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EV-D68 cleaves LARP1 and PABPC1 by 3Cpro to redirect host mRNA translation machinery toward its genomic RNA.

Enterovirus D68 (EV-D68) is an emerging pathogen associated with severe respiratory diseases and neurological complications, such as acute flaccid myelitis. EV-D68 has developed sophisticated mechanisms to hijack host translation machinery, facilitating its replication and impairing host mRNA translation. In this study, we demonstrate that EV-D68 cleaves La-related protein 1 (LARP1) and poly(A)-binding protein cytoplasmic 1 (PABPC1) through its proteases 3Cpro and 2Apro. Our results indicate that overexpressing LARP1 and PABPC1 significantly inhibits EV-D68 replication and reduces the virus-mediated suppression of host translation. While both LARP1 and PABPC1 regulate translation, they exert antiviral effects through distinct mechanisms. We found that LARP1 interacts with the 5'UTR of EV-D68 RNA through its LAM domain, and this interaction is crucial for its antiviral function. LARP1 translation modulation is also influenced by the mTOR and CDK1 signaling pathways. Viral infection inhibits mTOR and CDK1 phosphorylation, which enhances LARP1's binding to viral RNA and inhibits viral translation. To counteract this inhibition, EV-D68 cleaves LARP1 through 3Cpro, thereby promoting efficient viral translation. We also investigated other enteroviruses, such as EV-A71 and CV-A16, which similarly target LARP1 and PABPC1, indicating a conserved mechanism across enteroviruses. Our findings offer new insights into how EV-D68 manipulates host translation and highlight the potential of targeting LARP1 and PABPC1 for antiviral interventions.

Humans

TRIM21 induces selective autophagy of viruses and bacteria.

TRIM21 is an exceptionally versatile ubiquitin ligase that can be directed by antibodies to target oligomeric protein scaffolds, viral capsids, and proteopathic aggregates for intracellular degradation. How the cell degrades these typically resistant substrates remains poorly understood. To address this, we used TRIM21 viral restriction to create a genome-wide phenotypic screen for antibody-dependent capsid degradation. We identify an antimicrobial selective macroautophagy pathway in mammalian cells, which we term "antibody-directed xenophagy" (ADX). We show that this mechanism restricts structurally diverse pathogens, including adenovirus and Salmonella. Using quantitative microscopy, we demonstrate that TRIM21 rapidly intercepts antibody-pathogen complexes, leading to ubiquitin ligase activation. Following this, selective autophagy adaptors are recruited, and viral cargoes are delivered to lysosomes. This process reduces Salmonella pathology and bacterial tissue invasion in mice. We propose that TRIM21 evolved through competition with pathogens to induce autophagy of diverse and complex substrates, potentially explaining its versatility for targeted protein degradation.

TRIM21 Protein

Recent progress in the study of autoantibodies to nuclear antigens.

Autoantibodies to nuclear antigens can now be classified according to their immunologic specificities. They include antibodies that react with DNA, deoxyribonucleoprotein, nuclear histones, and nuclear acidic protein antigens. It has been established that there are several antinuclear antibodies that react with nuclear acidic proteins, and these include antibodies to Sm antigen, nuclear ribonucleoprotein, and SS-A and SS-B antigens. It has also been established that certain systemic rheumatic diseases, such as systemic lupus erythematosus, Sjögren's syndrome, and scleroderma, are characterized by antibodies of some specificities and not of others. Thus, distinct profiles of antibodies to nuclear antigens may be present, and these may be used as diagnostic aids. Further characterization of these specific nuclear antigen-antibody systems may help in unraveling the etiology and pathogenetic mechanims of these diseases.

Animals

Autoantibodies and the spectrum of Sjögren's syndrome.

In studies reported recently, the sera of patients with Sjögren's syndrome were found to contain precipitating antibodies to nuclear antigens that can be identified by immunodiffusion analysis. These precipitating autoantibodies have been termed SS-A and SS-B antibodies. We show that identification of these autoantibodies helped in establishing the diagnosis of Sjögren's syndrome in 12 of 30 patients in whom the diagnosis had not been considered at the time of the physician's initial examination. The reasons for this were related to lack of spontaneous complaints of keratoconjunctivitis sicca and xerostomia and prominence of symptoms associated with arthritis, myalgia, pulmonary fibrosis, and cardiac disease. This study re-emphasizes the importance of multisystem disease in Sjögren's syndrome and shows that specific serologic assays for autoantibodies aided in diagnosis.

Aged

A study of specificities of antinuclear antibodies in juvenile rheumatoid arthritis.

The sera from 77 children with juvenile rheumatoid arthritis were studied for the presence of antinuclear antibodies, rheumatoid factor, and for antibodies to seven well-characterized nuclear antigens which occur in specific rheumatic diseases of adults. These included: Sm, RNP, DNA, RNA, RAP, SS-A, and SS-B. Forty-nine percent of the sera from patients with JRA contained ANA. The most common pattern was speckled. The frequency of all other positive tests was too low (13%) to make correlations with disease states. However, a small group of girls with polyarticular and late-onset disease had a high incidence of RF or RAP. These two antibodies were not associated with each other as they are in adult RA.

Antibodies, Antinuclear