Identification of hypoxia-related gene signatures based on multi-omics analysis in lung adenocarcinoma.

Lung adenocarcinoma (LUAD) is the most common type of lung cancer and one of the malignancies with the highest incidence rate and mortality worldwide. Hypoxia is a typical feature of tumour microenvironment (TME), which affects the progression of LUAD from multiple molecular levels. However, the underlying molecular mechanisms behind LUAD hypoxia are not fully understood. In this study, we estimated the level of hypoxia by calculating a score based on 15 hypoxia genes. The hypoxia scores were relatively high in LUAD patients with poor prognosis and were bound up with tumour node metastasis (TNM) stage, tumour size, lymph node, age and gender. By comparison of high hypoxia score group and low hypoxia score group, 1820 differentially expressed genes were identified, among which up-regulated genes were mainly about cell division and proliferation while down-regulated genes were primarily involved in cilium-related biological processes. Besides, LUAD patients with high hypoxia scores had higher frequencies of gene mutations, among which TP53, TTN and MUC16 had the highest mutation rates. As for DNA methylation, 1015 differentially methylated probes-related genes were found and may play potential roles in tumour-related neurobiological processes and cell signal transduction. Finally, a prognostic model with 25 multi-omics features was constructed and showed good predictive performance. The area under curve (AUC) values of 1-, 3- and 5-year survival reached 0.863, 0.826 and 0.846, respectively. Above all, our findings are helpful in understanding the impact and molecular mechanisms of hypoxia in LUAD.

ncFANs v2.0: an integrative platform for functional annotation of non-coding RNAs.

Increasing evidence proves the essential regulatory roles of non-coding RNAs (ncRNAs) in biological processes. However, characterizing the specific functions of ncRNAs remains a challenging task, owing to the intensive consumption of the experimental approaches. Here, we present an online platform ncFANs v2.0 that is a significantly enhanced version of our previous ncFANs to provide multiple computational methods for ncRNA functional annotation. Specifically, ncFANs v2.0 was updated to embed three functional modules, including ncFANs-NET, ncFANs-eLnc and ncFANs-CHIP. ncFANs-NET is a new module designed for data-free functional annotation based on four kinds of pre-built networks, including the co-expression network, co-methylation network, long non-coding RNA (lncRNA)-centric regulatory network and random forest-based network. ncFANs-eLnc enables the one-stop identification of enhancer-derived lncRNAs from the de novo assembled transcriptome based on the user-defined or our pre-annotated enhancers. Moreover, ncFANs-CHIP inherits the original functions for microarray data-based functional annotation and supports more chip types. We believe that our ncFANs v2.0 carries sufficient convenience and practicability for biological researchers and facilitates unraveling the regulatory mechanisms of ncRNAs. The ncFANs v2.0 server is freely available at http://bioinfo.org/ncfans or http://ncfans.gene.ac.

Prognostic signatures and potential pathogenesis of eRNAs-related genes in colon adenocarcinoma.

Enhancer RNAs (eRNAs) are a subclass of long noncoding RNAs (lncRNAs) that have a wide effect in human tumors. However, the systematic analysis of potential functions of eRNAs-related genes (eRGs) in colon cancer (CC) remains unexplored. In this study, a total of 8231 eRGs including 6236 protein-coding genes and 1995 lncRNAs were identified in CC based on the multiple resources. These eRGs showed higher expression level and stability compared to other genes. What's more, the functions of these eRGs were closely related to cancer. Then a prognostic prediction model with 12 eRGs signatures were obtained for colon adenocarcinoma (COAD) patients. ROC curves showed the AUCs were 0.81, 0.77, and 0.78 for 1-, 3-, and 5-year survival prediction, respectively. And the prognostic model also manifested good performance in the validation datasets. Besides, the expression levels of two prognostic signatures, TMEM220 and LRRN2, were verified to be significantly lower in CC tissues than in adjacent noncancerous tissues (p < .05). Finally, the distinct molecular features were characterized between the high- and low-risk group through multiomics analysis including DNA mutation and methylation. Our results show eRGs signatures based prognostic model has high accuracy and may provide innovative biomarkers in COAD.

Ambiphilic Behavior of Ge(II)-Pseudohalides in Inter- and Intramolecular Frustrated Lewis Pair Alkyne Addition Reactions.

