bims-tunefa Biomed News
on Tumor necrosis factor superfamily and post-translational modifications
Issue of 2020–06–07
twenty papers selected by
John Silke, Walter and Eliza Hall Institute of Medical Research



  1. Oncogene. 2020 May 31.
      Using PROteolysis TArgeting Chimeras (PROTACs) to degrade proteins that are important for tumorigenesis has emerged as a potential therapeutic strategy for cancer. PROTACs are heterobifunctional molecules consisting of one ligand for binding to a protein of interest (POI) and another to an E3 ubiquitin (E3) ligase, connected via a linker. PROTACs recruit the E3 ligase to the POI and cause proximity-induced ubiquitination and degradation of the POI by the ubiquitin-proteasome system (UPS). PROTACs have been developed to degrade a variety of cancer targets with unprecedented efficacy against a multitude of tumor types. To date, most of the PROTACs developed have utilized ligands to recruit E3 ligases that are ubiquitously expressed in both tumor and normal tissues. These PROTACs can cause on-target toxicities if the POIs are not tumor-specific. Therefore, identifying and recruiting the E3 ligases that are enriched in tumors with minimal expression in normal tissues holds the potential to develop tumor-specific/selective PROTACs. In this review, we will discuss the potential of PROTACs to become anticancer therapeutics, chemical and bioinformatics approaches for PROTAC design, and safety concerns with a special focus on the development of tumor-specific/selective PROTACs. In addition, the identification of tumor types in terms of solid versus hematological malignancies that can be best targeted with PROTAC approach will be briefly discussed.
    DOI:  https://doi.org/10.1038/s41388-020-1336-y
  2. Nature. 2020 Jun 03.
      Molecular glue compounds induce protein-protein interactions that, in the context of a ubiquitin ligase, lead to protein degradation1. Unlike traditional enzyme inhibitors, these molecular glue degraders act substoichiometrically to catalyse the rapid depletion of previously inaccessible targets2. They are clinically effective and highly sought-after, but have thus far only been discovered serendipitously. Here, through systematically mining databases for correlations between the cytotoxicity of 4,518 clinical and preclinical small molecules and the expression levels of E3 ligase components across hundreds of human cancer cell lines3-5, we identify CR8-a cyclin-dependent kinase (CDK) inhibitor6-as a compound that acts as a molecular glue degrader. The CDK-bound form of CR8 has a solvent-exposed pyridyl moiety that induces the formation of a complex between CDK12-cyclin K and the CUL4 adaptor protein DDB1, bypassing the requirement for a substrate receptor and presenting cyclin K for ubiquitination and degradation. Our studies demonstrate that chemical alteration of surface-exposed moieties can confer gain-of-function glue properties to an inhibitor, and we propose this as a broader strategy through which target-binding molecules could be converted into molecular glues.
    DOI:  https://doi.org/10.1038/s41586-020-2374-x
  3. Nat Commun. 2020 Jun 05. 11(1): 2846
      Based on extensive structural analysis it was proposed that RING E3 ligases prime the E2~ubiquitin conjugate (E2~Ub) for catalysis by locking it into a closed conformation, where ubiquitin is folded back onto the E2 exposing the restrained thioester bond to attack by substrate nucleophile. However the proposal that the RING dependent closed conformation of E2~Ub represents the active form that mediates ubiquitin transfer has yet to be experimentally tested. To test this hypothesis we use single molecule Förster Resonance Energy Transfer (smFRET) to measure the conformation of a FRET labelled E2~Ub conjugate, which distinguishes between closed and alternative conformations. We describe a real-time FRET assay with a thioester linked E2~Ub conjugate to monitor single ubiquitination events and demonstrate that ubiquitin is transferred to substrate from the closed conformation. These findings are likely to be relevant to all RING E3 catalysed reactions ligating ubiquitin and other ubiquitin-like proteins (Ubls) to substrates.
    DOI:  https://doi.org/10.1038/s41467-020-16666-y
  4. Nat Chem Biol. 2020 Jun 01.
      Changes in the cellular environment modulate protein energy landscapes to drive important biology, with consequences for signaling, allostery and other vital processes. The effects of ubiquitination are particularly important because of their potential influence on degradation by the 26S proteasome. Moreover, proteasomal engagement requires unstructured initiation regions that many known proteasome substrates lack. To assess the energetic effects of ubiquitination and how these manifest at the proteasome, we developed a generalizable strategy to produce isopeptide-linked ubiquitin within structured regions of a protein. The effects on the energy landscape vary from negligible to dramatic, depending on the protein and site of ubiquitination. Ubiquitination at sensitive sites destabilizes the native structure and increases the rate of proteasomal degradation. In well-folded proteins, ubiquitination can even induce the requisite unstructured regions needed for proteasomal engagement. Our results indicate a biophysical role of site-specific ubiquitination as a potential regulatory mechanism for energy-dependent substrate degradation.
