Induction Of Endoplasmic Reticulum Stress Research Articles

Transcriptomic changes behind Sparus aurata hepatic response to different aquaculture challenges: An RNA-seq study and multiomics integration.

Gilthead seabream (Sparus aurata) is an important species in Mediterranean aquaculture. Rapid intensification of its production and sub-optimal husbandry practices can cause stress, impairing overall fish performance and raising issues related to sustainability, animal welfare, and food safety. The advent of next-generation sequencing technologies has greatly revolutionized the study of fish stress biology, allowing a deeper understanding of the molecular stress responses. Here, we characterized for the first time, using RNA-seq, the different hepatic transcriptome responses of gilthead seabream to common aquaculture challenges, namely overcrowding, net handling, and hypoxia, further integrating them with the liver proteome and metabolome responses. After reference-guided transcriptome assembly, annotation, and differential gene expression analysis, 7, 343, and 654 genes were differentially expressed (adjusted p-value < 0.01, log2|fold-change| >1) in the fish from the overcrowding, net handling, and hypoxia challenged groups, respectively. Gene set enrichment analysis (FDR < 0.05) suggested a scenario of challenge-specific responses, that is, net handling induced ribosomal assembly stress, whereas hypoxia induced DNA replication stress in gilthead seabream hepatocytes, consistent with proteomics and metabolomics' results. However, both responses converged upon the downregulation of insulin growth factor signalling and induction of endoplasmic reticulum stress. These results demonstrate the high phenotypic plasticity of this species and its differential responses to distinct challenging environments at the transcriptomic level. Furthermore, it provides significant resources for characterizing and identifying potentially novel genes that are important for gilthead seabream resilience and aquaculture production efficiency with regard to fish welfare.

Abstract 3335: A novel and potent IRE1α RNase inhibitor, HM100168 as a promising therapeutic strategy in solid cancers

Abstract Protein folding homeostasis in the endoplasmic reticulum (ER) is regulated by a signaling network called the unfolded protein response (UPR). Inositol-requiring enzyme 1α (IRE1α) is an ER membrane-resident kinase/RNase that mediates signal transmission in the most evolutionarily conserved way of the UPR. The IRE1α-XBP1 pathway, one of the most essential branches of the UPR, is activated in various types of cancer. When IRE1α is activated, the spliced form of XBP1 (XBP1s) is generated to activate the transcription of many pro-survival genes to prevent cellular death and relieve cellular stress. IRE1α plays an instrumental pro-tumoral role in various cancers, such as glioblastoma, myeloma, lung adenocarcinoma, and breast cancers, as well as high IRE1α activity is associated with poor prognoses. Moreover, IRE1-XBP1 plays an essential role in the UPR and ER stress responses, which have been implicated in the development of drug resistance. Thereby, blockade of the IRE1α-XBP1 pathway is crucial as it is considered as a potential anti-cancer strategy. Here, we developed a potent and selective IRE1α RNase inhibitor, which have a hydroxy-aryl-aldehydes (HAA) moiety that binds to IRE1α within the RNase catalytic site. Our lead compound, HM100168, potently inhibited the RNase activity of human IRE1α at nanomolar concentrations without affecting its kinase activity. Experiments were performed on MCF7 breast cancer cells to confirm the inhibitory effect in the mRNA and protein levels of XBP1s, which was increased by tunicamycin (TM), a ER stress inducer. HM100168 strongly inhibited ​​XBP1s levels in a dose-dependent manner, displaying the potent IC50 values. We tested cell growth inhibition activity in 3D as well as 2D cell culture condition of various cancer cell lines. Interestingly, HM100168 effectively inhibited cell proliferation of diverse cancer cell lines in both 2D and 3D culture condition. In addition, we explored the promising anti-cancer effects of HM100168 and its synergistic potential when combined with anti-tumorigenic agents. As a result, HM100168 in combination with anti-tumorigenic agents significantly enhanced suppression of tumor growth in human cancer cell transplanted mice. In conclusion, we have identified a novel compound with unique properties that specifically blocked the endonuclease activity of IRE1α. HM100168 inhibited IRE1α endonuclease activity, without affecting its kinase activity after endoplasmic reticulum stress in vitro. The identification of this novel IRE1α inhibitor supports the hypothesis that the IRE1α-XBP1 axis is a promising target for anticancer therapy. Also, co-targeting of IRE1α-XBP1 in combination with anti-tumorigenic agents can be considered a novel approach to overcome cancer resistance. Further preclinical studies will be performed and reported soon after the establishment of a preclinical candidate. Citation Format: Jisook Kim, Seung Hyun Jung, Minjeong Kim, Wongi Park, Jooyun Byun, Soonki Park, Miyoung Lee, Yu-Yon Kim, Junghwa Park, Seokhyun Hong, Minhwa Kim, Young Gil Ahn. A novel and potent IRE1α RNase inhibitor, HM100168 as a promising therapeutic strategy in solid cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3335.

