Post-Translational Modification Control of Innate Immunity

O-linked N -acetylglucosamine (O-GlcNAc) is an essential and dynamic post-translational modification found on hundreds of nucleocytoplasmic proteins in metazoa. Although a single enzyme, O-GlcNAc transferase (OGT), generates the entire cytosolic O-GlcNAc proteome, it is not understood how it recognizes its protein substrates, targeting only a fraction of serines/threonines in the metazoan proteome for glycosylation. We describe a trapped complex of human OGT with the C-terminal domain of TAB1, a key innate immunity-signalling O-GlcNAc protein, revealing extensive interactions with the tetratricopeptide repeats of OGT. Confirmed by mutagenesis, this interaction suggests that glycosylation substrate specificity is achieved by recognition of a degenerate sequon in the active site combined with an extended conformation C-terminal of the O-GlcNAc target site.

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Host ADP-ribosylation and the SARS-CoV-2 macrodomain

Biochemical Society Transactions ◽

10.1042/bst20201212 ◽

2021 ◽

Author(s):

Nicolas C. Hoch

Keyword(s):

Innate Immunity ◽

Viral Replication ◽

Disease Severity ◽

Protein Trafficking ◽

Post Translational Modification ◽

Adp Ribosylation ◽

Open Questions ◽

Parp Activity ◽

Viral Target ◽

Intense Research

The COVID-19 pandemic has prompted intense research efforts into elucidating mechanisms of coronavirus pathogenesis and to propose antiviral interventions. The interferon (IFN) response is the main antiviral component of human innate immunity and is actively suppressed by several non-structural SARS-CoV-2 proteins, allowing viral replication within human cells. Differences in IFN signalling efficiency and timing have emerged as central determinants of the variability of COVID-19 disease severity between patients, highlighting the need for an improved understanding of host–pathogen interactions that affect the IFN response. ADP-ribosylation is an underexplored post-translational modification catalyzed by ADP-ribosyl transferases collectively termed poly(ADP-ribose) polymerases (PARPs). Several human PARPs are induced by the IFN response and participate in antiviral defences by regulating IFN signalling itself, modulating host processes such as translation and protein trafficking, as well as directly modifying and inhibiting viral target proteins. SARS-CoV-2 and other viruses encode a macrodomain that hydrolyzes ADP-ribose modifications, thus counteracting antiviral PARP activity. This mini-review provides a brief overview of the known targets of IFN-induced ADP-ribosylation and the functions of viral macrodomains, highlighting several open questions in the field.

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Myeloid neddylation targets IRF7 and promotes host innate immunity against RNA viruses

PLoS Pathogens ◽

10.1371/journal.ppat.1009901 ◽

2021 ◽

Vol 17 (9) ◽

pp. e1009901

Author(s):

Min Zhao ◽

Yaolin Zhang ◽

Xiqin Yang ◽

Jiayang Jin ◽

Zhuo Shen ◽

...

Keyword(s):

Innate Immunity ◽

Virus Infection ◽

Nuclear Translocation ◽

Rna Viruses ◽

Rna Virus ◽

Innate Immune ◽

Type I ◽

Gene Promoters ◽

Post Translational Modification

Neddylation, an important type of post-translational modification, has been implicated in innate and adapted immunity. But the role of neddylation in innate immune response against RNA viruses remains elusive. Here we report that neddylation promotes RNA virus-induced type I IFN production, especially IFN-α. More importantly, myeloid deficiency of UBA3 or NEDD8 renders mice less resistant to RNA virus infection. Neddylation is essential for RNA virus-triggered activation of Ifna gene promoters. Further exploration has revealed that mammalian IRF7undergoes neddylation, which is enhanced after RNA virus infection. Even though neddylation blockade does not hinder RNA virus-triggered IRF7 expression, IRF7 mutant defective in neddylation exhibits reduced ability to activate Ifna gene promoters. Neddylation blockade impedes RNA virus-induced IRF7 nuclear translocation without hindering its phosphorylation and dimerization with IRF3. By contrast, IRF7 mutant defective in neddylation shows enhanced dimerization with IRF5, an Ifna repressor when interacting with IRF7. In conclusion, our data demonstrate that myeloid neddylation contributes to host anti-viral innate immunity through targeting IRF7 and promoting its transcriptional activity.