    DOI:  https://doi.org/10.1038/s41589-020-0556-3
  5. Blood Rev. 2020 May 07. pii: S0268-960X(20)30046-1. [Epub ahead of print] 100696
      Poly (ADP-ribose) polymerase (PARP) inhibitors, which induce synthetic lethality of BRCA mutant breast and ovarian cancers, are now under active exploration for treatment of acute leukemias, specifically acute myeloid leukemia (AML). Experimental data has revealed that DNA repair deficiencies similar to those found in BRCA mutant solid tumors function in malignant hematopoietic cells to enhance cell survival and promote therapy resistance. Preclinical studies have demonstrated that inhibition of PARP with a variety of agents can dramatically enhance the efficacy of other therapeutic approaches including cytotoxic and epigenetic chemotherapy, small molecule inhibitors (IDH and FLT3 inhibitors) and antibody drug conjugates. This has led to early stage clinical trials of multiple PARP inhibitors (PARPi) for AML patients. Despite small patient numbers, evidence of modest clinical efficacy and tolerability in combinatorial regimens support the further development of PARP inhibition as a novel therapeutic strategy for AML, particularly in select molecular subsets (MLL rearranged, FLT3 and IDH1 mutant disease.
    Keywords:  Acute myeloid leukemia; DNA damage; DNA repair; FLT3 mutation; IDH mutation; Olaparib; PARP inhibition; Talazoparib
    DOI:  https://doi.org/10.1016/j.blre.2020.100696
  6. Int J Mol Sci. 2020 May 30. pii: E3904. [Epub ahead of print]21(11):
      The Wnt signaling pathway plays important roles in embryonic development, homeostatic processes, cell differentiation, cell polarity, cell proliferation, and cell migration via the β-catenin binding of Wnt target genes. Dysregulation of Wnt signaling is associated with various diseases such as cancer, aging, Alzheimer's disease, metabolic disease, and pigmentation disorders. Numerous studies entailing the Wnt signaling pathway have been conducted for various cancers. Diverse signaling factors mediate the up- or down-regulation of Wnt signaling through post-translational modifications (PTMs), and aberrant regulation is associated with several different malignancies in humans. Of the numerous PTMs involved, most Wnt signaling factors are regulated by ubiquitination and deubiquitination. Ubiquitination by E3 ligase attaches ubiquitins to target proteins and usually induces proteasomal degradation of Wnt signaling factors such as β-catenin, Axin, GSK3, and Dvl. Conversely, deubiquitination induced by the deubiquitinating enzymes (DUBs) detaches the ubiquitins and modulates the stability of signaling factors. In this review, we discuss the effects of ubiquitination and deubiquitination on the Wnt signaling pathway, and the inhibitors of DUBs that can be applied for cancer therapeutic strategies.
    Keywords:  Wnt signaling; cancer; deubiquitinating enzymes; inhibitor; small molecules; ubiquitination
    DOI:  https://doi.org/10.3390/ijms21113904
  7. PLoS One. 2020 ;15(6): e0233643
      Chronic subdural hematoma (CSDH) is an angiogenic and inflammatory disease. Toll-like receptors (TLRs) transduce intracellular signals, resulting in the activation of nuclear factor κB (NF-κB), which leads to the production of inflammatory cytokines. High-mobility group box 1 (HMGB1) functions as a mediator of inflammatory responses through TLRs. In this study, we examined the expression of HMGB1 and components of the Toll-like receptor and NF-κB signaling pathways in the outer membrane of CSDH. Eight patients whose outer membrane was successfully obtained during trepanation surgery were included in this study. The expression of TLR4, myeloid differentiation factor 88 (MyD88), interleukin-1 receptor-associated kinase 4 (IRAK4), TNF receptor-associated factor 6 (TRAF6), TGFβ-activated kinase 1 (Tak1), interferon regulatory factors 3 (IRF3), IκB kinase β (IKKβ), IKKγ, IκBε, IκBα, NF-κB/p65 and β-actin was examined by Western blot analysis. The expression of TLR4, NF-κB/p65 and interleukin-6 (IL-6) was also examined by immunohistochemistry. The concentrations of HMGB1 and IL-6 in CSDH fluids were measured using ELISA kits. Above-mentioned molecules were detected in all cases. In addition, TLR4, NF-κB/p65 and IL-6 were localized in the endothelial cells of vessels within CSDH outer membranes. The concentrations of HMGB1 and IL-6 in CSDH fluids were significantly higher than that in the CSF and serum. There existed a correlation between the concentrations of HMGB1 and IL-6 in CSDH fluids. Our data suggest that HMGB1 in CSDH fluids produces the inflammatory cytokine IL-6 in endothelial cells through the Toll-like receptor and NF-κB signaling pathways. Anti-HMGB1 therapy might be a useful method to treat the growth of CSDH.