HTRA1-driven detachment of type I collagen from endoplasmic reticulum contributes to myocardial fibrosis in dilated cardiomyopathy

BackgroundThe aberrant secretion and excessive deposition of type I collagen (Col1) are important factors in the pathogenesis of myocardial fibrosis in dilated cardiomyopathy (DCM). However, the precise molecular mechanisms underlying the synthesis and secretion of Col1 remain unclear.Methods and resultsRNA-sequencing analysis revealed an increased HtrA serine peptidase 1 (HTRA1) expression in patients with DCM, which is strongly correlated with myocardial fibrosis. Consistent findings were observed in both human and mouse tissues by immunoblotting, quantitative reverse transcription polymerase chain reaction (qRT-PCR), immunohistochemistry, and immunofluorescence analyses. Pearson’s analysis showed a markedly positive correlation between HTRA1 level and myocardial fibrosis indicators, including extracellular volume fraction (ECV), native T1, and late gadolinium enhancement (LGE), in patients with DCM. In vitro experiments showed that the suppression of HTRA1 inhibited the conversion of cardiac fibroblasts into myofibroblasts and decreased Col1 secretion. Further investigations identified the role of HTRA1 in promoting the formation of endoplasmic reticulum (ER) exit sites, which facilitated the transportation of Col1 from the ER to the Golgi apparatus, thereby increasing its secretion. Conversely, HTRA1 knockdown impeded the retention of Col1 in the ER, triggering ER stress and subsequent induction of ER autophagy to degrade misfolded Col1 and maintain ER homeostasis. In vivo experiments using adeno-associated virus-serotype 9-shHTRA1-green fluorescent protein (AAV9-shHTRA1-GFP) showed that HTRA1 knockdown effectively suppressed myocardial fibrosis and improved left ventricular function in mice with DCM.ConclusionsThe findings of this study provide valuable insights regarding the treatment of DCM-associated myocardial fibrosis and highlight the therapeutic potential of targeting HTRA1-mediated collagen secretion.

Abstract 3153: Regulation of ATF4-mediated stress responses by NUAK2 in ovarian cancer

Abstract NUAK family kinase 2 (NUAK2) a member of the AMPK-related serine/threonine kinase family with crucial roles in various cancer cellular processes. The aim of this study was to elucidate the expression and functions of NUAK2 in ovarian cancer while investigating the underlying molecular mechanisms. Analysis of several publicly available databases suggested a significant increase in NUAK2 mRNA levels in ovarian cancer compared to normal tissue. The overexpression of NUAK2 in ovarian cancer was confirmed by immunohistochemistry of NUAK2 in our local collection of ovarian tumor tissues comprised of carcinomas of various histological types (N=88) as well as benign and borderline tumors (N=19). Intense nuclear NUAK2 immunoreactivity was observed in serous and clear-cell carcinomas. Furthermore, nuclear expression of NUAK2 was significantly correlated with higher tumor grade and poorer overall and disease-free survival. Knocking out NUAK2 in SKOV3 cells by CRISPR-Cas9 resulted in suppressed cell growth and migration. Transcriptome by RNA sequencing and pathway enrichment analysis of SKOV3 cells overexpressing NUAK2 revealed activation of activating transcription factor 4 (ATF4) -dependent unfolded protein response (UPR) in the cell. NUAK2 knockout exaggerated the reactive oxygen species level induced by the endoplasmic reticulum (ER) stress inducer tunicamycin treatment. NUAK2 upregulated ATF4 protein expression during ER stress, facilitating its translocation into the nucleus upon exposure to tunicamycin. SKOV3 with NUAK2 knockout grew significantly slower than its parental line in mice as demonstrated by in vivo imaging. Collectively, our study highlights NUAK2 as an oncogene in ovarian cancer and underscores its involvement in the UPR pathway. Citation Format: Li Chen, Oscar GW Wong, Claire LY Cheung, Esther SY Wong, Karen KL Chan, Hextan YS Ngan, Yusanne YS Chan, Annie NY Cheung. Regulation of ATF4-mediated stress responses by NUAK2 in ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3153.

Abstract 1476: OSBPL3 facilitates endoplasmic reticulum stress and stemness in triple negative breast cancer

