mitophagy and endoplasmic reticulum stress during IS. PINK1, FUNDC1, Beclin1, and Mfn2 are highly concentrated in the MAM and play a crucial role in regulating mitochondrial autophagy. GRP78, IRE1, PERK, and Sig-1R participate in the unfolded protein response (UPR) within the MAM, regulating endoplasmic reticulum stress during IS. Hence, the diverse molecules on MAM operate independently and interact with each other, collectively contributing to the pathogenesis of IS as the covert orchestrator. [ABSTRACT FROM AUTHOR]

Aberrant regulation of unfolded protein response (UPR)/endoplasmic reticulum (ER) stress pathway is associated with cancer development, metastasis, and relapse, and the UPR signal transducer ATF6 has been proposed as a diagnostic and prognostic marker for many cancers. However, a causal molecular link between ATF6 activation and carcinogenesis is not established. Here, it is found that tumor protein D52 (TPD52) integrates ER stress and UPR signaling with the chaperone machinery by promoting S2P‐mediated cleavage of ATF6. Although TPD52 has been generally considered as an oncogene, TPD52 is identified as a novel tumor suppressor in bladder cancer. Significantly, attenuation of the ER stress via depletion of TPD52 facilitated tumorigenesis in a subset of human carcinomas. Furthermore, the APCCdc20 E3 ligase is validated as the upstream regulator marking TPD52 for polyubiquitination‐mediated proteolysis. In addition, inactivation of Cdc20 sensitized cancer cells to treatment with the ER stress inducer in a TPD52‐dependent manner. Thus, the study suggests that TPD52 is a novel Cdc20 substrate that may modulate ER stress to prevent tumorigenesis. [ABSTRACT FROM AUTHOR]

Various factors, both internal and external, can disrupt endoplasmic reticulum (ER) homeostasis and increase the burden of protein folding, resulting in ER stress. While short periods of ER stress can help cells return to normal function, excessive or prolonged ER stress triggers a complex signaling network that negatively affects cells. Numerous studies have demonstrated the significant role of ER stress in various kidney diseases, such as immune-related kidney injury, diabetic kidney diseases, renal ischemia reperfusion injury, and renal fibrosis. To date, there is a severe shortage of medications for the treatment of acute and chronic kidney diseases of all causes. Natural products derived from various traditional Chinese medicines (TCM), which are a major source of new drugs, have garnered considerable attention. Recent research has revealed that many natural products have renoprotective effects by targeting ER stress-mediated events, such as apoptosis, oxidative stress, inflammation, autophagy, and epithelial-mesenchymal transition. This article provides a comprehensive review of the current research progress on natural products targeting ER stress for the treatment of kidney diseases. [ABSTRACT FROM AUTHOR]

Clemastine is an antagonist of histamine H1 receptor may provide benefits in the treatment of osteosarcoma (OS). In the current study, we used hyperthermia approach to sensitize OS cells to clemastine-mediated cell death. Osteosarcoma U-2 OS and Saos-2 cells were treated with clemastine at 37°C, followed by 42°C for 2 h, and released at 37°C for 6 h. The impact of clemastine and hyperthermia on OS cell survival and autophagy-mediated cell death was investigated. Exposure of U-2 OS and Saos-2 cells to clemastine and hyperthermia (42°C) inhibited dose-dependent clemastine-mediated cell survival by increasing cell apoptosis. Hyperthermia and clemastine exposure modulated inflammatory and unfolded protein response (UPR) signaling differentially in U-2 OS and Saos-2 cells. Exposure of U-2 OS and Saos-2 cells to hyperthermia and clemastine inhibited AKT/mTOR and induced expression of the autophagy biomarkers LC3B II and LC3-positive puncta formation. The inhibition of autophagy by 3-methyladenine blocked hyperthermia and clemastine-mediated induction of LC3B II, LC3-positive puncta formation, and OS cell apoptosis. These results indicate that clemastine and hyperthermia sensitize OS cell lines by inducing increased autophagic cell death. Collectively, our data suggest that hyperthermia along with antihistamine therapy may provide an improved approach for the treatment of OS. [ABSTRACT FROM AUTHOR]

