Phosphatidylserine-specific phospholipase A1 involved in hepatitis C virus assembly through NS2 complex formation.

UNLABELLED: Several members of the phospholipase family have been reported to be involved in hepatitis C virus (HCV) replication. Here, we identified another phospholipase, phosphatidylserine-specific phospholipase A1 (PLA1A), as a host factor involved in HCV assembly. PLA1A was upregulated by HCV infection, and PLA1A knockdown significantly reduced J399EM (genotype 2a) HCV propagation at the assembly step but not the entry, RNA replication, and protein translation steps of the life cycle. Protein localization and interaction analysis further revealed a role of PLA1A in the interaction of NS2-E2 and NS2-NS5A, as the formation of the NS2-E2 and NS2-NS5A complexes was weakened in the absence of PLA1A. In addition, PLA1A stabilized the NS2/NS5A dotted structure during infection. These data suggest that PLA1A plays an important role in bridging the membrane-associated NS2-E2 complex and the NS5A-associated replication complex via its interaction with E2, NS2, and NS5A, which leads to a coordinating interaction between the structural and nonstructural proteins and facilitates viral assembly. IMPORTANCE: Hepatitis C virus (HCV) genomic replication is driven by the replication complex and occurs at the membranous web, while the lipid droplet is the organelle in which virion assembly is initiated. In this study, we identified phosphatidylserine-specific phospholipase A1 (PLA1A), a member of phospholipase A 1 family, as a novel host factor involved in the assembly process of HCV. PLA1A, which is induced by HCV infection at a late infection stage, interacts with HCV E2, NS2, and NS5A proteins and enhances and stabilizes the NS2-E2 and NS2-NS5A complex formation, which is essential for viral assembly. Thus, PLA1A is an important host factor which is involved in the initiation of the viral assembly in close proximity to Core-decorated lipid droplets through bringing together the HCV replication complex and envelope complex.

Protective effects of METRNL overexpression against pathological cardiac remodeling.

At present, meteorin-like protein (METRNL) has been proven to be widely expressed in the myocardium and participates in the pathogenic process of various cardiovascular diseases. However, the effects of METRNL on pathological cardiac hypertrophy is still unknown. In the present study, we used a mouse model of transverse aortic constriction (TAC) surgery to mimic pathological cardiac hypertrophy and gene delivery system to overexpress METRNL in vivo. The results showed that METRNL overexpression improved TAC-induced pathological cardiac hypertrophy in mice and neonatal cardiomyocytes. In addition, METRNL overexpression diminished TAC-induced cardiac oxidative damage, inflammation and cardiomyocyte apoptosis. Moreover, the cardioprotective effect of METRNL overexpression was directly related to the activation of AMP-activated protein kinase (AMPK) and sirtuin1 (SIRT1). In summary, our data identified that METRNL may be a promising therapeutic target to mitigate pathological cardiac hypertrophy in the future.

Inhibition mechanism of theaflavins on matrix metalloproteinase-2: inhibition kinetics, multispectral analysis, molecular docking and molecular dynamics simulation.

Dental caries is a chronic and destructive disease and matrix metalloproteinase-2 (MMP-2) plays a major role in caries. The inhibitory mechanisms of theaflavins [theaflavin (TF1), theaflavin-3-gallate (TF2A), theaflavin-3'-gallate (TF2B), and theaflavin-3,3'-digallate (TF3)] on MMP-2 were investigated using techniques such as enzyme inhibition kinetics, multi-spectral methods, molecular docking, and molecular dynamics simulations. The results showed that TF1, TF2A, TF2B, and TF3 all competitively and reversibly inhibited MMP-2 activity. Fluorescence spectra and molecular docking indicated that four theaflavins spontaneously bind to MMP-2 through noncovalent interactions, driven by hydrogen bonds and hydrophobic interactions, constituting a static quenching mechanism and resulting in an altered tryptophan residue environment around MMP-2. Molecular dynamic simulations demonstrated that four theaflavins can form stable, compact complexes with MMP-2. In addition, the order of theaflavins' ability to inhibit MMP-2 was found to be TF1 > TF2B > TF2A > TF3. Interestingly, the order of binding capacity between MMP-2 and TF1, TF2A, TF2B, and TF3 was consistent with the order of inhibitory capacity, and was opposite to the order of steric hindrance of theaflavins. This may be due to the narrow space of the active pocket of MMP-2, and the smaller the steric hindrance of theaflavins, the easier it is to enter the active pocket and bind to MMP-2. This study provided novel insights into theaflavins as functional components in the exploration of natural MMP-2 inhibitors.

