Dynamics of SLC25A51 reveal preference for oxidized NAD+ and substrate led transport.

SLC25A51 is a member of the mitochondrial carrier family (MCF) but lacks key residues that contribute to the mechanism of other nucleotide MCF transporters. Thus, how SLC25A51 transports NAD+ across the inner mitochondrial membrane remains unclear. To elucidate its mechanism, we use Molecular Dynamics simulations to reconstitute SLC25A51 homology models into lipid bilayers and to generate hypotheses to test. We observe spontaneous binding of cardiolipin phospholipids to three distinct sites on the exterior of SLC25A51's central pore and find that mutation of these sites impairs cardiolipin binding and transporter activity. We also observe that stable formation of the required matrix gate is controlled by a single salt bridge. We identify binding sites in SLC25A51 for NAD+ and show that its selectivity for NAD+ is guided by an electrostatic interaction between the charged nicotinamide ring in the ligand and a negatively charged patch in the pore. In turn, interaction of NAD+ with interior residue E132 guides the ligand to dynamically engage and weaken the salt bridge gate, representing a ligand-induced initiation of transport.

Flap endonuclease Rad27 cleaves the RNA of R-loop structures to suppress telomere recombination.

The long non-coding telomeric RNA transcript TERRA, in the form of an RNA-DNA duplex, regulates telomere recombination. In a screen for nucleases that affects telomere recombination, mutations in DNA2, EXO1, MRE11 and SAE2 cause severe delay in type II survivor formation, indicating that type II telomere recombination is mediated through a mechanism similar to repairing double-strand breaks. On the other hand, mutation in RAD27 results in early formation of type II recombination, suggesting that RAD27 acts as a negative regulator in telomere recombination. RAD27 encodes a flap endonuclease that plays a role in DNA metabolism, including replication, repair and recombination. We demonstrate that Rad27 suppresses the accumulation of the TERRA-associated R-loop and selectively cleaves TERRA of R-loop and double-flapped structures in vitro. Moreover, we show that Rad27 negatively regulates single-stranded C-rich telomeric DNA circles (C-circles) in telomerase-deficient cells, revealing a close correlation between R-loop and C-circles during telomere recombination. These results demonstrate that Rad27 participates in telomere recombination by cleaving TERRA in the context of an R-loop or flapped RNA-DNA duplex, providing mechanistic insight into how Rad27 maintains chromosome stability by restricting the accumulation of the R-loop structure within the genome.

Online Mixed-Bed Ion Exchange Chromatography for Native Top-Down Proteomics of Complex Mixtures.

Native top-down mass spectrometry (nTDMS) allows characterization of protein structure and noncovalent interactions with simultaneous sequence mapping and proteoform characterization. The majority of nTDMS studies utilize purified recombinant proteins, with significant challenges hindering application to endogenous systems. To perform native top-down proteomics (nTDP), where endogenous proteins from complex biological systems are analyzed by nTDMS, it is essential to separate proteins under nondenaturing conditions. However, it remains difficult to achieve high resolution with MS-compatible online chromatography while preserving protein tertiary structure and noncovalent interactions. Herein, we report the use of online mixed-bed ion exchange chromatography (IEC) to enable separation of endogenous proteins from complex mixtures under nondenaturing conditions, preserving noncovalent interactions for nTDP analysis. We have successfully detected large proteins (>146 kDa) and identified endogenous metal-binding and oligomeric protein complexes in human heart tissue lysate. The use of a mixed-bed stationary phase allowed retention and elution of proteins over a wide range of isoelectric points without altering the sample or mobile phase pH. Overall, our method provides a simple online IEC-MS platform that can effectively separate proteins from complex mixtures under nondenaturing conditions and preserve higher-order structure for nTDP applications.

MASH Native: a unified solution for native top-down proteomics data processing.

MOTIVATION: Native top-down proteomics (nTDP) integrates native mass spectrometry (nMS) with top-down proteomics (TDP) to provide comprehensive analysis of protein complexes together with proteoform identification and characterization. Despite significant advances in nMS and TDP software developments, a unified and user-friendly software package for analysis of nTDP data remains lacking. RESULTS: We have developed MASH Native to provide a unified solution for nTDP to process complex datasets with database searching capabilities in a user-friendly interface. MASH Native supports various data formats and incorporates multiple options for deconvolution, database searching, and spectral summing to provide a "one-stop shop" for characterizing both native protein complexes and proteoforms. AVAILABILITY AND IMPLEMENTATION: The MASH Native app, video tutorials, written tutorials, and additional documentation are freely available for download at https://labs.wisc.edu/gelab/MASH_Explorer/MASHSoftware.php. All data files shown in user tutorials are included with the MASH Native software in the download .zip file.