The reaction of the germylene chloride (NacNac)GeCl (1, NacNac = CH{(CMe)(2,6-iPr2C6H3N)}2), phenylacetylene, and B(C6F5)3 gives the intermolecular frustrated Lewis pair (FLP) addition product 2. In this case, the Ge(II) center acts as a base. In contrast, the analogous reaction of germylene thiocyanate 3 reacts independently with B(C6F5)3 to give the germylene cation salt [(NacNac)Ge][SCNB(C6F5)3] 4. Subsequent in the presence of alkynes, the Ge(II) cation and γ-C of 4 act as a Lewis acidic and basic center, respectively, to affect the addition of alkynes, affording products [(NacNac)Ge(RCCR')][SCNB(C6F5)3] 5 and 6. Compound 4 also reacts with Me3SiCN to give the cyanide-bridged Ge/B species 7, which also reacts with phenylacetylene to give CN abstraction and intramolecular addition yielding the salt [(NacNac)Ge(PhCCH)][NCB(C6F5)3] 8. Despite the similarity of 1 and 3, DFT calculations show that the highest occupied molecular orbital (HOMO) of 1 is mainly located at the more sterically hindered germylene center, while the HOMO of 3 is located on the less sterically hindered NCS group, prompting markedly different FLP addition products.

Oncogenic pseudogene DUXAP10 knockdown suppresses proliferation and invasion and induces apoptosis of papillary thyroid carcinoma cells by inhibition of Akt/mTOR pathway.

Pseudogenes, another novel group of non-coding segments without protein-coding capacity, are closely associated with tumourigenesis and cancer progression. Double homeoboxA pseudogene 10 (DUXAP10) is reported to be robustly expressed in thyroid carcinoma. However, the functional role and underlying mechanism of DUXAP10 in papillary thyroid carcinoma (PTC) progression remain undefined. DUXAP10 expression in PTC cells was detected by qRT-PCR. Cell proliferation and invasion were determined using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) and Transwell invasion assay, respectively. Apoptosis was evaluated using flow cytometry. Protein expression of matrix metalloproteinase (MMP)-2, MMP-9, protein kinase B (Akt), phosphorylated Akt, mammalian target of rapamycin (mTOR), and phosphorylated mTOR was examined by western blot. Results showed that DUXAP10 was significantly overexpressed in PTC cells compared with normal thyroid follicular epithelium cells. DUXAP10 silencing suppressed cell proliferation and invasive ability, reduced the expression of MMP-2 and MMP-9, and increased apoptotic rate and caspase-3 activity in PTC cells. Additionally, the Akt/mTOR pathway was inhibited following DUXAP10 knockdown in PTC cells. Activation of the Akt/mTOR pathway by 740Y-P and MHY1485 attenuated DUXAP10 knockdown-induced proliferation reduction, invasion suppression and apoptosis in PTC cells. In conclusion, DUXAP10 knockdown suppressed proliferation and invasion and induced apoptosis in PTC cells at least partially by inhibition of the Akt/mTOR pathway.

Enhanced inflammatory damage by microRNA-136 targeting Klotho expression in HK-2 cells by modulating JAK/STAT pathway.

MiR-136 acts as a tumor suppressor by promoting cell apoptosis and downregulating Bcl-2 in glioma cells. Hence, an attempt has been made to evaluate the role of miR-136 in regulation of inflammatory damage in HK-2 cells. HK-2 cells were cultured and assessed for viability. The cells were then transfected with miR-136 mimic, si- miR-136, si-Klotho, and NC. Dual luciferase test was performed to confirm the target of miR-136 which was assumed to be Klotho. Cell viability, apoptosis, expressions of inflammatory cytokines like TNF-α, IL-1ß, IL-6 and IL-8 were assessed in HK-2 cells with overexpressing miR-136 or with knocked down miR-136 activities, following exposure to LPS. LPS induced inflammatory damage decreased cell viability, induced cell apoptosis, and increased the expression of different inflammatory cytokines. It was found that LPS decreased the expression of miR-136. Over-expression of miR-136 inhibited cell viability, enhanced apoptosis, and increased expression of inflammatory cytokines while knockdown of miR-136 showed opposite results with p-values < 0.05. MiR-136 negatively regulated the expression of Klotho with p-value < 0.05. Over-expression of miR-136 inhibited the expression of Klotho and activated JAK/STAT and mTOR signaling pathways and vice versa. Hence, it can be concluded that miR-136 enhances inflammatory damage probably by targeting klotho as has been observed in luciferase assay by inactivation of JAK/STAT and mTOR signaling pathways.

