bims-tunefa Biomed News
on Tumor necrosis factor superfamily and post-translational modifications
Issue of 2020‒04‒12
twenty-one papers selected by
John Silke
Walter and Eliza Hall Institute of Medical Research


  1. Cell Rep. 2020 Apr 07. pii: S2211-1247(20)30370-3. [Epub ahead of print]31(1): 107492
    Balka KR, Louis C, Saunders TL, Smith AM, Calleja DJ, D'Silva DB, Moghaddas F, Tailler M, Lawlor KE, Zhan Y, Burns CJ, Wicks IP, Miner JJ, Kile BT, Masters SL, De Nardo D.
      Stimulator of Interferon Genes (STING) is a critical component of host innate immune defense but can contribute to chronic autoimmune or autoinflammatory disease. Once activated, the cyclic guanosine monophosphate (GMP)-adenosine monophosphate (AMP) (cGAMP) synthase (cGAS)-STING pathway induces both type I interferon (IFN) expression and nuclear factor-κB (NF-κB)-mediated cytokine production. Currently, these two signaling arms are thought to be mediated by a single upstream kinase, TANK-binding kinase 1 (TBK1). Here, using genetic and pharmacological approaches, we show that TBK1 alone is dispensable for STING-induced NF-κB responses in human and mouse immune cells, as well as in vivo. We further demonstrate that TBK1 acts redundantly with IκB kinase ε (IKKε) to drive NF-κB upon STING activation. Interestingly, we show that activation of IFN regulatory factor 3 (IRF3) is highly dependent on TBK1 kinase activity, whereas NF-κB is significantly less sensitive to TBK1/IKKε kinase inhibition. Our work redefines signaling events downstream of cGAS-STING. Our findings further suggest that cGAS-STING will need to be targeted directly to effectively ameliorate the inflammation underpinning disorders associated with STING hyperactivity.
    Keywords:  IKKε; NF-κB; STING; TBK1; cGAS; cytokines; innate immunity; protein kinases; signal transduction; type I interferons
    DOI:  https://doi.org/10.1016/j.celrep.2020.03.056
  2. Nat Commun. 2020 Apr 08. 11(1): 1747
    Laurien L, Nagata M, Schünke H, Delanghe T, Wiederstein JL, Kumari S, Schwarzer R, Corona T, Krüger M, Bertrand MJM, Kondylis V, Pasparakis M.
      Receptor interacting protein kinase 1 (RIPK1) regulates cell death and inflammatory responses downstream of TNFR1 and other receptors, and has been implicated in the pathogenesis of inflammatory and degenerative diseases. RIPK1 kinase activity induces apoptosis and necroptosis, however the mechanisms and phosphorylation events regulating RIPK1-dependent cell death signaling remain poorly understood. Here we show that RIPK1 autophosphorylation at serine 166 plays a critical role for the activation of RIPK1 kinase-dependent apoptosis and necroptosis. Moreover, we show that S166 phosphorylation is required for RIPK1 kinase-dependent pathogenesis of inflammatory pathologies in vivo in four relevant mouse models. Mechanistically, we provide evidence that trans autophosphorylation at S166 modulates RIPK1 kinase activation but is not by itself sufficient to induce cell death. These results show that S166 autophosphorylation licenses RIPK1 kinase activity to induce downstream cell death signaling and inflammation, suggesting that S166 phosphorylation can serve as a reliable biomarker for RIPK1 kinase-dependent pathologies.
    DOI:  https://doi.org/10.1038/s41467-020-15466-8
  3. Adv Exp Med Biol. 2020 ;1233 311-325
    Meroni G.
      The TRIM family comprises proteins characterized by the presence of the tripartite motif composed of a RING domain, one or two B-box domains and a coiled-coil region. The TRIM shared domain structure underscores a common biochemical function as E3 ligase within the ubiquitination cascade. The TRIM proteins represent one of the largest E3 ligase families counting in human more than 70 members. These proteins are implicated in a plethora of cellular processes such as apoptosis, cell cycle regulation, muscular physiology, and innate immune response. Consistently, their alteration results in several pathological conditions emphasizing their medical relevance. Here, the genetic and pathogenetic mechanisms of rare disorders directly caused by mutations in TRIM genes will be reviewed. These diseases fall into different pathological areas, from malformation birth defects due to developmental abnormalities, to neurological disorders and progressive teenage neuromuscular disorders. In many instances, TRIM E3 ligases act on several substrates thus exerting pleiotropic activities: the need of unraveling disease-specific TRIM pathways for a precise targeting therapy avoiding dramatic side effects will be discussed.