Abstract Background: Triple negative breast cancer (TNBC) is a type of aggressive breast cancer with a poor survival. Endoplasmic reticulum (ER) stress, induced by exposed to intrinsic (e.g. oncogenes) and external factors (e.g. chemotherapies), is an important factor in both tumor progression and responses to chemotherapies. Recent studies have demonstrated that the progression of ER stress may result in the emergence of cancer stem cells (CSC), which also arise as a consequence of metastasis. However, the mechanism of targeting ER stress signaling in cancer stem cells remains to be investigated. Aim: (i) To investigate the mechanistic role of Oxysterol binding protein-like 3 (OSBPL3) in TNBC and its links with breast cancer mortality, particularly caused by chemotherapeutic resistance and metastasis; and (ii) to test a hypothesis that OSBPL3 facilitates the abnormal activation of ER stress and cancer stemness, result in the resistance to chemotherapy and metastasis in TNBC. Methods: The expression level of OSBPL3 in TNBC was determined by immunohistochemical staining and the mRNA expression profiles from the TCGA database. Roles of OSBPL3 in cancer cell growth, metastasis, stemness and activation of ER stress were determined by molecular and cell biology methods. Immunoprecipitation was used to examine the binding of proteins and chromatin immunoprecipitation (ChIP), promoter luciferase reporter assay was included for detecting the transcription of OSBPL3 in TNBC. TNBC xenograft nude mice were used to study the inhibition of tumor development. Results: OSBPL3 is a novel TNBC target, which is overexpressed in TNBC tissues and significantly associated with clinical pathology of advanced TNM stage and poor prognosis of tumor patients. Mechanistically, Increased OSBPL3 induced ER stress and ER stress agonist (tunicamycin) treatment results in the translocation of XBP1, an ER stress sensor, into the nucleus to induce OSBPL3 expression through direct binding to the OSBPL3 promoter. In addition, OSBPL3 facilitates the stemness induced by ER stress via phosphorylating GSK3β and transporting accumulated β-catenin to the nucleus to promote the expression of stemness-related transcriptional factors, ultimately resulting in tumor metastasis and resistance to chemotherapy. Furthermore, OSBPL3-specific siRNAs encapsulated by jetPEI nanocarriers prominently inhibit tumor growth and epirubicin-induced resistance in vivo. Conclusion: We identified an important role of OSBPL3-ER stress-XBP1 feedback loop in the stemness and resistance to chemotherapy, representing a future biomarker and therapeutic target of TNBC. Citation Format: Shengyu Pu, Huimin Zhang, Yu Ren, Jianjun He, Na Hao. OSBPL3 facilitates endoplasmic reticulum stress and stemness in triple negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1476.

Abstract 2100: Novel LIPA targeted therapy for treating inflammatory breast cancer

Abstract Background: Inflammatory breast cancer (IBC) is a rare but incredibly aggressive subtype of breast cancer (BC). IBC accounts for 2-4% of all occurrences of breast cancer and results in 7-10% of breast cancer-related deaths. IBC is only partially treatable with current therapies such as chemotherapy, surgery, and radiotherapy. Identification of novel therapeutic targets is urgently required. The main organelle for the synthesis, folding, and modification of proteins is called the endoplasmic reticulum (ER). Since elevated basal ER stress (ERS) is usually found in many cancers including IBC, our hypothesis was that the high basal ERS in IBC constitutes a serious vulnerability that can be targeted. Recently, we developed a small molecule ERX41 that promotes ER stress by blocking Lysosomal acid lipase A (LIPA) function in ER of cancer cells. The goal of the project is to test the utility of ERX-41 in treating IBC. Methods: To study the effect of ERX-41, we have used three well-established IBC model cells. We evaluated the efficacy of ERX-41 as a novel therapeutic for treating IBC using cell viability assays. The long-term effects of ERX-41 on IBC cell survival were evaluated using colony formation assays. Annexin V assays were used to measure apoptosis. Reporter assays, splicing assays, RT-qPCR, and Western blotting were used in mechanistic investigations. The effectiveness of ERX-41 was examined in vivo using KPL4 cell-based xenografts. Results: ERX-41 significantly decreased the viability of all three IBC model cells (SUM149, SUM190PT, and KPL4), with an IC50 of about 125 nM in MTT assay. Additionally, ERX-41 treatment significantly decreased IBC cells capacity to form colonies and promoted apoptosis. Specificity of the ERX41 mediated actions were confirmed using LIPA KO cells. Using RTqPCR based splicing assays, we demonstrated increased splicing of XBP1 as early as 6 hours after ERX41 treatment. Western analyses showed robust induction of stress markers (CHOP, PERK, ATF4) in IBC cells upon treatment with ERX-41. In KPL4 xenograft studies, ERX-41 showed significant reduction in the tumor volume. IHC analyses confirmed decreased proliferation marker and increased ER stress markers. Conclusions: Collectively, our results suggest that ERX-41 is a novel therapeutic agent that targets the LIPA with a unique mechanism of action and implicate ERX-41 binding to LIPA induces ER stress and promotes apoptosis of IBC cells. Citation Format: Zenaida Fuentes, Rahul Gopalam, Bianca A. Romo, Khaled Mohamed Nassar, Xue Yang, Behnam Ebrahimi, Paulina Ramirez, Chia-Yuan Chen, Scott Elmore, Harika Nagandla, Uday Pratap, Christoforos Thomas, Suryavathi Viswanadhapalli, Jung-Mo Ahn, Ganesh Raj, Ratna K. Vadlamudi. Novel LIPA targeted therapy for treating inflammatory breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2100.