HMGA2 alleviates ferroptosis by promoting GPX4 expression in pancreatic cancer cells.

Pancreatic cancer is one of the most malignant tumor types and is characterized by high metastasis ability and a low survival rate. As a chromatin-binding protein, HMGA2 is widely overexpressed and considered an oncogene with various undefined regulatory mechanisms. Herein, we demonstrated that HMGA2 is highly expressed in pancreatic cancer tissues, mainly distributed in epithelial cells, and represents a subtype of high epithelial-mesenchymal transition. Deletion of HMGA2 inhibits tumor malignancy through cell proliferation, metastasis, and xenograft tumor growth in vivo. Moreover, HMGA2 enhanced the cellular redox status by inhibiting reactive oxygen species and promoting glutathione production. Importantly, ferroptotic cell death was significantly ameliorated in cells overexpressing HMGA2. Conversely, HMGA2 deletion exacerbated ferroptosis. Mechanistically, HMGA2 activated GPX4 expression through transcriptional and translational regulation. HMGA2 binds and promotes cis-element modification in the promoter region of the GPX4 gene by enhancing enhancer activity through increased H3K4 methylation and H3K27 acetylation. Furthermore, HMGA2 stimulated GPX4 protein synthesis via the mTORC1-4EBP1 and -S6K signaling axes. The overexpression of HMGA2 alleviated the decrease in GPX4 protein levels resulting from the pharmacologic inhibition of mTORC1. Conversely, compared with the control, HMGA2 deletion more strongly reduced the phosphorylation of 4EBP1 and S6K. A strong positive correlation between HMGA2 and GPX4 expression was confirmed using immunohistochemical staining. We also demonstrated that HMGA2 mitigated the sensitivity of cancer cells to combination treatment with a ferroptosis inducer and mTORC1 inhibition or gemcitabine. In summary, our results revealed a regulatory mechanism by which HMGA2 coordinates GPX4 expression and underscores the potential value of targeting HMGA2 in cancer treatment.

Stannyl phosphaketene as a synthon for phosphorus analogues of ß-lactams.

The reaction of the stannyl phosphaketene (Nacnac)SnPCO 1 (Nacnac = CH{(CMe)(2,6-iPr2C6H3N)}2) with B(C6F5)3 produced the 1,4-addition product of (Nacnac)SnPCO(B(C6F5)3). However, the corresponding reactions in the presence of dimethyl maleate, diisopropyl fumarate or diethyl-but-2-ynedioate gave [2+2] addition yielding four-membered phosphacycles, ((Nacnac)Sn(MeO2C))CHPC(OB(C6F5)3)CH(CO2Me), [(C6F5)3B)PC(OSn)C(CO2Me)CH(CO2Me)]2, (Nacnac)Sn(iPrO2C)CC(OAl(C6F5)3)P[CH(CO2iPr)CH2(CO2iPr)]CH(CO2iPr), and (Nacnac)SnP (EtO2CCC(CO2Et))CO(B(C6F5)3), respectively. In contrast, the corresponding reaction of phenylacetylene gave the FLP-addition product (Nacnac)SnOC(P)C(Ph)CH(B(C6F5)3). Collectively, this reactivity demonstrates that the stannyl phosphaketene 1 can act as a synthon for P-analogues of ß-lactam derivatives.

Neddylation inhibitor MLN4924 sensitizes head and neck squamous carcinoma cells to (S)-10-hydroxycamptothecin.

Head and neck squamous carcinoma (HNSCC) is the seventh most common cancer worldwide. Targeted therapeutic drugs for HNSCC are still being explored. Among them, (S)-10-hydroxycamptothecin (10-HCPT), a specific inhibitor of TOP1, functions by DNA double-strand breaks that can inhibit DNA replication and trigger apoptotic cell death subsequently. Previous studies have reported that MLN4924 exerts potent anti-tumor effects by inhibiting cullin-RING ligases and causing substrate accumulation in a variety of cancers. Here, we show that MLN4924 effectively causes dose-dependent accumulation of topoisomerase I (TOP1) and blocks TOP1 ubiquitination. Importantly, neddylation inhibition with MLN4924 acts synergistically with 10-HCPT to suppress cell growth, migration and apoptosis in HNSCC cells. Mechanistically, transcriptome sequencing shows that the cytotoxic effects of the combination of MLN4924 and 10-HCPT may involve activation of the NFKB1 pathway. Taken together, our results suggest that combined treatment with MLN4924 and 10-HCPT may be an effective strategy in HNSCC.

