bims-tunefa Biomed News
on Tumor necrosis factor superfamily and post-translational modifications
Issue of 2020‒05‒24
thirty-two papers selected by
John Silke
Walter and Eliza Hall Institute of Medical Research

  1. Immunity. 2020 May 10. pii: S1074-7613(20)30168-0. [Epub ahead of print]
    Tummers B, Mari L, Guy CS, Heckmann BL, Rodriguez DA, Rühl S, Moretti J, Crawford JC, Fitzgerald P, Kanneganti TD, Janke LJ, Pelletier S, Blander JM, Green DR.
      Cell death pathways regulate various homeostatic processes. Autoimmune lymphoproliferative syndrome (ALPS) in humans and lymphoproliferative (LPR) disease in mice result from abrogated CD95-induced apoptosis. Because caspase-8 mediates CD95 signaling, we applied genetic approaches to dissect the roles of caspase-8 in cell death and inflammation. Here, we describe oligomerization-deficient Caspase-8F122GL123G/F122GL123G and non-cleavable Caspase-8D387A/D387A mutant mice with defective caspase-8-mediated apoptosis. Although neither mouse developed LPR disease, removal of the necroptosis effector Mlkl from Caspase-8D387A/D387A mice revealed an inflammatory role of caspase-8. Ablation of one allele of Fasl, Fadd, or Ripk1 prevented the pathology of Casp8D387A/D387AMlkl-/- animals. Removing both Fadd alleles from these mice resulted in early lethality prior to post-natal day 15 (P15), which was prevented by co-ablation of either Ripk1 or Caspase-1. Our results suggest an in vivo role of the inflammatory RIPK1-caspase-8-FADD (FADDosome) complex and reveal a FADD-independent inflammatory role of caspase-8 that involves activation of an inflammasome.
    Keywords:  FADD; Inflammasome; apoptosis; autoimmune lymphoproliferative syndrome; caspase; inflammation; necroptosis; pyroptosis
  2. Apoptosis. 2020 Jun;25(5-6): 441-455
    Yang C, Ran Q, Zhou Y, Liu S, Zhao C, Yu X, Zhu F, Ji Y, Du Q, Yang T, Zhang W, He S.
      Smac/Diablo is a pro-apoptotic protein via interaction with inhibitors of apoptosis proteins (IAPs) to relieve their inhibition of caspases. Smac mimetic compounds (also known as antagonists of IAPs) mimic the function of Smac/Diablo and sensitize cancer cells to TNF-induced apoptosis. However, the majority of cancer cells are resistant to Smac mimetic alone. Doxorubicin is a widely used chemotherapeutic drug and causes adverse effect of cardiotoxicity in many patients. Therefore, it is important to find strategies of combined chemotherapy to increase chemosensitivity and reduce the adverse effects. Here, we report that doxorubicin synergizes with Smac mimetic to trigger TNF-mediated apoptosis, which is mechanistically distinct from doxorubicin-induced cell death. Doxorubicin sensitizes cancer cells including human pancreatic and colorectal cancer cells to Smac mimetic treatment. The combined treatment leads to synergistic induction of TNFα to initiate apoptosis through activating NF-κB and c-Jun signaling pathways. Knockdown of caspase-8 or knockout of FADD significantly blocked apoptosis synergistically induced by Smac mimetic and doxorubicin, but had no effect on cell death caused by doxorubicin alone. Moreover, Smac mimetic and doxorubicin-induced apoptosis requires receptor-interacting protein kinase 1 (RIPK1) and its deubiquitinating enzyme cylindromatosis (CYLD), not A20. These in vitro findings demonstrate that combination of Smac mimetic and doxorubicin synergistically triggers apoptosis through the TNF/CYLD/RIPK1/FADD/caspase-8 signaling pathway. Importantly, the combined treatment induced in vivo synergistic anti-tumor effects in the xenograft tumor model. Thus, the combined therapy using Smac mimetic and doxorubicin presents a promising apoptosis-inducing strategy with great potential for the development of anti-cancer therapy.
    Keywords:  Apoptosis; Cancer; Chemotherapy; Doxorubicin; Smac; Smac mimetic
  3. Apoptosis. 2020 May 21.
    Miles MA, Caruso S, Baxter AA, Poon IKH, Hawkins CJ.
