Summary Background The ongoing coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is a global public health concern due to relatively easy person-to-person transmission and the current lack of effective antiviral therapy. However, the exact molecular mechanisms of SARS-CoV-2 pathogenesis remain largely unknown. Methods Genome-wide screening was used to establish intraviral and viral-host interactomes. Quantitative proteomics was used to investigate the peripheral blood mononuclear cell (PBMC) proteome signature in COVID-19. Findings We elucidated 286 host proteins targeted by SARS-CoV-2 and >350 host proteins that are significantly perturbed in COVID-19-derived PBMCs. This signature in severe COVID-19 PBMCs reveals a significant upregulation of cellular proteins related to neutrophil activation and blood coagulation, as well as a downregulation of proteins mediating T cell receptor signaling. From the interactome, we further identified that non-structural protein 10 interacts with NF-κB-repressing factor (NKRF) to facilitate interleukin-8 (IL-8) induction, which potentially contributes to IL-8-mediated chemotaxis of neutrophils and the overexuberant host inflammatory response observed in COVID-19 patients. Conclusions Our study not only presents a systematic examination of SARS-CoV-2-induced perturbation of host targets and cellular networks but it also reveals insights into the mechanisms by which SARS-CoV-2 triggers cytokine storms, representing a powerful resource in the pursuit of therapeutic interventions. Funding National Key Research and Development Project of China, National Natural Science Foundation of China, National Science and Technology Major Project, Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning, Shanghai Science and Technology Commission, Shanghai Municipal Health Commission, Shanghai Municipal Key Clinical Specialty, Innovative Research Team of High-level Local Universities in Shanghai, Interdisciplinary Program of Shanghai Jiao Tong University, SII Challenge Fund for COVID-19 Research, Chinese Academy of Sciences (CAS) Large Research Infrastructure of Maintenance and Remolding Project, and Chinese Academy of Sciences Key Technology Talent Program.

Ferroptosis, an iron-dependent non-apoptotic cell death, is a highly regulated tumor suppressing process. However, functions and mechanisms of RNA binding proteins in regulation of evasion of ferroptosis during lung cancer progression are still largely unknown. Here we reported that the RNA binding protein RBMS1 participated in lung cancer development through mediating ferroptosis evasion. Through an shRNA-mediated systematic screen, we discovered that RBMS1 was a key ferroptosis regulator. Clinically, RBMS1 was elevated in lung cancer and its high expression was associated with reduced patient survival. Conversely, depletion of RBMS1 inhibited lung cancer progression both in vivo and in vitro. Mechanistically, RBMS1 interacted with the translation initiation factor eIF3d directly to bridge the 3¢-and 5¢-UTRs of SLC7A11. RBMS1 ablation inhibited the translation of SLC7A11, reduced SLC7A11-mediated cystine uptake and promotes ferroptosis. In a drug screen that targeted RBMS1, we further uncovered that nortriptyline hydrochloride decreased the level of RBMS1, thereby promoting ferroptosis.Importantly, RBMS1 depletion or inhibition by nortriptyline hydrochloride sensitized radioresistant lung cancer cells to radiotherapy. Our findings established RBMS1 as a translational regulator of ferroptosis and a prognostic factor with therapeutic potentials and clinical values.

The ongoing coronavirus disease pandemic caused by Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) is a global public health concern due to relatively easy person-to-person transmission and the current lack of effective antiviral therapy. However, the exact molecular mechanisms of SARS-CoV-2 pathogenesis remain largely unknown. We exploited an integrated proteomics approach to systematically investigate intra-viral and virus-host interactomes for the identification of unrealized SARS-CoV-2 host targets and participation of cellular proteins in the response to viral infection using peripheral blood mononuclear cells (PBMCs) isolated from COVID-19 patients. Using this approach, we elucidated 251 host proteins targeted by SARS-CoV-2 and more than 200 host proteins that are significantly perturbed in COVID-19 derived PBMCs. From the interactome, we further identified that non-structural protein nsp9 and nsp10 interact with NKRF, a NF-kB repressor, and may precipitate the strong IL-8/IL-6 mediated chemotaxis of neutrophils and overexuberant host inflammatory response observed in COVID-19 patients. Our integrative study not only presents a systematic examination of SARS-CoV-2-induced perturbation of host targets and cellular networks to reflect disease etiology, but also reveals insights into the mechanisms by which SARS-CoV-2 triggers cytokine storms and represents a powerful resource in the quest for therapeutic intervention.

