scholarly journals Multiple Regulatory Domains of IRF-5 Control Activation, Cellular Localization, and Induction of Chemokines That Mediate Recruitment of T Lymphocytes

2002 ◽  
Vol 22 (16) ◽  
pp. 5721-5740 ◽  
Author(s):  
Betsy J. Barnes ◽  
Merrill J. Kellum ◽  
Ann E. Field ◽  
Paula M. Pitha

ABSTRACT Transcription factors of the interferon regulatory factor (IRF) family have been identified as critical mediators of early inflammatory gene transcription in infected cells. We recently determined that, besides IRF-3 and IRF-7, IRF-5 serves as a direct transducer of virus-mediated signaling. In contrast to that mediated by the other two IRFs, IRF-5-mediated activation is virus specific. We show that, in addition to Newcastle disease virus (NDV) infection, vesicular stomatitis virus (VSV) and herpes simplex virus type 1 (HSV-1) infection activates IRF-5, leading to the induction of IFNA gene subtypes that are distinct from subtypes induced by NDV. The IRF-5-mediated stimulation of inflammatory genes is not limited to IFNA since in BJAB/IRF-5-expressing cells IRF-5 stimulates transcription of RANTES, macrophage inflammatory protein 1β, monocyte chemotactic protein 1, interleukin-8, and I-309 genes in a virus-specific manner. By transient- transfection assay, we identified constitutive-activation (amino acids [aa] 410 to 489) and autoinhibitory (aa 490 to 539) domains in the IRF-5 polypeptide. We identified functional nuclear localization signals (NLS) in the amino and carboxyl termini of IRF-5 and showed that both of these NLS are sufficient for nuclear translocation and retention in infected cells. Furthermore, we demonstrated that serine residues 477 and 480 play critical roles in the response to NDV infection. Mutation of these residues from serine to alanine dramatically decreased phosphorylation and resulted in a substantial loss of IRF-5 transactivation in infected cells. Thus, this study defines the regulatory phosphorylation sites that control the activity of IRF-5 in NDV-infected cells and provides further insight into the structure and function of IRF-5. It also shows that the range of IRF-5 immunoregulatory target genes includes members of the cytokine and chemokine superfamilies.

2003 ◽  
Vol 50 (3) ◽  
pp. 667-676 ◽  
Author(s):  
Krystyna W Nahlik ◽  
Anna K Mleczko ◽  
Magdalena K Gawlik ◽  
Hanna B Rokita

Vaccinia virus is able to replicate in many cell types and is known to modulate apoptosis in infected cells. In this study, expression of apoptosis-related genes was screened in human adherent monocytes after vaccinia infection using a DNA array. A marked increase of the key glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) expression was found. Increased expression and nuclear translocation of GAPDH have recently been reported to participate in apoptosis of many cell types. To confirm the array results, levels of GAPDH mRNA were estimated by RT-PCR, showing an increase at 4 h p.i. followed by a slight decrease, which correlated with the viral anti-apoptotic E3L gene transcript levels. Subcellular localization of the enzyme in human monocytes was examined by Western blot and immunostaining of the infected cells. Both experiments revealed accumulation of GAPDH in the nucleus at 14 h p.i., which was completely suppressed at 24 h p.i. This might indicate GAPDH as a novel target for vaccinia anti-apoptotic modulation.


2001 ◽  
Vol 360 (2) ◽  
pp. 321-333 ◽  
Author(s):  
Claire JOSSE ◽  
Johan R. BOELAERT ◽  
Martin BEST-BELPOMME ◽  
Jacques PIETTE

The transcription factor, nuclear factor κB (NF-κB), is activated by various stimuli including cytokines, radiation, viruses and oxidative stress. Here we show that, although induction with H2O2 gives rise to NF-κB nuclear translocation in both lymphocyte (CEM) and monocyte (U937) cells, it leads only to the production of mRNA species encoding interleukin-8 (IL-8) and macrophage inflammatory protein 1α in U937 cells. Under similar conditions these mRNA species are not observed in CEM cells. With the use of a transient transfection assay of U937 cells transfected with reporter constructs of the IL-8 promoter and subsequently treated with H2O2, we show that (1) IL-8-promoter-driven transcription is stimulated in both U937 and CEM cells and (2) the NF-κB site is crucial for activation because its deletion abolishes activation by H2O2. The production of IL-8 mRNA in U937 cells is inhibited by the NF-κB inhibitors clasto-lactacystin-β-lactone and E-64D (l-3-trans-ethoxycarbonyloxirane-2-carbonyl-l-leucine-3-methyl amide) but requires protein synthesis de novo. Moreover, inhibition of the p38 mitogen-activated protein kinase also decreases the IL-8 mRNA up-regulation mediated by H2O2. Taken together, these results show the importance of post-transcriptional events controlled by a p38-dependent pathway in the production of IL-8 mRNA in U937. The much lower activation of p38 in CEM cells in response to H2O2 could explain the lack of stabilization of IL-8 mRNA in these cells.


