Requirements for different components of the host cell cytoskeleton distinguish ecotropic murine leukemia virus entry via endocytosis from entry via surface fusion

Kizhatil, Krishnakumar; Albritton, Lorraine M.

doi:10.1128/jvi.71.10.7145-7156.1997

Cited by 91 publications

(34 citation statements)

References 56 publications

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“…After treatment, the cells were infected with ISKNV for 4 h at 27 • C, in the presence of mSDP. Noninternalized viruses were removed by removing virus inocula and washing the cells with citrate buffer (40 mM sodium citrate, 10 mM KCl, 135 mM NaCl, pH 3.0) for 1 min at room temperature (Kizhatil and Albritton, 1997). Western blotting and immunofluorescence analysis for ISKNV membrane protein ORF101L expression were carried out at 72 h post-infection.…”

Section: Effects Of Msdp On Isknv Infectionmentioning

confidence: 99%

Involvement of caveolin-1 in the Jak–Stat signaling pathway and infectious spleen and kidney necrosis virus infection in mandarin fish (Siniperca chuatsi)

Guo

Yang

et al. 2011

Molecular Immunology

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Caveolae, the major source of caveolin-1 protein, are specialized invaginated microdomains of the plasma membrane that act as organizing centers for signaling molecules in the immune system. In the present study, we report the cloning and characterization of caveolin-1 (mCav-1) from mandarin fish (Siniperca chuatsi) and study on the roles of mCav-1 in the fish Jak-Stat signaling pathway and in virus infection. The cDNA sequence of mCav-1 was 707bp in size, encoding a protein of 181 amino acids, which was different from the mammalian protein (178 amino acids). The deduced amino acid sequence of mCav-1 shared similar architecture with vertebrate caveolin-1 proteins, but mCav-1 lacked a phosphorylation site (y14). The major subcellular location of mCav-1 was in the caveolae, where the protein appeared to have major functions. Real-time PCR revealed that the expression of the mandarin fish Mx, IRF-1, SOCS1, and SOCS3 genes involved in the poly(I:C)-induced Jak-Stat signaling pathway was impaired by the mCav-1 scaffolding domain peptide (mSDP). In mandarin fish fry (MFF-1) cells, the protein levels of mCav-1 were markedly up-regulated at 12 and 24h post-infection with ISKNV (infectious spleen and kidney necrosis virus). In addition, ISKNV entry into MFF-1 cells was significantly inhibited by mSDP, and the inhibition was dose-dependent. Thus, ISKNV infection was apparently associated with mCav-1 protein and may utilize the caveolae-related endocytosis pathway. The findings reported here further our understanding of the function of caveolin-1 in the complex signal transduction network in fish immune systems and in the cellular entry mechanism of iridoviruses.

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Section: Effects Of Msdp On Isknv Infectionmentioning

confidence: 99%

Involvement of caveolin-1 in the Jak–Stat signaling pathway and infectious spleen and kidney necrosis virus infection in mandarin fish (Siniperca chuatsi)

Guo

Yang

et al. 2011

Molecular Immunology

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“…Virus binding assay and syncytium induction. The virus binding assays were performed as described previously (15), except that some cells were incubated in medium containing 100 M CA-074 Me at 37°C for 30 min prior to detachment of cells and during the 1-h incubation of replication-competent wild-type Moloney MLV with NIH 3T3 cells. To quantify virus-induced cell-cell fusion, XC or NIH 3T3 cells seeded at 50% confluence in 24-well tissue culture plates were preincubated in the presence or absence of the indicated amounts of CA-074Me for 2 h to inhibit endogenous cathepsin B, the inhibitor was washed out once with regular culture medium, and then replicate wells (n ϭ 3; in some cases, n ϭ 4) were exposed to replication-defective MLV particles pseudotyped with Moloney MLV Env.…”

Section: Cell Lines and Virusesmentioning

confidence: 99%

Host Cell Cathepsins Potentiate Moloney Murine Leukemia Virus Infection

Kumar

Nachagari

Fields

et al. 2007

J Virol

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The roles of cellular proteases in Moloney murine leukemia virus (MLV) infection were investigated using MLV particles pseudotyped with vesicular stomatitis virus (VSV) G glycoprotein as a control for effects on core MLV particles versus effects specific to Moloney MLV envelope protein (Env). The broad-spectrum inhibitors cathepsin inhibitor III and E-64d gave comparable dose-dependent inhibition of Moloney MLV Env and VSV G pseudotypes, suggesting that the decrease did not involve the envelope protein. Whereas, CA-074 Me gave a biphasic response that differentiated between Moloney MLV Env and VSV G at low concentrations, at which the drug is highly selective for cathepsin B, but was similar for both glycoproteins at higher concentrations, at which CA-074 Me inhibits other cathepsins. Moloney MLV infection was lower on cathepsin B knockout fibroblasts than wild-type cells, whereas VSV G infection was not reduced on the B ؊/؊ cells. Taken together, these results support the notion that cathepsin B acts at an envelope-dependent step while another cathepsin acts at an envelope-independent step, such as uncoating or viral-DNA synthesis. Virus binding was not affected by CA-074 Me, whereas syncytium induction was inhibited in a dose-dependent manner, consistent with cathepsin B involvement in membrane fusion. Western blot analysis revealed specific cathepsin B cleavage of SU in vitro, while TM and CA remained intact. Infection could be enhanced by preincubation of Moloney MLV with cathepsin B, consistent with SU cleavage potentiating infection. These data suggested that during infection of NIH 3T3 cells, endocytosis brings Moloney MLV to early lysosomes, where the virus encounters cellular proteases, including cathepsin B, that cleave SU.

