Necroptosis molecular mechanisms: Recent findings regarding novel necroptosis regulators

AbstractNecroptosis is a form of programmed necrosis that is mediated by various cytokines and pattern recognition receptors (PRRs). Cells dying by necroptosis show necrotic phenotypes, including swelling and membrane rupture, and release damage-associated molecular patterns (DAMPs), inflammatory cytokines, and chemokines, thereby mediating extreme inflammatory responses. Studies on gene knockout or necroptosis-specific inhibitor treatment in animal models have provided extensive evidence regarding the important roles of necroptosis in inflammatory diseases. The necroptosis signaling pathway is primarily modulated by activation of receptor-interacting protein kinase 3 (RIPK3), which phosphorylates mixed-lineage kinase domain-like protein (MLKL), mediating MLKL oligomerization. In the necroptosis process, these proteins are fine-tuned by posttranslational regulation via phosphorylation, ubiquitination, glycosylation, and protein–protein interactions. Herein, we review recent findings on the molecular regulatory mechanisms of necroptosis.

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Necroptosis in Pulmonary Diseases: A New Therapeutic Target

Frontiers in Pharmacology ◽

10.3389/fphar.2021.737129 ◽

2021 ◽

Vol 12 ◽

Author(s):

Lingling Wang ◽

Ling Zhou ◽

Yuhao Zhou ◽

Lu Liu ◽

Weiling Jiang ◽

...

Keyword(s):

Cell Death ◽

Plasma Membranes ◽

Inflammatory Responses ◽

Neurological Diseases ◽

Kinase Domain ◽

The Body ◽

Interacting Protein ◽

Membrane Rupture ◽

Regulated Cell Death ◽

Scientific Attention

In the past decades, apoptosis has been the most well-studied regulated cell death (RCD) that has essential functions in tissue homeostasis throughout life. However, a novel form of RCD called necroptosis, which requires receptor-interacting protein kinase-3 (RIPK3) and mixed-lineage kinase domain-like pseudokinase (MLKL), has recently been receiving increasing scientific attention. The phosphorylation of RIPK3 enables the recruitment and phosphorylation of MLKL, which oligomerizes and translocates to the plasma membranes, ultimately leading to plasma membrane rupture and cell death. Although apoptosis elicits no inflammatory responses, necroptosis triggers inflammation or causes an innate immune response to protect the body through the release of damage-associated molecular patterns (DAMPs). Increasing evidence now suggests that necroptosis is implicated in the pathogenesis of several human diseases such as systemic inflammation, respiratory diseases, cardiovascular diseases, neurodegenerative diseases, neurological diseases, and cancer. This review summarizes the emerging insights of necroptosis and its contribution toward the pathogenesis of lung diseases.

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Elucidation of the Molecular Pathways Involved in the Protective Effects of AUY-922 in LPS-Induced Inflammation in Mouse Lungs

Pharmaceuticals ◽

10.3390/ph14060522 ◽

2021 ◽

Vol 14 (6) ◽

pp. 522

Author(s):

Mohammad S. Akhter ◽

Mohammad A. Uddin ◽

Khadeja-Tul Kubra ◽

Nektarios Barabutis

Keyword(s):

Molecular Mechanisms ◽

Inflammatory Diseases ◽

Intratracheal Instillation ◽

Hsp90 Inhibitor ◽

Molecular Pathways ◽

Protective Effects ◽

Inflammatory Pathways ◽

Cytokines And Chemokines ◽

The Unfolded Protein Response ◽

Mouse Lungs

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) cause thousands of deaths every year and are associated with high mortality rates (~40%) due to the lack of efficient therapies. Understanding the molecular mechanisms associated with those diseases will most probably lead to novel therapeutics. In the present study, we investigated the effects of the Hsp90 inhibitor AUY-922 in the major inflammatory pathways of mouse lungs. Mice were treated with LPS (1.6 mg/kg) via intratracheal instillation for 24 h and were then post-treated intraperitoneally with AUY-922 (10 mg/kg). The animals were examined 48 h after AUY-922 injection. LPS activated the TLR4-mediated signaling pathways, which in turn induced the release of different inflammatory cytokines and chemokines. AUY-922 suppressed the LPS-induced inflammation by inhibiting major pro-inflammatory pathways (e.g., JAK2/STAT3, MAPKs), and downregulated the IL-1β, IL-6, MCP-1 and TNFα. The expression levels of the redox regulator APE1/Ref1, as well as the DNA-damage inducible kinases ATM and ATR, were also increased after LPS treatment. Those effects were counteracted by AUY-922. Interestingly, this Hsp90 inhibitor abolished the LPS-induced pIRE1α suppression, a major component of the unfolded protein response. Our study elucidates the molecular pathways involved in the progression of murine inflammation and supports our efforts on the development of new therapeutics against lung inflammatory diseases and sepsis.

