scholarly journals Mapping and Functional Role of the Self-Association Domain of Vesicular Stomatitis Virus Phosphoprotein

2006 ◽  
Vol 80 (19) ◽  
pp. 9511-9518 ◽  
Author(s):  
Mingzhou Chen ◽  
Tomoaki Ogino ◽  
Amiya K. Banerjee
Keyword(s):  
Amino Acids ◽  
Vesicular Stomatitis Virus ◽  
Critical Role ◽  
The Self ◽  
Dependent Manner ◽  
P Protein ◽  
Vesicular Stomatitis ◽  
Self Association

ABSTRACT The phosphoprotein (P protein) of vesicular stomatitis virus (VSV) is an essential subunit of the viral RNA-dependent RNA polymerase complex and plays a central role in viral transcription and replication. Using both the yeast two-hybrid system and coimmunoprecipitation assays, we confirmed the self-association of the P protein of Indiana serotype (Pind) and heterotypic interaction between Pind and the P protein of New Jersey serotype (Pnj). Furthermore, by using various truncation and deletion mutants of Pind, the self-association domain of the Pind protein was mapped to amino acids 161 to 210 within the hinge region. The self-association domain of Pind protein is not required for its binding to nucleocapsid and large proteins. We further demonstrated that the self-association domain of Pind protein is essential for VSV transcription in a minireplicon system and that a synthetic peptide spanning amino acids 191 to 210 in the self-association domain of Pind protein strongly inhibited the transcription of the VSV genome in vitro in a dose-dependent manner. These results indicated that the self-association domain of Pind protein plays a critical role in VSV transcription.

scholarly journals Identification of a Novel Tripartite Complex Involved in Replication of Vesicular Stomatitis Virus Genome RNA

2003 ◽  
Vol 77 (1) ◽  
pp. 732-738 ◽  
Author(s):  
Ashim K. Gupta ◽  
Daniel Shaji ◽  
Amiya K. Banerjee
Keyword(s):  
Vesicular Stomatitis Virus ◽  
Reverse Genetics ◽  
Insect Cells ◽  
Recombinant Baculovirus ◽  
Wild Type ◽  
Bhk Cells ◽  
P Protein ◽  
Vesicular Stomatitis

ABSTRACT Our laboratory's recent observations that transcriptionally inactive phosphoprotein (P) mutants can efficiently function in replicating vesicular stomatitis virus (VSV) defective interfering particle in a three-plasmid-based (L, P, and N) reverse genetics system in vivo (A. K. Pattnaik, L. Hwang, T. Li, N. Englund, M. Mathur, T. Das, and A. K. Banerjee, J. Virol. 71:8167-8175, 1997) led us to propose that a tripartite complex consisting of L-(N-P) protein may represent the putative replicase for synthesis of the full-length genome RNA. In this communication we demonstrate that such a complex is indeed detectable in VSV-infected BHK cells. Furthermore, coexpression of L, N, and P proteins in Sf21 insect cells by recombinant baculovirus containing the respective genes also resulted in the formation of a tripartite complex, as shown by immunoprecipitation with specific antibodies. A basic amino acid mutant of P protein, P260A, previously shown to be inactive in transcription but active in replication (T. Das, A. K. Pattnaik, A. M. Takacs, T. Li, L. N. Hwang, and A. K. Banerjee, Virology 238:103-114, 1997) was also capable of forming the mutant [L-(N-Pmut)] complex in both insect cells and BHK cells. Sf21 extract containing either the wild-type P protein or the mutant P protein along with the L and N proteins was capable of synthesizing 42S genome-sense RNA in an in vitro replication reconstitution reaction. Addition of N-Pmut or wild-type N-P complex further stimulated the synthesis of the genome-length RNA. These results indicate that the transcriptase and replicase complexes of VSV are possibly two distinct entities involved in carrying out capped mRNAs and uncapped genome and antigenome RNAs, respectively.

scholarly journals Role of Intermolecular Interactions of Vesicular Stomatitis Virus Nucleoprotein in RNA Encapsidation

