Inhibition of Alpha Nascent Polypeptide Associated Complex Protein May Induce Proliferation, Differentiation and Enhance the Cytotoxic Activity of Human CD8+ T Cells

Identifying Methylation Signatures and Rules for COVID-19 With Machine Learning Methods

The occurrence of coronavirus disease 2019 (COVID-19) has become a serious challenge to global public health. Definitive and effective treatments for COVID-19 are still lacking, and targeted antiviral drugs are not available. In addition, viruses can regulate host innate immunity and antiviral processes through the epigenome to promote viral self-replication and disease progression. In this study, we first analyzed the methylation dataset of COVID-19 using the Monte Carlo feature selection method to obtain a feature list. This feature list was subjected to the incremental feature selection method combined with a decision tree algorithm to extract key biomarkers, build effective classification models and classification rules that can remarkably distinguish patients with or without COVID-19. EPSTI1, NACAP1, SHROOM3, C19ORF35, and MX1 as the essential features play important roles in the infection and immune response to novel coronavirus. The six significant rules extracted from the optimal classifier quantitatively explained the expression pattern of COVID-19. Therefore, these findings validated that our method can distinguish COVID-19 at the methylation level and provide guidance for the diagnosis and treatment of COVID-19.

Identification and characterization of nascent polypeptide-associated complex alpha from Chinese mitten crab (Eriocheir sinensis): A novel stress and immune response gene in crustaceans

Disease in aquatic animals is tightly linked to environmental challenges and their immune responses are greatly modified by their external environment. The chaperone protein nascent polypeptide-associated complex alpha (NACA) has been suggested to play important roles in the cellular response to stress and immune challenges, while the related biological functions remain largely unknown in invertebrates. In the present study we identified a NACA gene (termed EsNACA) from Chinese mitten crab Eriocheir sinensis and analyzed its expression changes in response to ambient (salinity and pH) stresses and immune challenges. The EsNACA protein is comprised of 209 amino acid residues with a conserved DNA binding domain, a C-Jun binding domain, a NAC domain and an ubiquitin-associated domain and shows the highest sequence identity (87%) with its counterpart in shrimp Penaeus monodon. EsNACA mRNA transcripts are presented in all tested normal tissues with predominant expression in hepatopancreas and lower expression in hemocytes. In addition, EsNACA expression was significantly altered in response to the ambient salinity (15‰ and 30‰ salinities) and pH (pH 6 and 8.5) stresses in gill, hepatopancreas, muscle, hemocytes and intestine tissues. Furthermore, EsNACA gene expression was substantially induced upon LPS and Poly(I:C) immune stimulations in E. sinensis hemocytes in vitro. Finally, EsNACA expression was up-regulated in E. sinensis hemocytes, gill, hepatopancreas, intestine and muscle tissues in response to Vibrio anguillarum challenges in vivo. Taken together, our findings for the first time show that EsNACA is an inducible gene involved in stress and immune response in crustaceans.

Crystal structures of NAC domains of human nascent polypeptide-associated complex (NAC) and its αNAC subunit

Nascent polypeptide associated complex (NAC) and its two isolated subunits, αNAC and βNAC, play important roles in nascent peptide targeting. We determined a 1.9 Å resolution crystal structure of the interaction core of NAC heterodimer and a 2.4 Å resolution crystal structure of αNAC NAC domain homodimer. These structures provide detailed information of NAC heterodimerization and αNAC homodimerization. We found that the NAC domains of αNAC and βNAC share very similar folding despite of their relative low identity of amino acid sequences. Furthermore, different electric charge distributions of the two subunits at the NAC interface provide an explanation to the observation that the heterodimer of NAC complex is more stable than the single subunit homodimer. In addition, we successfully built a βNAC NAC domain homodimer model based on homologous modeling, suggesting that NAC domain dimerization is a general property of the NAC family. These 3D structures allow further studies on structure-function relationship of NAC.