Abstract 4521: Investigating bAP15, a new inhibitor of UCHL5/USP14 deubiquitinating enzymes, as a potential treatment for chondrosarcoma: A comprehensive in vivo and in vitro study

Abstract Chondrosarcoma, a highly resilient cancer characterized by limited effective treatment options, represents a significant therapeutic challenge. bAP15, a novel inhibitor of deubiquitylating enzymes (DUBs), has emerged as a promising therapeutic agent, exhibiting anti-tumor activity in various cancer models. This study investigated the efficacy of bAP15 against chondrosarcoma in vitro and in vivo. To evaluate bAP15's effects on chondrosarcoma cells, the SW1353 and JJ012 cell lines were employed. Cell viability, apoptosis, and cell cycle progression were assessed using MTT assay and flow cytometry. Western blotting was utilized to analyze apoptosis, cell stress, and endoplasmic reticulum (ER) stress. Additionally, a xenograft mouse model was established to examine the in vivo anti-tumor potential of bAP15. Compared to normal cartilage tissue, chondrosarcoma cells exhibited significantly higher expression of the DUB UCHL5, suggesting its potential involvement in chondrosarcoma development. Treatment with bAP15 effectively induced apoptosis in chondrosarcoma cells by activating caspases and cleaving PARP. Furthermore, bAP15 enhanced ER stress by activating caspase-4 and CHOP. In the xenograft mouse model, bAP15 demonstrated remarkable anti-tumor efficacy with minimal toxicity. These findings highlight the potential of bAP15 as a therapeutic strategy for chondrosarcoma. Its ability to induce ER stress and cell cycle arrest, coupled with its in vivo anti-tumor activity, provides compelling evidence for its further development as a novel treatment option for this challenging cancer. Citation Format: Kuan-Lin Kuo, Fu-Shun Hsu, Shang-Jen Chang, Shih-Ming Liao, Wei-Chou Lin, Tzt-Yao Ke, Tzu-Ting Liu, Kuo-Yuan Huang. Investigating bAP15, a new inhibitor of UCHL5/USP14 deubiquitinating enzymes, as a potential treatment for chondrosarcoma: A comprehensive in vivo and in vitro study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4521.

Abstract 394: Preclinical evaluation of ERX-208, a potent inducer of ER stress for the treatment of ovarian cancer

Abstract Background: Ovarian cancer (OCa) is the deadliest kind of gynecologic cancer in the United States. The long-term survival rate for OCa is less than 20% after five years. Intra-tumoral and inter-tumoral heterogeneity is implicated in tumor resistance to conventional therapies and the unsatisfactory clinical outcomes. Addressing these issues necessitates innovative therapies that target intrinsic common vulnerabilities within OCa. Recent studies have highlighted that high basal level of endoplasmic reticulum stress (ERS) in OCa as a critical vulnerability. We have identified a promising compound, ERX-208 that potently induces ERS in cancer cells. The objective of this study is to characterize the mechanisms and activity of ERX-208 using preclinical models. Methods: The biological activity of ERX-208 was examined across 17 distinct OCa cells, representing 5 diverse OCa subtypes. Mechanistic studies utilized Western blotting, immunohistochemistry (IHC), RNA-Seq analysis, and CRISPR/Cas9 knockouts (KO). Pharmacokinetics (PK) and toxicity studies were performed on C57BL/6 mice. Comprehensive preclinical assessments were carried out through cell line-derived xenografts (CDXs), patient-derived xenografts (PDXs), organoids (PDOs) and explants (PDEs). Results: ERX-208 demonstrated an IC50 of approximately 50-100 nM inducing ERS and reducing cell viability in OCa cells. Conversely, normal ovarian surface epithelial cells exhibited minimal effects from ERX-208. In vitro experiments revealed strong ERX-208-induced apoptosis in OCa cell lines. Mechanistic studies employing RNA sequencing, Western blotting, and RT-qPCR, confirmed activation of ERS pathways observed as early as 5 hours post-ERX-208 treatment. Our studies identified LIPA as a potential target, and KO of LIPA significantly diminished ERX-208 activity. Moreover, LIPA KO substantially impeded in vivo OCa tumor growth. ERX-208 up to a dose of 25 mg/kg showed no observable organ toxicity and had no effect on the mice's body weight. Dose range studies identified 10 mg/kg intraperitoneal as the minimal effective dose, achieving more than 50% tumor reduction. In preclinical models, ERX-208 inhibited the growth of OCa CDXs, PDXs, and ex vivo PDEs and PDO’s. IHC analyses indicated reduced proliferation (Ki-67) and increased activation of ERS markers, such as GRP78 and p-PERK. Conclusions: Collectively, our findings underscore the preclinical promise of ERX-208 as a potential therapeutic agent for treating OCa. Conflict: The patents surrounding ERX-208 are licensed to EtiraRx. Citation Format: Suryavathi Viswanadhapalli, Tae-Kyung Lee, Scott Elmore, Gaurav Sharma, Rahul Gopalam, Karla Parra, Tanner Reese, Michael Hsieh, Uday P. Pratap, Xue Yang, Behnam Ebrahimi, Henry Neal, Chia-Yuan Chen, Kara Kassees, Christian Cervantes, Zhenming Xu, Edward Kost, Gangadhara Reddy Sareddy, Rajeshwar R. Tekmal, Jung-Mo Ahn, Ganesh V. Raj, Ratna K. Vadlamudi. Preclinical evaluation of ERX-208, a potent inducer of ER stress for the treatment of ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 394.