2007 ◽  
Vol 82 (2) ◽  
pp. 674-682 ◽  
Author(s):  
Xin Zhang ◽  
Todd J. Green ◽  
Jun Tsao ◽  
Shihong Qiu ◽  
Ming Luo
Keyword(s):  
Crystal Structure ◽  
Intermolecular Interactions ◽  
Vesicular Stomatitis Virus ◽  
N Protein ◽  
P Protein ◽  
Intermolecular Contacts ◽  
Vesicular Stomatitis ◽  
Nucleoprotein N ◽  
Stable Ring

ABSTRACT The crystal structure of the vesicular stomatitis virus nucleoprotein (N) in complex with RNA reveals extensive and specific intermolecular interactions among the N molecules in the 10-member oligomer. What roles these interactions play in encapsidating RNA was studied by mutagenesis of the N protein. Three N mutants intended for disruption of the intermolecular interactions were designed and coexpressed with the phosphoprotein (P) in an Escherichia coli system previously described (T. J. Green et al., J. Virol. 74:9515-9524, 2000). Mutants N (Δ1-22), N (Δ347-352), and N (320-324, (Ala)5) lost RNA encapsidation and oligomerization but still bound with P. Another mutant, N (Ser290→Trp), was able to form a stable ring-like N oligomer and bind with the P protein but was no longer able to encapsidate RNA. The crystal structure of N (Ser290→Trp) at 2.8 Å resolution showed that this mutant can maintain all the same intermolecular interactions as the wild-type N except for a slight unwinding of the N-terminal lobe. These results suggest that the intermolecular contacts among the N molecules are required for encapsidation of the viral RNA.

Pleiotropic role of VEGF-A in regulating fetal pulmonary mesenchymal cell turnover

2006 ◽  
Vol 290 (6) ◽  
pp. L1183-L1192 ◽  
Author(s):  
S. Majka ◽  
K. Fox ◽  
B. McGuire ◽  
J. Crossno ◽  
P. McGuire ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Critical Role ◽  
Subsequent Development ◽  
Mesenchymal Cell ◽  
Normal Lung ◽  
Vegf Receptor ◽  
Dependent Manner ◽  
Inhibitory Protein

Tight regulation of VEGF-A production and signaling is important for the maintenance of lung development and homeostasis. VEGF null mice have provided little insight into the role of VEGF during the later stages of lung morphogenesis. Therefore, we examined the in vitro effects of autocrine and paracrine VEGF-A production and the inhibition of VEGF-A signaling on a Flk-1-negative subset of fetal pulmonary mesenchymal cells (pMC). We hypothesized that VEGF-A receptor signaling regulates turnover of fetal lung mesenchyme in a cell cycle-dependent manner. VEGF receptor blockade with SU-5416 caused cell spreading and decreased proliferation and bcl-2 localization. Nuclear expression of the cell cycle inhibitory protein, p21, was increased with SU-5416 treatment, and p27 was absent. Autocrine VEGF production by pMC resulted in proliferation and p21/p27-dependent contact inhibition. In contrast, exogenous VEGF-A increased cell progression through the cell cycle. Selective activation of Flt by placental growth factor demonstrated the importance of this receptor/kinase in the VEGF-A responsiveness of pMC. The expression and localization of the survival factor bcl-2 was dependent on VEGF. These results provide evidence that VEGF-A plays a critical role in the regulation of fetal pulmonary mesenchymal proliferation, survival, and the subsequent development of normal lung architecture through bcl-2 and p21/p27-dependent cell cycle control.

scholarly journals Structural Properties of the C Terminus of Vesicular Stomatitis Virus N Protein Dictate N-RNA Complex Assembly, Encapsidation, and RNA Synthesis

2012 ◽  
Vol 86 (16) ◽  
pp. 8720-8729 ◽  
Author(s):  
Bianca S. Heinrich ◽  
Benjamin Morin ◽  
Amal A. Rahmeh ◽  
Sean P. J. Whelan
Keyword(s):  
Gene Expression ◽  
Vesicular Stomatitis Virus ◽  
Rna Synthesis ◽  
Critical Role ◽  
Viral Gene Expression ◽  
Viral Gene ◽  
C Terminus ◽  
Vesicular Stomatitis ◽  
Rna Complex

