60S ribosomal protein L35 regulates β-casein translational elongation and secretion in bovine mammary epithelial cells

RPL35 downregulated by mechanical overloading promotes chondrocyte senescence and osteoarthritis development via Hedgehog-Gli1 signaling

Objectives

To investigate the potential role of Ribosomal protein L35 (RPL35) in regulating chondrocyte catabolic metabolism and to examine whether osteoarthritis (OA) progression can be delayed by overexpressing RPL35 in a mouse compression loading model.

Methods

RNA sequencing analysis was performed on chondrocytes treated with or without 20 % elongation strain loading for 24 h. Experimental OA in mice was induced by destabilization of the medial meniscus and compression loading. Mice were randomly assigned to a sham group, an intra-articular adenovirus-mediated overexpression of the negative group, and an intra-articular adenovirus-mediated overexpression of the RPL35 operated group. The Osteoarthritis Research Society International score was used to evaluate cartilage degeneration. Immunostaining and western blot analyses were conducted to detect relative protein levels. Primary mouse chondrocytes were treated with 20 % elongation strain loading for 24 h to investigate the role of RPL35 in modulating chondrocyte catabolic metabolism and regulating cellular senescence in chondrocytes.

Results

The protein expression of RPL35 in mouse chondrocytes was significantly reduced when excessive mechanical loading was applied, while elevated protein levels of RPL35 protected articular chondrocytes from degeneration. In addition, the RPL35 knockdown alone induced chondrocyte senescence, decreased the expression of anabolic markers, and increased the expression of catabolic markers in vitro in part through the hedgehog (Hh) pathway.

Conclusions

These findings demonstrated a functional pathway important for OA development and identified intra-articular injection of RPL35 as a potential therapy for OA prevention and treatment.

The translational potential of this article

It is necessary to develop new targeted drugs for OA due to the limitations of conventional pharmacotherapy. Our study explores and demonstrates the protective effect of RPL35 against excessive mechanical stress in OA models in vivo and in vitro in animals. These findings might provide novel insights into OA pathogenesis and show its translational potential for OA therapy.

Identification and characterization of the Bicupin domain family and functional analysis of GhBCD11 in response to verticillium wilt in cotton

Bicupin domain protein (BCD) family, an important component of Cupin domain superfamily, plays important roles in oxalic acid (OA) degradation and stress responses in high plants. However, no studies have been reported on the Cupin domain family in cotton up till now. In our study, a total 110 proteins including Cupin domain were identified from the upland cotton (Gossypium hirsutum). Among them, 17 proteins contained Bicupin domain. Subsequently, we found that V. dahliae produces OA leading to cotton leaf wilting. RT-qPCR analysis of GhBCDs revealed that OA and V. dahliae Vd080 significantly enhanced the expression of GhBCD11. The Virus-induced gene silencing and overexpression analysis showed that GhBCD11 positively regulates plant resistance to V. dahliae. Subcellular localization showed GhBCD11 located on the plasma membrane. The analysis of expression pattern showed that GhBCD11 can be induced via hormone-mediated signal pathway including salicylic acid (SA), ethephon (ET), methyl jasmonate (JA) and abscisic acid (ABA). In addition, we identified an interaction between 60 S ribosomal protein GhRPL12-3 and GhBCD11 by yeast double hybridization. Overall, this is the first study, where we identified Cupin domain family in cotton, clarified the role of GhBCD11 in cotton for resistance to V. dahliae and found an interaction between GhRPL12-3 and GhBCD11.

Genetics, environmental stress, and amino acid supplementation affect lactational performance via mTOR signaling pathway in bovine mammary epithelial cells

Mammary glands are known for their ability to convert nutrients present in the blood into milk contents. In cows, milk synthesis and the proliferation of cow mammary epithelial cells (CMECs) are regulated by various factors, including nutrients such as amino acids and glucose, hormones, and environmental stress. Amino acids, in particular, play a crucial role in regulating cell proliferation and casein synthesis in mammalian epithelial cells, apart from being building blocks for protein synthesis. Studies have shown that environmental factors, particularly heat stress, can negatively impact milk production performance in dairy cattle. The mammalian target of rapamycin complex 1 (mTORC1) pathway is considered the primary signaling pathway involved in regulating cell proliferation and milk protein and fat synthesis in cow mammary epithelial cells in response to amino acids and heat stress. Given the significant role played by the mTORC signaling pathway in milk synthesis and cell proliferation, this article briefly discusses the main regulatory genes, the impact of amino acids and heat stress on milk production performance, and the regulation of mTORC signaling pathway in cow mammary epithelial cells.