Unlocking the effective alliance of β-lapachone and hydroxytyrosol against triple-negative breast cancer cells

Triple-negative breast cancer (TNBC) is characterised by its aggressiveness and resistance to chemotherapy, demanding the development of effective strategies against its unique characteristics. Derived from lapacho tree bark, β-lapachone (β-LP) selectively targets cancer cells with elevated levels of the detoxifying enzyme NQO1. Hydroxytyrosol (HT) is a phenolic compound derived from olive trees with important anticancer properties that include the inhibition of cancer stem cells (CSCs) and metastatic features in TNBC, as well as relevant antioxidant activities by mechanisms such as the induction of NQO1. We aimed to study whether these compounds could have synergistic anticancer activity in TNBC cells and the possible role of NQO1. For this pourpose, we assessed the impact of β-LP (0.5 or 1.5 μM) and HT (50 and 100 μM) on five TNBC cell lines. We demonstrated that the combination of β-LP and HT exhibits anti-proliferative, pro-apoptotic, and cell cycle arrest effects in several TNBC cells, including docetaxel-resistant TNBC cells. Additionally, it effectively inhibits the self-renewal and clonogenicity of CSCs, modifying their aggressive phenotype. However, the notable impact of the β-LP-HT combination does not appear to be solely associated with the levels of the NQO1 protein and ROS. RNA-Seq analysis revealed that the combination's anticancer activity is linked to a strong induction of endoplasmic reticulum stress and apoptosis through the unfolded protein response. In conclusion, in this study, we demonstrated how the combination of β-LP and HT could offer an affordable, safe, and effective approach against TNBC.

APOE and Alzheimer's disease: Pathologic clues from transgenic Drosophila melanogaster

Alzheimer's disease (AD) is one of the most common forms of neurodegenerative diseases. Apolipoprotein E4 (ApoE4) is the main genetic risk factor in the development of late-onset AD. However, the exact mechanism underlying ApoE4-mediated neurodegeneration remains unclear. We utilized Drosophila melanogaster to examine the neurotoxic effects of various human APOE isoforms when expressed specifically in glial and neural cells. We assessed impacts on mitochondrial dynamics, ER stress, lipid metabolism, and bio-metal ion concentrations in the central nervous system (CNS) of the transgenic flies. Dachshund antibody staining revealed a reduction in the number of Kenyon cells. Behavioral investigations including ethanol tolerance and learning and memory performance demonstrated neuronal dysfunction in APOE4-expressing larvae and adult flies. Transcription level of marf and drp-1 were found to be elevated in APOE4 flies, while atf4, atf6, and xbp-1 s showed down regulation. Enhanced concentrations of triglyceride and cholesterol in the CNS were observed in APOE4 transgenic flies, with especially pronounced effects upon glial-specific expression of the gene. Spectrophotometry of brain homogenate revealed enhanced Fe++ and Zn++ ion levels in conjunction with diminished Cu++ levels upon APOE4 expression. To explore therapeutic strategies, we subjected the flies to heat-shock treatment, aiming to activate heat-shock proteins (HSPs) and assess their potential to mitigate the neurotoxic effects of APOE isoforms. The results showed potential therapeutic benefits for APOE4-expressing flies, hinting at an ability to attenuate memory deterioration. Overall, our findings suggest that APOE4 can alter lipid metabolism, bio metal ion homeostasis, and disrupt the harmonious fission-fusion balance of neuronal and glial mitochondria, ultimately inducing ER stress. These alterations mirror the main clinical manifestations of AD in patients. Therefore, our work underscores the suitability of Drosophila as a fertile model for probing the pathological roles of APOE and furthering our understanding of diverse isoform-specific functions.

Mechanistic insights into the antitumoral potential and in vivo antiproliferative efficacy of a silver-based core@shell nanosystem

This study delves into the biomolecular mechanisms underlying the antitumoral efficacy of a hybrid nanosystem, comprised of a silver core@shell (Ag@MSNs) functionalized with transferrin (Tf). Employing a SILAC proteomics strategy, we identified over 150 de-regulated proteins following exposure to the nanosystem. These proteins play pivotal roles in diverse cellular processes, including mitochondrial fission, calcium homeostasis, endoplasmic reticulum (ER) stress, oxidative stress response, migration, invasion, protein synthesis, RNA maturation, chemoresistance, and cellular proliferation. Rigorous validation of key findings substantiates that the nanosystem elicits its antitumoral effects by activating mitochondrial fission, leading to disruptions in calcium homeostasis, as corroborated by RT-qPCR and flow cytometry analyses. Additionally, induction of ER stress was validated through western blotting of ER stress markers. The cytotoxic action of the nanosystem was further affirmed through the generation of cytosolic and mitochondrial reactive oxygen species (ROS). Finally, in vivo experiments using a chicken embryo model not only confirmed the antitumoral capacity of the nanosystem, but also demonstrated its efficacy in reducing cellular proliferation. These comprehensive findings endorse the potential of the designed Ag@MSNs-Tf nanosystem as a groundbreaking chemotherapeutic agent, shedding light on its multifaceted mechanisms and in vivo applicability.