Background/Objectives: Endothelial hyperpermeability is the hallmark of severe disease, including sepsis and acute respiratory syndrome (ARDS). The development of medical countermeasures to treat the corresponding illness is of utmost importance. Synthetic somatostatin analogs (SSA) are FDA-approved drugs prescribed in patients with neuroendocrine tumors, and they act via growth hormone (GH) suppression. Preclinical investigations suggest that Octreotide (OCT) alleviates Lipopolysaccharide (LPS)-induced injury. The aim of the study is to investigate the involvement of activating transcription factor 6 (ATF6) in the protective effects of OCT in endothelial dysfunction. To the best of our knowledge, the available information on that topic is limited. Methods: Human lung microvascular endothelial cells (HULEC-5a) and bovine pulmonary artery endothelial cells (BPAEC) which expressed elevated levels of ATF6 due to AA147 were exposed to OCT or vehicle. Protein expression, endothelial permeability, and reactive oxygen species (ROS) generation were assessed utilizing Western blot analysis, Fluorescein isothiocyanate (FITC)-Dextran assay, and Dichlorofluorescein diacetate measurements, respectively. Results: Our observations suggest that ATF6 activation significantly improves OCT-induced endothelial barrier enhancement. This combination led to increased expression of binding immunoglobulin protein (BiP) and glucose-regulated protein 94 (Grp94), which are downstream unfolded protein response (UPR) targets. Moreover, ATF6 activation prior to OCT treatment resulted in decreased activation of myosin light chain 2 (MLC2) and cofilin; and reduced reactive oxygen species (ROS) generation. ATF6 activation enhanced the anti-inflammatory effects of OCT, as reflected in the suppression of transducer and activator of transcription (STAT) 1, STAT3, and P38 phosphorylation. Conclusions: Our findings suggest that ATF6 activation prior to OCT treatment enhances the beneficial effects of OCT in the endothelium. [ABSTRACT FROM AUTHOR]

Endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) play critical roles in tumorigenesis, cancer progression, and drug resistance. Persistent activation of the ER stress system enhances the survival capacities of malignant tumor cells, including increased proliferation, invasion, and resistance to treatment. Dysregulation of ER function and the resultant stress is a common cellular response to cancer therapies and may lead to cancer cell death. Currently, growing evidence suggests that Traditional Chinese medicine (TCM), either as a monotherapy or in combination with other treatments, offers significant advantages in preventing cancer, inhibiting tumor growth, reducing surgical complications, improving drug sensitivity, and mitigating drug-induced damage. Some of these natural products have even entered clinical trials as primary or complementary anticancer agents. In this review, we summarize the anticancer effects of TCM monomers/natural products on the gastrointestinal (GI) tumors and explore their mechanisms through ER stress modulation. We believe that ongoing laboratory research and the clinical development of TCM-based cancer therapies hold considerable potential for advancing future cancer treatments. [ABSTRACT FROM AUTHOR]

Alkylphenols are byproducts of anthropogenic activities that widely contaminate waters, soils and air; among them, the most represented are 4-nonylphenol (4-NP) and 4-octylphenol (4-OP). These compounds tend to bioaccumulate in animal and plant tissues and also represent a risk to human health. Indeed, humans are constantly exposed to alkylphenols through ingestion of contaminated water and food, inhalation and dermal absorption. In the present work, we characterized the cytotoxic ability of 4-OP towards several human cell lines, representing the potential main targets in the human body, also comparing its effect with that of 4-NP and of a mixture of both 4-OP and 4-NP in a range of concentrations between 1 and 100 μM. Viability assays demonstrated that each cell type had a peculiar sensitivity to 4-OP and that, in some cases, a combination of the two alkylphenols displayed a higher cytotoxic activity with respect to the single compound. Then, we focused our attention on a liver cell line (HepG2) in which we observed that 4-OP increased cell death and also caused interference with protective physiological cell processes, such as the unfolded protein response, autophagy and the antioxidant response. Finally, our experimental data were compared and correlated with ADMET properties originating from an in silico analysis. Altogether, our findings highlight a possible contribution of this pollutant to deregulation of the normal homeostasis in human liver cells. [ABSTRACT FROM AUTHOR]

The endothelial semipermeable monolayers ensure tissue homeostasis, are subjected to a plethora of stimuli, and their function depends on cytoskeletal integrity and remodeling. The permeability of those membranes can fluctuate to maintain organ homeostasis. In cases of severe injury, inflammation or disease, barrier hyperpermeability can cause irreparable damage of endothelium‐dependent issues, and eventually death. Elucidation of the signaling regulating cytoskeletal structure and barrier integrity promotes the development of targeted pharmacotherapies towards disorders related to the impaired endothelium (e.g., acute respiratory distress syndrome, sepsis). Recent reports investigate the role of unfolded protein response in barrier function. Herein we review the cytoskeletal components, the unfolded protein response function; and their interrelations on health and disorder. Moreover, we emphasize on unfolded protein response modulators, since they ameliorate illness related to endothelial leak. Summary: Endothelial barrier function is crucial for tissue function. An emerging body of evidence suggests that unfolded protein response (UPR) affects cytoskeletal structure and vascular integrity. Hence, UPR manipulation may represent a novel therapeutic possibility in diseases related to endothelial leak, including ARDS. [ABSTRACT FROM AUTHOR]