      Smac mimetics, or IAP antagonists, are a class of drugs currently being evaluated as anti-cancer therapeutics. These agents antagonize IAP proteins, including cIAP1/2 and XIAP, to induce cell death via apoptotic or, upon caspase-8 deficiency, necroptotic cell death pathways. Many cancer cells are unresponsive to Smac mimetic treatment as a single agent but can be sensitized to killing in the presence of the cytokine TNFα, provided either exogenously or via autocrine production. We found that high concentrations of a subset of Smac mimetics could provoke death in cells that did not produce TNFα, despite sensitization at lower concentrations by TNFα. The ability of these drugs to kill did not correlate with valency. These cells remained responsive to the lethal effects of Smac mimetics at high concentrations despite genetic or pharmacological impairments in apoptotic, necroptotic, pyroptotic, autophagic and ferroptotic cell death pathways. Analysis of dying cells revealed necrotic morphology, which was accompanied by the release of lactate dehydrogenase and cell membrane rupture without prior phosphatidylserine exposure implying cell lysis, which occurred over a several hours. Our study reveals that cells incapable of autocrine TNFα production are sensitive to some Smac mimetic compounds when used at high concentrations, and this exposure elicits a lytic cell death phenotype that occurs via a mechanism not requiring apoptotic caspases or necroptotic effectors RIPK3 or MLKL. These data reveal the possibility that non-canonical cell death pathways can be triggered by these drugs when applied at high concentrations.
    Keywords:  Apoptosis; Cell death; IAP antagonist; Necroptosis; Smac mimetic
  4. Future Med Chem. 2020 May 20.
    Liu X, Zhang X, Lv D, Yuan Y, Zheng G, Zhou D.
      Targeted protein degradation by small-molecule degraders represents an emerging mode of action in drug discovery. Proteolysis targeting chimeras (PROTACs) are small molecules that can recruit an E3 ligase and a protein of interest (POI) into proximity, leading to induced ubiquitination and degradation of the POI by the proteasome system. To date, the design and optimization of PROTACs remain empirical due to the complicated mechanism of induced protein degradation. Nevertheless, it is increasingly appreciated that profiling step-by-step along the ubiquitin-proteasome degradation pathway using biochemical and biophysical assays are essential in understanding the structure-activity relationship and facilitating the rational design of PROTACs. This review aims to summarize these assays and to discuss the potential of expanding the toolbox with other new techniques.
    Keywords:  PROTAC; biochemical assay; biophysical assay; degraders; protein degradation; protein ubiquitination; ternary complex
  5. Biochem Biophys Res Commun. 2020 May 18. pii: S0006-291X(20)30860-3. [Epub ahead of print]
    Pourfarjam Y, Kasson S, Tran L, Ho C, Lim S, Kim IK.
      Poly(ADP-ribosyl)ation (PARylation) regulates DNA damage response, chromatin structure, and cell-fate. Dynamic regulation of cellular PAR levels is crucial for the maintenance of genomic integrity and excessive cellular PAR activates a PAR-dependent cell death pathway. Thus, PAR serves as a cell-death signal; however, it has been debated how the protein-free PAR is generated. Here, we demonstrate that PAR glycohydrolases (PARGs) from mammals to bacteria have a robust endo-glycohydrolase activity, releasing protein-free PAR chains longer than three ADP-ribose units as early reaction products. Released PAR chains are transient and rapidly degraded to monomeric ADP-ribose, which is consistent with a short half-life of PAR during DNA damage responses. Computational simulations using a tri-ADP-ribose further support that PARG can efficiently bind to internal sites of PAR for the endo-glycosidic cleavage. Our collective results suggest PARG as a key player in producing protein-free PAR during DNA damage signaling and establish bacterial PARG as a useful tool to enrich short PAR chains that emerge as important reagents for biomedical research.
    Keywords:  Endo-glycohydrolase; Exo-glycohydrolase; PARG; PARP1; Poly(ADP-ribose)
  6. Semin Cancer Biol. 2020 May 19. pii: S1044-579X(20)30098-5. [Epub ahead of print]
    Wang P, Dai X, Jiang W, Li Y, Wei W.
      RING-in-between-RING (RBR) E3 ligases are one class of E3 ligases that is characterized by the unique RING-HECT hybrid mechanism to function with E2s to transfer ubiquitin to target proteins for degradation. Emerging evidence has demonstrated that RBR E3 ligases play an essential role in neurodegenerative diseases, infection, inflammation and cancer. Accumulated evidence has revealed that RBR E3 ligases exert their biological functions in various types of cancers by modulating the degradation of tumor promoters or suppressors. Hence, we summarize the differential functions of RBR E3 ligases in a variety of human cancers. In general, ARIH1, RNF14, RNF31, RNF144B, RNF216, and RBCK1 exhibit primarily oncogenic roles, whereas ARIH2, PARC and PARK2 mainly have tumor suppressive functions. Moreover, the underlying mechanisms by which different RBR E3 ligases are involved in tumorigenesis and progression are also described. We discuss the further investigation is required to comprehensively understand the critical role of RBR E3 ligases in carcinogenesis. We hope our review can stimulate the researchers to deeper explore the mechanism of RBR E3 ligases-mediated carcinogenesis and to develop useful inhibitors of these oncogenic E3 ligases for cancer therapy.