Prognostic iron-metabolism signature robustly stratifies single-cell characteristics of hepatocellular carcinoma.

Cancer immunotherapy has shown to be a promising method in treating hepatocellular carcinoma (HCC), but suboptimal responses in patients are attributed to cellular and molecular heterogeneity. Iron metabolism-related genes (IRGs) are important in maintaining immune system homeostasis and have the potential to help develop new strategies for HCC treatment. Herein, we constructed and validated the iron-metabolism gene prognostic index (IPX) using univariate Cox proportional hazards regression and LASSO Cox regression analysis, successfully categorizing HCC patients into two groups with distinct survival risks. Then, we performed single-sample gene set enrichment analysis, weighted correlation network analysis, gene ontology enrichment analysis, cellular lineage analysis, and SCENIC analysis to reveal the key determinants underlying the ability of this model based on bulk and single-cell transcriptomic data. We identified several driver transcription factors specifically activated in specific malignant cell sub-populations to contribute to the adverse survival outcomes in the IPX-high subgroup. Within the tumor microenvironment (TME), T cells displayed significant diversity in their cellular characteristics and experienced changes in their developmental paths within distinct clusters identified by IPX. Interestingly, the proportion of Treg cells was increased in the high-risk group compared with the low-risk group. These results suggest that iron-metabolism could be involved in reshaping the TME, thereby disrupting the cell cycle of immune cells. This study utilized IRGs to construct a novel and reliable model, which can be used to assess the prognosis of patients with HCC and further clarify the molecular mechanisms of IRGs in HCC at single-cell resolution.

Dense mapping of IL2RA shows no association with Graves' disease in Chinese Han population.

OBJECTIVE: Associations between IL2RA and various autoimmune diseases have been reported in Caucasians. We investigated whether genetic polymorphisms at the IL2RA locus were associated with Graves' disease (GD) in the Chinese Han population. DESIGN: We performed a genome-wide association study (GWAS) in 1 536 GD patients and 1 516 controls. The 1000 Genomes Project data were adopted as references for imputation analysis. After forward and conditional logistic regressions, we found that rs11256313 was the major risk variant in the CD25/IL2RA region. Thus, we further genotyped rs11256313 in a replication cohort with 3 694 GD patients and 3 510 controls using ABI 7900HT TaqMan Real-Time PCR System. RESULTS: Nine single nucleotide polymorphisms (SNPs) in the IL2RA block were nominally associated with GD in our GWAS (0·01 < P < 0·05). After imputation analysis, 13 imputed SNPs in the IL2RA block were weakly associated with GD (P ≤ 0·05). Logistic regression analysis suggested that the imputed rs11256313 could represent the IL2RA block (P = 0·003). However, we failed to replicate the association of rs11256313 in a larger cohort (P = 0·145). A subphenotype analysis of rs11256313 on thyroid hormone receptor antibody (TRAb) and gender showed that there was no association in any of the subphenotype groups (P > 0·05). CONCLUSIONS: The results suggested that common genetic polymorphisms at IL2RA do not exert a significant genetic effect on the development of GD in the Chinese Han population. Previously reported associations between CD25/IL2RA and autoimmune diseases including GD in Caucasians again imply that heterogeneity exists in different ethnic populations.

Characteristics of HPV integration in cervical adenocarcinoma and squamous carcinoma.

