Autophagy has been linked to a wide range of functions, including a degradative process that defends host cells against pathogens. Although the involvement of autophagy in HBV infection has become ...apparent, it remains unknown whether selective autophagy plays a critical role in HBV restriction. Here, we report that a member of the galectin family, GAL9, directs the autophagic degradation of HBV HBc. BRET screening revealed that GAL9 interacts with HBc in living cells. Ectopic expression of GAL9 induces the formation of HBc-containing cytoplasmic puncta through interaction with another antiviral factor viperin, which co-localized with the autophagosome marker LC3. Mechanistically, GAL9 associates with HBc via viperin at the cytoplasmic puncta and enhanced the auto-ubiquitination of RNF13, resulting in p62 recruitment to form LC3-positive autophagosomes. Notably, both GAL9 and viperin are type I IFN-stimulated genes that act synergistically for the IFN-dependent proteolysis of HBc in HBV-infected hepatocytes. Collectively, these results reveal a previously undescribed antiviral mechanism against HBV in infected cells and a form of crosstalk between the innate immune system and selective autophagy in viral infection.
The structure of protoaculeine B, the N-terminal residue of the marine peptide toxin aculeine B, is revised to the cis-1,3-disubstituted tetrahydro-β-carboline framework. We prepared two truncated ...model compounds that lack a long-chain polyamine using the one-step Pictet–Spengler reaction of tryptophan and compared their NMR, mass spectra, and chemical reactivity with those of the natural protoaculeine B. The synthetic models reproduced the profiles of the natural product well, which confirmed the appropriateness of the structure revision.
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IJS, KILJ, NUK, PNG, UL, UM
Weaver syndrome (WS) is a rare congenital overgrowth disorder caused by heterozygous mutations in EZH2 (enhancer of zeste homolog 2) or EED (embryonic ectoderm development). EZH2 and EED are core ...components of the polycomb repressive complex 2 (PRC2), which possesses histone methyltransferase activity and catalyzes trimethylation of histone H3 at lysine 27. Here, we analyzed eight probands with clinically suspected WS by whole‐exome sequencing and identified three mutations: a 25.4‐kb deletion partially involving EZH2 and CUL1 (individual 1), a missense mutation (c.707G>C, p.Arg236Thr) in EED (individual 2), and a missense mutation (c.1829A>T, p.Glu610Val) in SUZ12 (suppressor of zeste 12 homolog) (individual 3) inherited from her father (individual 4) with a mosaic mutation. SUZ12 is another component of PRC2 and germline mutations in SUZ12 have not been previously reported in humans. In vitro functional analyses demonstrated that the identified EED and SUZ12 missense mutations cause decreased trimethylation of lysine 27 of histone H3. These data indicate that loss‐of‐function mutations of PRC2 components are an important cause of WS.
In this report, we describe novel mutations in three genes encoding polycomb repressive complex 2 (PRC2) subunits associated with Weaver syndrome: a 25.4‐kb deletion partially involving EZH2 and CUL1, a missense mutation (p.Arg236Thr) in EED, and a missense mutation (p.Glu610Val) in SUZ12. In vitro functional analyses demonstrated that the all identified mutations cause decreased trimethylation of lysine 27 in histone H3. These results indicate that a loss‐of‐function of PRC2 is one of important causes in Weaver syndrome.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The scallop
accumulates carotenoids in the ovary during the maturation stage. Its conspicuous pink color implies the presence of carotenoprotein. However, the carotenoprotein from the scallop ovary ...has never been isolated and characterized, probably due to its instability and complexity. Here, we developed an extraction and isolation procedure for the carotenoprotein by employing a basic buffer containing potassium bromide to facilitate its efficient extraction from the ovary, and we succeeded in obtaining the carotenoprotein, termed pectenovarin. The carotenoid composition of the pectenovarin was similar to that of the ovary. The N-terminal and internal amino acid sequences of pectenovarin showed a high similarity to those of vitellogenin, the precursor of egg yolk protein under analysis.