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Unfulfilled Inflammatory Resolution: A Key Factor in the Pathogenesis of Psoriasis

Iranian Journal of Allergy Asthma and Immunology ◽

10.18502/ijaai.v19i4.4130 ◽

2020 ◽

Author(s):

Zohreh Jadali

Keyword(s):

Inflammatory Response ◽

Chronic Inflammation ◽

Molecular Mechanisms ◽

Inflammatory Responses ◽

Inflammatory Diseases ◽

Relevant Literature ◽

Regulatory Mechanisms ◽

Immune Mediated ◽

Key Factor ◽

Inflammation Resolution

Recent literature has highlighted the importance of chronic inflammation in psoriasis pathogenesis. Non-resolving inflammation can trigger progressive tissue damage and inflammatory mediator release which in turn perpetuate the inflammatory cycle. Under normal conditions, inflammatory responses are tightly controlled through several mechanisms that restore normal tissue function and structure. Defects in regulatory mechanisms of the inflammatory response can result in persistent unresolved inflammation and further increases of inflammation. Therefore, this review focuses on defects in regulatory mechanisms of inflammatory responses that lead to uncontrolled chronic inflammation in psoriasis. Databases such as Pubmed Embase, ISI, and Iranian databases including Iranmedex, and SID were researched to identify relevant literature. The results of this review indicate that dysregulation of the inflammatory response may be a likely cause of various immune-mediated inflammatory disorders such as psoriasis. Based on current findings, advances in understanding the cellular and molecular mechanisms involved in inflammation resolution are not only improving our knowledge of the pathogenesis of chronic inflammatory diseases but also supporting the development of new therapeutic strategies.

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An Autocrine Wnt5a Loop Promotes NF-κB Pathway Activation and Cytokine/Chemokine Secretion in Melanoma

Cells ◽

10.3390/cells8091060 ◽

2019 ◽

Vol 8 (9) ◽

pp. 1060 ◽

Cited By ~ 8

Author(s):

Gastón Barbero ◽

María Victoria Castro ◽

María Belén Villanueva ◽

María Josefina Quezada ◽

Natalia Brenda Fernández ◽

...

Keyword(s):

Nuclear Translocation ◽

Epithelial Mesenchymal Transition ◽

Inflammatory Responses ◽

Inflammatory Diseases ◽

Melanoma Cells ◽

Dominant Negative ◽

Migration And Invasion ◽

Soluble Receptor ◽

Mesenchymal Transition ◽

Cytokines And Chemokines

Wnt5a signaling has been implicated in the progression of cancer by regulating multiple cellular processes, largely migration and invasion, epithelial-mesenchymal transition (EMT), and metastasis. Since Wnt5a signaling has also been involved in inflammatory processes in infectious and inflammatory diseases, we addressed the role of Wnt5a in regulating NF-κB, a pivotal mediator of inflammatory responses, in the context of cancer. The treatment of melanoma cells with Wnt5a induced phosphorylation of the NF-κB subunit p65 as well as IKK phosphorylation and IκB degradation. By using cDNA overexpression, RNA interference, and dominant negative mutants we determined that ROR1, Dvl2, and Akt (from the Wnt5a pathway) and TRAF2 and RIP (from the NF-κB pathway) are required for the Wnt5a/NF-κB crosstalk. Wnt5a also induced p65 nuclear translocation and increased NF-κB activity as evidenced by reporter assays and a NF-κB-specific upregulation of RelB, Bcl-2, and Cyclin D1. Further, stimulation of melanoma cells with Wnt5a increased the secretion of cytokines and chemokines, including IL-6, IL-8, IL-11, and IL-6 soluble receptor, MCP-1, and TNF soluble receptor I. The inhibition of endogenous Wnt5a demonstrated that an autocrine Wnt5a loop is a major regulator of the NF-κB pathway in melanoma. Taken together, these results indicate that Wnt5a activates the NF-κB pathway and has an immunomodulatory effect on melanoma through the secretion of cytokines and chemokines.