ZMYM2 restricts 53BP1 at DNA double-strand breaks to favor BRCA1 loading and homologous recombination.

An inability to repair DNA double-strand breaks (DSBs) threatens genome integrity and can contribute to human diseases, including cancer. Mammalian cells repair DSBs mainly through homologous recombination (HR) and nonhomologous end-joining (NHEJ). The choice between these pathways is regulated by the interplay between 53BP1 and BRCA1, whereby BRCA1 excludes 53BP1 to promote HR and 53BP1 limits BRCA1 to facilitate NHEJ. Here, we identify the zinc-finger proteins (ZnF), ZMYM2 and ZMYM3, as antagonizers of 53BP1 recruitment that facilitate HR protein recruitment and function at DNA breaks. Mechanistically, we show that ZMYM2 recruitment to DSBs and suppression of break-associated 53BP1 requires the SUMO E3 ligase PIAS4, as well as SUMO binding by ZMYM2. Cells deficient for ZMYM2/3 display genome instability, PARP inhibitor and ionizing radiation sensitivity and reduced HR repair. Importantly, depletion of 53BP1 in ZMYM2/3-deficient cells rescues BRCA1 recruitment to and HR repair of DSBs, suggesting that ZMYM2 and ZMYM3 primarily function to restrict 53BP1 engagement at breaks to favor BRCA1 loading that functions to channel breaks to HR repair. Identification of DNA repair functions for these poorly characterized ZnF proteins may shed light on their unknown contributions to human diseases, where they have been reported to be highly dysregulated, including in several cancers.

Sample Size-Comparable Spectral Library Enhances Data-Independent Acquisition-Based Proteome Coverage of Low-Input Cells.

Despite advancements of data-independent acquisition mass spectrometry (DIA-MS) to provide comprehensive and reproducible proteome profiling, its utility in very low-input samples is limited. Due to different proteome complexities and corresponding peptide ion abundances, the conventional LC-MS/MS acquisition and widely used large-scale DIA libraries may not be suitable for the micro-nanogram samples. In this study, we report a sample size-comparable library-based DIA approach to enhance the proteome coverage of low-input nanoscale samples (i.e., nanogram cells, ∼5-50 cells). By constructing sample size-comparable libraries, 2380 and 3586 protein groups were identified from as low as 0.75 (∼5 cells) and 1.5 ng (∼10 cells), respectively, highlighting one of the highest proteome coverage with good reproducibility (86%-99% in triplicate results). For the 0.75 ng sample (∼5 cells), significantly superior identification (2380 proteins) was achieved by small-size library-based DIA, compared to 1908, 1749, and 107 proteins identified from medium-size and large-size libraries and a lung cancer resource spectral library, respectively. A similar trend was observed using a different instrument and data analysis pipeline, indicating the generalized conclusion of the approach. Furthermore, the small-size library uniquely identified 518 (22%) proteins in the low-abundant region and spans over a 5-order dynamic range. Spectral similarity analysis revealed that the fragmentation ion pattern in the DIA-MS/MS spectra of the dataset and spectral library play crucial roles for mapping low abundant proteins. With these spectral libraries made freely available, the optimized library-based DIA strategy and DIA digital map will advance quantitative proteomics applications for mass-limited samples.

A Terpyridine Zinc Complex for Selective Detection of Lipid Pyrophosphates: A Model System for Monitoring Bacterial O- and N-Transglycosylations.

To develop an effective method for probing O- and N-glycosyltransfer reactions that are accompanied by the release of undecaprenyl pyrophosphate, solanesyl pyrophosphate (SPP) is used as a surrogate to bind a terpyridine zinc complex (Tpy-Zn), forming a fluorescent [Tpy-Zn]-SPP complex (Kass 106,000 M-1 in EtOH-CHCl3) with 5.8 µM LOD in HEPES buffer (10 mM, pH 7.4) containing 10 mM CaCl2 and 0.08% decyl PEG, which is similar to the bioassay conditions for lipid II polymerization.