    Keywords:  Degradation; Oncogene; RBR E3; Tumor suppressor; Ubiquitination
  7. Angew Chem Int Ed Engl. 2020 May 19.
    Luh LM, Scheib U, Jünemann K, Wortmann L, Brands M, Cromm PM.
      Targeted protein degradation (TPD), the ability to control a proteins fate by triggering its degradation in a highly selective and effective manner, has created tremendous excitement in chemical biology and drug discovery within the past decades. The TPD field is spearheaded by small molecule induced protein degradation with molecular glues and proteolysis targeting chimeras (PROTACs) paving the way to expand the druggable space and to create a new paradigm in drug discovery. However, besides the therapeutic angle of TPD a plethora of novel techniques to modulate and control protein levels have been developed. This enables chemical biologists to better understand protein function and to discover and verify new therapeutic targets. This review gives a comprehensive overview of chemical biology techniques inducing TPD. The manuscript explains the strengths and weaknesses of these methods in the context of drug discovery and discusses their future potential from a medicinal chemist's perspective.
    Keywords:  PROTACs; chemical biology; medicinal chemistry; molecular glue; targeted protein degradation
  8. Cell Rep. 2020 May 19. pii: S2211-1247(20)30603-3. [Epub ahead of print]31(7): 107650
    Zhang H, Wu X, Li X, Li M, Li F, Wang L, Zhang X, Zhang Y, Luo Y, Wang H, Jiang Y, Zhang H.
      Receptor-interacting protein kinase 3 (RIPK3) has been identified as an essential regulator of necroptosis, apoptosis, and inflammatory signaling. RIPK3 contains an N-terminal kinase domain and a C-terminal RIP homotypic interaction motif (RHIM). However, the physiological roles of RIPK3 RHIM remain unclear. Here we generate knockin mice endogenously expressing the RIPK3 RHIM mutant, RIPK3V448P. Cells expressing RIPK3V448P are resistant to RIPK1 kinase-dependent apoptosis and necroptosis, and Ripk3V448P/V448P mice rescue embryonic lethality of Fadd-deficient mice by intercrossing. Strikingly, Ripk3V448P/V448PFadd-/- mice display more severe lymphoproliferative disease with a marked increase in abnormal CD3+B220+ lymphocytes compared with Ripk3-/-Fadd-/- mice. More importantly, these inflammatory morbidities in Ripk3V448P/V448PFadd-/- mice are profoundly inhibited by additional deletion of Ripk1. Taken together, these results reveal a previously unidentified physiological function of RHIM of RIPK3 in regulating RIPK1-dependent cell death and lymphoproliferative disease.
    Keywords:  FADD; MLKL; RHIM; RIPK1; RIPK3; Receptor-interacting protein homotypic interaction motifs; embryonic development; inflammation; lymphoproliferative disease; necroptosis
  9. J Immunol. 2020 May 20. pii: ji2000359. [Epub ahead of print]
    Zhang J, Kodali S, Chen M, Wang J.
      In response to T cell-dependent Ag encounter, naive B cells develop into germinal center (GC) B cells, which can further differentiate into Ab-secreting plasma cells or memory B cells. GC B cells are short lived and are prone to caspase-mediated apoptosis. However, how apoptotic caspases regulate GC B cell fate has not been fully characterized. In this study, we show that mice with B cell-specific knockout of caspase-9 had decreases in GC B cells and Ab production after immunization. Caspase-9-deficient B cells displayed defects in caspase-dependent apoptosis but increases in necroptosis signaling. Additional deletion of Ripk3 restored GC B cells and Ab production in mice with B cell-specific knockout of caspase-9. Our results indicate that caspase-9 plays an important role in the maintenance of Ab responses by promoting apoptosis and inhibiting necroptosis in B cells.
  10. Trends Pharmacol Sci. 2020 Apr 23. pii: S0165-6147(20)30091-2. [Epub ahead of print]
    Ding Y, Fei Y, Lu B.
      Traditional drug discovery focuses on identifying direct inhibitors of target proteins. This typically relies on a measurable biochemical readout and accessible binding sites whose occupancy influences the function of the target protein. These requirements preclude many disease-causing proteins from being 'druggable' targets, and these proteins are categorized as 'undruggable'. The proteolysis-targeting chimera (PROTAC) technology provides powerful tools to degrade these undruggable targets and has become a promising approach for drug discovery. However, the PROTAC technology has some limitations, and emerging new degrader technologies may greatly broaden the spectrum of targets that could be selectively degraded by harnessing a second major degradation pathway in cells. We review key emerging technologies that exploit the lysosomal degradation pathway and discuss their potential applications and limitations.