Identification of ribosomal protein family as immune-cell-related biomarkers of NAFLD by bioinformatics and experimental analyses

Background

Immune cells play an integral role in the development and progression of non-alcoholic fatty liver disease (NAFLD). This study was to identify immune-cell-related biomarkers for the diagnosis and treatment of NAFLD.

Methods and findings

First, we introduced human liver transcriptome data from the GEO database (GSE48452 and GSE126848) and performed a weighted gene co-expression network analysis (WGCNA) to screen out the modules related to immune cell infiltration and to identify immune-cell-related differentially expressed genes (ICR-DEGs) associated with NAFLD progression. Further, the protein-protein interaction (PPI) network of ICR-DEGs was established to obtain hub genes and subsequently, the expression trend analysis was conducted to identify immune-cell-related biomarkers of NAFLD. Finally, the mRNA expression of biomarkers was validated in a NAFLD mouse model induced by high-fat diet (HFD) feeding. In total, we identified 66 ICR-DEGs and 13 hub genes associated with NAFLD. Among them, 9 hub genes (CD247, CD74, FCGR2B, IL2RB, INPP5D, MRPL16, RPL35, RPS3A, RPS8) were correlated with the infiltrating immune cells by the Pearson correlation analysis. Subsequently, 4 immune-cell-related biomarkers (RPL35, RPS3A, RPS8, and MRPL16) with the same expression trends in GSE48452 and GSE126848 datasets were identified. These biomarkers were enriched in immune-related pathways and had a good ability to distinguish between NASH and healthy samples. Moreover, we constructed a competing endogenous RNA (ceRNA) network of biomarkers and predicted twenty potential therapeutic drugs targeting RPS3A such as taxifolin and sitagliptin. Finally, experimental validation indicated that the hepatic mRNA expression of Rpl35, Rps3A, and Rps8 was significantly decreased in NAFLD mice.

Conclusions

This study identified four ribosomal protein genes (RPL35, RPS3A, RPS8, and MRPL16) as immune-cell-related biomarkers of NAFLD, which may actively participate in the immune processes during NAFLD progression and could serve as potential targets for the diagnosis and treatment of NAFLD.

Specialized Ribosomes in Health and Disease

Ribosomal heterogeneity exists within cells and between different cell types, at specific developmental stages, and occurs in response to environmental stimuli. Mounting evidence supports the existence of specialized ribosomes, or specific changes to the ribosome that regulate the translation of a specific group of transcripts. These alterations have been shown to affect the affinity of ribosomes for certain mRNAs or change the cotranslational folding of nascent polypeptides at the exit tunnel. The identification of specialized ribosomes requires evidence of the incorporation of different ribosomal proteins or of modifications to rRNA and/or protein that lead(s) to physiologically relevant changes in translation. In this review, we summarize ribosomal heterogeneity and specialization in mammals and discuss their relevance to several human diseases.

Proteomic screening identifies RPLp2 as a specific regulator for the translation of coronavirus

Viral mRNA of coronavirus translates in an eIF4E-dependent manner, and the phosphorylation of eIF4E can modulate this process, but the role of p-eIF4E in coronavirus infection is not yet entirely evident. p-eIF4E favors the translation of selected mRNAs, specifically the mRNAs that encode proteins associated with cell proliferation, inflammation, the extracellular matrix, and tumor formation and metastasis. In the present work, two rounds of TMT relative quantitative proteomics were used to screen 77 cellular factors that are upregulated upon infection by coronavirus PEDV and are potentially susceptible to a high level of p-eIF4E. PEDV infection increased the translation level of ribosomal protein lateral stalk subunit RPLp2 (but not subunit RPLp0/1) in a p-eIF4E-dependent manner. The bicistronic dual-reporter assay and polysome profile showed that RPLp2 is essential for translating the viral mRNA of PEDV. RNA binding protein and immunoprecipitation assay showed that RPLp2 interacted with PEDV 5'UTR via association with eIF4E. Moreover, the cap pull-down assay showed that the viral nucleocapsid protein is recruited in m⁷GTP-precipitated complexes with the assistance of RPLp2. The heterogeneous ribosomes, which are different in composition, regulate the selective translation of specific mRNAs. Our study proves that viral mRNA and protein utilize translation factors and heterogeneous ribosomes for preferential translation initiation. This previously uncharacterized process may be involved in the selective translation of coronavirus.