Correction: Stannyl phosphaketene as a synthon for phosphorus analogues of ß-lactams.

Correction for 'Stannyl phosphaketene as a synthon for phosphorus analogues of ß-lactams' by Yong-an Luo et al., Chem. Commun., 2023, https://doi.org/10.1039/d3cc03117a.

Single-cell discovery of the scene and potential immunotherapeutic target in hypopharyngeal tumor environment.

Hypopharyngeal carcinoma is a cancer with the worst prognosis. We constructed the first single-cell transcriptome map for hypopharyngeal carcinoma and explored its underlying mechanisms. We systematically studied single-cell transcriptome data of 17,599 cells from hypopharyngeal carcinoma and paracancerous tissues. We identified categories of cells by dimensionality reduction and performed further subgroup analysis. Focusing on the potential mechanism in the cellular communication of hypopharyngeal carcinoma, we predicted ligand-receptor interactions and verified them via immunohistochemical and cellular experiments. In total, seven cell types were identified, including epithelial and myeloid cells. Subsequently, subgroup analysis showed significant tumor heterogeneity. Based on the pathological type of squamous cell carcinoma, we focused on intercellular communication between epithelial cells and various cells. We predicted the crosstalk and inferred the regulatory effect of cellular active ligands on the surface receptor of epithelial cells. From the top potential pairs, we focused on the BMPR2 receptor for further research, as it showed significantly higher expression in epithelial cancer tissue than in adjacent tissue. Further bioinformatics analysis, immunohistochemical staining, and cell experiments also confirmed its cancer-promoting effects. Overall, the single-cell perspective revealed complex crosstalk in hypopharyngeal cancer, in which BMPR2 promotes its proliferation and migration, providing a rationale for further study and treatment of this carcinoma.

Macrophage-mediated trogocytosis contributes to destroying human schistosomes in a non-susceptible rodent host, Microtus fortis.

Schistosoma parasites, causing schistosomiasis, exhibit typical host specificity in host preference. Many mammals, including humans, are susceptible to infection, while the widely distributed rodent, Microtus fortis, exhibits natural anti-schistosome characteristics. The mechanisms of host susceptibility remain poorly understood. Comparison of schistosome infection in M. fortis with the infection in laboratory mice (highly sensitive to infection) offers a good model system to investigate these mechanisms and to gain an insight into host specificity. In this study, we showed that large numbers of leukocytes attach to the surface of human schistosomes in M. fortis but not in mice. Single-cell RNA-sequencing analyses revealed that macrophages might be involved in the cell adhesion, and we further demonstrated that M. fortis macrophages could be mediated to attach and kill schistosomula with dependence on Complement component 3 (C3) and Complement receptor 3 (CR3). Importantly, we provided direct evidence that M. fortis macrophages could destroy schistosomula by trogocytosis, a previously undescribed mode for killing helminths. This process was regulated by Ca2+/NFAT signaling. These findings not only elucidate a novel anti-schistosome mechanism in M. fortis but also provide a better understanding of host parasite interactions, host specificity and the potential generation of novel strategies for schistosomiasis control.

Synthesis of polyethylene containing allene groups: a simple and efficient route to functional polyethylene.

Allene groups are first employed as the reactive moiety in the simple and efficient synthesis of well-defined functional polyethylene. By copolymerization of ethylene with allene group substituted norbornene, the allene group is successfully introduced into the polyethylene with a high content. The retained allene groups are demonstrated to be highly reactive in following photoinduced functionalized reactions and can be efficiently converted into the functional groups without the multi-step, time consuming processes that have generally been required in previous reports, providing the side group-functionalized polyethylene with a wide range of functional group content.

Single-cell transcriptomic landscapes of a rare human laryngeal chondrosarcoma.

PROPOSE: Laryngeal chondrosarcoma is a rare non-epithelial malignant tumor. At present, the cell type composition and molecular mechanism of laryngeal chondrosarcoma have not been systematically studied. METHODS: This study focused on the histopathological and imaging features of a rare primary laryngeal chondrosarcoma in a 74-year-old male. The tumor and its paracancerous cartilage tissue were single-cell sequenced and analyzed and a total of 5455 single cells were obtained. Immunohistochemical levels were also verified. RESULTS: In total five cell types were identified, including chondrocytes, myeloid cells, fibroblasts, lymphocytes, and endothelial cells. We carried out further subgroup analysis, focusing on the classification and differentiation of chondrocytes, functional enrichment analysis, and cellular communication analysis of all cell types, and explored the tumor microenvironment (TME) of laryngeal chondrosarcoma. Immunohistochemistry revealed the SLAMF9 gene was specifically expressed in non-immune cells of chondrosarcoma, but was barely expressed in the normal cartilage tissues adjacent to chondrosarcomas. CONCLUSION: This single-cell sequencing approach provides clues for deciphering the potential mechanisms of tumor heterogeneity and TME composition in laryngeal chondrosarcoma, and represents an important step towards the treatment of laryngeal chondrosarcoma.