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Post-Translational Modification of HMGB1 Disulfide Bonds in Stimulating and Inhibiting Inflammation

Cells ◽

10.3390/cells10123323 ◽

2021 ◽

Vol 10 (12) ◽

pp. 3323

Author(s):

Ulf Andersson ◽

Kevin J. Tracey ◽

Huan Yang

Keyword(s):

Innate Immunity ◽

Disulfide Bonds ◽

Nuclear Dna ◽

High Mobility ◽

Post Translational Modification ◽

Receptor System ◽

Surface Receptors ◽

Oxidation Reduction ◽

Molecular Pattern ◽

Glycation End Products

High mobility group box 1 protein (HMGB1), a highly conserved nuclear DNA-binding protein, is a “damage-associated molecular pattern” molecule (DAMP) implicated in both stimulating and inhibiting innate immunity. As reviewed here, HMGB1 is an oxidation-reduction sensitive DAMP bearing three cysteines, and the post-translational modification of these residues establishes its proinflammatory and anti-inflammatory activities by binding to different extracellular cell surface receptors. The redox-sensitive signaling mechanisms of HMGB1 also occupy an important niche in innate immunity because HMGB1 may carry other DAMPs and pathogen-associated molecular pattern molecules (PAMPs). HMGB1 with DAMP/PAMP cofactors bind to the receptor for advanced glycation end products (RAGE) which internalizes the HMGB1 complexes by endocytosis for incorporation in lysosomal compartments. Intra-lysosomal HMGB1 disrupts lysosomal membranes thereby releasing the HMGB1-transported molecules to stimulate cytosolic sensors that mediate inflammation. This HMGB1-DAMP/PAMP cofactor pathway slowed the development of HMGB1-binding antagonists for diagnostic or therapeutic use. However, recent discoveries that HMGB1 released from neurons mediates inflammation via the TLR4 receptor system, and that cancer cells express fully oxidized HMGB1 as an immunosuppressive mechanism, offer new paths to targeting HMGB1 for inflammation, pain, and cancer.

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How Influenza A Virus NS1 Deals with the Ubiquitin System to Evade Innate Immunity

Viruses ◽

10.3390/v13112309 ◽

2021 ◽

Vol 13 (11) ◽

pp. 2309

Author(s):

Laurie-Anne Lamotte ◽

Lionel Tafforeau

Keyword(s):

Immune Response ◽

Innate Immunity ◽

Influenza A Virus ◽

Virulence Factors ◽

Influenza A ◽

Innate Immune ◽

Structural Protein ◽

Post Translational Modification ◽

Cellular Processes ◽

Ubiquitin System

Ubiquitination is a post-translational modification regulating critical cellular processes such as protein degradation, trafficking and signaling pathways, including activation of the innate immune response. Therefore, viruses, and particularly influenza A virus (IAV), have evolved different mechanisms to counteract this system to perform proper infection. Among IAV proteins, the non-structural protein NS1 is shown to be one of the main virulence factors involved in these viral hijackings. NS1 is notably able to inhibit the host’s antiviral response through the perturbation of ubiquitination in different ways, as discussed in this review.

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Chemical tools to probe cellular O-GlcNAc signalling

Biochemical Journal ◽

10.1042/bj20131081 ◽

2013 ◽

Vol 456 (1) ◽

pp. 1-12 ◽

Cited By ~ 20

Author(s):

Adam Ostrowski ◽

Daan M. F. van Aalten

Keyword(s):

Signal Transduction ◽

Innate Immunity ◽

Stress Response ◽

Growth Factor ◽

Cell Lines ◽

Human Cell ◽

Primary Cells ◽

Post Translational Modification ◽

Reversible Addition ◽

Proteosomal Degradation

Protein O-GlcNAcylation is an abundant, dynamic and reversible type of protein post-translational modification in animals that has been implicated in signalling processes linked to innate immunity, stress response, growth factor response, transcription, translation and proteosomal degradation. Only two enzymes, O-GlcNAc (O-linked N-acetylglucosamine) transferase and O-GlcNAcase, catalyse the reversible addition of the O-GlcNAc residue to over 1000 target proteins in the human cell. Recent advances in our understanding of the structures and mechanisms of these enzymes have resulted in the development of potent and selective inhibitors. The present review gives an overview of these inhibitors and how they have been used on cell lines, primary cells and animals to modulate O-GlcNAc levels and study the effects on signal transduction.

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Metabolic engineering of CHO cells to prepare glycoproteins

Emerging Topics in Life Sciences ◽

10.1042/etls20180056 ◽

2018 ◽

Vol 2 (3) ◽

pp. 433-442 ◽

Cited By ~ 1

Author(s):

Qiong Wang ◽

Michael J. Betenbaugh

Keyword(s):