Unlike other ubiquitin-like family members, UBL5 is structurally and functionally atypical, and a novel role in various biological processes and diseases has been discovered. UBL5 can stabilize the structure of the spliceosome, can promote post-transcriptional processing, and has been implicated in both DNA damage repair and protein unfolding reactions, as well as cellular mechanisms that are frequently exploited by viruses for their own proliferation during viral infections. In addition, UBL5 can inhibit viral infection by binding to the non-structural protein 3 of rice stripe virus and mediating its degradation. Therefore, UBL5 is an important link between viral infections and immunity, and its study will be beneficial for the prevention and treatment of viral infections in the future. However, a review of the current findings on the role of UBL5 in viral infection has not been undertaken. Therefore, in this review, we summarize the recent progress in understanding the functions of UBL5 and discuss its putative role in viral infections. [ABSTRACT FROM AUTHOR]

Morbillivirus canis, commonly named Canine distemper virus (CDV), is a morbillivirus implicated in several signs in the Canidae family. In dogs (Canis lupus familiaris), common signs of infection include conjunctivitis, digital hyperkeratosis and neuropathologies. Even with vaccination, the canine distemper disease persists worldwide so the molecular pathways implicated in the infection processes have been an interesting and promising area in new therapeutic drugs research in recent years. It is known that in the process of virus infection, the endoplasmic reticulum (ER) loses its homeostasis, inducing stress and the subsequent unfolded protein response or UPR in which three ER-trans-membrane proteins are implicated: PERK, IRE1 and ATF6. Moreover, in prolonged ER stress, the apoptosis is induced through the CHOP, as a final step of viral infection. Cell culture and molecular techniques such as RT-qPCR and RT-PCR were used in the present study. We demonstrate the activation in vitro of the three UPR pathways after infection with an attenuated strain of CDV. Also, the implication of a MAPK pathway through the p38 protein and the apoptotic CHOP was demonstrated to contribute to the process of infection. Even more, our study suggested that CDV replication occurs in a PERK-dependent manner. [ABSTRACT FROM AUTHOR]

We illustrate and discuss the relevance of key endoplasmic reticulum (ER)-associated RNA decay pathways – including inositol-requiring enzyme 1α (IRE1α)-dependent mRNA decay (RIDD), RIDD lacking endomotif (RIDDLE), ER-associated RNA silencing (ERAS), regulation of aberrant protein production (RAPP), and ER nonsense-mediated mRNA decay (ER-NMD) – for the unfolded protein response (UPR) and ER homeostasis. Multiple parallel ER-associated RNA decay pathways may exist to ensure substrate specificity and to efficiently address diverse ER homeostasis and viral challenges. We summarize recent insights into the intricate interplay of these pathways, and highlight gaps in our knowledge regarding target selectivity, recruitment of degradation machinery, and the physiological relevance of ER-associated RNA decay pathways. An emerging ER–ribosome-associated quality control (RQC) mechanism involves coordinated ER-associated processes of RNA degradation – IRE1α, Argonaute 2 (AGO2), UPF1 – and protein degradation (LTN1, HRD1, VCP). The endoplasmic reticulum (ER) is central to the processing of luminal, transmembrane, and secretory proteins, and maintaining a functional ER is essential for organismal physiology and health. Increased protein-folding load on the ER causes ER stress, which activates quality control mechanisms to restore ER function and protein homeostasis. Beyond protein quality control, mRNA decay pathways have emerged as potent ER fidelity regulators, but their mechanistic roles in ER quality control and their interrelationships remain incompletely understood. Herein, we review ER-associated RNA decay pathways – including regulated inositol-requiring enzyme 1α (IRE1α)-dependent mRNA decay (RIDD), nonsense-mediated mRNA decay (NMD), and Argonaute-dependent RNA silencing – in ER homeostasis, and highlight the intricate coordination of ER-targeted RNA and protein decay mechanisms and their association with antiviral defense. [ABSTRACT FROM AUTHOR]