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The nuclear pore complex (NPC) is a huge protein complex embedded in the nuclear envelope. It has central functions in nucleocytoplasmic transport, nuclear framework, and gene regulation. Nucleoporin ...107 kDa (NUP107) is a component of the NPC central scaffold and is an essential protein in all eukaryotic cells. Here, we report on biallelic NUP107 mutations in nine affected individuals who are from five unrelated families and show early-onset steroid-resistant nephrotic syndrome (SRNS). These individuals have pathologically focal segmental glomerulosclerosis, a condition that leads to end-stage renal disease with high frequency. NUP107 is ubiquitously expressed, including in glomerular podocytes. Three of four NUP107 mutations detected in the affected individuals hamper NUP107 binding to NUP133 (nucleoporin 133 kDa) and NUP107 incorporation into NPCs in vitro. Zebrafish with nup107 knockdown generated by morpholino oligonucleotides displayed hypoplastic glomerulus structures and abnormal podocyte foot processes, thereby mimicking the pathological changes seen in the kidneys of the SRNS individuals with NUP107 mutations. Considering the unique properties of the podocyte (highly differentiated foot-process architecture and slit membrane and the inability to regenerate), we propose a “podocyte-injury model” as the pathomechanism for SRNS due to biallelic NUP107 mutations.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Lentiviruses have evolved to acquire an auxiliary protein Vpx to counteract the intrinsic host restriction factor SAMHD1. Although Vpx is phosphorylated, it remains unclear whether such ...phosphorylation indeed regulates its activity toward SAMHD1. Here we identify the PIM family of serine/threonine protein kinases as the factors responsible for the phosphorylation of Vpx and the promotion of Vpx-mediated SAMHD1 counteraction. Integrated proteomics and subsequent functional analysis reveal that PIM family kinases, PIM1 and PIM3, phosphorylate HIV-2 Vpx at Ser13 and stabilize the interaction of Vpx with SAMHD1 thereby promoting ubiquitin-mediated proteolysis of SAMHD1. Inhibition of the PIM kinases promotes the antiviral activity of SAMHD1, ultimately reducing viral replication. Our results highlight a new mode of virus-host cell interaction in which host PIM kinases facilitate promotion of viral infectivity by counteracting the host antiviral system, and suggest a novel therapeutic strategy involving restoration of SAMHD1-mediated antiviral response.
Interferon regulatory factor-5 (IRF5), a transcription factor critical for the induction of innate immune responses, contributes to the pathogenesis of the autoimmune disease systemic lupus ...erythematosus (SLE) in humans and mice. Lyn, a Src family kinase, is also implicated in human SLE, and Lyn-deficient mice develop an SLE-like disease. Here, we found that Lyn physically interacted with IRF5 to inhibit ubiquitination and phosphorylation of IRF5 in the TLR-MyD88 pathway, thereby suppressing the transcriptional activity of IRF5 in a manner independent of Lyn’s kinase activity. Conversely, Lyn did not inhibit NF-κB signaling, another major branch downstream of MyD88. Monoallelic deletion of Irf5 alleviated the hyperproduction of cytokines in TLR-stimulated Lyn–/– dendritic cells and the development of SLE-like symptoms in Lyn–/– mice. Our results reveal a role for Lyn as a specific suppressor of the TLR-MyD88-IRF5 pathway and illustrate the importance of fine-tuning IRF5 activity for the maintenance of immune homeostasis.
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•Lyn binds to and inhibits the activity of IRF5 in the TLR-MyD88 pathway•Lyn inhibits post-translational modifications of IRF5 without Lyn’s kinase activity•Lyn deficiency causes IRF5 hyperactivation in DCs•SLE symptoms in Lyn–/– mice are ameliorated by monoallelic deletion of Irf5
How IRF5 activity is negatively regulated remains largely unknown. Tamura and colleagues identify Lyn as an IRF5-binding protein that suppresses the TLR-MyD88-IRF5 pathway. IRF5 is hyperactivated in Lyn-deficient mice suffering from the autoimmune disease SLE, but reducing the abundance of IRF5 ameliorates the disease development.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Pneumococcal cell surface‐exposed choline‐binding proteins (CBPs) play pivotal roles in multiple infectious processes with pneumococci. Intracellular pneumococci can be recognized at multiple steps ...during bactericidal autophagy. However, whether CBPs are involved in pneumococci‐induced autophagic processes remains unknown. In this study, we demonstrate that CbpC from S. pneumoniae strain TIGR4 activates autophagy through an interaction with Atg14. However, S. pneumoniae also interferes with autophagy by deploying CbpC as a decoy to cause autophagic degradation of Atg14 through an interaction with p62/SQSTM1. Thus, S. pneumoniae suppresses the autophagic degradation of intracellular pneumococci and survives within cells. Domain analysis reveals that the coiled‐coil domain of Atg14 and residue Y83 of the dp3 domain in the N‐terminal region of CbpC are crucial for both the CbpC–Atg14 interaction and the subsequent autophagic degradation of Atg14. Although homology modeling indicates that CbpC orthologs have similar structures in the dp3 domain, autophagy induction through Atg14 binding is an intrinsic property of CbpC. Our data provide novel insights into the evolutionary hijacking of host‐defense systems by intracellular pneumococci.