    Keywords:  ATTEC; AUTAC; LYTAC; PROTAC; protein degradation; undruggable targets
  11. Cells. 2020 May 19. pii: E1259. [Epub ahead of print]9(5):
    Vigneswara V, Ahmed Z.
      Caspase-2 is the most evolutionarily conserved member of the mammalian caspase family and has been implicated in both apoptotic and non-apoptotic signaling pathways, including tumor suppression, cell cycle regulation, and DNA repair. A myriad of signaling molecules is associated with the tight regulation of caspase-2 to mediate multiple cellular processes far beyond apoptotic cell death. This review provides a comprehensive overview of the literature pertaining to possible sophisticated molecular mechanisms underlying the multifaceted process of caspase-2 activation and to highlight its interplay between factors that promote or suppress apoptosis in a complicated regulatory network that determines the fate of a cell from its birth and throughout its life.
    Keywords:  activation; apoptosis; caspase-2; extrinsic; intrinsic; neurons; procaspase; splice variants
  12. Nat Rev Mol Cell Biol. 2020 May 18.
    Hopfner KP, Hornung V.
      The cGAS-STING signalling axis, comprising the synthase for the second messenger cyclic GMP-AMP (cGAS) and the cyclic GMP-AMP receptor stimulator of interferon genes (STING), detects pathogenic DNA to trigger an innate immune reaction involving a strong type I interferon response against microbial infections. Notably however, besides sensing microbial DNA, the DNA sensor cGAS can also be activated by endogenous DNA, including extranuclear chromatin resulting from genotoxic stress and DNA released from mitochondria, placing cGAS-STING as an important axis in autoimmunity, sterile inflammatory responses and cellular senescence. Initial models assumed that co-localization of cGAS and DNA in the cytosol defines the specificity of the pathway for non-self, but recent work revealed that cGAS is also present in the nucleus and at the plasma membrane, and such subcellular compartmentalization was linked to signalling specificity of cGAS. Further confounding the simple view of cGAS-STING signalling as a response mechanism to infectious agents, both cGAS and STING were shown to have additional functions, independent of interferon response. These involve non-catalytic roles of cGAS in regulating DNA repair and signalling via STING to NF-κB and MAPK as well as STING-mediated induction of autophagy and lysosome-dependent cell death. We have also learnt that cGAS dimers can multimerize and undergo liquid-liquid phase separation to form biomolecular condensates that could importantly regulate cGAS activation. Here, we review the molecular mechanisms and cellular functions underlying cGAS-STING activation and signalling, particularly highlighting the newly emerging diversity of this signalling pathway and discussing how the specificity towards normal, damage-induced and infection-associated DNA could be achieved.
  13. Saudi Pharm J. 2020 May;28(5): 621-629
    Alshammari MA, Khan MR, Majid Mahmood H, Alshehri AO, Alasmari FF, Alqahtani FM, Alasmari AF, Alsharari SD, Alhossan A, Ahmad SF, Nadeem A, Alshammari TK.
      Research studies have indicated that the comorbidity burden of mood disorders and obesity is reasonably high. Insulin signaling has been shown to modulate multiple physiological functions in the brain, indicating its association with neuropsychiatric diseases, including mood disorders. Leptin is a hormone responsible for regulating body weight and insulin homeostasis. Previous studies on db/db mice (a mouse model that carries a spontaneous genetic mutation in leptin receptor Leprdb ) have shown that they exhibit inflammation as well as neurobehavioral traits associated with mood. Therefore, targeting inflammatory pathways such as TNF-α may be an effective strategy in the treatment of obesity-linked mood disorders. The objective of this study was to investigate the effect of long-term administration of etanercept (a TNF-α blocker) on anxiety and depressive-like behaviors in db/db mice. This was performed using light/dark box, forced swim, and open field tests with lean littermate wild type (WT) mice serving as a control group. Using flow cytometry in peripheral blood, we further examined the molecular effects of etanercept on NF-κB p65, TNF-α, IL-17A, and TLR-4 expressing CD4+, CD8+, and CD14+ cells in the peripheral blood. Our data show that peripheral administration of etanercept decreased these cells in db/db mice. Furthermore, our results indicated that peripheral administration of etanercept reduced anxiety and depressive-like behaviors. Therefore, targeting TNF-α signaling might be an effective strategy for modulating obesity-associated depression and anxiety.