Purpose: The Endoplasmic reticulum (ER) organelle is necessary for protein folding and, in this regard, has a determined capacity. Increased protein synthesis beyond endoplasmic reticulum capacity, leads to ER dyshomeostasis, unfolded proteins accumulation, ER stress, and unfolded protein response (UPR) induction which mediating by three transmembrane sensor proteins. Various studies have shown that in diabetes, greater demand for insulin production is one of the causes of UPR induction giving rise both ameliorative and destructive effects through modulation activity of different branches. Our purpose is to investigate precise role of UPR on diabetes management. Methods: Inclusion criteria were English language and full text publications. Diseases other than diabetes and mechanisms other than UPR were excluded. Search was done in PubMed, web of science (WOS) and Scopus using keywords. Results: After assessing bias, total of 22,364 articles were initially identified. Duplication (1593) was deleted using hand- screening, 20,771 papers met all inclusion criteria and selected. Both review and unrelated articles were excluded. Finally, 36 articles assessed for the precise role of the UPR on diabetes management. The most of studies (29) showed improving effects of UPR, (17 studies) investigated activity of only one arm, and protein kinase RNA like endoplasmic reticulum kinase (PERK) was the most investigated (31) arm. Different findings might be explained by different endoplasmic reticulum stress induction strategies, treatment duration, and varied investigations in these studies. We summarize the role of UPR on diabetes management, but despite promising and ameliorating results of this review, further studies are needed to clarify the helpfulness in clinical management of diabetes. [ABSTRACT FROM AUTHOR]

Preeclamptic patients, both lean and obese, present with elevated leptin levels which are associated with the development of maternal endothelial dysfunction and adverse fetal outcomes, such as growth restriction, leading to low birth weight. Recent studies in pregnant mice demonstrate that mid-late gestation leptin infusion induces clinical characteristics of preeclampsia, including elevated maternal blood pressure, maternal endothelial dysfunction and fetal growth restriction. However, whether leptin triggers placental stress responses that contribute to adverse fetal outcomes as in preeclampsia is unknown. In the current study we measured the expression of proteins involved in the endoplasmic reticulum (UPRer) and mitochondrial (UPRmt) unfolded protein responses in placentas of wild-type sham normal pregnant and leptin-infused preeclamptic mice. The data show that mid-late gestation leptin infusion induced activation of indices of placental UPRer and UPRmt, while reducing placental repair mechanisms to UPRmt in preeclamptic mice. Mid-late gestation infusion with leptin upregulated markers of placental oxidative stress, reduced the placental expression levels of mitochondrial electron transport chain complexes I and II and increased the expression of placental endothelin-1 (ET-1) in preeclamptic mice. The leptin-induced activation of several placental UPRmt markers as well as ET-1 levels correlated with fetal growth restriction and impaired maternal endothelial function in preeclamptic mice. Collectively, these data indicate that elevated levels of leptin in mid-late pregnancy in mice promote placental stress responses, akin to those in pregnant women with preeclampsia. [Display omitted] • Leptin induces placental expression of unfolded protein responses in endoplasmic reticulum and mitochondria which correlate with adverse outcomes. • Leptin induces ROS , suppresses ROS scavenging and induces mitochondrial alterations in placentas of pregnant mice. • Elevations in leptin in pregnant mice increases placental endothelin-1 production, which correlates with vascular endothelial dysfunction. [ABSTRACT FROM AUTHOR]

Introduction: Earlier, we documented that a combination of vitamins A and D3 synergistically inhibited the growth of MCF-7, T48:A18 and SKBR3 breast cancer cells with the best activity seen in the ER+ cell line MCF-7. Transcriptomic analysis of treated MCF-7 cells also showed that the combination significantly upregulated the apoptosis and unfolded protein response canonical pathways, and reduced estrogen signaling. Objective: This study aimed to explore the impact of increasing vitamin A and D3 dose combinations over time in a postmenopausal model of breast cancer using ovariectomized athymic female mice bearing MCF-7 xenografts and further analyze mechanisms of action in MCF-7 cells using RNA-seq analysis. Methods: MCF-7 breast cancer cells were grown in culture for the xenograft experiments. Athymic female mice were injected with MCF-7 cells (1 x 10^6 in 100 µl of 50% Matrigel mixed with sterile PBS) via subcutaneous injection. Once the tumors reached an average volume of 100 mm³, the mice were randomly divided into four groups and treated with different vitamin A and D3 combinations. Tumor sizes and mouse body weights were monitored on a biweekly basis. After the treatment period, the mice were euthanized, and the tumors were surgically removed and measured. RNA-seq data from the treated MCF-7 cells were then further evaluated using IPA. Results: As compared with controls, treatment with vitamin A (25,000 IU) and vitamin D (10,000 IU) led to a significant reduction in tumor volume >70%, (p < 0.05-0.01) in OVX athymic mice with MCF-7 xenografts as determined by a twotailed Student T test. Over the treatment period, the tumor volume in mice treated with vitamin A (10,000 IU) and vitamin D (5,000 IU) or vitamin A (25,000 IU) and vitamin D (5,000 IU) also trended downward and was statistically significant using one-way analysis of variance (ANOVA) followed by Dunnett's multiple comparison test (p<0.05 and p<0.0001, respectively) but was not significant using a two-tailed Student T test. In cultured MCF-7 cells, Ingenuity Pathway Analysis of mRNA-seq data showed that the vitamin A and D combination significantly altered the expression of 101 genes out of 864 in the molecular mechanisms in cancer canonical pathway, downregulating gene expression in the integrin/P13K/Akt/mTOR pathway. Conclusions: The findings showed that the combination of vitamins A and D3 effectively reduced tumor burden in a postmenopausal MCF-7 xenograft mouse model, with effects that were both dose-dependent and time-dependent. The combination also significantly altered the expression of genes in the molecular mechanisms of cancer canonical pathway in cultured MCF-7 cells. These preclinical data support the use of vitamins A and D3 in the management of estrogendependent breast cancers, with the caveat that higher doses and longer treatment periods may be needed to observe anti-tumor effects. [ABSTRACT FROM AUTHOR]