Proteomic profiling of the endogenous peptides of MRSA and MSSA

Staphylococcus aureus is a Gram-positive bacterium that can cause diverse skin and soft tissue infections. Methicillin-resistant Staphylococcus aureus (MRSA) can cause more severe infections than methicillin-susceptible Staphylococcus aureus (MSSA). Nevertheless, the physiological and metabolic regulation of MSSA and MRSA has not been well studied. In light of the increased interest in endogenous peptides and recognition of the important roles that they play, we studied the endogenous peptidome of MSSA and MRSA. We identified 1,065 endogenous peptides, among which 435 were differentially expressed (DE), with 292 MSSA-abundant endogenous peptides and 35 MRSA-abundant endogenous peptides. MSSA-abundant endogenous peptides have significantly enriched “VXXXK” motif of at the C-terminus. MSSA-abundant endogenous peptides are involved in penicillin-binding and immune responses, whereas MRSA-abundant endogenous peptides are associated with antibiotic resistance and increased toxicity. Our characterization of the peptidome of MSSA and MRSA provides a rich resource for future studies to explore the functional regulation of drug resistance in S. aureus and may also help elucidate the mechanisms of its pathogenicity and the development of treatments.

Application of Genetic Algorithm-Based Support Vector Machine in Identification of Gene Expression Signatures for Psoriasis Classification: A Hybrid Model

BACKGROUND

Psoriasis is a chronic autoimmune disease impairing significantly the quality of life of the patient. The diagnosis of the disease is done via a visual inspection of the lesional skin by dermatologists. Classification of psoriasis using gene expression is an important issue for the early and effective treatment of the disease. Therefore, gene expression data and selection of suitable gene signatures are effective sources of information.

METHODS

We aimed to develop a hybrid classifier for the diagnosis of psoriasis based on two machine learning models of the genetic algorithm and support vector machine (SVM). The method also conducts gene signature selection. A publically available gene expression dataset was used to test the model.

RESULTS

A number of 181 probe sets were selected among the original 54,675 probes using the hybrid model with a prediction accuracy of 100% over the test set. A number of 10 hub genes were identified using the protein-protein interaction network. Nine out of 10 identified genes were found in significant modules.

CONCLUSIONS

The results showed that the genetic algorithm improved the SVM classifier performance significantly implying the ability of the proposed model in terms of detecting relevant gene expression signatures as the best features.

Drug Development for Target Ribosomal Protein rpL35/uL29 for Repair of LAMB3R635X in Rare Skin Disease Epidermolysis Bullosa

INTRODUCTION

Epidermolysis bullosa (EB) describes a family of rare genetic blistering skin disorders. Various subtypes are clinically and genetically heterogeneous, and a lethal postpartum form of EB is the generalized severe junctional EB (gs-JEB). gs-JEB is mainly caused by premature termination codon (PTC) mutations in the skin anchor protein LAMB3 (laminin subunit beta-3) gene. The ribosome in majority of translational reads of LAMB3PTC mRNA aborts protein synthesis at the PTC signal, with production of a truncated, nonfunctional protein. This leaves an endogenous readthrough mechanism needed for production of functional full-length Lamb3 protein albeit at insufficient levels. Here, we report on the development of drugs targeting ribosomal protein L35 (rpL35), a ribosomal modifier for customized increase in production of full-length Lamb3 protein from a LAMB3PTC mRNA.

METHODS

Molecular docking studies were employed to identify small molecules binding to human rpL35. Molecular determinants of small molecule binding to rpL35 were further characterized by titration of the protein with these ligands as monitored by nuclear magnetic resonance (NMR) spectroscopy in solution. Changes in NMR chemical shifts were used to map the docking sites for small molecules onto the 3D structure of the rpL35.