Factors associated with hospitalization for community-acquired pneumonia in home health care patients in Taiwan.

BACKGROUND: Pneumonia is a leading cause of hospitalization and death worldwide. However, studies focusing on risk factors of community-acquired pneumonia (CAP) in the home health care (HHC) population remain scarce. AIMS: This study aimed to evaluate risk factors associated with hospitalization for CAP among HHC patients in Taiwan. METHODS: This retrospective cross-sectional study extracted data from patients' electronic medical records between 1 January 2017 and 31 December 2017. Multiple logistic regression analyses were performed to explore factors associated with hospitalization for CAP. RESULTS: In total, 598 patients (men/women: 236/362) were included. One hundred ninety-nine patients (33.28%) were hospitalized for pneumonia. Inpatients showed a higher proportion of the following: male sex, functional impairment, hypoalbuminemia, anemia, nasogastric tube use, excessive polypharmacy, stroke, dementia, heart failure, chronic respiratory disease, and chronic liver disease. Furthermore, nasogastric tube use (odds ratio [OR] 3.01, 95% confidence interval [CI] 1.88-4.82), anemia (OR 2.37, 95% CI 1.48-3.80), male sex (OR 2.14, 95% CI 1.43-3.20), chronic respiratory disease (OR 2.09, 95% CI 1.33-3.30), dementia (OR 1.94, 95% CI 1.27-2.97), heart failure (OR 1.69, 95% CI 1.11-2.56), and hypoalbuminemia (OR 1.57, 95% CI 1.03-2.40) significantly increased the risk of hospitalization for CAP. CONCLUSIONS: Our results revealed risk factors associated with hospitalization for CAP in HHC patients. In addition to chronic diseases, malnutrition is an important risk factor. Caregivers should make prompt assessments and take preventive measures for such patients.

A performance guide for major risk factors control in patients with atherosclerotic cardiovascular disease in Taiwan.

Atherosclerotic cardiovascular disease (ASCVD), including coronary artery disease, cerebrovascular disease, and peripheral artery disease, carries a high morbidity and mortality. Risk factor control is especially important for patients with ASCVD to reduce recurrent cardiovascular events. Clinical guidelines have been developed by the Taiwan Society of Cardiology, Taiwan Society of Lipids and Atherosclerosis, and Diabetes Association of Republic of China (Taiwan) to assist health care professionals in Taiwan about the control of hypertension, hypercholesterolemia and diabetes mellitus. This article is to highlight the recommendations about blood pressure, cholesterol, and sugar control for ASCVD. Some medications that are beneficial for ASCVD were also reviewed. We hope the clinical outcomes of ASCVD can be improved in Taiwan through the implementation of these recommendations.

High-Rate Hydrogen Generation by Direct Sunlight Irradiation with a Triruthenium Complex.

Herein we report a biomimetic triruthenium catalyst that, when under direct sunlight irradiation, facilitates high-rate H2 production from formic acid (FA) dehydrogenation. The system consists of 2 µmol of catalyst and 6 µmol of tri- o-tolylphosphine in 1 mL of dimethylformamide (DMF) and 4 mL of FA/triethylamine (TEA; 5:2). With 0.4 mM catalyst loaded, a high turnover frequency of 1.15 × 106 h-1 was detected when under direct sunlight irradiation. In an experiment with 0.2 mM catalyst loaded, more than 140 L of H2 (280 L of H2 + CO2) was produced, and a turnover number of approximately 2.78 × 106 was obtained within 5 h without decline in H2 generation activity, making it suitable for high-rate H2 production.

Skp2 targeting suppresses tumorigenesis by Arf-p53-independent cellular senescence.

Cellular senescence has been recently shown to have an important role in opposing tumour initiation and promotion. Senescence induced by oncogenes or by loss of tumour suppressor genes is thought to critically depend on induction of the p19(Arf)-p53 pathway. The Skp2 E3-ubiquitin ligase can act as a proto-oncogene and its aberrant overexpression is frequently observed in human cancers. Here we show that although Skp2 inactivation on its own does not induce cellular senescence, aberrant proto-oncogenic signals as well as inactivation of tumour suppressor genes do trigger a potent, tumour-suppressive senescence response in mice and cells devoid of Skp2. Notably, Skp2 inactivation and oncogenic-stress-driven senescence neither elicit activation of the p19(Arf)-p53 pathway nor DNA damage, but instead depend on Atf4, p27 and p21. We further demonstrate that genetic Skp2 inactivation evokes cellular senescence even in oncogenic conditions in which the p19(Arf)-p53 response is impaired, whereas a Skp2-SCF complex inhibitor can trigger cellular senescence in p53/Pten-deficient cells and tumour regression in preclinical studies. Our findings therefore provide proof-of-principle evidence that pharmacological inhibition of Skp2 may represent a general approach for cancer prevention and therapy.