Microbiology ◽  
2000 ◽  
Vol 81 (2) ◽  
pp. 401-406 ◽  
Author(s):  
Takayuki Murata ◽  
Fumi Goshima ◽  
Tohru Daikoku ◽  
Kyoko Inagaki-Ohara ◽  
Hiroki Takakuwa ◽  
...  

In this study, mitochondria migrated to a perinuclear region in the cytoplasm in herpes simplex virus (HSV)-infected cells. HSV infection did not promote the expression of cytochrome c oxidase subunit 2 but did promote that of stress-responsive HSP60, both of which are known to be components of mitochondria. The levels of cellular ATP and lactate and mitochondrial membrane potential were maintained for at least 6 h but decreased at the late stage of infection. It was also found that the UL41 and UL46 gene products, both of which are known to be tegument proteins, accumulated in the perinuclear region. The clustering of mitochondria and the accumulation of tegument proteins were completely blocked by the addition of nocodazole and vinblastine. These results suggest that mitochondria respond to the stimulation of HSV infection, migrating with tegument proteins along microtubules to a site around the nucleus, and maintain function until at least the middle stage of infection.


1999 ◽  
Vol 19 (2) ◽  
pp. 959-966 ◽  
Author(s):  
Rongtuan Lin ◽  
Christophe Heylbroeck ◽  
Pierre Genin ◽  
Paula M. Pitha ◽  
John Hiscott

ABSTRACT Localized and systemic cytokine production in virus-infected cells play an important role in the outcome of viral infection and pathogenicity. Activation of the interferon regulatory factors (IRF) in turn is a critical mediator of cytokine gene transcription. Recent studies have focused on the 55-kDa IRF-3 gene product as a direct transcriptional regulator of type 1 interferon (IFN-α and IFN-β) activation in response to virus infection. Virus infection induces phosphorylation of IRF-3 on specific C-terminal serine residues and permits cytoplasmic-to-nuclear translocation of IRF-3, activation of DNA binding and transactivation potential, and association with the CBP/p300 coactivator. We previously generated constitutively active [IRF-3(5D)] and dominant-negative forms of IRF-3 that control IFN-β and IFN-α gene expression. In an effort to characterize the range of immunoregulatory genes controlled by IRF-3, we now demonstrate that endogenous human RANTES gene transcription is directly induced in tetracycline-inducible IRF-3(5D)-expressing cells or paramyxovirus-infected cells. We also show that a dominant-negative IRF-3 mutant inhibits virus-induced expression of the RANTES promoter. Specific mutagenesis of overlapping ISRE-like sites located between nucleotides −123 and −96 in the RANTES promoter reduces virus-induced and IRF-3-dependent activation. These studies broaden the range of IRF-3 immunoregulatory target genes to include at least one member of the chemokine superfamily.


1999 ◽  
Vol 73 (5) ◽  
pp. 3893-3903 ◽  
Author(s):  
Susana Asin ◽  
Julie A. Taylor ◽  
Sergey Trushin ◽  
Gary Bren ◽  
Carlos V. Paya

ABSTRACT Human monocytes and macrophages are persistent reservoirs of human immunodeficiency virus (HIV) type-1. Persistent HIV infection of these cells results in increased levels of NF-κB in the nucleus secondary to increased IκBα, IκBβ, and IκBɛ degradation, a mechanism postulated to regulate viral persistence. To characterize the molecular mechanisms regulating HIV-mediated degradation of IκB, we have sought to identify the regulatory domains of IκBα targeted by HIV infection. Using monocytic cells stably expressing different transdominant molecules of IκBα, we determined that persistent HIV infection of these cells targets the NH2 but not the COOH terminus of IκBα. Further analysis demonstrated that phosphorylation at S32 and S36 is necessary for HIV-dependent IκBα degradation and NF-κB activation. Of the putative N-terminal IκBα kinases, we demonstrated that the Iκκ complex, but not p90 rsk , is activated by HIV infection and mediates HIV-dependent NF-κB activation. Analysis of viral replication in cells that constitutively express IκBα negative transdominant molecules demonstrated a lack of correlation between virus-induced NF-κB (p65/p50) nuclear translocation and degree of viral persistence in human monocytes.