Dynamics of ER stress-induced gene regulation in plants.

Endoplasmic reticulum (ER) stress is a potentially lethal condition that is induced by the abnormal accumulation of unfolded or misfolded secretory proteins in the ER. In eukaryotes, ER stress is managed by the unfolded protein response (UPR) through a tightly regulated, yet highly dynamic, reprogramming of gene transcription. Although the core principles of the UPR are similar across eukaryotes, unique features of the plant UPR reflect the adaptability of plants to their ever-changing environments and the need to balance the demands of growth and development with the response to environmental stressors. The past decades have seen notable progress in understanding the mechanisms underlying ER stress sensing and signalling transduction pathways, implicating the UPR in the effects of physiological and induced ER stress on plant growth and crop yield. Facilitated by sequencing technologies and advances in genetic and genomic resources, recent efforts have driven the discovery of transcriptional regulators and elucidated the mechanisms that mediate the dynamic and precise gene regulation in response to ER stress at the systems level.

BURNS INDUCE ALTERATIONS IN THE ACYL PROTEOME OF MICE AND HUMANS.

Hypermetabolic reprogramming triggered by thermal injury causes substantial morbidity and mortality. Despite the therapeutic potential of targeting this response, the underlying mechanisms remain poorly understood. Interestingly, protein S-acylation is a reversible posttranslational modification induced by metabolic alterations via DHHC acyltransferases. While this modification aids in the regulation of cellular functions, deregulated S-acylation contributes to various diseases by altering protein structure, stability, and localization. However, whether and how S-acylation may impact morbidity and mortality during postburn hypermetabolism is unknown. In this study, we discovered that alterations in the acyl proteome play a key role in mediating adverse outcomes that occur after burn injury. Using a murine model, we show that burn injury induces profound changes in the expression of various DHHC isoforms in metabolic organs central to regulating postburn hypermetabolism, the adipose tissue, and liver. This was accompanied by increased levels of S-acylated proteins in several pathways involved in mediating the adverse hypermetabolic response, including ER stress, lipolysis, and browning. In fact, similar results were also observed in adipose tissue from severely burned patients, as reflected by increased S-acylation of ERK1/2, eIF2a, ATGL, FGF21, and UCP1 relative to nonburn controls. Importantly, pharmacologically targeting this posttranslational modification using a nonselective DHHC inhibitor effectively attenuated burn-induced ER stress, lipolysis, and browning induction in an ex vivo explant model. Together, these findings suggest that S-acylation may facilitate the protein activation profile that drives burn-induced hypermetabolism and that targeting it could potentially be an effective strategy to restore metabolic function and improve outcomes after injury.

Alpha-tocopheryl succinate induces ER stress, disregulates lipid metabolism and leads to apoptosis in normal and tumorous cell lines of epidermal origin

Vitamin E succinate (VES, α-tocopheryl succinate), is a potential antitumor agent known to selectively affect the mitochondria of tumor cells. However, the data on the proapoptotic mechanism of action of VES are unclear, and the effect of VES on normal, non-tumorigenic cells has not been fully investigated. Previously, we showed that VES induces apoptosis via the mitochondrial pathway in A431 human epidermoid carcinoma cells. The goal of this work is to investigate the effect of VES on non-tumorigenic cells and to reveal commonalities and differences in pathways activated in normal and tumorous cells. To achieve this, we studied how VES affects such organelles as the ER and the Golgi apparatus, analyzed the expression of ER stress-associated genes, and also assessed the ROS content and the accumulation of lipid droplets in A431 human epidermoid carcinoma cells and HaCaT immortalized human keratinocytes. We show that in both cell lines there are signs of ER stress, the amount of ROS and lipid droplets increases, as does the number of apoptotic cells. At the same time, the key difference in the mechanisms apoptotic cell death induction in A431 and HaCaT cells treated with VES lies in the reaction of mitochondria: in A431 cells, apoptotic cell death is triggered via the mitochondrial pathway, while HaCaT cells initiate apoptosis without involving mitochondria. Thus, the targets of VES in normal and tumor cells may differ and can possibly complement each other during apoptosis induction.