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Current translational potential and underlying molecular mechanisms of necroptosis

Cell Death and Disease ◽

10.1038/s41419-019-2094-z ◽

2019 ◽

Vol 10 (11) ◽

Cited By ~ 14

Author(s):

Tamás Molnár ◽

Anett Mázló ◽

Vera Tslaf ◽

Attila Gábor Szöllősi ◽

Gabriella Emri ◽

...

Keyword(s):

Cell Death ◽

Protein Kinase ◽

Posttranslational Modifications ◽

Molecular Mechanisms ◽

Inflammatory Diseases ◽

Immune Surveillance ◽

Kinase Domain ◽

Tumor Formation

Abstract Cell death has a fundamental impact on the evolution of degenerative disorders, autoimmune processes, inflammatory diseases, tumor formation and immune surveillance. Over the past couple of decades extensive studies have uncovered novel cell death pathways, which are independent of apoptosis. Among these is necroptosis, a tightly regulated, inflammatory form of cell death. Necroptosis contribute to the pathogenesis of many diseases and in this review, we will focus exclusively on necroptosis in humans. Necroptosis is considered a backup mechanism of apoptosis, but the in vivo appearance of necroptosis indicates that both caspase-mediated and caspase-independent mechanisms control necroptosis. Necroptosis is regulated on multiple levels, from the transcription, to the stability and posttranslational modifications of the necrosome components, to the availability of molecular interaction partners and the localization of receptor-interacting serine/threonine-protein kinase 1 (RIPK1), receptor-interacting serine/threonine-protein kinase 3 (RIPK3) and mixed lineage kinase domain-like protein (MLKL). Accordingly, we classified the role of more than seventy molecules in necroptotic signaling based on consistent in vitro or in vivo evidence to understand the molecular background of necroptosis and to find opportunities where regulating the intensity and the modality of cell death could be exploited in clinical interventions. Necroptosis specific inhibitors are under development, but >20 drugs, already used in the treatment of various diseases, have the potential to regulate necroptosis. By listing necroptosis-modulated human diseases and cataloging the currently available drug-repertoire to modify necroptosis intensity, we hope to kick-start approaches with immediate translational potential. We also indicate where necroptosis regulating capacity should be considered in the current applications of these drugs.

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Novel control of cAMP-regulated transcription in vascular endothelial cells

Biochemical Society Transactions ◽

10.1042/bst20110606 ◽

2012 ◽

Vol 40 (1) ◽

pp. 1-5 ◽

Cited By ~ 9

Author(s):

Gillian R. Milne ◽

Timothy M. Palmer ◽

Stephen J. Yarwood

Keyword(s):

Endothelial Cells ◽

Molecular Mechanisms ◽

Inflammatory Responses ◽

Vascular Endothelial Cells ◽

Inflammatory Diseases ◽

Circulatory System ◽

Vascular Endothelial ◽

Protective Mechanisms ◽

Enhancer Binding Protein ◽

Developed World

Chronic inflammatory diseases, such as atherosclerosis, are a major cause of death and disability in the developed world. In this respect, although cholesterol obviously plays a predominant role in atherosclerosis, targeting inflammation at lesion sites may be just as important. Indeed, elevated IL-6 (interleukin 6) levels are as strongly associated with coronary heart disease as increased cholesterol. We have been investigating novel cAMP-regulated pathways that combat the action of pro-inflammatory cytokines, such as IL-6 and leptin, in the VECs (vascular endothelial cells) of the circulatory system. In this respect, we have begun to unravel new molecular mechanisms by which the cAMP/Epac1 (exchange protein directly activated by cAMP 1)/Rap1 pathway can initiate a rigorous programme of protective anti-inflammatory responses in VECs. Central to this is the coupling of cAMP elevation to the mobilization of two C/EBP (CCAAT/enhancer-binding protein) family transcription factors, resulting in the induction of the SOCS3 (suppressor of cytokine signalling 3) gene, which attenuates pro-inflammatory cytokine signalling in VECs. These novel ‘protective’ mechanisms of cAMP action will inform the development of the next generation of pharmaceuticals specifically designed to combat endothelial inflammation associated with cardiovascular disease.