    Keywords:  Anxiety-like behavior; Depression; Depressive-like behavior; Etanercept; Inflammation; Obesity; TNF-α; db/db mice
  14. Front Cell Dev Biol. 2020 ;8 314
    Levoin N, Jean M, Legembre P.
      CD95 is a pre-ligand-associated transmembrane (TM) receptor. The interaction with its ligand CD95L brings to a next level its aggregation and triggers different signaling pathways, leading to cell motility, differentiation or cell death. This diversity of biological responses associated with a unique receptor devoid of enzymatic property raises the question of whether different ligands exist, or whether the fine-tuned control of CD95 aggregation and conformation, its distribution within certain plasma membrane sub-domains or the pattern of post-translational modifications account for this such broad-range of cell signaling. Herein, we review how the different domains of CD95 and their post-translational modifications or the different forms of CD95L can participate in the receptor aggregation and induction of cell signaling. Understanding how CD95 response goes from cell death to cell proliferation, differentiation and motility is a prerequisite to reveal novel therapeutic options to treat chronic inflammatory disorders and cancers.
    Keywords:  Fas; aggregation; apoptosis; inflammation; migration; stoichiometry
  15. Nat Neurosci. 2020 May 18.
    Garancher A, Suzuki H, Haricharan S, Chau LQ, Masihi MB, Rusert JM, Norris PS, Carrette F, Romero MM, Morrissy SA, Skowron P, Cavalli FMG, Farooq H, Ramaswamy V, Jones SJM, Moore RA, Mungall AJ, Ma Y, Thiessen N, Li Y, Morcavallo A, Qi L, Kogiso M, Du Y, Baxter P, Henderson JJ, Crawford JR, Levy ML, Olson JM, Cho YJ, Deshpande AJ, Li XN, Chesler L, Marra MA, Wajant H, Becher OJ, Bradley LM, Ware CF, Taylor MD, Wechsler-Reya RJ.
      Many immunotherapies act by enhancing the ability of cytotoxic T cells to kill tumor cells. Killing depends on T cell recognition of antigens presented by class I major histocompatibility complex (MHC-I) proteins on tumor cells. In this study, we showed that medulloblastomas lacking the p53 tumor suppressor do not express surface MHC-I and are therefore resistant to immune rejection. Mechanistically, this is because p53 regulates expression of the peptide transporter Tap1 and the aminopeptidase Erap1, which are required for MHC-I trafficking to the cell surface. In vitro, tumor necrosis factor (TNF) or lymphotoxin-β receptor agonist can rescue expression of Erap1, Tap1 and MHC-I on p53-mutant tumor cells. In vivo, low doses of TNF prolong survival and synergize with immune checkpoint inhibitors to promote tumor rejection. These studies identified p53 as a key regulator of immune evasion and suggest that TNF could be used to enhance sensitivity of tumors to immunotherapy.
  16. Clin Exp Immunol. 2020 May 16.
    Luo Y, Hara T, Kawashima A, Ishido Y, Suzuki S, Ishii N, Kambara T, Suzuki K.
      Psoriasis is characterized by excessive growth and aberrant differentiation of epidermal keratinocytes due to persistent inflammation. However, the underlying mechanism that triggers immune activation in psoriasis is not clear. In this study, we explored excessive DNA as a potential trigger of psoriasis using cultured human keratinocytes and psoriatic skin tissues. We demonstrated that human genomic DNA fragments induced tumor necrosis factor-α (TNF-α) expression, hyperproliferation, and overexpression of heparin-binding EGF-like growth factor (HB-EGF) and transforming growth factor α (TGF-α), accompanied by defective expression of keratins 1 and 10 in cultured normal human epidermal keratinocytes, which have a similar phenotype as that of keratinocytes in psoriatic skin lesions. In psoriatic lesions, we found high levels of double-stranded (ds)DNA fragments, accompanying keratinocytes expressing Ki-67, HB-EGF and TNF-α. In addition, we showed that 1,25-dihydroxyvitamin D3 inhibited genomic DNA fragment-induced TNFA and interleukin-1β (IFNB) expression in human keratinocytes, and intact function of cathelicidin antimicrobial peptide was required for this effect. These results suggest that excessive dsDNA fragments likely act as a risk factor for immune activation in psoriasis, and the active form of vitamin D can prevent genomic DNA-mediated skin inflammation via cathelicidin antimicrobial peptide.
    Keywords:  active vitamin D; genomic DNA; inflammation; keratinocyte; psoriasis
  17. Cell Biol Int. 2020 May 21.
    Zheng LW, Wang WC, Mao XZ, Luo YH, Tong ZY, Li D.