CT-guided placement of microcoil end in the pleural cavity for video-assisted thoracic surgical resection of ground-glass opacity: a retrospective study.

BACKGROUND: The aim of the study was to investigate and summarize the effectiveness and safety of CT-guided microcoil localization before video-assisted thoracic surgery (VATS) for the removal of ground-glass opacity (GGO). METHODS: A total of 147 patients with GGO who were treated at our hospital between January 2019 and February 2021 were retrospectively analyzed. They were divided into two groups according to the final position at the end of the microcoil: intracavity (n = 78) and extracavity (n = 69), which were compared based on puncture complications and influence of the coil end position on VATS. RESULTS: The proportions of supine and prone positions in the intracavity group were significantly higher than those in the extracavity group (82.1% vs. 66.7%, P < 0.05). The incidence of intrapulmonary hemorrhage, chest pain, and coil displacement in the intracavity group was significantly lower than that in the extracavity group (28.2% vs. 46.4%, 19.2% vs. 39.1%, 1.3% vs. 11.6%, P < 0.05, respectively); however, the incidence of pneumothorax was not significantly different (P > 0.05). The time of VATS and the rate of conversion to thoracotomy in the intracavity group were significantly lower than those in the extracavity group (103.4 ± 21.0 min vs. 112.2 ± 17.3 min, 0% vs. 5.8%, P < 0.05, respectively). CONCLUSION: CT-guided placement of the microcoil is a practical, simple, and convenient localization method before VATS, with a high success rate and few complications. Furthermore, it is a better alternative method to place the end of the coil in the pleural cavity because of the lower complication rate, shorter VATS time, and lower rate of thoracotomy conversion.

Comparative Study on Nosocomial Biliary Tract Infection Rate Between Biliary Stent Loaded with Radioactive 125 I Seeds and Conventional Biliary Stent in the Treatment of Distal Malignant Biliary Obstruction.

BACKGROUND: The purpose of this prospective randomized study was to compare the nosocomial biliary tract infection rate of biliary stent implantation with a biliary stent loaded with radioactive 125 I seeds (radioactive biliary stent, RBS) and conventional biliary stent (CBS); additionally, to preliminary discuss the causes of postoperative cholangitis. Moreover, the results will provide clinical evidence for the prevention of postoperative biliary tract infection. MATERIALS AND METHODS: We prospectively analyzed the nosocomial infection rate of the distal malignant biliary obstruction (MBO) treatment by stent implantation with RBS and CBS. All MBO patients who initially visited our tertiary hospital between July 2015 and December 2019 (n= 196) were evaluated, enrolled, and randomly divided into 2 groups, RBS (n=97) and CBS (n=99) group. χ 2 test was used to evaluate the categorical data, and t test was used to evaluate the numerical data. RESULTS: Our analysis of the study showed the incidence of postoperative infections of a biliary tract of the RBS group (23.7%) was significantly higher than the CBS group (11.1%). The difference was statistically significant (χ 2 =5.425, P =0.020). Our study also showed the most common pathogenic bacteria after surgery was Escherichia coli (26.5%). CONCLUSION: Treatment for distal MBO with biliary stent loaded with radioactive 125 I seeds had a higher nosocomial infection rate, and the most common pathogenic bacteria was E coli. , Supplemental Digital Content 1, http://links.lww.com/sle/A350.

The study of immune checkpoint inhibitors in chronic hepatitis B virus infection.

Chronic hepatitis B (CHB) is a contagious disease caused by the hepatitis B virus, which can damage the liver via cirrhosis or cancer. Existing CHB treatments are not completely effective; immune checkpoint inhibitors show potential hope for treating CHB, but their safety and efficacy need to be further validated. In this review, we introduce the mechanisms of CHB virus infection, the expression of immune checkpoints during CHB, and the treatments that are currently available. Finally, we discuss the possibilities for using immune checkpoint inhibitors to treat CHB.