    Keywords:  E3 ubiquitin ligases; RING domain; Rare genetic diseases; Tripartite motif, TRIM; Ubiquitination
    DOI:  https://doi.org/10.1007/978-3-030-38266-7_14
  4. J Bone Miner Res. 2020 Apr 08.
    Li J, Yi X, Yao Z, Chakkalakal JV, Xing L, Boyce BF.
      During aging, muscle mass decreases, leading to sarcopenia, associated with low-level chronic inflammation (inflammaging), which induces sarcopenia by promoting proteolysis of muscle fibers and inhibiting their regeneration. Patients with a variety of pathologic conditions associated with sarcopenia, including rheumatoid arthritis (RA), have systemically elevated TNFα serum levels, and transgenic mice with TNFα over-expression (TNF-Tg mice, a model of RA) develop sarcopenia between adolescence and adulthood before they age. However, if and how TNFα contributes to the pathogenesis of sarcopenia during the normal aging process and in RA remains largely unknown. We report that TNFα levels are increased in skeletal muscles of aged WT mice, associated with muscle atrophy and decreased numbers of satellite cells and Type IIA myofibers, a phenotype that we also observed in adult TNF-Tg mice. Aged WT mice also have increased numbers of myeloid lineage cells in their skeletal muscles, including macrophages and granulocytes. These cells have increased TNFα expression, which impairs myogenic cell differentiation. Expression levels of TNF receptor-associated factor 6 (TRAF6), an E3 ubiquitin ligase, which mediates signaling by some TNF receptor (TNFR) family members, is elevated in skeletal muscles of both aged WT mice and adult TNF-Tg mice. TRAF6 binds to TNFR2 in C2C12 myoblasts and mediates TNFα-induced muscle atrophy through NF-κB-induced transcription of the muscle-specific E3 ligases, Atrogen1 and Murf1, which promote myosin heavy chain degradation. Haplo-deficiency of TRAF6 prevents muscle atrophy and the decrease in numbers of satellite cells, Type IIA myofibers, and myogenic regeneration in TRAF6+/- ;TNF-Tg mice. Our findings suggest that pharmacologic inhibition of TRAF6 signaling in skeletal muscles during aging could treat/prevent age- and RA-related sarcopenia by preventing TNFα-induced proteolysis and inhibition of muscle fiber regeneration. This article is protected by copyright. All rights reserved.
    Keywords:  Muscle atrophy; NF-κB; TNFα; TRAF6; inflammaging; muscle environmental cells; rheumatoid arthritis; sarcopenia
    DOI:  https://doi.org/10.1002/jbmr.4021
  5. ACS Chem Biol. 2020 Apr 07.
    Roberts BL, Ma ZX, Gao A, Leisten ED, Yin D, Xu W, Tang W.
      Proteolysis targeting chimeras (PROTACs) have emerged as useful chemical probes and potential therapeutics by taking advantage of the ubiquitin-proteasome-system to degrade intracellular disease-associated proteins. PROTACs are heterobifunctional molecules composed of a target protein ligand, E3 ubiquitin ligase ligand, and linker between them. Generation of efficient PROTACs requires screening of many parameters, especially the length and type of the linkers. We report our proof-of-concept study using a two-stage strategy to facilitate the development of PROTACs against estrogen receptor (ER). In stage-one, a library of close to 100 PROTACs was synthesized by simply mixing a library of ER ligands containing a hydrazide functional group at different positions with a pre-assembled library of E3 ligase ligands bearing different types and lengths of linkers with a terminal aldehyde group in a 1:1 ratio. Cell-based screening occurred without further purification, because the formation of the acylhydrazone linkage is highly efficient and produces water as the only byproduct. Compound A3 was the most potent ER degrader in two ER+ cell lines (DC50= ~10 nM, Dmax= ≥95%). Stage-two involved transformation to a more stable amide linker to generate a more drug-like molecule. The new compound, AM-A3, showed comparable biological activity (DC50=1.1 nM, Dmax=98%) and induced potent anti-proliferation (IC50= 13.2 nM, Imax= 69%) in MCF-7. This proof-of -concept study demonstrates that the two-stage strategy can significantly facilitate the development of PROTACs against ER without the tedious process of making large numbers of PROTACs one by one. It has the potential to be expanded to many other targets.