C/EBPα-p30 confers AML cell susceptibility to the terminal unfolded protein response and resistance to Venetoclax by activating DDIT3 transcription

BackgroundAcute myeloid leukemia (AML) with biallelic (CEBPAbi) as well as single mutations located in the bZIP region is associated with a favorable prognosis, but the underlying mechanisms are still unclear. Here, we propose that two isoforms of C/EBPα regulate DNA damage-inducible transcript 3 (DDIT3) transcription in AML cells corporately, leading to altered susceptibility to endoplasmic reticulum (ER) stress and related drugs.MethodsHuman AML cell lines and murine myeloid precursor cell line 32Dcl3 cells were infected with recombinant lentiviruses to knock down CEBPA expression or over-express the two isoforms of C/EBPα. Quantitative real-time PCR and western immunoblotting were employed to determine gene expression levels. Cell apoptosis rates were assessed by flow cytometry. CFU assays were utilized to evaluate the differentiation potential of 32Dcl3 cells. Luciferase reporter analysis, ChIP-seq and ChIP-qPCR were used to validate the transcriptional regulatory ability and affinity of each C/EBPα isoform to specific sites at DDIT3 promoter. Finally, an AML xenograft model was generated to evaluate the in vivo therapeutic effect of agents.ResultsWe found a negative correlation between CEBPA expression and DDIT3 levels in AML cells. After knockdown of CEBPA, DDIT3 expression was upregulated, resulting in increased apoptotic rate of AML cells induced by ER stress. Cebpa knockdown in mouse 32Dcl3 cells also led to impaired cell viability due to upregulation of Ddit3, thereby preventing leukemogenesis since their differentiation was blocked. Then we discovered that the two isoforms of C/EBPα regulate DDIT3 transcription in the opposite way. C/EBPα-p30 upregulated DDIT3 transcription when C/EBPα-p42 downregulated it instead. Both isoforms directly bound to the promoter region of DDIT3. However, C/EBPα-p30 has a unique binding site with stronger affinity than C/EBPα-p42. These findings indicated that balance of two isoforms of C/EBPα maintains protein homeostasis and surveil leukemia, and at least partially explained why AML cells with disrupted C/EBPα-p42 and/or overexpressed C/EBPα-p30 exhibit better response to chemotherapy stress. Additionally, we found that a low C/EBPα p42/p30 ratio induces resistance in AML cells to the BCL2 inhibitor venetoclax since BCL2 is a major target of DDIT3. This resistance can be overcome by combining ER stress inducers, such as tunicamycin and sorafenib in vitro and in vivo.ConclusionOur results indicate that AML patients with a low C/EBPα p42/p30 ratio (e.g., CEBPAbi) may not benefit from monotherapy with BCL2 inhibitors. However, this issue can be resolved by combining ER stress inducers.

Endoplasmic reticulum stress enhances the expression of TLR3-induced TSLP by airway epithelium.

Thymic stromal lymphopoietin (TSLP) is an epithelial-derived pleiotropic cytokine that regulates T-helper 2 (Th2) immune responses in the lung and plays a major role in severe uncontrolled asthma. Emerging evidence suggests a role for endoplasmic reticulum (ER) stress in the pathogenesis of asthma. In this study, we determined if ER stress and the unfolded protein response (UPR) signaling are involved in TSLP induction in the airway epithelium. For this, we treated human bronchial epithelial basal cells and differentiated primary bronchial epithelial cells with ER stress inducers and the TSLP mRNA and protein expression was determined. A series of siRNA gene knockdown experiments were conducted to determine the ER stress-induced TSLP signaling pathways. cDNA collected from asthmatic bronchial biopsies was used to determine the gene correlation between ER stress and TSLP. Our results show that ER stress signaling induces TSLP mRNA expression via the PERK-C/EBP homologous protein (CHOP) signaling pathway. AP-1 transcription factor is important in regulating this ER stress-induced TSLP mRNA induction, though ER stress alone cannot induce TSLP protein production. However, ER stress significantly enhances TLR3-induced TSLP protein secretion in the airway epithelium. TSLP and ER stress (PERK) mRNA expression positively correlates in bronchial biopsies from participants with asthma, particularly in neutrophilic asthma. In conclusion, these results suggest that ER stress primes TSLP that is then enhanced further upon TLR3 activation, which may induce severe asthma exacerbations. Targeting ER stress using pharmacological interventions may provide novel therapeutics for severe uncontrolled asthma.NEW & NOTEWORTHY TSLP is an epithelial-derived cytokine and a key regulator in the pathogenesis of severe uncontrolled asthma. We demonstrate a novel mechanism by which endoplasmic reticulum stress signaling upregulates airway epithelial TSLP mRNA expression via the PERK-CHOP signaling pathway and enhances TLR3-mediated TSLP protein secretion.

Salicylic acid- and ethylene-dependent effects of the ER stress-inducer tunicamycin on the photosynthetic light reactions in tomato plants