RESULTS

Molecular docking studies identified 2 FDA-approved drugs, atazanavir and artesunate, as candidate small-molecule binders of rpL35. Molecular interaction studies predicted several binding clusters for both compounds scattered throughout the rpL35 structure. NMR titration studies identified the amino acids participating in the ligand interaction. Combining docking predictions for atazanavir and artesunate with rpL35 and NMR analysis of rpL35 ligand interaction, one binding cluster located near the N-terminus of rpL35 was identified. In this region, the nonidentical binding sites for atazanavir and artesunate overlap and are accessible when rpL35 is integrated in its natural ribosomal environment.

CONCLUSION

Atazanavir and artesunate were identified as candidate compounds binding to ribosomal protein rpL35 and may now be tested for their potential to trigger a rpL35 ribosomal switch to increase production of full-length Lamb3 protein from a LAMB3PTC mRNA for targeted systemic therapy in treating gs-JEB.

Increased Environment-Related Metabolism and Genetic Expression in the In Vitro Matured Mouse Oocytes by Transcriptome Analysis

Infertility in humans at their reproductive age is a world-wide problem. Oocyte in vitro maturation (IVM) is generally used in such cases to acquire the embryo in assisted reproductive technology (ART). However, the differences between an in vivo (IVO) and IVM culture environment in the RNA expression profile in oocytes, remains unclear. In this study, we compared the global RNA transcription pattern of oocytes from in vitro and in vivo maturation. Our results showed that 1,864 genes differentially expressed between the IVO and IVM oocytes. Among these, 1,638 genes were up-regulated, and 226 genes were down-regulated, and these changes were mainly divided into environmental adaption, metabolism, and genetic expression. Our detailed analysis showed that the expression of genes that belonged to metabolism-related processes such as energy metabolism, nucleotide metabolism, and carbohydrate metabolism was changed; and these genes also belonged to organismal systems including environmental adaptation and the circulatory system; moreover, we also found that the relative gene expression of genetic expression processes, such as protein synthesis, modification, and DNA replication and repair were also altered. In conclusion, our data suggests that in vitro maturation of mouse oocyte resulted in metabolism and genetic expression changes due to environmental changes compared with in vivo matured oocytes.

Selective regulation in ribosome biogenesis and protein production for efficient viral translation

As intracellular parasites, viruses depend heavily on host cell structures and their functions to complete their life cycle and produce new viral particles. Viruses utilize or modulate cellular translational machinery to achieve efficient replication; the role of ribosome biogenesis and protein synthesis in viral replication particularly highlights the importance of the ribosome quantity and/or quality in controlling viral protein synthesis. Recently reported studies have demonstrated that ribosome biogenesis factors (RBFs) and ribosomal proteins (RPs) act as multifaceted regulators in selective translation of viral transcripts. Here we summarize the recent literature on RBFs and RPs and their association with subcellular redistribution, post-translational modification, enzyme catalysis, and direct interaction with viral proteins. The advances described in this literature establish a rationale for targeting ribosome production and function in the design of the next generation of antiviral agents.

Ribosomal Protein L13 Promotes IRES-Driven Translation of Foot-and-Mouth Disease Virus in a Helicase DDX3-Dependent Manner

Internal ribosome entry site (IRES)-driven translation is a common strategy among positive-sense, single-stranded RNA viruses for bypassing the host cell requirement of a 5' cap structure. In the current study, we identified the ribosomal protein L13 (RPL13) as a critical regulator of IRES-driven translation of foot-and-mouth disease virus (FMDV) but found that it is not essential for cellular global translation. RPL13 is also a determinant for translation and infection of Seneca Valley virus (SVV) and classical swine fever virus (CSFV), and this suggests that its function may also be conserved in unrelated IRES-containing viruses. We further showed that depletion of DEAD box helicase DDX3 disrupts binding of RPL13 to the FMDV IRES, whereas the reduction in RPL13 expression impairs the ability of DDX3 to promote IRES-driven translation directly. DDX3 cooperates with RPL13 to support the assembly of 80S ribosomes for optimal translation initiation of viral mRNA. Finally, we demonstrated that DDX3 affects the recruitment of the eukaryotic initiation factor eIF3 subunits e and j to the viral IRES. This work provides the first connection between DDX3 and eIF3e/j and recognition of the role of RPL13 in modulating viral IRES-dependent translation. This previously uncharacterized process may be involved in selective mRNA translation.IMPORTANCE Accumulating evidence has unveiled the roles of ribosomal proteins (RPs) belonging to the large 60S subunit in regulating selective translation of specific mRNAs. The translation specificity of the large-subunit RPs in this process is thought provoking, given the role they play canonically in catalyzing peptide bond formation. Here, we have identified the ribosomal protein L13 (RPL13) as a critical regulator of IRES-driven translation during FMDV infection. Our study supports a model whereby the FMDV IRESs recruit helicase DDX3 recognizing RPL13 to facilitate IRES-driven translation, with the assistance of eIF3e and eIF3j. A better understanding of these specific interactions surrounding IRES-mediated translation initiation could have important implications for the selective translation of viral mRNA and thus for the development of effective prevention of viral infection.