PURPOSE: HPV integration usually occurs in HPV-related cancer, and is the main cause of cancer. But the carcinogenic mechanism of HPV integration is unclear. The study aims to provide a theoretical basis for understanding the pathogenesis of cervical adenocarcinoma (AC) and cervical squamous carcinoma (SCC). METHODS: We used HPV capture sequencing to obtain HPV integration sites in AC and SCC, and analyzed cytobands, distribution of genetic and genomic elements, identified integration hotspot genes, clinicopathological parameters, breakpoints of HPV16 and performed pathway analysis. Then we conducted immunohistochemical (IHC) assay to preliminarily verify the expression of most frequently integrated genes in AC, STARD3 and ERBB2. RESULTS: The results revealed that the most frequently observed integrated cytoband was 17q12 in AC and 21p11.2 in SCC, respectively. The breakpoints in both AC and SCC were more tended to occur within gene regions, compared to intergenetic regions. Compared to SCC samples, AC samples had a higher prevalence of genomic elements. In AC, HPV integration has no significantly difference with clinicopathological parameters, but in SCC integration correlated with differentiation (P < 0.05). Breakpoints of HPV in SCC located in LCR more frequently compared to AC, which destroyed the activation of promoter p97. Hotspot genes of HPV integration were STARD3 and ERBB2 in AC, and RNA45S rDNA and MIR3648-1 in SCC, respectively. Meanwhile, we preliminarily proved that the expression of STARD3 and ERBB2, the most frequently integrated genes, would increase after integration. CONCLUSION: These results suggested that HPV may utilize the powerful hosts' promoters to express viral oncogenes and overexpression of viral oncogenes plays a significant role in the carcinogenesis of SCC. In AC, HPV integration may affect hosts' oncogenes, and the dysregulation of oncogenes may primarily contribute to progression of AC.

PHOSPHO1 Serves as a Key Metabolism-Related Biomarker in the Tumorigenesis of Diffuse Large B-cell Lymphoma.

OBJECTIVE: Diffuse large B-cell lymphoma (DLBCL) is an aggressive type of non-Hodgkin lymphoma. Due to its genetic heterogeneity and abnormal metabolism, many DLBCL patients have a poor prognosis. This study investigated the key metabolism-related genes and potential mechanisms. METHODS: Differentially expressed genes, differentially expressed transcription factors (TFs), and differentially expressed metabolism-related genes (DEMRGs) of glucose and lipid metabolic processes were identified using the edgeR package. Key DEMRGs were screened by Lasso regression, and a prediction model was constructed. The cell type identification by estimating relative subsets of RNA transcripts algorithm was utilized to assess the fraction of immune cells, and Gene Set Enrichment Analysis was used to determine immune-related pathways. A regulatory network was constructed with significant co-expression interactions among TFs, DEMRGs, immune cells/pathways, and hallmark pathways. RESULTS: A total of 1551 DEMRGs were identified. A prognostic model with a high applicability (area under the curve=0.921) was constructed with 13 DEMRGs. Tumorigenesis of DLBCL was highly related to the neutrophil count. Four DEMRGs (PRXL2AB, CCN1, DECR2 and PHOSPHO1) with 32 TF-DEMRG, 36 DEMRG-pathway, 14 DEMRG-immune-cell, 9 DEMRG-immune-gene-set, and 67 DEMRG-protein-chip interactions were used to construct the regulatory network. CONCLUSION: We provided a prognostic prediction model based on 13 DEMRGs for DLBCL. We found that phosphatase, orphan 1 (PHOSPHO1) is positively regulated by regulatory factor X5 (RFX5) and mediates MYC proto-oncogene (MYC) targeting the V2 pathway and neutrophils.

The expression of mimecan in adrenal tissue plays a role in an organism's responses to stress.

Mimecan encodes a secretory protein that is secreted into the human serum as two mature proteins with molecular masses of 25 and 12 kDa. We found 12-kDa mimecan to be a novel satiety hormone mediated by the upregulation of the expression of interleukin (IL)-1ß and IL-6 in the hypothalamus. Mimecan was found to be expressed in human pituitary corticotroph cells and was up-regulated by glucocorticoids, while the secretion of adrenocorticotropic hormone (ACTH) in pituitary corticotroph AtT-20 cells was induced by mimecan. However, the effects of mimecan in adrenal tissue on the hypothalamic-pituitary-adrenal (HPA) axis functions remain unknown. We demonstrated that the expression of mimecan in adrenal tissues is significantly downregulated by hypoglycemia and scalded stress. It was down-regulated by ACTH, but upregulated by glucocorticoids through in vivo and in vitro studies. We further found that 12-kDa mimecan fused protein increased the corticosterone secretion of adrenal cells in vivo and in vitro. Interestingly, compared to litter-mate mice, the diurnal rhythm of corticosterone secretion was disrupted under basal conditions, and the response to restraint stress was stronger in mimecan knockout mice. These findings suggest that mimecan stimulates corticosterone secretion in the adrenal tissues under basal conditions; however, the down-regulated expression of mimecan by increased ACTH secretion after stress in adrenal tissues might play a role in maintaining the homeostasis of an organism's responses to stress.