A ruthenium-based biomimetic hydrogen cluster for efficient photocatalytic hydrogen generation from formic acid.

A ruthenium-based biomimetic hydrogen cluster, [Ru2 (CO)6 (µ-SCH2 CH2 CH2 S)] (1), has been synthesized and, in the presence of the P ligand tri(o-tolyl)phosphine, demonstrated efficient photocatalytic hydrogen generation from formic acid decomposition. Turnover frequencies (TOFs) of 5500 h(-1) and turnover numbers (TONs) over 24 700 were obtained with less than 50 ppm of the catalyst, thus representing the highest TOFs for ruthenium complexes as well as the best efficiency for photocatalytic hydrogen production from formic acid. Moreover, 1 showed high stability with no significant degradation of the photocatalyst observed after prolonged photoirradiation at 90 °C.

Optimism and proactive coping in relation to burnout among nurses.

AIM: The study investigated the three symptoms of burnout among hospital nurses and examined the buffering effects of optimism and proactive coping in relation to burnout. BACKGROUND: Nursing is a profession that can easily lead to burnout. Burnout has been one of the most investigated work outcomes in current research. Previous research has largely ignored the positive influence of individuals on job outcomes and has not tested a constructive framework that might facilitate interventions to prevent burnout. METHOD: A cross-sectional survey of 314 staff nurses in general hospitals in Taiwan. Participants completed a set of questionnaires with demographic information. FINDING: The findings suggested that higher levels of proactive coping behaviours and optimism were associated with lower levels of burnout. Optimism was found to have the strongest relationship with the decreased personal accomplishment of burnout. CONCLUSION: The findings of this study confirmed the importance of optimism and proactive coping in prevention of symptoms of burnout. IMPLICATIONS FOR NURSING MANAGEMENT: The results of this study provided important recommendations regarding stress management interventions for health-care managers, nurses, psychologists and human resource staff in the reduction of burnout to promote mental health in an organisation.

Extending the Coverage of Lys-C/Trypsin-Based Bottom-up Proteomics by Cysteine S-Aminoethylation.

To improve the coverage in bottom-up proteomics, S-aminoethylation of cysteine residues (AE-Cys) was carried out with 2-bromoethylamine, followed by cleavage with lysyl endopeptidase (Lys-C) or Lys-C/trypsin. A model study with bovine serum albumin showed that the C-terminal side of AE-Cys was successfully cleaved by Lys-C. The frequency of side reactions at amino acids other than Cys was less than that in the case of carbamidomethylation of Cys with iodoacetamide. Proteomic analysis of A549 cell extracts in the data-dependent acquisition mode after AE-Cys modification afforded a greater number of identified protein groups, especially membrane proteins. In addition, label-free quantification of proteins in mouse nonsmall cell lung cancer (NSCLC) tissue in the data-independent acquisition mode after AE-Cys modification showed improved NSCLC pathway coverage and greater reproducibility. Furthermore, the AE-Cys method could identify an epidermal growth factor receptor peptide containing the T790 M mutation site, a well-established lung-cancer-related mutation site that has evaded conventional bottom-up methods. Finally, AE-Cys was found to fully mimic Lys in terms of collision-induced dissociation fragmentation, ion mobility separation, and cleavage by Lys-C/trypsin, except for sulfoxide formation during sample preparation.

SLC25A51 decouples the mitochondrial NAD+/NADH ratio to control proliferation of AML cells.