The Selection of Reference Genes for Quantitative Real-Time PCR in the Ashidan Yak Mammary Gland During Lactation and Dry Period

Simple Summary

The Ashidan yak is a new cultivated breed which has polled characteristics and a mild temperament. Improving milk yield is an important aspect of a breeding program for this breed. The mammary gland undergoes dramatic physiological and metabolic changes during the transition from lactation to dry periods, which involves the expression and regulation of a great number of genes. Quantification of gene expression levels by real-time quantitative polymerase chain reaction (RT-qPCR) is important to reveal the molecular mechanisms of mammary gland development and lactation. The accuracy of RT-qPCR is strongly influenced by the expression stability of reference genes, however, a systematic approach for selecting reference genes used for analyzing gene expression of the Ashidan yak has not been developed. In this study, we selected reference genes and analyzed their expression stability at different physiological stages (lactation and dry period). We found the hydroxymethylbilane synthase gene (HMBS) and the tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein, zeta polypeptide gene (YWHAZ) were the most stable genes of the mammary gland of the Ashidan yak. These results help to improve the accuracy of gene expression analysis and provide a basis for future functional studies of target gene expression in the mammary gland of the Ashidan yak.

Abstract

Investigating the critical genes related to milk synthesis is essential for the improvement of the milk yield of the yak. Real-time quantitative polymerase chain reaction (RT-qPCR) is a reliable and widely used method to measure and evaluate gene expression levels. Selection of suitable reference genes is mandatory to acquire accurate normalization of gene expression results from RT-qPCR. To select the most stable reference genes for reliable normalization of mRNA expression by RT-qPCR in the mammary gland of the Ashidan yak, we selected 16 candidate reference genes and analyzed their expression stability at different physiological stages (lactation and dry period). The expression stability of the candidate reference genes was assessed using geNorm, NormFinder, BestKeeper, Delta Ct, and RefFinder methods. The results showed that the hydroxymethylbilane synthase gene (HMBS) and the tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein, zeta polypeptide gene (YWHAZ) were the most stable genes across all treatment samples. The reliability of selected reference genes was validated by normalizing relative expression of the lactation-related 60S ribosomal protein L35 gene (RPL35). The relative expression of RPL35 varied considerably according to the different reference genes. This work provides valuable information to further promote research in the molecular mechanisms involved in lactation and mammary gland development and provides a foundation for the improvement of the milk yield and quality of the Ashidan yak.

The long noncoding RNA lncNB1 promotes tumorigenesis by interacting with ribosomal protein RPL35

The majority of patients with neuroblastoma due to MYCN oncogene amplification and consequent N-Myc oncoprotein over-expression die of the disease. Here our analyses of RNA sequencing data identify the long noncoding RNA lncNB1 as one of the transcripts most over-expressed in MYCN-amplified, compared with MYCN-non-amplified, human neuroblastoma cells and also the most over-expressed in neuroblastoma compared with all other cancers. lncNB1 binds to the ribosomal protein RPL35 to enhance E2F1 protein synthesis, leading to DEPDC1B gene transcription. The GTPase-activating protein DEPDC1B induces ERK protein phosphorylation and N-Myc protein stabilization. Importantly, lncNB1 knockdown abolishes neuroblastoma cell clonogenic capacity in vitro and leads to neuroblastoma tumor regression in mice, while high levels of lncNB1 and RPL35 in human neuroblastoma tissues predict poor patient prognosis. This study therefore identifies lncNB1 and its binding protein RPL35 as key factors for promoting E2F1 protein synthesis, N-Myc protein stability and N-Myc-driven oncogenesis, and as therapeutic targets.