Retrospective analysis of T-lymphocyte subsets and cytokines in malignant obstructive jaundice before and after external and internal biliary drainage.

OBJECTIVE: To study changes in T lymphocyte subsets, cytokines, and liver enzymes in patients with malignant obstructive jaundice (MOJ) before and after external biliary drainage (percutaneous transhepatic cholangiography drainage, PTCD) and internal biliary drainage (percutaneous transhepatic insertion of biliary stents, PTIBS). METHODS: MOJ patients undergoing PTCD (n = 44) and PTIBS (n = 38) at our hospital were enrolled in the study from January 2017 until December 2019. Peripheral blood total bilirubin (TBIL), direct bilirubin (DBIL), aspartate aminotransferase (AST), alanine aminotransferase (ALT), CD3+%, CD4+%, CD4+/CD8+ ratio, interleukin (IL)-2, IL-6, and tumor necrosis factor (TNF)-α were measured before and 1 week after biliary drainage. RESULTS: There was no significant difference in any parameter between the two groups before biliary drainage. TBIL, DBIL, AST and ALT following PTCD were significantly lower than before PTCD. By contrast, CD3+%, CD4+%, CD4+/CD8+ ratio, IL-2, IL-6 and TNF-α showed no significant difference before and 1 week after PTCD. TBIL, DBIL, AST, ALT, IL-6 and TNF-α were significantly lower following PTIBS than before PTIBS. CD3+%, CD4+%, CD4+/CD8+ ratio and IL-2 were significantly higher following PTIBS than before PTIBS. CONCLUSION: Both PTCD and PTIBS were effective for treatment of MOJ, but PTIBS was more beneficial for recovery of immune function.

Bioinformatics analysis reveals the competing endogenous RNA (ceRNA) coexpression network in the tumor microenvironment and prognostic biomarkers in soft tissue sarcomas.

Soft tissue sarcomas (STSs) are rare, heterogeneous mesenchymal neoplasias. Understanding the tumor microenvironment (TME) and identifying potential biomarkers for prognosis associated with the TME of STS might provide effective clues for immune therapy. We evaluated the immune scores and stromal scores of STS patients by using the RNA sequencing dataset from The Cancer Genome Atlas (TCGA) database and the ESTIMATE algorithm. Then, the differentially expressed mRNAs (DEGs), miRNAs (DEMs) and lncRNAs (DELs) were identified after comparing the high- and low-score groups. Next, we established a competing endogenous RNA (ceRNA) network and explored the prognostic values of biomarkers involved in the network with the help of bioinformatics analysis. High immune score was significantly associated with favorable overall survival in STS patients. A total of 328 DEGs, 18 DEMs and 67 DELs commonly regulated in the immune and stromal score groups were obtained. A ceRNA network and protein-protein interaction (PPI) network identified some hub nodes with considerable importance in the network. Kaplan-Meier survival analysis demonstrated that nine mRNAs, two miRNAs and three lncRNAs were closely associated with overall survival of STS patients. Gene set enrichment analysis (GSEA) suggested that these three lncRNAs were mainly involved in immune response-associated pathways in STS patients. Finally, the expression levels of five mRNAs (APOL1, EFEMP1, LYZ, RARRES1 and TNFAIP2) were verified, which were consistent with the results of the TCGA cohort. The results of our study confirmed the prognostic value of immune scores for STS patients. We also identified several TME-related biomarkers that might contribute to prognostic prediction and immune therapy.

Role of key amino acids in the transmembrane domain of the Newcastle disease virus fusion protein.

Newcastle disease (ND), caused by the Newcastle disease virus (NDV), is transmitted by poultry with severe infectivity and a high fatality rate. The fusion (F) protein on the NDV envelope facilitates the merger of the viral and host cell membranes with the help of the homologous hemagglutinin-neuraminidase protein (HN). The transmembrane (TM) domains of viral fusion proteins are typically required for fusion, but the key amino acids in NDV F TM domains have not been identified. Site-directed mutagenesis was utilized to change the conserved amino acids at 500, 501, 502, 505, 510, 513, 516, 519, and 520 to alanine. It was found that mutants L519 and V520 had an interrupted protein expression, decreased to below 10%, and mutants A500, I505, V513, and V516 had a hypoactive impact on fusion activity, decreased to 85.38%, 67.05%, 55.38% and 51.13% of wt F, respectively. The results indicated that the TM domain plays a vital part in the fusion activity of the NDV F protein.