    DOI:  https://doi.org/10.1021/acschembio.0c00140
  6. Future Med Chem. 2020 Apr 09.
    Wan Y, Yan C, Gao H, Liu T.
      Proteolysis-targeting chimera (PROTAC) is a new technology to selectively degrade target proteins via ubiquitin-proteasome system. PROTAC molecules (PROTACs) are a class of heterobifunctional molecules, which contain a ligand targeting the protein of interest, a ligand recruiting an E3 ligase and a linker connecting these two ligands. They provide several advantages over traditional inhibitors in potency, selectivity and drug resistance. Thus, many promising PROTACs have been developed in the recent two decades, especially small-molecule PROTACs. In this review, we briefly introduce the mechanism of PROTACs and focus on the progress of small-molecule PROTACs based on different E3 ligases. In addition, we also introduce the opportunities and challenges of small-molecule PROTACs for cancer therapy.
    Keywords:  E3 ligases; PROTACs; anticancer; protein degradation; small-molecule inhibitors
    DOI:  https://doi.org/10.4155/fmc-2019-0340
  7. Adv Exp Med Biol. 2020 ;1233 3-28
    Pérez-Benavente B, Nasresfahani AF, Farràs R.
      Ubiquitin ligases (E3) play a crucial role in the regulation of different cellular processes such as proliferation and differentiation via recognition, interaction, and ubiquitination of key cellular proteins in a spatial and temporal regulated manner. The type of ubiquitin chain formed determines the fate of the substrates. The ubiquitinated substrates can be degraded by the proteasome, display altered subcellular localization, or can suffer modifications on their interaction with functional protein complexes. Deregulation of E3 activities is frequently found in various human pathologies, including cancer. The illegitimated or accelerated degradation of oncosuppressive proteins or, inversely, the abnormally high accumulation of oncoproteins, contributes to cell proliferation and transformation. Anomalies in protein abundance may be related to mutations that alter the direct or indirect recognition of proteins by the E3 enzymes or alterations in the level of expression or activity of ubiquitin ligases. Through a few examples, we illustrate here the complexity and diversity of the molecular mechanisms related to protein ubiquitination involved in cell cycle regulation. We will discuss the role of ubiquitin-dependent degradation mediated by the proteasome, the role of non-proteolytic ubiquitination during cell cycle progression, and the consequences of this deregulation on cellular transformation. Finally, we will highlight the novel opportunities that arise from these studies for therapeutic intervention.
    Keywords:  Cancer; Cell cycle; E3 ligases; Eukaryotic ubiquitin conjugation; Non-proteolytic ubiquitination; Ubiquitin; Ubiquitin-dependent degradation
    DOI:  https://doi.org/10.1007/978-3-030-38266-7_1
  8. Front Immunol. 2020 ;11 475
    Kanazawa N.
      "Autoinflammatory disease (AiD)" has first been introduced in 1999 when the responsible gene for the familial Hibernean fever or autosomal dominant-type familial Mediterranean fever-like periodic fever syndrome was reportedly identified as tumor necrosis factor receptor superfamily 1. Linked with the rapid research progress in the field of innate immunity, "autoinflammation" has been designated for dysregulated innate immunity in contrast to "autoimmunity" with dysregulated acquired immunity. As hereditary periodic fever syndromes represent the prototype of AiD, monogenic systemic diseases are the main members of AiD. However, skin manifestations provide important clinical information and there are even some AiDs originating from skin diseases. Recently, AiD showing psoriasis and related keratinization diseases have specifically been designated as "autoinflammatory keratinization diseases (AiKD)" and CARD14-associated psoriasis and deficiency of interleukin-36 receptor antagonist previously called as generalized pustular psoriasis are included. Similarly, a number of autoinflammatory skin diseases can be proposed; autoinflamatory urticarial dermatosis (AiUD) such as cryopyrin-associated periodic syndrome; autoinflammatory neutrophilic dermatosis (AiND) such as pyogenic sterile arthritis, pyoderma gangrenosm, and acne syndrome; autoinflammatory granulomatosis (AiG) such as Blau syndrome; autoinflammatory chilblain lupus (AiCL) such as Aicardi-Goutieres syndrome; autoinflammatory lipoatrophy (AiL) such as Nakajo-Nishimura syndrome; autoinflammatory angioedema (AiAE) such as hereditary angioedema; and probable autoinflammatory bullous disease (AiBD) such as granular C3 dermatosis. With these designations, skin manifestations in AiD can easily be recognized and, even more importantly, autoinflammatory pathogenesis of common skin diseases are expected to be more comprehensive.