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The molecular mechanisms of MLKL-dependent and MLKL-independent necrosis

Journal of Molecular Cell Biology ◽

10.1093/jmcb/mjaa055 ◽

2020 ◽

Author(s):

Lu Li ◽

An Tong ◽

Qiangsheng Zhang ◽

Yuquan Wei ◽

Xiawei Wei

Keyword(s):

Molecular Mechanisms ◽

Death Receptor ◽

Kinase Domain ◽

External Stress ◽

Programmed Necrosis ◽

Interacting Protein ◽

Mixed Lineage Kinase ◽

Caspase Inhibition ◽

Regulated Necrosis ◽

Receptor Family

Abstract Necrosis, a type of unwanted and passive cell demise, usually occurs under the excessive external stress and is considered to be unregulated. However, under some special conditions such as caspase inhibition, necrosis is regulable in a well-orchestrated way. The term ‘regulated necrosis’ has been proposed to describe such programmed necrosis. Recently, several forms of necrosis, including necroptosis, pyroptosis, ferroptosis, parthanatos, oxytosis, NETosis, and Na+/K+-ATPase-mediated necrosis, have been identified, and some crucial regulators governing regulated necrosis have also been discovered. Mixed lineage kinase domain-like pseudokinase (MLKL), a core regulator in necroptosis, acts as an executioner in response to ligands of death receptor family. Its activation requires the receptor-interacting protein kinases, RIP1 and RIP3. However, MLKL is only involved in necroptosis, that is, MLKL is dispensable for necrosis. Therefore, this review is aimed at summarizing the molecular mechanisms of MLKL-dependent and MLKL-independent necrosis.

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Inhibitory Effects of the Two Novel TSPO Ligands 2-Cl-MGV-1 and MGV-1 on LPS-induced Microglial Activation

Cells ◽

10.3390/cells8050486 ◽

2019 ◽

Vol 8 (5) ◽

pp. 486 ◽

Cited By ~ 7

Author(s):

Sheelu Monga ◽

Rafi Nagler ◽

Rula Amara ◽

Abraham Weizman ◽

Moshe Gavish

Keyword(s):

Inflammatory Responses ◽

Inflammatory Diseases ◽

Cell Metabolism ◽

Interferon Γ ◽

Translocator Protein ◽

Ros Generation ◽

Protective Effects ◽

Neuronal Progenitor ◽

Cytokines And Chemokines ◽

Factor Α

The 18 kDa translocator protein (TSPO) ligands 2-Cl-MGV-1 and MGV-1 can attenuate cell death of astrocyte-like cells (U118MG) and induce differentiation of neuronal progenitor cells (PC-12). Lipopolysaccharide (LPS) is a bacterial membrane endotoxin that activates cellular inflammatory pathways by releasing pro-inflammatory molecules, including cytokines and chemokines. The aim of the present study was to assess the immuno-modulatory effect of TSPO ligands in activated microglial cells. We demonstrated that the TSPO ligands 2-Cl-MGV-1 and MGV-1 can prevent LPS-induced activation of microglia (BV-2 cell line). Co-treatment of LPS (100 ng/mL) with these TSPO ligands (final concentration- 25 µM) reduces significantly the LPS-induced release of interleukin-6 (IL-6) from 16.9-fold to 2.5-fold, IL-β from 8.3-fold to 1.6-fold, interferon-γ from 16.0-fold to 2.2-fold, and tumor necrosis factor-α from 16.4-fold to 1.8-fold. This anti-inflammatory activity seems to be achieved by inhibition of NF-κB p65 activation. Assessment of initiation of ROS generation and cell metabolism shows significant protective effects of these two novel TSPO ligands. The IL-10 and IL-13 levels were not affected by any of the TSPO ligands. Thus, it appears that the ligands suppress the LPS-induced activation of some inflammatory responses of microglia. Such immunomodulatory effects may be relevant to the pharmacotherapy of neuro-inflammatory diseases.