      Previous studies have shown that the tumor necrosis factor-α (TNF-α) levels in serum and bone tissues form avascular necrosis of femoral head (ANFH) patients were higher than that of normal individuals, indicating TNF-α might play a role in the pathogenesis of ANFH. However, the underlying mechanisms remain unclear. Hematoxylin and Eosin (HE) staining was performed to show the pathological changes of ANFH bone tissues. TNF-α expression in normal and ANFH tissues was examined by qRT-PCR and western blot. Osteoblast autophagy and apoptosis, as well as signaling pathways activation, were measured by their corresponding marker proteins. Osteoblast proliferation, autophagy and apoptosis were evaluated using CCK-8, transmission electron microscope and flow cytometry. The structures of bone tissues of ANFH were obviously damaged. TNF-α expression was significantly upregulated in ANFH bone tissues compared to normal tissues. Autophagy and apoptosis were remarkably promoted, and p38 MAPK/NF-κB signaling pathways were markedly activated in ANFH. Suppression of p38 MAPK/NF-κB pathway significantly attenuated the TNF-α induced autophagy, however, enhanced the TNF-α induced apoptosis in osteoblast. Increased TNF-α in ANFH regulated osteoblast autophagy and apoptosis by p38 MAPK/NF-κB signaling pathways, blocking the pathway by inhibitors exacerbated TNF-α induced apoptosis through impairing the autophagy flux. This article is protected by copyright. All rights reserved.
    Keywords:  TNF-α; apoptosis; autophagy; avascular necrosis of the femoral head (ANFH); osteoblast
  18. EMBO Mol Med. 2020 May 18. e10979
    Smith HG, Jamal K, Dayal JH, Tenev T, Kyula-Currie J, Guppy N, Gazinska P, Roulstone V, Liccardi G, Davies E, Roxanis I, Melcher AA, Hayes AJ, Inman GJ, Harrington KJ, Meier P.
      Drugs that mobilise the immune system against cancer are dramatically improving care for many people. Dying cancer cells play an active role in inducing anti-tumour immunity but not every form of death can elicit an immune response. Moreover, resistance to apoptosis is a major problem in cancer treatment and disease control. While the term "immunogenic cell death" is not fully defined, activation of receptor-interacting serine/threonine-protein kinase 1 (RIPK1) can induce a type of death that mobilises the immune system against cancer. However, no clinical treatment protocols have yet been established that would harness the immunogenic potential of RIPK1. Here, we report the first pre-clinical application of an in vivo treatment protocol for soft-tissue sarcoma that directly engages RIPK1-mediated immunogenic cell death. We find that RIPK1-mediated cell death significantly improves local disease control, increases activation of CD8+ T cells as well as NK cells, and enhances the survival benefit of immune checkpoint blockade. Our findings warrant a clinical trial to assess the survival benefit of RIPK1-induced cell death in patients with advanced disease at limb extremities.
    Keywords:  RIPK1; SMAC mimetics; TNF; apoptosis; soft-tissue sarcoma
  19. Front Immunol. 2020 ;11 733
    Ueda Y, Kondo N, Kinashi T.
      The STE20-like serine/threonine kinases MST1 and MST2 (MST1/2) are mammalian homologs of Hippo in flies. MST1/2 regulate organ size by suppressing the transcription factor YAP, which promotes proliferation. MST1 is predominantly expressed in immune cells, where it plays distinct roles. Here, we review the functions of MST1/2 in immune cells, uncovered by a series of recent studies, and discuss the connection between MST1/2 function and immune responses. MST1/2 regulate lymphocyte development, trafficking, survival, and antigen recognition by naive T cells. MST1/2 also regulate the function of regulatory T cells and effector T cell differentiation, thus acting to balance immune activation and tolerance. Interestingly, MST1/2 elicit these functions not by the "canonical" Hippo pathway, but by the non-canonical Hippo pathway or alternative pathways. In these pathways, MST1/2 regulates cellular processes relating to immune response, such as chemotaxis, cell adhesion, immunological synapse, gene transcriptions. Recent advances in our understanding of the molecular mechanisms of these processes have revealed important roles of MST1/2 in regulating cytoskeleton remodeling, integrin activation, and vesicular transport in lymphocytes. We discuss the significance of the MST1/2 signaling in lymphocytes in the regulation of organelle dynamics.
    Keywords:  Mst1/2; cell polarity and adhesion; effector differentiation; integrin; lymphocyte trafficking; vesicle transport
  20. Crit Rev Immunol. 2020 ;40(1): 1-39
    Kunnumakkara AB, Shabnam B, Girisa S, Harsha C, Banik K, Devi TB, Choudhury R, Sahu H, Parama D, Sailo BL, Thakur KK, Gupta SC, Aggarwal BB.