Plant hormones such as ethylene (ET) and salicylic acid (SA) have an elementary role in the regulation of ER stress and unfolded protein response (UPR) in plants via modulating defence responses or inducing oxidative stress. Chloroplasts can be sources and targets of reactive oxygen species (ROS) that affect photosynthetic efficiency, which has not been investigated under tunicamycin (Tm)-induced ER stress. In this study, the direct and indirect effects of Tm on chloroplastic ROS production were first investigated in leaves of wild-type tomato (Solanum lycopersicum L.) plants. Secondly changes in activities of photosystem II and I were analysed under Tm exposure and after application of the chemical chaperone 4-phenylbutyrate (PBA) in different genotypes, focusing on the regulatory role of SA and ET Tm treatments significantly but indirectly induced ROS production in tomato leaves and in parallel it decreased the effective quantum yield of PSII [Y(II)] and PSI [Y(I)], as well as the photochemical quenching coefficient (qP) and the quantum yield of non-photochemical energy dissipation in PSI due to acceptor-side limitation [Y(NA)]. At the same time, Tm increased non-photochemical quenching (NPQ) and cyclic electron flow (CEF) in tomato leaves after 24 h. However, the photosynthetic activity of the SA hydroxylase-overexpressing NahG tomato plants was more severely affected by Tm as compared to wild-type and ET-insensitive Never ripe (Nr) plants. These results suggest the protective role of SA in the regulation of photosynthetic activity contributing to UPR and the survival of plants under ER stress. Interestingly, the activation of photoprotective mechanisms by NPQ was independent of SA but dependent on active ET signalling under ER stress, whereas CEF was reduced by ET due to its higher ratio in Nr plants.

Therapeutic Potential of Targeting the PERK Signaling Pathway in Ischemic Stroke.

Many pathologic states can lead to the accumulation of unfolded/misfolded proteins in cells. This causes endoplasmic reticulum (ER) stress and triggers the unfolded protein response (UPR), which encompasses three main adaptive branches. One of these UPR branches is mediated by protein kinase RNA-like ER kinase (PERK), an ER stress sensor. The primary consequence of PERK activation is the suppression of global protein synthesis, which reduces ER workload and facilitates the recovery of ER function. Ischemic stroke induces ER stress and activates the UPR. Studies have demonstrated the involvement of the PERK pathway in stroke pathophysiology; however, its role in stroke outcomes requires further clarification. Importantly, considering mounting evidence that supports the therapeutic potential of the PERK pathway in aging-related cognitive decline and neurodegenerative diseases, this pathway may represent a promising therapeutic target in stroke. Therefore, in this review, our aim is to discuss the current understanding of PERK in ischemic stroke, and to summarize pharmacologic tools for translational stroke research that targets PERK and its associated pathways.

Polystyrene microplastic-induced endoplasmic reticulum stress contributes to growth plate endochondral ossification disorder in young rat.

Previous studies on the effects of microplastics (MPs) on bone in early development are limited. This study aimed to investigate the adverse effects of MPs on bone in young rats and the potential mechanism. Three-week-old female rats were orally administered MPs for 28 days, and endoplasmic reticulum (ER) stress inhibitor salubrinal (SAL) and ER stress agonist tunicamycin (TM) were added to evaluate the effect of ER stress on toxicity of MPs. The indicators of growth and plasma markers of bone turnover were evaluated. Tibias were analyzed using micro-computed tomography (micro-CT). Histomorphological staining of growth plates was performed, and related gene expression of growth plate chondrocytes was tested. After exposure of MPs, the rats had decreased growth, shortened tibial length, and altered blood calcium and phosphorus metabolism. Trabecular bone was sparse according to micro-CT inspection. In the growth plate, the thickness of proliferative zone substantial reduced while the thickness of hypertrophic zone increased significantly, and the chondrocytes were scarce and irregularly arranged according to tibial histological staining. The transcription of the ER stress-related genes BIP, PERK, ATF4, and CHOP dramatically increased, and the transcription factors involved in chondrocyte proliferation, differentiation, apoptosis, and matrix secretion were aberrant according to RT-qPCR and western blotting. Moreover, the addition of TM showed higher percentage of chondrocyte death. Administration of SAL alleviated all of the MPs-induced symptoms. These results indicated that MPs could induce growth retardation and longitudinal bone damage in early development. The toxicity of MPs may attribute to induced ER stress and impaired essential processes of the endochondral ossification after MPs exposure.

Autophagy and Symbiosis: Membranes, ER, and Speculations.

The interaction of plants and soil bacteria rhizobia leads to the formation of root nodule symbiosis. The intracellular form of rhizobia, the symbiosomes, are able to perform the nitrogen fixation by converting atmospheric dinitrogen into ammonia, which is available for plants. The symbiosis involves the resource sharing between two partners, but this exchange does not include equivalence, which can lead to resource scarcity and stress responses of one of the partners. In this review, we analyze the possible involvement of the autophagy pathway in the process of the maintenance of the nitrogen-fixing bacteria intracellular colony and the changes in the endomembrane system of the host cell. According to in silico expression analysis, ATG genes of all groups were expressed in the root nodule, and the expression was developmental zone dependent. The analysis of expression of genes involved in the response to carbon or nitrogen deficiency has shown a suboptimal access to sugars and nitrogen in the nodule tissue. The upregulation of several ER stress genes was also detected. Hence, the root nodule cells are under heavy bacterial infection, carbon deprivation, and insufficient nitrogen supply, making nodule cells prone to autophagy. We speculate that the membrane formation around the intracellular rhizobia may be quite similar to the phagophore formation, and the induction of autophagy and ER stress are essential to the success of this process.