    Keywords:  angioedema; autoinflammatory skin manifestations; bullous disease; chilblain lupus; granulomatosis; lipoatrophy; neutrophilic dermatosis; urticarial dermatosis
    DOI:  https://doi.org/10.3389/fimmu.2020.00475
  9. Front Immunol. 2020 ;11 484
    Yang H, Wang H, Andersson U.
      High mobility group box 1 (HMGB1) is a highly conserved, nuclear protein present in all cell types. It is a multi-facet protein exerting functions both inside and outside of cells. Extracellular HMGB1 has been extensively studied for its prototypical alarmin functions activating innate immunity, after being actively released from cells or passively released upon cell death. TLR4 and RAGE operate as the main HMGB1 receptors. Disulfide HMGB1 activates the TLR4 complex by binding to MD-2. The binding site is separate from that of LPS and it is now feasible to specifically interrupt HMGB1/TLR4 activation without compromising protective LPS/TLR4-dependent functions. Another important therapeutic strategy is established on the administration of HMGB1 antagonists precluding RAGE-mediated endocytosis of HMGB1 and HMGB1-bound molecules capable of activating intracellular cognate receptors. Here we summarize the role of HMGB1 in inflammation, with a focus on recent findings on its mission as a damage-associated molecular pattern molecule and as a therapeutic target in inflammatory diseases. Recently generated HMGB1-specific inhibitors for treatment of inflammatory conditions are discussed.
    Keywords:  HMGB1; RAGE; TLR4; danger signal; drug target; inflammation
    DOI:  https://doi.org/10.3389/fimmu.2020.00484
  10. Curr Opin Cell Biol. 2020 Apr 06. pii: S0955-0674(20)30044-2. [Epub ahead of print]63 194-203
    Shi M, Zhang P, Vora SM, Wu H.
      Higher-order supramolecular complexes-dubbed signalosomes carry out key signaling and effector functions in innate immunity and inflammation. In this review, we present several recently discovered signalosomes that are formed either by stable protein-protein interactions or by dynamic liquid-liquid phase separation. Structural features of these signalosomes are highlighted to elucidate their functions and biological insights.
    DOI:  https://doi.org/10.1016/j.ceb.2020.03.002
  11. Int Rev Cell Mol Biol. 2020 ;pii: S1937-6448(19)30117-0. [Epub ahead of print]351 197-236
    Flores-Romero H, Ros U, García-Sáez AJ.
      Lipids are fundamental to life as structural components of cellular membranes and for signaling. They are also key regulators of different cellular processes such as cell division, proliferation, and death. Regulated cell death (RCD) requires the engagement of lipids and lipid metabolism for the initiation and execution of its killing machinery. The permeabilization of lipid membranes is a hallmark of RCD that involves, for each kind of cell death, a unique lipid profile. While the permeabilization of the mitochondrial outer membrane allows the release of apoptotic factors to the cytosol during apoptosis, permeabilization of the plasma membrane facilitates the release of intracellular content in other nonapoptotic types of RCD like necroptosis and ferroptosis. Lipids and lipid membranes are important accessory molecules required for the activation of protein executors of cell death such as BAX in apoptosis and MLKL in necroptosis. Peroxidation of membrane phospholipids and the subsequent membrane destabilization is a prerequisite to ferroptosis. Here, we discuss how lipids are essential players in apoptosis, the most common form of RCD, and also their role in necroptosis and ferroptosis. Altogether, we aim to highlight the contribution of lipids and membrane dynamics in cell death regulation.