      Most chronic diseases, caused by lifestyle factors, appear to be linked to inflammation. Inflammation is activated mechanistically, and nuclear factor-κB (NF-κB) is a significant mediator. NF-κB, one of the most studied transcription factors, was first identified in the nucleus of B lymphocytes almost three decades ago. This protein has a key function in regulating the human immune system, and its dysregulation has been linked to many chronic diseases including asthma, cancer, diabetes, rheumatoid arthritis, inflammation, and neurological disorders. Physiologically, many cytokines have been discovered that activate NF-κB. Pathologically, environmental carcinogens such as cigarette smoke, radiation, bacteria, and viruses can also activate this transcription factor. NF-κB activation controls expression of more than 500 genes, and most are deleterious to the human body when dysregulated. More than 70,000 articles have been published regarding NF-κB. This review emphasizes the upside and downside of NF-κB in normal and disease conditions and the ways in which we can control this critical transcription factor in patients.
  21. DNA Repair (Amst). 2020 Apr 28. pii: S1568-7864(20)30095-1. [Epub ahead of print]90 102850
    Prasad R, Horton JK, Wilson SH.
    Keywords:  AP site/abasic site, apurinic/apyrimidinic site; BER, base excision repair; DPC, DNA-protein crosslink; PARP-1, poly(ADP-ribose) polymerase 1
  22. Int J Tryptophan Res. 2020 ;13 1178646920919755
    Borghi M, Puccetti M, Pariano M, Renga G, Stincardini C, Ricci M, Giovagnoli S, Costantini C, Romani L.
      Amino acid catabolism occurs during inflammation and regulates innate and adaptive immunity. The role of commensal bacteria in amino acid catabolism and the production of metabolites able to regulate the development and function of the innate immune system is increasingly being recognized. Therefore, commensal bacteria are key players in the maintenance of immune homeostasis. However, the intestinal microbiota also contributes to susceptibility and response to infectious diseases. This is self-evident for fungal infections known to occur as a consequence of weakened immune system and broad-spectrum antibiotic use or abuse. Thus, diseases caused by opportunistic fungi can no longer be viewed as dependent only on a weakened host but also on a disrupted microbiota. Based on these premises, the present review focuses on the role of amino acid metabolic pathways in the dialogue between the mammalian host and its microbiota and the potential implications in fungal commensalism and infectivity.
    Keywords:  3-dioxygenase 1; Tryptophan; aryl hydrocarbon receptor; fungal infections; indoleamine 2; indoles; metabolic syndrome
  23. Immunity. 2020 May 19. pii: S1074-7613(20)30167-9. [Epub ahead of print]52(5): 729-731
    Ireland AS, Oliver TG.
      Neutrophil extracellular traps (NETs) can promote tumor growth and metastases, but whether NETs impact the tumor immune microenvironment remains underexplored. In this issue of Immunity, Teijeira et al. discover that NETs shield tumor cells from cytotoxic immune cells, resulting in impaired tumor clearance.
  24. Proc Natl Acad Sci U S A. 2020 May 19. pii: 202003425. [Epub ahead of print]
    Korman A, Sun H, Hua B, Yang H, Capilato JN, Paul R, Panja S, Ha T, Greenberg MM, Woodson SA.
      Small ribozymes such as Oryza sativa twister spontaneously cleave their own RNA when the ribozyme folds into its active conformation. The coupling between twister folding and self-cleavage has been difficult to study, however, because the active ribozyme rapidly converts to product. Here, we describe the synthesis of a photocaged nucleotide that releases guanosine within microseconds upon photosolvolysis with blue light. Application of this tool to O. sativa twister achieved the spatial (75 µm) and temporal (≤30 ms) control required to resolve folding and self-cleavage events when combined with single-molecule fluorescence detection of the ribozyme folding pathway. Real-time observation of single ribozymes after photo-deprotection showed that the precleaved folded state is unstable and quickly unfolds if the RNA does not react. Kinetic analysis showed that Mg2+ and Mn2+ ions increase ribozyme efficiency by making transitions to the high energy active conformation more probable, rather than by stabilizing the folded ground state or the cleaved product. This tool for light-controlled single RNA folding should offer precise and rapid control of other nucleic acid systems.
    Keywords:  RNA folding; nucleic acid chemistry; photocaged nucleotide; ribozyme catalysis; single-molecule FRET
  25. Gastroenterology. 2020 May 17. pii: S0016-5085(20)30668-5. [Epub ahead of print]
    Khanna R, McCurdy J, Afif W.
    Keywords:  Crohn’s disease; drug concentrations; immunogencity; therapeutic drug monitoring
  26. Curr Biol. 2020 May 18. pii: S0960-9822(20)30493-0. [Epub ahead of print]30(10): R419-R420
    Murray A.