    DOI:  https://doi.org/10.1371/journal.pone.0233643
  8. Acta Neuropathol Commun. 2020 Jun 05. 8(1): 81
      Preclinical and clinical proof-of-concept studies have suggested the effectiveness of pharmacological modulation of inflammatory cytokines in ischemic stroke. Experimental evidence shows that targeting tumor necrosis factor (TNF) and interleukin (IL)-1 holds promise, and these cytokines are considered prime targets in the development of new stroke therapies. So far, however, information on the cellular expression of TNF and IL-1 in the human ischemic brain is sparse.We studied 14 cases of human post-mortem ischemic stroke, representing 21 specimens of infarcts aged 1 to > 8 days. We characterized glial and leukocyte reactions in the infarct/peri-infarct (I/PI) and normal-appearing tissue (NAT) and the cellular location of TNF, TNF receptor (TNFR)1 and TNFR2, IL-1α, IL-1β, and IL-1 receptor antagonist (IL-1Ra). The immunohistochemically stained tissue sections received a score reflecting the number of immunoreactive cells and the intensity of the immunoreactivity (IR) in individual cells where 0 = no immunoreactive cells, 1 = many intermediately to strongly immunoreactive cells, and 2 = numerous and intensively immunoreactive cells. Additionally, we measured blood TNF, TNFR, and IL-1 levels in surviving ischemic stroke patients within the first 8 h and again at 72 h after symptom onset and compared levels to healthy controls.We observed IL-1α and IL-1β IR in neurons, glia, and macrophages in all specimens. IL-1Ra IR was found in glia, in addition to macrophages. TNF IR was initially found in neurons located in I/PI and NAT but increased in glia in older infarcts. TNF IR increased in macrophages in all specimens. TNFR1 IR was found in neurons and glia and macrophages, while TNFR2 was expressed only by glia in I/PI and NAT, and by macrophages in I/PI. Our results suggest that TNF and IL-1 are expressed by subsets of cells and that TNFR2 is expressed in areas with increased astrocytic reactivity. In ischemic stroke patients, we demonstrate that plasma TNFR1 and TNFR2 levels increased in the acute phase after symptom onset compared to healthy controls, whereas TNF, IL-1α, IL-1β, and IL-1Ra did not change.Our findings of increased brain cytokines and plasma TNFR1 and TNFR2 support the hypothesis that targeting post-stroke inflammation could be a promising add-on therapy in ischemic stroke patients.
    Keywords:  Apoplexy; Cytokines; Leukocytes; Microglia
    DOI:  https://doi.org/10.1186/s40478-020-00957-y
  9. ACS Chem Neurosci. 2020 Jun 01.
      Post-traumatic epilepsy (PTE) is one of the detrimental outcomes of traumatic brain injury (TBI), resulting in recurrent seizures which impact daily life. However, the pathological relationship between PTE and TBI remains unclear, and commonly prescribed anti-epileptic drugs (AED) are ineffective against PTE. Fortunately, emerging research implicates neuroinflammation particularly the tumor necrosis factor-alpha (TNFα) as the key mediator for PTE development. Thus, this review aims to examine the available literature regarding the role of TNFα in PTE pathology and consecutively, evaluate TNFα as a possible target for its treatment. A comprehensive literature search was conducted on four databases including PubMed, CINAHL, Embase, and Scopus. Articles with relevance in investigating TNF-α expression by PTE were considered in this review. Critical evaluation of four articles that met the inclusion criteria suggests a proportional relationship between TNFα expression and seizure susceptibility, and that neutralization or suppression of TNFα release results in lesser susceptibility to seizures. In conclusion, this review elucidates the importance of TNF-α expression in epileptogenesis post-injury and urges future research to focus more on clinical studies involving TNFα which may provide a clearer insight to PTE prevention and therefore improving the lives of PTE patients.