Expression of adiponectin receptors in mouse adrenal glands and the adrenocortical Y-1 cell line: adiponectin regulates steroidogenesis.

Obesity is frequently associated with malfunctions of the hypothalamus-pituitary-adrenal (HPA) axis and hyperaldosteronism, but the mechanism underlying this association remains unclear. Since the adrenal glands are embedded in adipose tissue, direct cross-talk between adipose tissue and the adrenal gland has been proposed. A previous study found that adiponectin receptor mRNA was expressed in human adrenal glands and aldosterone-producing adenoma (APA). However, the expression of adiponectin receptors in adrenal glands has not been confirmed at the protein level or in other species. Furthermore, it is unclear whether adiponectin receptors expressed in adrenal cells are functional. We found, for the first time, that adiponectin receptor (AdipoR1 and AdipoR2) mRNA and protein were expressed in mouse adrenal and adrenocortical Y-1 cells. However, adiponectin itself was not expressed in mouse adrenal or Y-1 cells. Furthermore, adiponectin acutely reduced basal levels of corticosterone and aldosterone secretion. ACTH-induced steroid secretion was also inhibited by adiponectin, and this was accompanied by a parallel change in the expression of the key genes involved in steroidogenesis. These findings indicate that adiponectin may take part in the modulation of steroidogenesis. Thus, adiponectin is likely to have physiological and/or pathophysiological significance as an endocrine regulator of adrenocortical function.

RBM24 stabilizes hepatitis B virus pregenomic RNA but inhibits core protein translation by targeting the terminal redundancy sequence.

The terminal redundancy (TR) sequence of the 3.5-kb hepatitis B virus (HBV) RNA contains sites that govern many crucial functions in the viral life cycle, including polyadenylation, translation, RNA packaging, and DNA synthesis. In the present study, RNA-binding motif protein 24 (RBM24) is shown to be involved in the modulation of HBV replication by targeting the TR of HBV RNA. In HBV-transfected hepatoma cell lines, both knockdown and overexpression of RBM24 led to decreased HBV replication and transcription. Ectopic expression of RBM24 inhibited HBV replication, which was partly restored by knockdown of RBM24, indicating that a proper level of RBM24 was required for HBV replication. The regulation of RBM24 of HBV replication and translation was achieved by the interaction between the RNA-binding domains of RBM24 and both the 5' and 3' TR of 3.5-kb RNA. RBM24 interacted with the 5' TR of HBV pregenomic RNA (pgRNA) to block 80S ribosome assembly on HBV pgRNA and thus inhibited core protein translation, whereas the interaction between RBM24 and the 3' TR enhanced the stability of HBV RNA. Finally, the regulatory function of RBM24 on HBV replication was further confirmed in a HBV infection model. In conclusion, the present study demonstrates the dual functions of RBM24 by interacting with different TRs of viral RNA and reveals that RBM24 is an important host gene for HBV replication.

RNA binding protein 24 regulates the translation and replication of hepatitis C virus.