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Modeling Inflammation in Zebrafish for the Development of Anti-inflammatory Drugs

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2020.620984 ◽

2021 ◽

Vol 8 ◽

Author(s):

Yufei Xie ◽

Annemarie H. Meijer ◽

Marcel J. M. Schaaf

Keyword(s):

Immune System ◽

Inflammatory Response ◽

Molecular Mechanisms ◽

Inflammatory Responses ◽

Inflammatory Diseases ◽

Critical Role ◽

Model Systems ◽

Trinitrobenzene Sulfonic Acid ◽

Inflammatory Drugs ◽

Anti Inflammatory

Dysregulation of the inflammatory response in humans can lead to various inflammatory diseases, like asthma and rheumatoid arthritis. The innate branch of the immune system, including macrophage and neutrophil functions, plays a critical role in all inflammatory diseases. This part of the immune system is well-conserved between humans and the zebrafish, which has emerged as a powerful animal model for inflammation, because it offers the possibility to image and study inflammatory responses in vivo at the early life stages. This review focuses on different inflammation models established in zebrafish, and how they are being used for the development of novel anti-inflammatory drugs. The most commonly used model is the tail fin amputation model, in which part of the tail fin of a zebrafish larva is clipped. This model has been used to study fundamental aspects of the inflammatory response, like the role of specific signaling pathways, the migration of leukocytes, and the interaction between different immune cells, and has also been used to screen libraries of natural compounds, approved drugs, and well-characterized pathway inhibitors. In other models the inflammation is induced by chemical treatment, such as lipopolysaccharide (LPS), leukotriene B4 (LTB4), and copper, and some chemical-induced models, such as treatment with trinitrobenzene sulfonic acid (TNBS), specifically model inflammation in the gastro-intestinal tract. Two mutant zebrafish lines, carrying a mutation in the hepatocyte growth factor activator inhibitor 1a gene (hai1a) and the cdp-diacylglycerolinositol 3-phosphatidyltransferase (cdipt) gene, show an inflammatory phenotype, and they provide interesting model systems for studying inflammation. These zebrafish inflammation models are often used to study the anti-inflammatory effects of glucocorticoids, to increase our understanding of the mechanism of action of this class of drugs and to develop novel glucocorticoid drugs. In this review, an overview is provided of the available inflammation models in zebrafish, and how they are used to unravel molecular mechanisms underlying the inflammatory response and to screen for novel anti-inflammatory drugs.

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Regulation of common neurological disorders by gut microbial metabolites

Experimental & Molecular Medicine ◽

10.1038/s12276-021-00703-x ◽

2021 ◽

Author(s):

Jeongho Park ◽

Chang H. Kim

Keyword(s):

Neurological Disorders ◽

Molecular Mechanisms ◽

Inflammatory Responses ◽

Inflammatory Diseases ◽

Short Chain Fatty Acids ◽

Autism Spectrum ◽

Molecular Networks ◽

Microbial Metabolites ◽

Cns Diseases ◽

The Impact

AbstractThe gut is connected to the CNS by immunological mediators, lymphocytes, neurotransmitters, microbes and microbial metabolites. A mounting body of evidence indicates that the microbiome exerts significant effects on immune cells and CNS cells. These effects frequently result in the suppression or exacerbation of inflammatory responses, the latter of which can lead to severe tissue damage, altered synapse formation and disrupted maintenance of the CNS. Herein, we review recent progress in research on the microbial regulation of CNS diseases with a focus on major gut microbial metabolites, such as short-chain fatty acids, tryptophan metabolites, and secondary bile acids. Pathological changes in the CNS are associated with dysbiosis and altered levels of microbial metabolites, which can further exacerbate various neurological disorders. The cellular and molecular mechanisms by which these gut microbial metabolites regulate inflammatory diseases in the CNS are discussed. We highlight the similarities and differences in the impact on four major CNS diseases, i.e., multiple sclerosis, Parkinson’s disease, Alzheimer’s disease, and autism spectrum disorder, to identify common cellular and molecular networks governing the regulation of cellular constituents and pathogenesis in the CNS by microbial metabolites.

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