Metabolic Engineering ◽

Cho Cells ◽

Genetic Manipulation ◽

Chinese Hamster ◽

Post Translational Modification ◽

Effector Functions ◽

Recombinant Glycoproteins ◽

Production Platform ◽

Chemical Inhibitors ◽

Amino Acid Mutations

As a complex and common post-translational modification, N-linked glycosylation affects a recombinant glycoprotein's biological activity and efficacy. For example, the α1,6-fucosylation significantly affects antibody-dependent cellular cytotoxicity and α2,6-sialylation is critical for antibody anti-inflammatory activity. Terminal sialylation is important for a glycoprotein's circulatory half-life. Chinese hamster ovary (CHO) cells are currently the predominant recombinant protein production platform, and, in this review, the characteristics of CHO glycosylation are summarized. Moreover, recent and current metabolic engineering strategies for tailoring glycoprotein fucosylation and sialylation in CHO cells, intensely investigated in the past decades, are described. One approach for reducing α1,6-fucosylation is through inhibiting fucosyltransferase (FUT8) expression by knockdown and knockout methods. Another approach to modulate fucosylation is through inhibition of multiple genes in the fucosylation biosynthesis pathway or through chemical inhibitors. To modulate antibody sialylation of the fragment crystallizable region, expressions of sialyltransferase and galactotransferase individually or together with amino acid mutations can affect antibody glycoforms and further influence antibody effector functions. The inhibition of sialidase expression and chemical supplementations are also effective and complementary approaches to improve the sialylation levels on recombinant glycoproteins. The engineering of CHO cells or protein sequence to control glycoforms to produce more homogenous glycans is an emerging topic. For modulating the glycosylation metabolic pathways, the interplay of multiple glyco-gene knockouts and knockins and the combination of multiple approaches, including genetic manipulation, protein engineering and chemical supplementation, are detailed in order to achieve specific glycan profiles on recombinant glycoproteins for superior biological function and effectiveness.

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Dicarbonyl derived post-translational modifications: chemistry bridging biology and aging-related disease

Essays in Biochemistry ◽

10.1042/ebc20190057 ◽

2020 ◽

Vol 64 (1) ◽

pp. 97-110

Author(s):

Christian Sibbersen ◽

Mogens Johannsen

Keyword(s):

Mass Spectrometry ◽

Future Research ◽

Amino Acid Residues ◽

Post Translational Modification ◽

Dicarbonyl Compounds ◽

Protein Targets ◽

Post Translational Modifications ◽

Reactive Protein ◽

Glycation End Products ◽

Direct Mass Spectrometry

Abstract In living systems, nucleophilic amino acid residues are prone to non-enzymatic post-translational modification by electrophiles. α-Dicarbonyl compounds are a special type of electrophiles that can react irreversibly with lysine, arginine, and cysteine residues via complex mechanisms to form post-translational modifications known as advanced glycation end-products (AGEs). Glyoxal, methylglyoxal, and 3-deoxyglucosone are the major endogenous dicarbonyls, with methylglyoxal being the most well-studied. There are several routes that lead to the formation of dicarbonyl compounds, most originating from glucose and glucose metabolism, such as the non-enzymatic decomposition of glycolytic intermediates and fructosyl amines. Although dicarbonyls are removed continuously mainly via the glyoxalase system, several conditions lead to an increase in dicarbonyl concentration and thereby AGE formation. AGEs have been implicated in diabetes and aging-related diseases, and for this reason the elucidation of their structure as well as protein targets is of great interest. Though the dicarbonyls and reactive protein side chains are of relatively simple nature, the structures of the adducts as well as their mechanism of formation are not that trivial. Furthermore, detection of sites of modification can be demanding and current best practices rely on either direct mass spectrometry or various methods of enrichment based on antibodies or click chemistry followed by mass spectrometry. Future research into the structure of these adducts and protein targets of dicarbonyl compounds may improve the understanding of how the mechanisms of diabetes and aging-related physiological damage occur.

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Spindle scaling mechanisms

Essays in Biochemistry ◽

10.1042/ebc20190064 ◽

2020 ◽

Vol 64 (2) ◽

pp. 383-396

Author(s):

Lara K. Krüger ◽

Phong T. Tran

Keyword(s):

Cell Size ◽

Spindle Assembly ◽

Dependent Manner ◽

Post Translational Modification ◽

Size Dependent ◽

A Cell ◽

Chromosome Separation ◽

Spindle Elongation ◽

Protein Gradients ◽

Spindle Structure

Abstract The mitotic spindle robustly scales with cell size in a plethora of different organisms. During development and throughout evolution, the spindle adjusts to cell size in metazoans and yeast in order to ensure faithful chromosome separation. Spindle adjustment to cell size occurs by the scaling of spindle length, spindle shape and the velocity of spindle assembly and elongation. Different mechanisms, depending on spindle structure and organism, account for these scaling relationships. The limited availability of critical spindle components, protein gradients, sequestration of spindle components, or post-translational modification and differential expression levels have been implicated in the regulation of spindle length and the spindle assembly/elongation velocity in a cell size-dependent manner. In this review, we will discuss the phenomenon and mechanisms of spindle length, spindle shape and spindle elongation velocity scaling with cell size.

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