Intracellular double-stranded RNA (dsRNA) is a chief sign of replication for many viruses. Host mechanisms detect the dsRNA and initiate antiviral responses. In this report, we identify retinoic acid inducible gene I (RIG-I), which encodes a DExD/H box RNA helicase that contains a caspase recruitment domain, as an essential regulator for dsRNA-induced signaling, as assessed by functional screening and assays. A helicase domain with intact ATPase activity was responsible for the dsRNA-mediated signaling. The caspase recruitment domain transmitted 'downstream' signals, resulting in the activation of transcription factors NF-kappaB and IRF-3. Subsequent gene activation by these factors induced antiviral functions, including type I interferon production. Thus, RIG-I is key in the detection and subsequent eradication of the replicating viral genomes.

The RNA helicase RIG-I has an essential function in double-stranded RNA-induced innate antiviral responses.

Over the past decade, the Nomenclature Committee on Cell Death (NCCD) has formulated guidelines for the definition and interpretation of cell death from morphological, biochemical, and functional perspectives. Since the field continues to expand and novel mechanisms that orchestrate multiple cell death pathways are unveiled, we propose an updated classification of cell death subroutines focusing on mechanistic and essential (as opposed to correlative and dispensable) aspects of the process. As we provide molecularly oriented definitions of terms including intrinsic apoptosis, extrinsic apoptosis, mitochondrial permeability transition (MPT)-driven necrosis, necroptosis, ferroptosis, pyroptosis, parthanatos, entotic cell death, NETotic cell death, lysosome-dependent cell death, autophagy-dependent cell death, immunogenic cell death, cellular senescence, and mitotic catastrophe, we discuss the utility of neologisms that refer to highly specialized instances of these processes. The mission of the NCCD is to provide a widely accepted nomenclature on cell death in support of the continued development of the field.

https://biblio.ugent.be/publication/8555786/file/8555788.pdf

Molecular mechanisms of cell death: recommendations of the Nomenclature Committee on Cell Death 2018.

■ Abstract Apoptosis is a genetically programmed, morphologically distinct form of cell death that can be triggered by a variety of physiological and pathological stimuli. Studies performed over the past 10 years have demonstrated that proteases play critical roles in initiation and execution of this process. The caspases, a family of cysteine-dependent aspartate-directed proteases, are prominent among the death proteases. Caspases are synthesized as relatively inactive zymogens that become activated by scaffold-mediated transactivation or by cleavage via upstream proteases in an intracellular cascade. Regulation of caspase activation and activity occurs at several different levels: ( a) Zymogen gene transcription is regulated; ( b) antiapoptotic members of the Bcl-2 family and other cellular polypeptides block proximity-induced activation of certain procaspases; and ( c) certain cellular inhibitor of apoptosis proteins (cIAPs) can bind to and inhibit active caspases. Once activated, caspases cleave a variety of intracellular polypeptides, including major structural elements of the cytoplasm and nucleus, components of the DNA repair machinery, and a number of protein kinases. Collectively, these scissions disrupt survival pathways and disassemble important architectural components of the cell, contributing to the stereotypic morphological and biochemical changes that characterize apoptotic cell death.

Mammalian caspases: structure ,a ctivation ,s ubstrates, and functions during apoptosis

In 2009, the Nomenclature Committee on Cell Death (NCCD) proposed a set of recommendations for the definition of distinct cell death morphologies and for the appropriate use of cell death-related terminology, including 'apoptosis', 'necrosis' and 'mitotic catastrophe'. In view of the substantial progress in the biochemical and genetic exploration of cell death, time has come to switch from morphological to molecular definitions of cell death modalities. Here we propose a functional classification of cell death subroutines that applies to both in vitro and in vivo settings and includes extrinsic apoptosis, caspase-dependent or -independent intrinsic apoptosis, regulated necrosis, autophagic cell death and mitotic catastrophe. Moreover, we discuss the utility of expressions indicating additional cell death modalities. On the basis of the new, revised NCCD classification, cell death subroutines are defined by a series of precise, measurable biochemical features.

/pdf/molecular-definitions-of-cell-death-subroutines-q5g428rlyi.pdf

Molecular definitions of cell death subroutines: recommendations of the Nomenclature Committee on Cell Death 2012

Interleukin 6 (IL-6) has a broad effect on cells of the immune system and those not of the immune system and often displays hormone-like characteristics that affect homeostatic processes. IL-6 has context-dependent pro- and anti-inflammatory properties and is now regarded as a prominent target for clinical intervention. However, the signaling cassette that controls the activity of IL-6 is complicated, and distinct intervention strategies can inhibit this pathway. Clinical experience with antagonists of IL-6 has raised new questions about how and when to block this cytokine to improve disease outcome and patient wellbeing. Here we discuss the effect of IL-6 on innate and adaptive immunity and the possible advantages of various antagonists of IL-6 and consider how the immunobiology of IL-6 may inform clinical decisions.

/pdf/il-6-as-a-keystone-cytokine-in-health-and-disease-c7lxehv1qz.pdf

IL-6 as a keystone cytokine in health and disease

Edaravone and carnosic acid synergistically enhance the expression of nerve growth factor in human astrocytes under hypoxia/reoxygenation.