    Keywords:  Apoptosis; Ferroptosis; Membrane dynamics; Mitochondria; Necroptosis; Plasma membrane; Regulated cell death
    DOI:  https://doi.org/10.1016/bs.ircmb.2019.11.004
  12. JCI Insight. 2020 Apr 07. pii: 134356. [Epub ahead of print]
    Collins MK, Shotland AM, Wade MF, Atif SM, Richards DJ, Torres-Llompart M, Mack DG, Martin AK, Fontenot AP, McKee AS.
      Chronic beryllium disease (CBD) is a metal hypersensitivity/autoimmune disease in which damage-associated molecular patterns (DAMPs) promote a break in T cell tolerance and expansion of Be2+/self-peptide reactive CD4+ T cells. In this study, we investigated the mechanism of cell death induced by beryllium particles (Be) in alveolar macrophages (AMΦs) and its impact on DAMP release. We found that phagocytosis of Be led to AM cell death independently of caspase, RIP1K, RIP3K or ROS activity. Prior to cell death, Be-exposed AMΦs secreted TNFalpha that boosted intracellular stores of IL-1alpha followed by caspase 8-dependent fragmentation of DNA. IL-1alpha and nucleosomal DNA were subsequently released from AMΦs upon loss of plasma membrane integrity. In contrast, necrotic AMs released only unfragmented DNA and necroptotic AMΦs released only IL-1alpha. In mice exposed to Be, TNFalpha promoted release of both DAMPs and was required for the mobilization of immunogenic DCs, expansion of Be-reactive CD4+ T cells and pulmonary inflammation in a mouse model of CBD. Thus, early autocrine effects of particle-induced TNFalpha on AMs led to a break in peripheral tolerance. This novel mechanism may underlie the known relationship between fine particle inhalation, TNFalpha and loss of peripheral tolerance in T cell-mediated autoimmune disease and hypersensitivities.
    Keywords:  Adaptive immunity; Dendritic cells; Immunology; Macrophages
    DOI:  https://doi.org/10.1172/jci.insight.134356
  13. Nat Rev Mol Cell Biol. 2020 Apr 06.
    Boada-Romero E, Martinez J, Heckmann BL, Green DR.
      Multiple modes of cell death have been identified, each with a unique function and each induced in a setting-dependent manner. As billions of cells die during mammalian embryogenesis and daily in adult organisms, clearing dead cells and associated cellular debris is important in physiology. In this Review, we present an overview of the phagocytosis of dead and dying cells, a process known as efferocytosis. Efferocytosis is performed by macrophages and to a lesser extent by other 'professional' phagocytes (such as monocytes and dendritic cells) and 'non-professional' phagocytes, such as epithelial cells. Recent discoveries have shed light on this process and how it functions to maintain tissue homeostasis, tissue repair and organismal health. Here, we outline the mechanisms of efferocytosis, from the recognition of dying cells through to phagocytic engulfment and homeostatic resolution, and highlight the pathophysiological consequences that can arise when this process is abrogated.
    DOI:  https://doi.org/10.1038/s41580-020-0232-1
  14. Immunol Lett. 2020 Apr 04. pii: S0165-2478(20)30163-2. [Epub ahead of print]
    Oja AE, Brasser G, Slot E, van Lier RAW, Pascutti MF, Nolte MA.
      Follicular helper CD4+ T-cells (Tfh) control humoral immunity by driving affinity maturation and isotype-switching of activated B-cells. Tfh localize within B-cell follicles and, upon encounter with cognate antigen, drive B-cell selection in germinal centers (GCs) as GC-Tfh. Tfh functionality is controlled by Foxp3-expressing Tfh, which are known as regulatory T follicular cells (Tfr). Thus far, it remains unclear which factors determine the balance between these functionally opposing follicular T-cell subsets. Here, we demonstrate in human and mouse that Tfh and GC-Tfh, as well as their regulatory counterparts, express glucocorticoid-induced TNF receptor related protein (GITR) on their surface. This costimulatory molecule not only helps to identify follicular T-cell subsets, but also increases the ratio of Tfh vs. Tfr, both within and outside the GC. Correspondingly, GITR triggering increases the number of IL-21 producing CD4+ T-cells, which also produce more IFN-γ and IL-10. The latter are known switch factors for IgG2c and IgG1, respectively, which corresponds to a concomitant increase in IgG2c and IgG1 production upon GITR-mediated costimulation. These results demonstrate that GITR can skew the functional balance between Tfh and Tfr, which offers new therapeutic possibilities in steering humoral immunity.