SLC25A51 selectively imports oxidized NAD+ into the mitochondrial matrix and is required for sustaining cell respiration. We observed elevated expression of SLC25A51 that correlated with poorer outcomes in patients with acute myeloid leukemia (AML), and we sought to determine the role SLC25A51 may serve in this disease. We found that lowering SLC25A51 levels led to increased apoptosis and prolonged survival in orthotopic xenograft models. Metabolic flux analyses indicated that depletion of SLC25A51 shunted flux away from mitochondrial oxidative pathways, notably without increased glycolytic flux. Depletion of SLC25A51 combined with 5-azacytidine treatment limits expansion of AML cells in vivo. Together, the data indicate that AML cells upregulate SLC25A51 to decouple mitochondrial NAD+/NADH for a proliferative advantage by supporting oxidative reactions from a variety of fuels. Thus, SLC25A51 represents a critical regulator that can be exploited by cancer cells and may be a vulnerability for refractory AML.

Native Top-Down Mass Spectrometry for Characterizing Sarcomeric Proteins Directly from Cardiac Tissue Lysate.

Native top-down mass spectrometry (nTDMS) has emerged as a powerful structural biology tool that can localize post-translational modifications (PTMs), explore ligand-binding interactions, and elucidate the three-dimensional structure of proteins and protein complexes in the gas-phase. Fourier-transform ion cyclotron resonance (FTICR) MS offers distinct capabilities for nTDMS, owing to its ultrahigh resolving power, mass accuracy, and robust fragmentation techniques. Previous nTDMS studies using FTICR have mainly been applied to overexpressed recombinant proteins and protein complexes. Here, we report the first nTDMS study that directly analyzes human heart tissue lysate by direct infusion FTICR MS without prior chromatographic separation strategies. We have achieved comprehensive nTDMS characterization of cardiac contractile proteins that play critical roles in heart contraction and relaxation. Specifically, our results reveal structural insights into ventricular myosin light chain 2 (MLC-2v), ventricular myosin light chain 1 (MLC-1v), and alpha-tropomyosin (α-Tpm) in the sarcomere, the basic contractile unit of cardiac muscle. Furthermore, we verified the calcium (Ca2+) binding domain in MLC-2v. In summary, our nTDMS platform extends the application of FTICR MS to directly characterize the structure, PTMs, and metal-binding of endogenous proteins from heart tissue lysate without prior separation methods.

Andrographolide suppresses the malignancy of pancreatic cancer via alleviating DNMT3B-dependent repression of tumor suppressor gene ZNF382.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive cancer type that urgently requires effective therapeutic strategies. Andrographolide, a labdane diterpenoid compound abundant in Andrographis paniculata, has anticancer effects against various cancer types, but its anticancer activity and mechanism against PDAC remain largely uncharacterized. PURPOSE: This study explores novel drug target(s) and underlying molecular mechanism of andrographolide against PDAC. STUDY DESIGN AND METHODS: The malignant phenotypes of PDAC cells, PANC-1 and MIA PaCa-2 cells, were measured using MTT, clonogenic assays, and Transwell migration assays. A PDAC xenograft animal model was used to evaluate tumor growth in vivo. Western blot, immunofluorescence and immunohistochemistry were used for measuring protein expression. The TCGA database was analyzed to evaluate promoter methylation status, gene expression, and their relationship with patient survival rates. RT-qPCR was used for detecting mRNA expression. Reporter assays were used for detecting signal transduction pathways. Promoter DNA methylation was determined by sodium bisulfite treatment and methylation-specific PCR (MSP). The biological function and role of specific genes involved in drug effects were measured through gene overexpression. RESULTS: Andrographolide treatment suppressed the proliferation and migration of PDAC cells and impaired tumor growth in vivo. Furthermore, andrographolide induced the mRNA and protein expression of zinc finger protein 382 (ZNF382) in PDAC cells. Overexpression of ZNF382 inhibited malignant phenotypes and cancer-associated signaling pathways (AP-1, NF-κB and ß-catenin) and oncogenes (ZEB-1, STAT-3, STAT-5, and HIF-1α). Overexpression of ZNF382 delayed growth of PANC-1 cells in vivo. ZNF382 mRNA and protein expression was lower in tumor tissues than in adjacent normal tissues of pancreatic cancer patients. Analysis of the TCGA database found the ZNF382 promoter is hypermethylated in primary pancreatic tumors which correlates with its low expression. Furthermore, andrographolide inhibited the expression of DNA methyltransferase 3 beta (DNMT3B) and increased the demethylation of the ZNF382 promoter in PDAC cells. Overexpression of DNMT3B attenuated the andrographolide-suppressed proliferation and migration of PDAC cells. CONCLUSION: Our finding revealed that ZNF382 acts as a tumor suppressor gene in pancreatic cancer and andrographolide restores ZNF382 expression to suppress pancreatic cancer, providing a novel molecular target and a promising therapeutic approach for treating pancreatic cancer.