2001 ◽  
Vol 75 (20) ◽  
pp. 9955-9965 ◽  
Author(s):  
Emily S. Scott ◽  
Sophie Malcomber ◽  
Peter O'Hare

ABSTRACT Transcription factors of the NFAT (nuclear factor of activated T cells) family are expressed in most immune system cells and in a range of other cell types. Signaling through NFAT is implicated in the regulation of transcription for the immune response and other processes, including differentiation and apoptosis. NFAT normally resides in the cytoplasm, and a key aspect of the NFAT activation pathway is the regulation of its nuclear import by the Ca2+/calmodulin-dependent phosphatase calcineurin. In a cell line stably expressing green fluorescent protein (GFP)-NFAT, this import can be triggered by elevation of intracellular calcium and visualized in live cells. Here we show that the inducible nuclear import of GFP-NFAT is efficiently blocked at early stages of herpes simplex virus (HSV) infection. This is a specific effect, since we observed abundant nuclear accumulation of a test viral protein and no impediment to general nuclear localization signal-dependent nuclear import and retention in infected cells. We show that virus binding at the cell surface is not itself sufficient to inhibit the signaling that induces NFAT nuclear translocation. Since the block occurs following infection in the presence of phosphonoacetic acid but not cycloheximide, we infer that the entry of the virion and early gene transcription are required but the effect is independent of DNA replication or late virus gene expression. A consequence of the block to GFP-NFAT import is a reduction in NFAT-dependent transcriptional activation from the interleukin-2 promoter in infected cells. This HSV-mediated repression of the NFAT pathway may constitute an immune evasion strategy or subversion of other NFAT-dependent cellular processes to promote viral replication.


Author(s):  
Z. Hong Zhou ◽  
Jing He ◽  
Joanita Jakana ◽  
J. D. Tatman ◽  
Frazer J. Rixon ◽  
...  

Herpes simplex virus-1 (HSV-1) is a ubiquitous virus which is implicated in diseases ranging from self-curing cold sores to life-threatening infections. The 2500 Å diameter herpes virion is composed of a glycoprotein spike containing, lipid envelope, enclosing a protein layer (the tegument) in which is embedded the capsid (which contains the dsDNA genome). The B-, and A- and C-capsids, representing different morphogenetic stages in HSV-1 infected cells, are composed of 7, and 5 structural proteins respectively. The three capsid types are organized in similar T=16 icosahedral shells with 12 pentons, 150 hexons, and 320 connecting triplexes. Our previous 3D structure study at 26 Å revealed domain features of all these structural components and suggested probable locations for the outer shell proteins, VP5, VP26, VP19c and VP23. VP5 makes up most of both pentons and hexons. VP26 appeared to bind to the VP5 subunit in hexon but not to that in penton.


2009 ◽  
Vol 83 (9) ◽  
pp. 4376-4385 ◽  
Author(s):  
Haidong Gu ◽  
Bernard Roizman

ABSTRACT Among the early events in herpes simplex virus 1 replication are localization of ICP0 in ND10 bodies and accumulation of viral DNA-protein complexes in structures abutting ND10. ICP0 degrades components of ND10 and blocks silencing of viral DNA, achieving the latter by dislodging HDAC1 or -2 from the lysine-specific demethylase 1 (LSD1)/CoREST/REST repressor complex. The role of this process is apparent from the observation that a dominant-negative CoREST protein compensates for the absence of ICP0 in a cell-dependent fashion. HDAC1 or -2 and the CoREST/REST complex are independently translocated to the nucleus once viral DNA synthesis begins. The focus of this report is twofold. First, we report that in infected cells, LSD1, a key component of the repressor complex, is partially degraded or remains stably associated with CoREST and is ultimately also translocated, in part, to the cytoplasm. Second, we examined the distribution of the components of the repressor complex and ICP8 early in infection in wild-type-virus- and ICP0 mutant virus-infected cells. The repressor component and ultimately ICP8 localize in structures that abut the ND10 nuclear bodies. There is no evidence that the two compartments fuse. We propose that ICP0 must dynamically interact with both compartments in order to accomplish its functions of degrading PML and SP100 and suppressing silencing of viral DNA through its interactions with CoREST. In turn, the remodeling of the viral DNA-protein complex enables recruitment of ICP8 and initiation of formation of replication compartments.


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