The secondary structures of hepatitis C virus (HCV) RNA and the cellular proteins that bind to them are important for modulating both translation and RNA replication. However, the sets of RNA-binding proteins involved in the regulation of HCV translation, replication and encapsidation remain unknown. Here, we identified RNA binding motif protein 24 (RBM24) as a host factor participated in HCV translation and replication. Knockdown of RBM24 reduced HCV propagation in Huh7.5.1 cells. An enhanced translation and delayed RNA synthesis during the early phase of infection was observed in RBM24 silencing cells. However, both overexpression of RBM24 and recombinant human RBM24 protein suppressed HCV IRES-mediated translation. Further analysis revealed that the assembly of the 80S ribosome on the HCV IRES was interrupted by RBM24 protein through binding to the 5'-UTR. RBM24 could also interact with HCV Core and enhance the interaction of Core and 5'-UTR, which suppresses the expression of HCV. Moreover, RBM24 enhanced the interaction between the 5'- and 3'-UTRs in the HCV genome, which probably explained its requirement in HCV genome replication. Therefore, RBM24 is a novel host factor involved in HCV replication and may function at the switch from translation to replication.

Mimecan, a Hormone Abundantly Expressed in Adipose Tissue, Reduced Food Intake Independently of Leptin Signaling.

Adipokines such as leptin play important roles in the regulation of energy metabolism, particularly in the control of appetite. Here, we describe a hormone, mimecan, which is abundantly expressed in adipose tissue. Mimecan was observed to inhibit food intake and reduce body weight in mice. Intraperitoneal injection of a mimecan-maltose binding protein (-MBP) complex inhibited food intake in C57BL/6J mice, which was attenuated by pretreatment with polyclonal antibody against mimecan. Notably, mimecan-MBP also induced anorexia in A(y)/a and db/db mice. Furthermore, the expression of interleukin (IL)-1ß and IL-6 was up-regulated in the hypothalamus by mimecan-MBP, as well as in N9 microglia cells by recombinant mouse mimecan. Taken together, the results suggest that mimecan is a satiety hormone in adipose tissue, and that mimecan inhibits food intake independently of leptin signaling by inducing IL-1ß and IL-6 expression in the hypothalamus.

Construction of a chimeric hepatitis C virus replicon based on a strain isolated from a chronic hepatitis C patient.

Subgenomic replicons of hepatitis C virus (HCV) have been widely used for studying HCV replication. Here, we report a new subgenomic replicon based on a strain isolated from a chronically infected patient. The coding sequence of HCV was recovered from a Chinese chronic hepatitis C patient displaying high serum HCV copy numbers. A consensus sequence designated as CCH strain was constructed based on the sequences of five clones and this was classified by sequence alignment as belonging to genotype 2a. The subgenomic replicon of CCH was replication-deficient in cell culture, due to dysfunctions in NS3 and NS5B. Various JFH1/CCH chimeric replicons were constructed, and specific mutations were introduced. The introduction of mutations could partially restore the replication of chimeric replicons. A replication-competent chimeric construct was finally obtained by the introduction of NS3 from JFH1 into the backbone of the CCH strain.

Persistent hepatitis C virus infections and hepatopathological manifestations in immune-competent humanized mice.

The majority of hepatitis C virus (HCV) infection develops chronic infection, which causes steatosis, cirrhosis and hepatocellular carcinoma. However, understanding HCV chronicity and pathogenesis is hampered by its narrow host range, mostly restricted to human and chimpanzee. Recent endeavour to infect a variety of humanized mice has not been able to achieve persistent HCV infection unless the essential innate immune responsive genes are knocked out. Nevertheless, such immune-compromised humanized mice still lacked HCV infection-induced hepatopathogenesis. Here we report that transgenic mice in ICR background harboring both human CD81 and occludin genes (C/O(Tg)) are permissive to HCV infection at a chronicity rate comparable to humans. In this mouse model, HCV accomplishes its replication cycle, leading to sustained viremia and infectivity for more than 12 months post infection with expected fibrotic and cirrhotic progression. Host factors favorable for HCV replication, and inadequate innate immune-response may contribute to the persistence. Lastly, NS3/4 protease inhibitor telaprevir can effectively inhibit de novo RNA synthesis and acute HCV infection of C/O(Tg) mice. Thus, chronic HCV infection with complete replication cycle and hepatopathologic manifestations is recapitulated, for the first time, in immune-competent mice. This model will open a new venue to study the mechanisms of chronic hepatitis C and develop better treatments.