Surveillance of multidrug-resistant tuberculosis in Taiwan, 2008-2019.

BACKGROUND: Drug-resistant tuberculosis (DR-TB) is a major contributor to global cases of antimicrobial resistance and remains a public health challenge. To understand the extent and trend of DR-TB under an enhanced multidrug-resistant TB (MDR-TB) management program, we conducted a population-based retrospective study of 1511 Taiwanese MDR-TB cases reported from 2008 to 2019. METHODS: We obtained patient demographics and clinical and bacteriological information from the National TB Registry and the Infectious Disease Notification System. RESULTS: Of the 1511 MDR-TB patients, 941 were new cases, 485 were previously treated, and 85 had an unknown history of treatment. The male to female ratio was 2.75, and the median age of the patients was 57 years (IQR: 45-72). We observed a significant decline in MDR-TB cases, with annual percentage change (APC) of -4.17%. However, new and previously treated MDR-TB cases had APCs of -1.41% and -9.18%, respectively. The rates of MDR-TB resistance to ethambutol, streptomycin and pyrazinamide were 47.2%, 42.4% and 28.9%, respectively, whereas the rates of resistance to fluoroquinolones and second-line injectable drugs (SLIDs) were 4.1-7.1%, 9.0-14.1%; and the rate of extensively drug-resistant TB was 1.9%, respectively. Furthermore, we observed a decreasing trend of resistance to SLIDs (APCs -7.0% to -8.2%) in new cases and a significant decreasing trend of resistance to moxifloxacin (-24.6%) and levofloxacin (-23.3%) in previously treated cases. CONCLUSION: The decreasing trend of MDR-TB and resistance to second-line drugs suggested that our programmatic management of TB was effective and that the impact on TB control was profound.

Association between Serum Uric Acid Levels and Bone Mineral Density in Taiwanese Elderly Population.

Osteoporosis is a progressive metabolic bone disorder characterised by a decline in bone mineral density (BMD). Some previous studies have reported a controversial relationship between uric acid and osteoporosis. This cross-sectional study aimed to assess the association between serum uric acid levels and BMD in older adults from Taiwan. Data from participants aged ≥ 60 years were collected from 2008 to 2018. Furthermore, the participants were classified based on uric acid level quartiles. Regression models were used to assess the association between uric acid levels and bone health, including BMD values and risk of at least osteopenia. Crude and adjusted models of potential confounders, including age, sex and body mass index (BMI), were used. Compared with the first quartile of uric acid levels, the odds ratios for osteoporosis decreased in the higher uric acid level groups after adjustment for age, sex and BMI. The boxplot analysis showed that BMD values were higher in the groups with higher uric acid levels; moreover, the results of the multivariable linear regression model showed a consistent pattern. Notably, uric acid levels were positively correlated with BMD values. Higher uric acid levels in the elderly population might decrease the risk of at least osteopenia. As opposed to the anti-hyperuricemic policy for younger adults with a relatively lower risk of osteoporosis, BMD evaluation and urate-lowering therapy, goal adjustments should be considered for older adults with lower uric acid levels.

SARS-CoV-2 N protein mediates intercellular nucleic acid dispersion, a feature reduced in Omicron.

The coronavirus nucleocapsid (N) protein is known to bind to nucleic acids and facilitate viral genome encapsulation. Here we report that the N protein can mediate RNA or DNA entering neighboring cells through ACE2-independent, receptor (STEAP2)-mediated endocytosis, and achieve gene expression. The effect is more pronounced for the N protein of wild-type SARS-CoV-2 than that of the Omicron variant and other human coronaviruses. This effect is enhanced by RANTES (CCL5), a chemokine induced by N protein, and lactate, a metabolite produced in hypoxia, to cause more damage. These findings might explain the clinical observations in SARS-CoV-2-infected cases. Moreover, the N protein-mediated function can be inhibited by N protein-specific monoclonal antibodies or p38 mitogen-activated protein kinase inhibitors. Since the N-protein-mediated nucleic acid endocytosis involves a receptor commonly expressed in many types of cells, our findings suggest that N protein may have an additional role in SARS-CoV-2 pathogenesis.