Background: Targeted therapies (e.g., ibrutinib) have markedly improved chronic lymphocytic leukemia (CLL) management; however, ~20% of patients experience disease relapse, suggesting the inadequate depth and durability of these front-line strategies. Moreover, immunotherapeutic success in CLL has been stifled by its pro-tumor microenvironment milieu and low mutational burden, cultivating poor antigenicity and limited ability to generate anti-tumor immunity through adaptive immune cell engagement. Previously, we have demonstrated how a three-carbon-linker spirocyclic dimer (SpiD3) promotes futile activation of the unfolded protein response (UPR) in CLL cells through immense misfolded-protein mimicry, culminating in insurmountable ER stress and programmed CLL cell death. Method: Herein, we used flow cytometry and cell-based assays to capture the kinetics and magnitude of SpiD3-induced damage-associated molecular patterns (DAMPs) in CLL cell lines and primary samples. Result: SpiD3 treatment, in vitro and in vivo, demonstrated the capacity to propagate immunogenic cell death through emissions of classically immunogenic DAMPs (CALR, ATP, HMGB1) and establish a chemotactic gradient for bone marrow-derived dendritic cells. Conclusions: Thus, this study supports future investigation into the relationship between novel therapeutics, manners of cancer cell death, and their contributions to adaptive immune cell engagement as a means for improving anti-cancer therapy in CLL. [ABSTRACT FROM AUTHOR]

Small molecule inhibitors of the mitochondrial electron transport chain (ETC) hold significant promise to provide valuable insights to the field of mitochondrial research and aging biology. In this study, we investigated two molecules: mycothiazole (MTZ) - from the marine sponge C. mycofijiensis and its more stable semisynthetic analog 8-O-acetylmycothiazole (8-OAc) as potent and selective chemical probes based on their high efficiency to inhibit ETC complex I function. Similar to rotenone (Rote), MTZ, a newly employed ETC complex I inhibitor, exhibited higher cytotoxicity against cancer cell lines compared to certain non-cancer cell lines. Interestingly, 8-OAc demonstrated greater selectivity for cancer cells when compared to both MTZ and Rote, which has promising potential for anticancer therapeutic development. Furthermore, in vivo experiments with these small molecules utilizing a C. elegans model demonstrate their unexplored potential to investigate aging studies. We observed that both molecules have the ability to induce a mitochondria-specific unfolded protein response (UPRMT) pathway, that extends lifespan of worms when applied in their adult stage. We also found that these two molecules employ different pathways to extend lifespan in worms. Whereas MTZ utilizes the transcription factors ATFS-1 and HSF1, which are involved in the UPRMT and heat shock response (HSR) pathways respectively, 8-OAc only required HSF1 and not ATFS-1 to mediate its effects. This observation underscores the value of applying stable, potent, and selective next generation chemical probes to elucidate an important insight into the functional roles of various protein subunits of ETC complexes and their regulatory mechanisms associated with aging. [ABSTRACT FROM AUTHOR]

The December 2024 issue of Virologica Sinica features research articles on topics such as viral load dynamics in Omicron BA. 2 patients, immunological responses to genital herpes, and the discovery of severe fever with thrombocytopenia virus in Beijing. Additionally, the issue includes studies on mutations in viral proteins, the development of Nipah virus glycoprotein vaccines, and a reverse genetics system for bovine rotavirus. The issue also presents a case study on human norovirus infection and a mouse model for studying severe human adenovirus infections. The cover article discusses the development of a live attenuated hepatitis A virus vaccine and its genetic analysis for vaccine development. [Extracted from the article]