    Keywords:  Antibodies; GITR; IL-21; Tfh; Tfr
    DOI:  https://doi.org/10.1016/j.imlet.2020.03.008
  15. Cells. 2020 Apr 02. pii: E857. [Epub ahead of print]9(4):
    Hammouda MB, Ford AE, Liu Y, Zhang JY.
      The c-Jun N-terminal kinases (JNKs), with its members JNK1, JNK2, and JNK3, is a subfamily of (MAPK) mitogen-activated protein kinases. JNK signaling regulates a wide range of cellular processes, including cell proliferation, differentiation, survival, apoptosis, and inflammation. Dysregulation of JNK pathway is associated with a wide range of immune disorders and cancer. Our objective is to provide a review of JNK proteins and their upstream regulators and downstream effector molecules in common skin disorders, including psoriasis, dermal fibrosis, scleroderma, basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and melanoma.
    Keywords:  BCC; JNK; SCC; fibrosis; keratinocytes; melanoma; psoriasis; scleroderma; skin inflammation
    DOI:  https://doi.org/10.3390/cells9040857
  16. J Cell Sci. 2020 Apr 07. pii: jcs228072. [Epub ahead of print]133(7):
    Wang Y, Argiles-Castillo D, Kane EI, Zhou A, Spratt DE.
      Homologous to E6AP C-terminus (HECT) E3 ubiquitin ligases play a critical role in various cellular pathways, including but not limited to protein trafficking, subcellular localization, innate immune response, viral infections, DNA damage responses and apoptosis. To date, 28 HECT E3 ubiquitin ligases have been identified in humans, and recent studies have begun to reveal how these enzymes control various cellular pathways by catalyzing the post-translational attachment of ubiquitin to their respective substrates. New studies have identified substrates and/or interactors with different members of the HECT E3 ubiquitin ligase family, particularly for E6AP and members of the neuronal precursor cell-expressed developmentally downregulated 4 (NEDD4) family. However, there still remains many unanswered questions about the specific roles that each of the HECT E3 ubiquitin ligases have in maintaining cellular homeostasis. The present Review discusses our current understanding on the biological roles of the HECT E3 ubiquitin ligases in the cell and how they contribute to disease development. Expanded investigations on the molecular basis for how and why the HECT E3 ubiquitin ligases recognize and regulate their intracellular substrates will help to clarify the biochemical mechanisms employed by these important enzymes in ubiquitin biology.
    Keywords:  Cancer; Cell signaling; E3 ubiquitin ligase; HECT; Neurodegeneration; Neurodevelopmental disorders; Neurological disorders; Protein turnover; Protein-protein interactions; Ubiquitin; Ubiquitylation
    DOI:  https://doi.org/10.1242/jcs.228072
  17. FEBS J. 2020 Apr 07.
    Celen AB, Sahin U.
      Sumoylation is an essential post-translational modification intimately involved in a diverse range of eukaryotic cellular mechanisms. SUMO protein isoforms can be reversibly linked to lysine residues that reside within specific motifs on thousands of target substrates, leading to modulations in stability, solubility, localization, and interactor profile. Since its initial discovery almost 25 years ago, SUMO has been described as a key regulator of genomic stability, cell proliferation, and infection among other processes. In this review, we trace the exciting developments in the history of this critical modifier, highlighting SUMO's roles in pathogenesis as well as its potential for the development of targeted therapies for numerous diseases.
    Keywords:  PML nuclear bodies; PML/RARα oncogene; SUMO; cancer; cross-talk; degradation; neurodegeneration; post-translational modification; proteasome; ubiquitin
    DOI:  https://doi.org/10.1111/febs.15319
  18. J Cell Sci. 2020 Apr 07. pii: jcs.244566. [Epub ahead of print]
    Renz C, Albanèse V, Tröster V, Albert TK, Santt O, Jacobs SC, Khmelinskii A, Léon S, Ulrich HD.