The vesicular stomatitis virus (VSV) nucleoprotein (N) associates tightly with the viral genomic RNA. This N-RNA complex constitutes the template for the RNA-dependent RNA polymerase L, which engages the nucleocapsid via its phosphoprotein cofactor P. While N and P proteins play important roles in regulating viral gene expression, the molecular basis of this regulation remains incompletely understood. Here we show that mutations in the extreme C terminus of N cause defects in viral gene expression. To determine the underlying cause of such defects, we examined the effects of the mutations separately on encapsidation and RNA synthesis. Expression of N together with P inEscherichia coliresults predominantly in the formation of decameric N-RNA rings. In contrast, nucleocapsid complexes containing the substitution NY415Aor NK417Awere more loosely coiled, as revealed by electron microscopy (EM). In addition, the NEF419/420AAmutant was unable to encapsidate RNA. To further characterize these mutants, we engineered an infectious cDNA clone of VSV and employed N-RNA templates from those viruses to reconstitute RNA synthesisin vitro. The transcription assays revealed specific defects in polymerase utilization of the template that result in overall decreased RNA quantities, including reduced amounts of leader RNA. Passage of the recombinant viruses in cell culture led to the accumulation of compensatory second-site mutations in close proximity to the original mutations, underscoring the critical role of structural features within the C terminus in regulating N function.

scholarly journals Role of the Hypervariable Hinge Region of Phosphoprotein P of Vesicular Stomatitis Virus in Viral RNA Synthesis and Assembly of Infectious Virus Particles

2005 ◽  
Vol 79 (13) ◽  
pp. 8101-8112 ◽  
Author(s):  
Subash C. Das ◽  
Asit K. Pattnaik
Keyword(s):  
Amino Acid ◽  
Vesicular Stomatitis Virus ◽  
Rna Synthesis ◽  
Hinge Region ◽  
Viral Rna ◽  
Insertion Mutagenesis ◽  
Insertion Mutant ◽  
P Protein ◽  
Vesicular Stomatitis

ABSTRACT The phosphoprotein (P protein) of vesicular stomatitis virus (VSV) is an essential subunit of the viral RNA-dependent RNA polymerase and has multiple functions residing in its different domains. In the present study, we examined the role of the hypervariable hinge region of P protein in viral RNA synthesis and recovery of infectious VSV by using transposon-mediated insertion mutagenesis and deletion mutagenesis. We observed that insertions of 19-amino-acid linker sequences at various positions within this region affected replication and transcription functions of the P protein to various degrees. Interestingly, one insertion mutant was completely defective in both transcription and replication. Using a series of deletion mutants spanning the hinge region of the protein, we observed that amino acid residues 201 through 220 are required for the activity of P protein in both replication and transcription. Neither insertion nor deletion had any effect on the interaction of P protein with N or L proteins. Infectious VSVs with a deletion in the hinge region possessed retarded growth characteristics and exhibited small-plaque morphology. Interestingly, VSV containing one P protein deletion mutant (PΔ7, with amino acids 141 through 200 deleted), which possessed significant levels of replication and transcription activity, could be amplified only by passage in cells expressing the wild-type P protein. We conclude that the hypervariable hinge region of the P protein plays an important role in viral RNA synthesis. Furthermore, our results provide a previously unidentified function for the P protein: it plays a critical role in the assembly of infectious VSV.