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“…After 1 h, the cells were infected with A-MLV (8 g/ml Polybrene) in the presence (1:50 to 1:1,000 dilutions) or absence (control) of anti-FN antibody. Noninternalized viral particles were inactivated 24 h later by using citrate buffer (40 mM sodium citrate, 10 mM KCl, 135 mM NaCl, pH 3.1) (18). The cells were investigated 24 h later for infection events using the ␤-Gal assay.…”

Section: Production Of Infectious and Fluorescent Noninfectious A-mlvmentioning

confidence: 99%

Matrix Fibronectin Binds Gammaretrovirus and Assists in Entry: New Light on Viral Infections

Beer¹,

Pedersen

2007

J Virol

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A major entry route for the gammaretrovirus amphotropic murine leukemia virus (A-MLV) into NIH 3T3 fibroblasts is via caveola-dependent endocytosis. However, during the infection time, few viral particles can be observed intracellularly. Analyzing the dynamics of the A-MLV infection process by using total internal reflection fluorescence microscopy, we show that the majority of viruses are extracellular and bound to the fibronectin matrix. Moreover, the amounts of bound virus and of fibronectin correlated. Using confocal microscopy, nanoparticles targeted to fibronectin by a III1C-fibronectin fragment or anti-fibronectin antibody were detected intracellularly in NIH 3T3 cells; unconjugated nanoparticles neither bound to cells nor were detectable intracellularly. Furthermore, A-MLV colocalized intracellularly with the fibronectin-targeted nanoparticles, suggesting that they were taken up by the same cellular pathway. Both A-MLV entry and fibronectin turnover depend on caveolar endocytosis, and we found that inhibiting viral binding to the extracellular NIH 3T3 fibronectin-matrix dramatically reduced A-MLV infection, indeed, showing an active role of fibronectin in infection. We suggest that binding to the cellular fibronectin matrix provides a new mechanism by which viruses can enter cells.Knowledge of the role of cellular factors in retroviral entry increases our understanding of how viruses can exploit cellular features to enter host cells. Gammaretroviruses, like other enveloped viruses, are dependent on specific cellular receptors for fusion of the viral membrane with the cellular membrane; e.g., amphotropic murine leukemia virus (A-MLV) depends on the presence of the ubiquitously expressed sodium-dependent phosphate transporter Pit2 (17,29,48,50). MLV-based retroviral vectors including vectors carrying A-MLV envelope proteins are widely used in gene therapy protocols, and although retroviruses and retroviral vectors can infect a variety of dividing cell types, the efficiencies vary greatly among different cell types despite the fact that these cells all express Pit2 (48). Specifically, efficient transduction of hematopoietic cells can only be achieved when infection occurs in the presence of chymotryptic fibronectin (FN) fragments like 30/35 FN, recombinant chimeric FN fragments like CH-296 (RetroNectin) (13, 32), or shed FN (sFN) derived from NIH 3T3-based packaging cell lines (21 and C. S. Søndergaard, C. Haldrup, C. Beer, D. B. Kohn, and L. Pedersen, submitted for publication). It has been suggested that increased infection is due to concomitant binding of vectors and cells to the fibronectin fragments and that this increases the likelihood that a vector and a cell will interact compared to the situation where both vectors and cells would be in suspension (13, 31). In agreement with this hypothesis, we could recently show that gammaretroviral vectors bind to sFN from NIH 3T3 cultures (Søndergaard et al., submitted).However, the role of naturally occurring FN in viral entry is largely unknown.FN is a compo...

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Requirements for different components of the host cell cytoskeleton distinguish ecotropic murine leukemia virus entry via endocytosis from entry via surface fusion

Cited by 91 publications

References 56 publications

Involvement of caveolin-1 in the Jak–Stat signaling pathway and infectious spleen and kidney necrosis virus infection in mandarin fish (Siniperca chuatsi)

Involvement of caveolin-1 in the Jak–Stat signaling pathway and infectious spleen and kidney necrosis virus infection in mandarin fish (Siniperca chuatsi)

Host Cell Cathepsins Potentiate Moloney Murine Leukemia Virus Infection

Matrix Fibronectin Binds Gammaretrovirus and Assists in Entry: New Light on Viral Infections

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