MYCN amplification is common in neuroblastomas. Here, the authors identify a long noncoding RNA, lncNB1 in these cancers and show that it promotes tumorigenesis by binding to ribosomal protein, RPL35 to enhance E2F1 and DEPDC1B protein synthesis, which phosphorylates ERK to stabilise N-Myc.

Septin6 regulates cell growth and casein synthesis in dairy cow mammary epithelial cells via mTORC1 pathway

This research paper addresses the hypothesis that Septin6 is a key regulatory factor influencing amino acid (AA)-mediated cell growth and casein synthesis in dairy cow mammary epithelial cells (DCMECs). DCMECs were treated with absence of AA (AA-), restricted concentrations of AA (AAr) or normal concentrations of AA (AA+) for 24 h. Cell growth, expression of CSN2 and Septin6 were increased in response to AA supply. Overexpressing or inhibiting Septin6 demonstrated that cell growth, expression of CSN2, mTOR, p-mTOR, S6K1 and p-S6K1 were up-regulated by Septin6. Furthermore, overexpressing or inhibiting mTOR demonstrated that the increase in cell growth and expression of CSN2 in response to Septin6 overexpression were inhibited by mTOR inhibition, and vice versa. Our hypothesis was supported; we were able to show that Septin6 is an important positive factor for cell growth and casein synthesis, it up-regulates AA-mediated cell growth and casein synthesis through activating mTORC1 pathway in DCMECs.

Protein 14-3-3ε Regulates Cell Proliferation and Casein Synthesis via PI3K-mTOR Pathway in Dairy Cow Mammary Epithelial Cells

Cell proliferation and casein synthesis of dairy cow mammary epithelial cells (DCMECs) are regulated by many factors. This research aimed to investigate the effect of 14-3-3ε on cell proliferation and casein synthesis in DCMECs and to reveal the underlying mechanism. Overexpressing or inhibiting 14-3-3ε demonstrated that cell proliferation; casein synthesis; expression of mTOR, p-mTOR, S6K1, and p-S6K1; and lysosomal localization of mTOR were all up-regulated by 14-3-3ε overexpressing and down-regulated by 14-3-3ε inhibiting. In addition, inhibiting mTOR demonstrated that the up-regulation of cell proliferation and casein synthesis in response to 14-3-3ε overexpressing was removed by inhibiting mTOR. Furthermore, the regulatory mechanism of 14-3-3ε was analyzed by coimmunoprecipitation, and we found that 14-3-3ε could interact with PI3K and activate mTORC1 pathway via PI3K. In addition, DCMECs were treated with insulin and prolactin, and the result showed that the cell proliferation and the expression of CSN2 and 14-3-3ε were all up-regulated by these hormones. In conclusion, the current research showed that 14-3-3ε is an important positive regulatory factor for cell proliferation and casein synthesis in DCMECs, as it up-regulates cell proliferation and casein synthesis via activating PI3K-mTOR pathway.

CD109 is identified as a potential nasopharyngeal carcinoma biomarker using aptamer selected by cell-SELEX

Nasopharyngeal carcinoma (NPC) is one of the most prevailing cancers in southern China and southern Asia. Because of the nonspecific symptoms and lack of effective biomarker, most patients are diagnosed at advanced stages, resulting in poor 5-year survival rate. To identify a novel NPC biomarker facilitating early detection and effective therapy of NPC, a two-step strategy consisting of cancer cell-Systematic Evolution of Ligands by EXponential enrichment (cell-SELEX) procedure and aptamer-based purification approach was developed. Using cell-SELEX procedure, four aptamers (S3, S5, S12 and S27) differentiating the molecular differences between NPC cells and NP cells were successfully screened. Then, using aptamer-based protein purification, membrane protein CD109 was identified as the target of aptamer S3. CD109 protein was further identified to be over-expressed in NPC cell lines and clinic tissues, but not or low in NP cell line and clinic NP tissues, detected by western blot and immunohistochemistry experiments. Our study demonstrated that CD109 identified by cell-SELEX and aptamer-based purification strategy might be used as a potential NPC biomarker for early diagnosis and targeted therapy.