    DOI:  https://doi.org/10.1021/acschemneuro.0c00301
  10. Biochem J. 2020 Jun 01. pii: BCJ20200289. [Epub ahead of print]
      The Baculoviridae family of viruses encode a viral Ubiquitin gene. Though the viral Ubiquitin (vUb) is homologous to the host eukaryotic Ubiquitin (Ub), its preservation in the viral genome indicates unique functions that are not compensated by the host Ub. We report the structural, biophysical, and biochemical properties of the vUb from Autographa Californica Multiple Nucleo-Polyhedrosis Virus (AcMNPV). The packing of central helix α1 to the beta-sheet b1-b5 is different between vUb and Ub. Consequently, its stability is lower compared to Ub. However, the surface properties, ubiquitination activity, and the interaction with Ubiquitin binding domains are similar between vUb and Ub. Interestingly, vUb forms atypical polyubiquitin chain linked by lysine at the 54th position (K54), and the deubiquitinating enzymes are ineffective against the K54-linked polyubiquitin chains. We propose that the modification of host/viral proteins with the K54-linked chains is an effective way selected by the virus to protect the vUb signal from host DUBs.
    Keywords:  NMR spectroscopy; host-pathogen interactions; post translational modification; ubiquitins
    DOI:  https://doi.org/10.1042/BCJ20200289
  11. Mol Cell. 2020 Jun 04. pii: S1097-2765(20)30339-7. [Epub ahead of print]78(5): 803-805
      In this issue of Molecular Cell, Schumann et al. (2020) present a novel strategy to dissect the regulation of protein O-glycosylation by a large family of isoenzymes in cells. They employ a bump-and-hole engineering approach to capture the specific contribution of individual isoenzymes to O-glycosylation of proteins.
    DOI:  https://doi.org/10.1016/j.molcel.2020.05.019
  12. Virus Res. 2020 May 31. pii: S0168-1702(20)30093-9. [Epub ahead of print] 198036
      Interferon (IFN)-stimulated gene product 15 (ISG15) is a ubiquitin-like protein critical for the control of microbial infections. ISG15 appears to serve a wide variety of functions, which regulate multiple cellular responses contributing to the development of an antiviral state. ISG15 is a versatile molecule directly modulating both host and virus protein function which regulate many signaling pathways, including its own synthesis. Here we review the various roles ISG15 plays in the antiviral immune response, and examine the mechanisms by which viruses attempt to mitigate or exploit ISG15 activity.
    Keywords:  Coronavirus; ISG15; Innate immune response; Nairovirus; Viral pathogenesis; deISGylase
    DOI:  https://doi.org/10.1016/j.virusres.2020.198036
  13. Cell Stem Cell. 2020 Jun 04. pii: S1934-5909(20)30160-0. [Epub ahead of print]26(6): 801-803
      In this issue of Cell Stem Cell, Shook et al. (2020) reveal that dermal adipocytes regulate skin wound repair via release of fatty acids that promote macrophage recruitment and accelerated revascularization. Furthermore, mature dermal adipocytes dedifferentiate into migratory extracellularmatrix-producing myofibroblasts.
    DOI:  https://doi.org/10.1016/j.stem.2020.04.021
  14. Int J Mol Sci. 2020 May 30. pii: E3921. [Epub ahead of print]21(11):
      Ubiquitylation plays multiple roles not only in proteasome-mediated protein degradation but also in various other cellular processes including DNA repair, signal transduction, and endocytosis. Ubiquitylation is mediated by ubiquitin ligases, which are predicted to be encoded by more than 600 genes in humans. RING finger (RNF) proteins form the majority of these ubiquitin ligases. It has also been predicted that there are 49 RNF proteins containing transmembrane regions in humans, several of which are specifically localized to membrane compartments in the secretory and endocytic pathways. Of these, RNF183, RNF186, RNF182, and RNF152 are closely related genes with high homology. These genes share a unique common feature of exhibiting tissue-specific expression patterns, such as in the kidney, nervous system, and colon. The products of these genes are also reported to be involved in various diseases such as cancers, inflammatory bowel disease, Alzheimer's disease, and chronic kidney disease, and in various biological functions such as apoptosis, endoplasmic reticulum stress, osmotic stress, nuclear factor-kappa B (NF-κB), mammalian target of rapamycin (mTOR), and Notch signaling. This review summarizes the current knowledge of these tissue-specific ubiquitin ligases, focusing on their physiological roles and significance in diseases.
