of coronavirus disease (COVID-19) had been reported globally since December 2019 (1), severely burdening the healthcare system (2). The extremely fast transmission capability of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has aroused concern about its various transmission routes.The main transmission routes for SARS-CoV-2 are respiratory droplets and close contact (3). Knowing the extent of environmental contamination of SARS-CoV-2 in COVID-19 wards is critical for improving safety practices for medical staff and answering questions about SARS-CoV-2 transmission among the public. However, whether SARS-CoV-2 can be transmitted by aerosols remains controversial, and the exposure risk for close contacts has not been systematically evaluated. Researchers have detected SARS-CoV-2 on surfaces of objects in a symptomatic patient's room and toilet area (4). However, that study was performed in a small sample from regions with few confirmed cases, which might not reflect real conditions in outbreak regions where hospitals are operating at full capacity. In this study, we tested surface and air samples from an intensive care unit (ICU) and a general COVID-19 ward (GW) at Huoshenshan Hospital in Wuhan, China (Figure 1). The StudyFrom February 19 through March 2, 2020, we collected swab samples from potentially contaminated objects in the ICU and GW as described previously (5). The ICU housed 15 patients with severe disease and the GW housed 24 patients with milder disease. We also sampled indoor air and the air outlets to detect aerosol exposure. Air samples were collected by using a SASS 2300 Wetted Wall Cyclone Sampler (Research International, Inc., https://www.resrchintl.com) at 300 L/min for of 30 min. We used sterile premoistened swabs to sample the floors, computer mice, trash cans, sickbed handrails, patient masks, personal protective equipment, and air outlets. We tested air and surface samples for the open reading frame (ORF) 1ab and nucleoprotein (N) genes of SARS-CoV-2 by quantitative real-time PCR. (Appendix, https://wwwnc.cdc.gov/EID/ article/26/7/20-0885-App1.pdf).Almost all positive results were concentrated in the contaminated areas (ICU 54/57, 94.7%; GW 9/9, 100%); the rate of positivity was much higher for the ICU (54/124, 43.5%) than for the GW (9/114, 7.9%) (Tables 1, 2). The rate of positivity was

30Qing Mao (Phone +86 135 9418 0020;Abstract: An excessive immune response contributes to SARS-CoV, MERS-CoV and SARS-CoV-2 pathogenesis and lethality, but the mechanism remains unclear. In this study, the N proteins of SARS-CoV, MERS-CoV and SARS-CoV-2 were found to bind to MASP-2, the key serine protease in the lectin pathway of complement activation, resulting in aberrant complement activation and aggravated inflammatory lung injury. Either blocking the N protein:MASP-2 5 interaction or suppressing complement activation can significantly alleviate N protein-induced complement hyper-activation and lung injury in vitro and in vivo. Complement hyper-activation was also observed in COVID-19 patients, and a promising suppressive effect was observed when the deteriorating patients were treated with anti-C5a monoclonal antibody. Complement suppression may represent a common therapeutic approach for pneumonia induced by these 10 highly pathogenic coronaviruses. Short Title: SARS-CoV N over-activates complement by MASP-2One Sentence Summary: The lectin pathway of complement activation is a promising target for 15 the treatment of highly pathogenic coronavirus induced pneumonia.All rights reserved. No reuse allowed without permission.(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

SUMMARY Histone acetylation plays critical roles in chromatin remodeling, DNA repair, and epigenetic regulation of gene expression, but the underlying mechanisms are unclear. Proteasomes usually catalyze ATP- and polyubiquitin-dependent proteolysis. Here we show that the proteasomes containing the activator PA200 catalyze the polyubiquitin-independent degradation of histones. Most proteasomes in mammalian testes (“spermatoproteasomes”) contain a spermatid/sperm-specific α-subunit α4s/PSMA8 and/or the catalytic β-subunits of immunoproteasomes in addition to PA200. Deletion of PA200 in mice abolishes acetylation-dependent degradation of somatic core histones during DNA double-strand breaks, and delays core histone disappearance in elongated spermatids. Purified PA200 greatly promotes ATP-independent proteasomal degradation of the acetylated core histones, but not polyubiquitinated proteins. Furthermore, acetylation on histones is required for their binding to the bromodomain-like regions in PA200 and its yeast ortholog, Blm10. Thus, PA200/Blm10 specifically targets the core histones for acetylation-mediated degradation by proteasomes, providing mechanisms by which acetylation regulates histone degradation, DNA repair, and spermatogenesis.

Severe acute respiratory syndrome (SARS) is a respiratory disease, caused by a coronavirus (SARS-CoV), that is characterized by atypical pneumonia. The nucleocapsid protein (N protein) of SARS-CoV plays an important role in inhibition of type I interferon (IFN) production via an unknown mechanism. In this study, the SARS-CoV N protein was found to bind to the SPRY domain of the tripartite motif protein 25 (TRIM25) E3 ubiquitin ligase, thereby interfering with the association between TRIM25 and retinoic acid-inducible gene I (RIG-I) and inhibiting TRIM25-mediated RIG-I ubiquitination and activation. Type I IFN production induced by poly I·C or Sendai virus (SeV) was suppressed by the SARS-CoV N protein. SARS-CoV replication was increased by overexpression of the full-length N protein but not N amino acids 1 to 361, which could not interact with TRIM25. These findings provide an insightful interpretation of the SARS-CoV-mediated host innate immune suppression caused by the N protein.IMPORTANCE The SARS-CoV N protein is essential for the viral life cycle and plays a key role in the virus-host interaction. We demonstrated that the interaction between the C terminus of the N protein and the SPRY domain of TRIM25 inhibited TRIM25-mediated RIG-I ubiquitination, which resulted in the inhibition of IFN production. We also found that the Middle East respiratory syndrome CoV (MERS-CoV) N protein interacted with TRIM25 and inhibited RIG-I signaling. The outcomes of these findings indicate the function of the coronavirus N protein in modulating the host's initial innate immune response.