The association of ribosomal protein L18 (RPL18) with infectious bursal disease virus viral protein VP3 enhances viral replication

Infectious bursal disease (IBD) is an acute, highly contagious, and immunosuppressive avian disease caused by IBD virus (IBDV). IBDV VP3 is a multifunctional protein playing a key role in virus assembly and pathogenesis. To investigate the role of VP3 in pathogenesis, we transfected DF-1 cells with pRK5-FLAG-vp3 and found that VP3 enhanced type I interferon expression and suppressed IBDV replication. Furthermore we found that VP3 interacted with chicken Ribosomal Protein L18 (chRPL18) in host cells and knockdown of chRPL18 by RNAi significantly promoted Type I interferon expression and inhibited IBDV replication. Moreover, our data show that chicken double-stranded RNA-activated protein kinase (chPKR) interacted with both VP3 and chRPL18. Thus chRPL18 in association with VP3 and chPKR affects viral replication.

Proteomic Analysis of Liver Proteins in a Rat Model of Chronic Restraint Stress-Induced Depression

Depression is a global mental disorder disease and greatly threatened human health and stress is considered to be one of the important factors that lead to depression. In this study, we used newly developed iTRAQ labeling and high performance liquid chromatography (HPLC) and mass spectrum united analysis technology obtained the 2176 accurate proteins. Successively, we used the GO analysis and IPA software to analyze the 98 differentially expressed proteins of liver in depression rats due to chronic restraint stress, showing a map of proteomics analysis of liver proteins from the aspects of related functions, disease and function analysis, canonical pathway analysis, and associated network. This study provide important information for comprehensively understanding the mechanisms of dysfunction or injury in the liver in depression.

RPLP1 and RPLP2 Are Essential Flavivirus Host Factors That Promote Early Viral Protein Accumulation

The Flavivirus genus contains several arthropod-borne viruses that pose global health threats, including dengue viruses (DENV), yellow fever virus (YFV), and Zika virus (ZIKV). In order to understand how these viruses replicate in human cells, we previously conducted genome-scale RNA interference screens to identify candidate host factors. In these screens, we identified ribosomal proteins RPLP1 and RPLP2 (RPLP1/2) to be among the most crucial putative host factors required for DENV and YFV infection. RPLP1/2 are phosphoproteins that bind the ribosome through interaction with another ribosomal protein, RPLP0, to form a structure termed the ribosomal stalk. RPLP1/2 were validated as essential host factors for DENV, YFV, and ZIKV infection in two human cell lines: A549 lung adenocarcinoma and HuH-7 hepatoma cells, and for productive DENV infection of Aedes aegypti mosquitoes. Depletion of RPLP1/2 caused moderate cell-line-specific effects on global protein synthesis, as determined by metabolic labeling. In A549 cells, global translation was increased, while in HuH-7 cells it was reduced, albeit both of these effects were modest. In contrast, RPLP1/2 knockdown strongly reduced early DENV protein accumulation, suggesting a requirement for RPLP1/2 in viral translation. Furthermore, knockdown of RPLP1/2 reduced levels of DENV structural proteins expressed from an exogenous transgene. We postulate that these ribosomal proteins are required for efficient translation elongation through the viral open reading frame. In summary, this work identifies RPLP1/2 as critical flaviviral host factors required for translation.

IMPORTANCE

Flaviviruses cause important diseases in humans. Examples of mosquito-transmitted flaviviruses include dengue, yellow fever and Zika viruses. Viruses require a plethora of cellular factors to infect cells, and the ribosome plays an essential role in all viral infections. The ribosome is a complex macromolecular machine composed of RNA and proteins and it is responsible for protein synthesis. We identified two specific ribosomal proteins that are strictly required for flavivirus infection of human cells and mosquitoes: RPLP1 and RPLP2 (RPLP1/2). These proteins are part of a structure known as the ribosomal stalk and help orchestrate the elongation phase of translation. We show that flaviviruses are particularly dependent on the function of RPLP1/2. Our findings suggest that ribosome composition is an important factor for virus translation and may represent a regulatory layer for translation of specific cellular mRNAs.