Valosin-containing protein (VCP) is associated with multiple cellular functions, including ubiquitin-dependent protein degradation. Mutations in VCP are known to cause inclusion body myopathy with Paget's disease and frontotemporal dementia and familial amyotrophic lateral sclerosis (fALS; ALS14), both of which are characterized by trans-activation response DNA protein 43 (TDP-43)-positive neuronal cytoplasmic and nuclear inclusions. Recently, immunoreactivity for fALS-associated proteins (TDP-43, fused in sarcoma (FUS), optineurin and ubiquilin-2) were reported to be present in cytoplasmic and nuclear inclusions in various neurodegenerative diseases. However, the extent and frequency of VCP-immunoreactive structures in these neurodegenerative diseases are uncertain. We immunohistochemically examined the brains of 72 cases with neurodegenerative diseases and five control cases. VCP immunoreactivity was present in Lewy bodies in Parkinson's disease and dementia with Lewy bodies, and neuronal nuclear inclusions in five polyglutamine diseases and intranuclear inclusion body disease, as well as in Marinesco bodies in aged control subjects. However, other neuronal and glial cytoplasmic inclusions in tauopathies and TDP-43 proteinopathies were unstained. These findings suggest that VCP may have common mechanisms in the formation or degradation of cytoplasmic and nuclear inclusions of neurons, but not of glial cells, in several neurodegenerative conditions.

Valosin-containing protein immunoreactivity in tauopathies, synucleinopathies, polyglutamine diseases and intranuclear inclusion body disease.

Amino acids exert many biological functions, serving as allosteric regulators and neurotransmitters, as constituents in proteins and as nutrients. GCN2-mediated phosphorylation of eukaryotic initiation factor 2 alpha (elF2α) restores homeostasis in response to amino acid starvation (AAS) through the inhibition of the general translation and upregulation of amino acid biosynthetic enzymes and transporters by activating the translation of Gcn4 and ATF4 in yeast and mammals, respectively. GCN1 is a GCN2-binding protein that possesses an RWD binding domain (RWDBD) in its C-terminus. In yeast, Gcn1 is essential for Gcn2 activation by AAS; however, the roles of GCN1 in mammals need to be established. Here, we revealed a novel role of GCN1 that does not depend on AAS by generating two Gcn1 mutant mouse lines: Gcn1-knockout mice (Gcn1 KO mice (Gcn1-/-)) and RWDBD-deleted mutant mice (Gcn1ΔRWDBD mice). Both mutant mice showed growth retardation, which was not observed in the Gcn2 KO mice, such that the Gcn1 KO mice died at the intermediate stage of embryonic development because of severe growth retardation, while the Gcn1ΔRWDBD embryos showed mild growth retardation and died soon after birth, most likely due to respiratory failure. Extension of pregnancy by 24 h through the administration of progesterone to the pregnant mothers rescued the expression of differentiation markers in the lungs and prevented lethality of the Gcn1ΔRWDBD pups, indicating that perinatal lethality of the Gcn1ΔRWDBD embryos was due to simple growth retardation. Similar to the yeast Gcn2/Gcn1 system, AAS- or UV irradiation-induced elF2α phosphorylation was diminished in the Gcn1ΔRWDBD mouse embryonic fibroblasts (MEFs), suggesting that GCN1 RWDBD is responsible for GCN2 activity. In addition, we found reduced cell proliferation and G2/M arrest accompanying a decrease in Cdk1 and Cyclin B1 in the Gcn1ΔRWDBD MEFs. Our results demonstrated, for the first time, that GCN1 is essential for both GCN2-dependent stress response and GCN2-independent cell cycle regulation.

/pdf/ribosome-binding-protein-gcn1-regulates-the-cell-cycle-and-pzgo1795jw.pdf

Ribosome binding protein GCN1 regulates the cell cycle and cell proliferation and is essential for the embryonic development of mice.

Tau phosphorylation is associated with neurite outgrowth and morphogenesis in neurons. Since inflammatory stimuli induce marked morphological changes in astrocytes, we examined the effect of interleukin 1alpha (IL-1alpha), an inflammatory cytokine, on the expression and phosphorylation of tau protein in cultured human astrocytes. Western blot analysis showed a rapid and transient increase (3-30 min) of tau phosphorylation at the AT8 epitope. The cells began to extend processes from 24 h after IL-1alpha stimulation. It is known that tau phosphorylation at the AT8 epitope reduces its ability to bind to, and stabilize, microtubules. The early tau phosphorylation induced by IL-1alpha might create a plastic environment for morphological changes in astrocytes.

Kunikazu Tanji

Papers

Edaravone and carnosic acid synergistically enhance the expression of nerve growth factor in human astrocytes under hypoxia/reoxygenation.

Valosin-containing protein immunoreactivity in tauopathies, synucleinopathies, polyglutamine diseases and intranuclear inclusion body disease.

Ribosome binding protein GCN1 regulates the cell cycle and cell proliferation and is essential for the embryonic development of mice.

Interleukin-1 induces tau phosphorylation and morphological changes in cultured human astrocytes.

YOD1 attenuates neurogenic proteotoxicity through its deubiquitinating activity