Up-Regulation of GATA4 Regulates Human Lens Epithelial Cell Function in Age-Related Cataract

2020 ◽  
Vol 63 (6) ◽  
pp. 564-571
Author(s):  
Xiaodong Xie ◽  
Xiaofei Song ◽  
Xin Liu ◽  
Xiaogang Luo ◽  
Maidina Nabijiang ◽  
...  
Keyword(s):  
Prolonged Exposure ◽  
Cell Function ◽  
Critical Role ◽  
Lens Epithelial Cell ◽  
Human Lens ◽  
Dependent Manner ◽  
Age Related

<b><i>Purpose:</i></b> GATA4 has emerged as a novel regulator that plays a critical role in mediating senescence. However, the role of GATA4 in age-related cataract (ARC), the leading cause of visual impairment, requires further elucidation. <b><i>Methods:</i></b> GATA4 expression was measured by quantitative RT-PCR and capillary Western immunoassay (WES). The MTT assay, EdU assay, and rhodamine-123/Hoechst and calcein-AM/propidium iodide double staining were used to investigate the role of GATA4 in the viability, proliferation, and apoptosis of cultured human lens epithelial cells (HLECs). <b><i>Results:</i></b> HLECs were subjected to 3 different treatment models, including prolonged exposure to low-dose H<sub>2</sub>O<sub>2</sub>, UVB irradiation, and mild heating, to simulate senescence and apoptosis. GATA4 expression was significantly increased in these models in a time- and dose-dependent manner. Overexpression of GATA4 reduced cell viability, accelerated apoptosis development, and reduced the proliferation of HLECs. Furthermore, the expression of GATA4 from ARC was up-regulated at both mRNA and at protein level compared with clear lenses. <b><i>Conclusion:</i></b> GATA4 is up-regulated in all 3 models of HLECs in vitro and the cells from ARC lenses in vivo. Up-regulation of GATA4 mediates HLEC dysfunction. GATA4-mediated effects in HLECs would provide a novel insight into the pathogenesis of ARC.

scholarly journals M2 macrophages, but not M1 macrophages, support megakaryopoiesis by upregulating PI3K-AKT pathway activity

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Hong-Yan Zhao ◽  
Yuan-Yuan Zhang ◽  
Tong Xing ◽  
Shu-Qian Tang ◽  
Qi Wen ◽  
...  
Keyword(s):  
Critical Role ◽  
Akt Pathway ◽  
Dependent Manner ◽  
M1 Macrophages ◽  
Specific Effects ◽  
High Ploidy ◽  
Opposing Effects ◽  
Cellular Components

AbstractDysfunctional megakaryopoiesis hampers platelet production, which is closely associated with thrombocytopenia (PT). Macrophages (MФs) are crucial cellular components in the bone marrow (BM) microenvironment. However, the specific effects of M1 MФs or M2 MФs on regulating megakaryocytes (MKs) are largely unknown. In the current study, aberrant BM-M1/M2 MФ polarization, characterized by increased M1 MФs and decreased M2 MФs and accompanied by impaired megakaryopoiesis-supporting abilities, was found in patients with PT post-allotransplant. RNA-seq and western blot analysis showed that the PI3K-AKT pathway was downregulated in the BM MФs of PT patients. Moreover, in vitro treatment with PI3K-AKT activators restored the impaired megakaryopoiesis-supporting ability of MФs from PT patients. Furthermore, we found M1 MФs suppress, whereas M2 MФs support MK maturation and platelet formation in humans. Chemical inhibition of PI3K-AKT pathway reduced megakaryopoiesis-supporting ability of M2 MФs, as indicated by decreased MK count, colony-forming unit number, high-ploidy distribution, and platelet count. Importantly, genetic knockdown of the PI3K-AKT pathway impaired the megakaryopoiesis-supporting ability of MФs both in vitro and in a MФ-specific PI3K-knockdown murine model, indicating a critical role of PI3K-AKT pathway in regulating the megakaryopoiesis-supporting ability of M2 MФs. Furthermore, our preliminary data indicated that TGF-β released by M2 MФs may facilitate megakaryopoiesis through upregulation of the JAK2/STAT5 and MAPK/ERK pathways in MKs. Taken together, our data reveal that M1 and M2 MФs have opposing effects on MKs in a PI3K-AKT pathway-dependent manner, which may lead to new insights into the pathogenesis of thrombocytopenia and provide a potential therapeutic strategy to promote megakaryopoiesis.

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