N6-methyladenosine (m6A) is the most abundant ribonucleotide modification among eukaryotic messenger RNAs. The m6A “writer” consists of the catalytic subunit m6A-METTL complex (MAC) and the regulatory subunit m6A-METTL-associated complex (MACOM), the latter being essential for enzymatic activity. Here, we report the cryo-electron microscopy (cryo-EM) structures of MACOM at a 3.0-Å resolution, uncovering that WTAP and VIRMA form the core structure of MACOM and that ZC3H13 stretches the conformation by binding VIRMA. Furthermore, the 4.4-Å resolution cryo-EM map of the MACOM–MAC complex, combined with crosslinking mass spectrometry and GST pull-down analysis, elucidates a plausible model of the m6A writer complex, in which MACOM binds to MAC mainly through WTAP and METTL3 interactions. In combination with in vitro RNA substrate binding and m6A methyltransferase activity assays, our results illustrate the molecular basis of how MACOM assembles and interacts with MAC to form an active m6A writer complex.

The spread of the coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has become a global health crisis. The binding affinity of SARS-CoV-2 (in particular the receptor binding domain, RBD) to its receptor angiotensin converting enzyme 2 (ACE2) and the antibodies is of great importance in understanding the infectivity of COVID-19 and evaluating the candidate therapeutic for COVID-19. We propose a new method based on molecular mechanics/Poisson–Boltzmann surface area (MM/PBSA) to accurately calculate the free energy of SARS-CoV-2 RBD binding to ACE2 and antibodies. The calculated binding free energy of SARS-CoV-2 RBD to ACE2 is –13.3 kcal/mol, and that of SARS-CoV RBD to ACE2 is –11.4 kcal/mol, which agree well with the experimental results of –11.3 kcal/mol and –10.1 kcal/mol, respectively. Moreover, we take two recently reported antibodies as examples, and calculate the free energy of antibodies binding to SARS-CoV-2 RBD, which is also consistent with the experimental findings. Further, within the framework of the modified MM/PBSA, we determine the key residues and the main driving forces for the SARS-CoV-2 RBD/CB6 interaction by the computational alanine scanning method. The present study offers a computationally efficient and numerically reliable method to evaluate the free energy of SARS-CoV-2 binding to other proteins, which may stimulate the development of the therapeutics against the COVID-19 disease in real applications.

Background and Purpose Like chili peppers, gingers produce pungent stimuli by a group of vanilloid compounds that activate the nociceptive transient receptor potential vanilloid 1 (TRPV1) ion channel. How these compounds interact with TRPV1 remains unclear. Experimental Approach We used computational structural modelling, functional tests (electrophysiology and calcium imaging), and mutagenesis to investigate the structural mechanisms underlying ligand–channel interactions. Key Results The potency of three principal pungent compounds from ginger —shogaol, gingerol, and zingerone—depends on the same two residues in the TRPV1 channel that form a hydrogen bond with the chili pepper pungent compound, capsaicin. Computational modelling revealed binding poses of these ginger compounds similar to those of capsaicin, including a “head‐down tail‐up” orientation, two specific hydrogen bonds, and important contributions of van der Waals interactions by the aliphatic tail. Our study also identified a novel horizontal binding pose of zingerone that allows it to directly interact with the channel pore when bound inside the ligand‐binding pocket. These observations offer a molecular level explanation for how unique structures in the ginger compounds affect their channel activation potency. Conclusions and Implications Mechanistic insights into the interactions of ginger compounds and the TRPV1 cation channel should help guide drug discovery efforts to modulate nociception.

The age-dependent decline in remyelination potential of the central nervous system during ageing is associated with a declined differentiation capacity of oligodendrocyte progenitor cells (OPCs). The molecular players that can enhance OPC differentiation or rejuvenate OPCs are unclear. Here we show that, in mouse OPCs, nuclear entry of SIRT2 is impaired and NAD+ levels are reduced during ageing. When we supplement β-nicotinamide mononucleotide (β-NMN), an NAD+ precursor, nuclear entry of SIRT2 in OPCs, OPC differentiation, and remyelination were rescued in aged animals. We show that the effects on myelination are mediated via the NAD+-SIRT2-H3K18Ac-ID4 axis, and SIRT2 is required for rejuvenating OPCs. Our results show that SIRT2 and NAD+ levels rescue the aged OPC differentiation potential to levels comparable to young age, providing potential targets to enhance remyelination during ageing.

Different starter unit and complex tailoring steps for type II polyketide synthase in trioxacarcin biosynthesis.