      Andrew Murray argues that you can use your forced exile from the lab to produce better future experiments by dissecting your past failures and successes and collaboratively critiquing the experiments you're planning for your return to the lab.
  27. Nat Commun. 2020 May 22. 11(1): 2591
    Goldsmith JR, Spitofsky N, Zamani A, Hood R, Boggs A, Li X, Li M, Reiner E, Ayyaz A, Etwebi Z, Lu L, Rivera Guzman J, Bou-Dargham MJ, Cathoupolis T, Hakonarson H, Sun H, Wrana JL, Gonzalez MV, Chen YH.
      The intestine is a highly dynamic environment that requires tight control of the various inputs to maintain homeostasis and allow for proper responses to injury. It was recently found that the stem cell niche and epithelium is regenerated after injury by de-differentiated adult cells, through a process that gives rise to Sca1+ fetal-like cells and is driven by a transient population of Clu+ revival stem cells (revSCs). However, the molecular mechanisms that regulate this dynamic process have not been fully defined. Here we show that TNFAIP8 (also known as TIPE0) is a regulator of intestinal homeostasis that is vital for proper regeneration. TIPE0 functions through inhibiting basal Akt activation by the commensal microbiota via modulating membrane phospholipid abundance. Loss of TIPE0 in mice results in injury-resistant enterocytes, that are hyperproliferative, yet have regenerative deficits and are shifted towards a de-differentiated state. Tipe0-/- enterocytes show basal induction of the Clu+ regenerative program and a fetal gene expression signature marked by Sca1, but upon injury are unable to generate Sca-1+/Clu+ revSCs and could not regenerate the epithelium. This work demonstrates the role of TIPE0 in regulating the dynamic signaling that determines the injury response and enables intestinal epithelial cell regenerative plasticity.
  28. J Invest Dermatol. 2020 May 15. pii: S0022-202X(20)31574-8. [Epub ahead of print]
    Shakya S, Mack JA, Alipour M, Maytin EV.
      We investigated how loss of tumor necrosis factor-stimulated gene-6 (TSG-6) affects wound closure and skin inflammation. TSG-6 has several known biological functions including enzymatic transfer of heavy chain proteins (HC) from inter-α-trypsin inhibitor to hyaluronan (HA) to form HC-HA complexes. TSG-6 and HC-HA are constitutively expressed in normal skin and increase post-wounding, but are completely absent in TSG-6 null mice. Wound closure rates are significantly delayed in TSG-6 null mice relative to wildtype mice. Neutrophil recruitment is delayed in early wounds (12 h and Day 1), whereas late wounds (Day 7) show elevated neutrophil accumulation. In addition, the granulation phase is delayed, with persistent blood vessels and reduced dermal collagen at 10 days. The pro-inflammatory cytokine TNFα is elevated >3 fold in unwounded TSG-6 null skin, and increases further after wounding (from 12 h to 7 days) before returning to baseline by day 10. Other cytokines examined such as IL-6, IL-10, and MCP-1 showed no consistent differences. Importantly, reintroduction of TSG-6 into TSG-6 null wounds rescues both the delay in wound closure and the aberrant neutrophil phenotype. In summary, our study indicates that TSG-6 plays an important role in regulating wound closure and inflammation during cutaneous wound repair.
  29. Ther Adv Respir Dis. 2020 Jan-Dec;14:14 1753466620926800
    Chen XY, Yan BX, Man XY.
      Increased inflammatory cytokines [such as tumor necrosis factor alpha (TNFα) and interleukin-6 (IL-6)] are observed in COVID-19 patients, especially in the severe group. The phenomenon of a cytokine storm may be the central inducer of apoptosis of alveolar epithelial cells, which leads to rapid progression in severe group patients. Given the similarities of clinical features and pathogenesis between toxic epidermal necrolysis (TEN) and COVID-19, we hypothesize that the application of etanercept, an inhibitor of TNFα, could attenuate disease progression in severe group COVID-19 patients by suppressing systemic auto-inflammatory responses. The reviews of this paper are available via the supplemental material section.
    Keywords:  COVID-19; TNFα inhibitor; etanercept; toxic epidermal necrolysis
  30. Cell Chem Biol. 2020 May 21. pii: S2451-9456(20)30151-3. [Epub ahead of print]27(5): 475-478
    Kerek EM, Cromwell CR, Hubbard BP.
      In this issue of Cell Chemical Biology, Erdogan et al. (2020) describe a new CRISPR/Cas9-based strategy for performing directed evolution of mammalian proteins in situ. Using this technique to select functional mRuby3 variants within lysosomes, they identify mCRISPRed, a fluorescent protein that displays robust stability and activity at low pH.