Synopsis
Pneumococcal cell surface‐exposed choline‐binding proteins play pivotal roles in multiple infectious processes. CbpC promotes selective autophagy of Atg14 through an interaction with p62, thereby dampening degradation and xenophagy of S. pneumonia.
The S. pneumoniae choline‐binding protein CbpC activates autophagy through an interaction with Atg14 and p62.
S. pneumoniae subverts autophagy by deploying CbpC as a decoy for autophagic degradation of Atg14.
Atg14‐elimination suppresses autophagic degradation of intracellular pneumococci and promotes their survival.
Pneumococcal cell surface‐exposed choline‐binding proteins play pivotal roles in multiple infectious processes. CbpC promotes selective autophagy of Atg14 through an interaction with p62, thereby dampening degradation and xenophagy of S. pneumonia.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Type-I interferons (IFN-I) are the innate immune system's principal defense against viral infections. Human immunodeficiency virus-1 (HIV-1) has evolved several ways to suppress or evade the host's ...innate immunity in order to survive and replicate to sustain infection. Suppression of IFN-I is one among the multiple escape strategies used by HIV-1 to prevent its clearance. HIV-1 protease which helps in viral maturation has also been observed to cleave host cellular protein kinases. In this study we performed a comprehensive screening of a human kinase library using AlphaScreen assay and identified that TANK binding kinase-1 (TBK1) was cleaved by HIV-1 protease (PR). We demonstrate that PR cleaved TBK1 fails to phosphorylate IFN regulatory factor 3 (IRF3), thereby reducing the IFN-I promoter activity and further reveal that the PR mediated suppression of IFN-I could be counteracted by protease inhibitors (PI)
. We have also revealed that mutations of HIV-1 PR that confer drug resistance to PIs reduce the enzyme's ability to cleave TBK1. The findings of this study unearth a direct link between HIV-1 PR activity and evasion of innate immunity by the virus, the possible physiological relevance of which warrants to be determined.
Current anti-hepatitis B virus (HBV) agents have limited effect in curing HBV infection, and thus novel anti-HBV agents with different modes of action are in demand. In this study, we applied ...AlphaScreen assay to high-throughput screening of small molecules inhibiting the interaction between HBV large surface antigen (LHBs) and the HBV entry receptor, sodium taurocholate cotransporting polypeptide (NTCP). From the chemical screening, we identified that rapamycin, an immunosuppressant, strongly inhibited the LHBs-NTCP interaction. Rapamycin inhibited hepatocyte infection with HBV without significant cytotoxicity. This activity was due to impaired attachment of the LHBs preS1 domain to cell surface. Pretreatment of target cells with rapamycin remarkably reduced their susceptibility to preS1 attachment, while rapamycin pretreatment to preS1 did not affect its attachment activity, suggesting that rapamycin targets the host side. In support of this, a surface plasmon resonance analysis showed a direct interaction of rapamycin with NTCP. Consistently, rapamycin also prevented hepatitis D virus infection, whose entry into cells is also mediated by NTCP. We also identified two rapamycin derivatives, everolimus and temsirolimus, which possessed higher anti-HBV potencies than rapamycin. Thus, this is the first report for application of AlphaScreen technology that monitors a viral envelope-receptor interaction to identify viral entry inhibitors.
•AlphaScreen evaluating LHBs-NTCP binding identified rapamycin as an anti-HBV agent.•Rapamycin directly interacted with NTCP.•Rapamycin inhibited the infection of HBV and HDV.•Everolimus and temsirolimus possessed higher anti-HBV potency than rapamycin.•First report applying AlphaScreen to the identification of viral entry inhibitors.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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