      Polyubiquitin chains linked via lysine (K) 63 play an important role in endocytosis and membrane trafficking. Their primary source is the ubiquitin protein ligase (E3) Rsp5/NEDD4, which acts as a key regulator of membrane protein sorting. The heterodimeric ubiquitin-conjugating enzyme (E2), Ubc13-Mms2, catalyses K63-specific polyubiquitylation in genome maintenance and inflammatory signalling. In budding yeast, the only ubiquitin protein ligase (E3) known to cooperate with Ubc13-Mms2 so far is a nuclear RING finger protein, Rad5, involved in the replication of damaged DNA. We now report a contribution of Ubc13-Mms2 to the sorting of membrane proteins to the yeast vacuole via the multivesicular body (MVB) pathway. In this context, Ubc13-Mms2 cooperates with Pib1, a FYVE-RING finger protein associated with internal membranes. Moreover, we identified a family of membrane-associated FYVE-(type)-RING finger proteins as cognate E3s for Ubc13-Mms2 in several species, and genetic analysis indicates that the contribution of Ubc13-Mms2 to membrane trafficking in budding yeast goes beyond its cooperation with Pib1. Thus, our results widely implicate Ubc13-Mms2 as an Rsp5-independent source of K63-linked polyubiquitin chains in the regulation of membrane protein sorting.
    Keywords:  FYVE domain; K63-polyubiquitin chains; Membrane protein sorting; RING finger; Ubiquitin-conjugating enzyme; Ubiquitin-protein ligase
    DOI:  https://doi.org/10.1242/jcs.244566
  19. Cell Rep. 2020 Apr 07. pii: S2211-1247(20)30344-2. [Epub ahead of print]31(1): 107466
    Donado CA, Cao AB, Simmons DP, Croker BA, Brennan PJ, Brenner MB.
      Interleukin-1β (IL-1β) is a key orchestrator of anti-microbial immunity whose secretion is typically dependent on activation of inflammasomes. However, many pathogens have evolved strategies to evade inflammasome activation. Here we describe an alternative, two-cell model for IL-1β release where invariant natural killer T (iNKT) cells use the death receptor pathway to instruct antigen-presenting cells to secrete IL-1β. Following cognate interactions with TLR-primed bone marrow-derived dendritic cells (BMDCs), iNKT cells rapidly translocate intracellular Fas ligand to the surface to engage Fas on BMDCs. Fas ligation activates a caspase-8-dependent signaling cascade in BMDCs that drives IL-1β release largely independent of inflammasomes. The apoptotic program initiated by Fas ligation rapidly transitions into a pyroptosis-like form of cell death mediated by gasdermin D. Together, our findings support a two-cell model for IL-1β secretion that may supersede inflammasome activation when cytosolic triggers fail.
    Keywords:  Fas; Fas ligand; NKT cell; apoptosis; caspase; cell death; gasdermin; inflammasome; interleukin-1; pyroptosis
    DOI:  https://doi.org/10.1016/j.celrep.2020.03.030
  20. Cell. 2020 Apr 05. pii: S0092-8674(20)30277-4. [Epub ahead of print]
    Dekoninck S, Hannezo E, Sifrim A, Miroshnikova YA, Aragona M, Malfait M, Gargouri S, de Neunheuser C, Dubois C, Voet T, Wickström SA, Simons BD, Blanpain C.
      During embryonic and postnatal development, organs and tissues grow steadily to achieve their final size at the end of puberty. However, little is known about the cellular dynamics that mediate postnatal growth. By combining in vivo clonal lineage tracing, proliferation kinetics, single-cell transcriptomics, and in vitro micro-pattern experiments, we resolved the cellular dynamics taking place during postnatal skin epidermis expansion. Our data revealed that harmonious growth is engineered by a single population of developmental progenitors presenting a fixed fate imbalance of self-renewing divisions with an ever-decreasing proliferation rate. Single-cell RNA sequencing revealed that epidermal developmental progenitors form a more uniform population compared with adult stem and progenitor cells. Finally, we found that the spatial pattern of cell division orientation is dictated locally by the underlying collagen fiber orientation. Our results uncover a simple design principle of organ growth where progenitors and differentiated cells expand in harmony with their surrounding tissues.
    Keywords:  development; differentiation; epidermis; growth; imbalance; postnatal; progenitors; self-renewal; skin; stem cells
    DOI:  https://doi.org/10.1016/j.cell.2020.03.015