    Keywords:  NF-κB; RING finger; RNF152; RNF182; RNF183; RNF186; endoplasmic reticulum stress; mTOR; osmotic stress; ubiquitin ligase
    DOI:  https://doi.org/10.3390/ijms21113921
  15. Thorax. 2020 Jun 01. pii: thoraxjnl-2019-214496. [Epub ahead of print]
      Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) reportedly promotes, or conversely, resolves inflammation in asthma. In this study of TRAIL and cell receptors in sputum, bronchoalveolar lavage and biopsy from subjects in the Severe Asthma Research Program at Wake Forest, the high TRAIL group had significant increases in all leucocytes, and was associated with increased type 1, type 2 and type 17 cytokines, but not type 9 interleukin 9. Two variants at loci in the TRAIL gene were associated with higher sputum levels of TRAIL. Increased TRAIL decoy receptor R3/DcR1 was observed on sputum leucocytes compared with death receptor R1/DR4, suggesting reduced apoptosis and prolonged cellular inflammation.
    Keywords:  asthma mechanisms; cytokine biology
    DOI:  https://doi.org/10.1136/thoraxjnl-2019-214496
  16. Leuk Res. 2020 Jul;pii: S0145-2126(20)30076-X. [Epub ahead of print]94 106371
      The clinical behavior of FL patients is heterogeneous. The levels of sIL-2R have been correlated with tumor burden and outcome in FL. However, the impact of IL-6 and TNF-α in this disease is unclear. We studied 253 patients diagnosed with grade 1-3a FL between 2002 and 2018, with available information on serum levels of sIL-2R, IL-6, and TNF-α at diagnosis. Patients with cytokine levels above the cutoff had features of a higher tumor burden and higher-risk disease. Levels of any of the studied cytokines above the cutoff and a higher number of cytokines above the cutoff impacted on a shorter PFS and OS. TNF-α levels were an independent predictor of a poorer PFS. No differences were observed in the risk of histological transformation or second malignancies. The determination of cytokine levels in FL patients is feasible in clinical practice, and elevated levels are associated with a higher tumor burden and poorer survival.
    Keywords:  Chemoimmunotherapy; Cytokines; Follicular lymphoma; Response; Survival
    DOI:  https://doi.org/10.1016/j.leukres.2020.106371
  17. FEBS J. 2020 Jun 02.
      Phosphatases are a diverse family of enzymes, comprising at least 10 distinct protein folds. Like most other enzyme families, many have sequence variations that predict an impairment or loss of catalytic activity classifying them as pseudophosphatases. Research on pseudoenzymes is an emerging area of interest, with new biological functions repurposed from catalytically active relatives. Here, we provide an overview of the pseudophosphatases identified to date in all major phosphatase families. We will highlight the degeneration of the various catalytic sequence motifs and discuss the challenges associated with the experimental determination of catalytic inactivity. We will also summarize the role of pseudophosphatases in various diseases and discuss the major challenges and future directions in this field.
    Keywords:  dephosphorylation; phosphatase; pseudoenzymes; pseudophosphatase
    DOI:  https://doi.org/10.1111/febs.15431
  18. Nature. 2020 May 06.
    Primary Immunodeficiency Consortium for the NIHR Bioresource
      Primary immunodeficiency (PID) is characterized by recurrent and often life-threatening infections, autoimmunity and cancer, and it poses major diagnostic and therapeutic challenges. Although the most severe forms of PID are identified in early childhood, most patients present in adulthood, typically with no apparent family history and a variable clinical phenotype of widespread immune dysregulation: about 25% of patients have autoimmune disease, allergy is prevalent and up to 10% develop lymphoid malignancies1-3. Consequently, in sporadic (or non-familial) PID genetic diagnosis is difficult and the role of genetics is not well defined. Here we address these challenges by performing whole-genome sequencing in a large PID cohort of 1,318 participants. An analysis of the coding regions of the genome in 886 index cases of PID found that disease-causing mutations in known genes that are implicated in monogenic PID occurred in 10.3% of these patients, and a Bayesian approach (BeviMed4) identified multiple new candidate PID-associated genes, including IVNS1ABP. We also examined the noncoding genome, and found deletions in regulatory regions that contribute to disease causation. In addition, we used a genome-wide association study to identify loci that are associated with PID, and found evidence for the colocalization of-and interplay between-novel high-penetrance monogenic variants and common variants (at the PTPN2 and SOCS1 loci). This begins to explain the contribution of common variants to the variable penetrance and phenotypic complexity that are observed in PID. Thus, using a cohort-based whole-genome-sequencing approach in the diagnosis of PID can increase diagnostic yield and further our understanding of the key pathways that influence immune responsiveness in humans.
    DOI:  https://doi.org/10.1038/s41586-020-2265-1
  19. Cancer Discov. 2020 Jun 05.
      Preliminary clinical data for ARV-110, a proteolysis-targeting chimera that flags the androgen receptor for degradation, indicate that the drug is safe and shows some efficacy in men with metastatic castration-resistant prostate cancer.
    DOI:  https://doi.org/10.1158/2159-8290.CD-NB2020-054