Mutations of G38R and D40G cause amyotrophic lateral sclerosis by reducing Annexin A11 protein stability / 中南大学学报(医学版)

To explore the role of the mutations G38R and D40G of Annexin A11 (ANXA11) in the onset of amyotrophic lateral sclerosis (ALS).
 Methods: The plasmids expressing ANXA11 wild type protein, ANXA11 G38R protein and ANXA11 D40G protein were constructed, respectively. The recombinant plasmids were then transfected into HEK293 cells respectively followed by cycloheximide (CHX) treatment for 0, 2, 4 and 8 h. The protein expressions of ANXA11 wild type, ANXA11 G38R and ANXA11 D40G mutations were determined by Western blot. Gray analysis by Image J was performed to compare the half-life of each protein. The NSC-34 cell lines constantly expressing ANXA11 wild type protein, ANXA11 G38R protein and ANXA11 D40G protein were established. The cells were treated with NP-40 lysis buffer to examine the protein solubility by Western blot.
 Results: Both ANXA11 G38R protein and ANXA11 D40G protein showed a shorter half-life than ANXA11 wild type protein (P0.05). There was no visible insoluble substance in the NP-40 lysates for ANXA11 wild type protein, ANXA11 G38R protein and ANXA11 D40G protein.
 Conclusion: G38R and D40G mutations reduce the stability of ANXA11 protein. G38R and D40G mutations do not alter ANXA11 solubility.

Aldosterone directly affects apelin expression and secretion in adipocytes.

There is a high incidence of metabolic syndrome among patients with primary aldosteronism (PA), which has recently been associated with an unfavorable cardiometabolic profile. However, the underlying mechanisms have not been clarified in detail. Characterizing aldosterone (Ald) target genes in adipocytes will help us to elucidate the deleterious effects associated with excess Ald. Apelin, a novel adipokine, exerts beneficial effects on obesity-associated disorders and cardiovascular homeostasis. The objective of this study was to investigate the effects of high Ald levels on apelin expression and secretion and the underlying mechanisms involved in adipocytes. In vivo, a single-dose Ald injection acutely decreased apelin serum levels and adipose tissue apelin production, which demonstrates a clear inverse relationship between the levels of plasma Ald and plasma apelin. Experiments using 3T3-L1 adipocytes showed that Ald decreased apelin expression and secretion in a time- and dose-dependent manner. This effect was reversed by glucocorticoid receptor (GR) antagonists or GR (NR3C1) knockdown; furthermore, putative HREs were identified in the apelin promoter. Subsequently, we verified that both glucocorticoids and mineralocorticoids regulated apelin expression through GR activation, although no synergistic effect was observed. Additionally, detailed potential mechanisms involved a p38 MAPK signaling pathway. In conclusion, our findings strengthen the fact that there is a direct interaction between Ald and apelin in adipocytes, which has important implications for hyperaldosteronism or PA-associated cardiometabolic syndrome and hoists apelin on the list of potent therapeutic targets for PA.

Targeting of AML1-ETO in t(8;21) leukemia by oridonin generates a tumor suppressor-like protein.

Nearly 60% of acute myeloid leukemia (AML) patients with the t(8;21)(q22;q22) translocation fail to achieve long-term disease-free survival. Our previous studies demonstrated that oridonin selectively induces apoptosis of t(8;21) leukemia cells and causes cleavage of AML1-ETO oncoprotein resulting from t(8;21), but the underlying mechanisms remain unclear. We show that oridonin interacted with glutathione and thioredoxin/thioredoxin reductase to increase intracellular reactive oxygen species, which in turn activated caspase-3 in t(8;21) cells. Moreover, oridonin bound AML1-ETO, directing the enzymatic cleavage at aspartic acid 188 via caspase-3 to generate a truncated AML1-ETO (ΔAML1-ETO) and preventing the protein from further proteolysis. ΔAML1-ETO interacted with AML1-ETO and interfered with the trans-regulatory functions of remaining AML1-ETO oncoprotein, thus acting as a tumor suppressor that mediates the anti-leukemia effect of oridonin. Furthermore, oridonin inhibited the activity of c-Kit(+) leukemia-initiating cells. Therefore, oridonin is a potential lead compound for molecular target-based therapy of leukemia.