The MUC1 heterodimeric transmembrane protein is aberrantly overexpressed by most human carcinomas. The MUC1 C-terminal subunit (MUC1-C) is devoid of a classical nuclear localization signal and is targeted to the nucleus by an unknown mechanism. The present results demonstrate that MUC1-C associates with importin ␤ and not importin ␣. The results also show that, like importin ␤, MUC1-C binds to Nup62 (nucleoporin p62). MUC1-C binds directly to the Nup62 central domain and indirectly to the Nup62 C-terminal ␣-helical coiled-coil domain. We demonstrate that MUC1-C forms oligomers and that oligomerization is necessary for binding to Nup62. The MUC1-C cytoplasmic domain contains a CQC motif that when mutated to AQA abrogates oligomerization and binding to Nup62. Stable expression of MUC1 with the CQC 3 AQA mutations was associated with targeting to the cell membrane and cytosol and attenuation of nuclear localization. The results further show that expression of MUC1(CQC-AQA) attenuates MUC1-induced (i) transcriptional coactivation, (ii) anchorageindependent growth, and (iii) tumorigenicity. These findings indicate that the MUC1-C oncoprotein is imported to the nucleus by a pathway involving Nup62.

Mutations in Parkin, an E3 ubiquitin ligase that regulates protein turnover, represent one of the major causes of familial Parkinson disease, a neurodegenerative disorder characterized by the loss of dopaminergic neurons and impaired mitochondrial functions. The underlying mechanism by which pathogenic Parkin mutations induce mitochondrial abnormality is not fully understood. Here, we demonstrate that Parkin interacts with and subsequently ubiquitinates dynamin-related protein 1 (Drp1), for promoting its proteasome-dependent degradation. Pathogenic mutation or knockdown of Parkin inhibits the ubiquitination and degradation of Drp1, leading to an increased level of Drp1 for mitochondrial fragmentation. These results identify Drp1 as a novel substrate of Parkin and suggest a potential mechanism linking abnormal Parkin expression to mitochondrial dysfunction in the pathogenesis of Parkinson disease. Parkinson disease (PD)4 is one of the most common neurodegenerative diseases affecting over 2% populations over 65 years of age. It is classically characterized by the loss of dopaminergic neurons that project from the midbrain substantia nigra to the striatum (1, 2). Although the loss of dopaminergic neurons is responsible for the symptom of movement disorder in PD, it is now clear that other types of neurons throughout the brain are also affected in the disease (3, 4). The identification of genes linking to PD has greatly advanced our understanding of the molecular pathogenesis of the disease (5-8). Mutations in Parkin represent one of major causes for early onset of familial PD (9 -11). Parkin is an E3 ubiquitin ligase that contains two ring finger domains (12-15). A handful of substrates have been identified, including Parkin itself and CDCrel-1, synphilin-1, Pael-R, glycosylated ␣-synuclein, FBP1 (far upstream elementbinding protein 1), and the RNA-processing protein subunit p38/AIMP2 (16 -19). A putative mechanism by which mutations of Parkin cause PD would be abnormal accumulation and aggregation of the above substrates due to insufficient E3 ligase activity for ubiquitin-proteasome-dependent protein turnover (18,20,21). Surprisingly, only p38/AIMP2 and FBP1 were found to be accumulated in the brain samples of PD patients or in Parkin knock-out mice (16,17,19). Even though a number of the putative substrates have been identified, the causative link between these substrates and the PD pathogenesis remains not fully understood.Over the past few decades, accumulating evidence has suggested that mitochondrial dysfunction and the resulting oxidative damage are associated with PD. This is supported by a large number of reports demonstrating impaired mitochondrial functions in PD patients (22)(23)(24)(25)(26). Mitochondria undergo frequent fission, fusion, and redistribution throughout the cytoplasm in response to the energy needs (27,28). Either disruption of the fusion process or enhancement of the fission process renders the normal, tubular network of mitochondria to fragment into short rods or spheres (29). Abnormal...

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Defective centrosome duplication is implicated in microcephaly and primordial dwarfism as well as various ciliopathies and cancers. Yet, how the centrosome biogenesis is regulated remains poorly understood. Here we report that the X-linked deubiquitinase USP9X is physically associated with centriolar satellite protein CEP131, thereby stabilizing CEP131 through its deubiquitinase activity. We demonstrate that USP9X is an integral component of centrosome and is required for centrosome biogenesis. Loss-of-function of USP9X impairs centrosome duplication and gain-of-function of USP9X promotes centrosome amplification and chromosome instability. Significantly, USP9X is overexpressed in breast carcinomas, and its level of expression is correlated with that of CEP131 and higher histologic grades of breast cancer. Indeed, USP9X, through regulation of CEP131 abundance, promotes breast carcinogenesis. Our experiments identify USP9X as an important regulator of centrosome biogenesis and uncover a critical role for USP9X/CEP131 in breast carcinogenesis, supporting the pursuit of USP9X/CEP131 as potential targets for breast cancer intervention.