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ABSTRACT: The skin has long been recognized as a prominent target tissue in systemic lupus erythematosus (SLE) which plays a crucial role in the initiation and perpetuation of the autoimmune reaction cascade as a consequence of ultraviolet (UV)-induced keratinocyte apoptosis. Antibodies against IFI16 (interferon-inducible protein 16) have been detected in the sera of patients with SLE.
To verify whether the induction of autoimmunity against IFI16 involves redistribution of this nuclear protein in keratinocytes during UVB-induced cell death.
An in vitro epidermal model was developed to investigate the fate of the IFI16 protein in keratinocytes after irradiation with UVB; both keratinocyte monolayers and human skin explants were used. IFI16 expression and localization were also analysed in diseased skin sections of patients with SLE.
We demonstrated that IFI16, normally restricted to the nucleus, can be induced to appear in the cytoplasm under conditions of UVB-induced cell injury. This nucleus to cytoplasm translocation was also observed in skin explants exposed to UVB and in the diseased skin sections from patients with SLE. In addition, IFI16 was found in the supernatants of UVB-exposed keratinocytes.
The finding that IFI16 is present in the cytoplasm of diseased skin cells from patients with SLE and the demonstration of IFI16 in the supernatants of UVB-exposed keratinocytes, suggest that UVB irradiation or other stimuli may favour an abnormal IFI16 presentation to the afferent limb of the immune system and potentially an autoimmune response against the protein itself.
British Journal of Dermatology 10/2010; 164(2):282-90. · 3.67 Impact Factor
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ABSTRACT: Expression of early (E) genes of human cytomegalovirus (HCMV) is stimulated cooperatively by the activities of host cell transcription factors and the viral immediate-early 2 (IE2) protein. Taking advantage of the IE2-dependent inducibility of E gene promoters, in this study, we generated cell-based assays in which the expression of the enhanced green fluorescence protein (EGFP) reporter gene was driven by the UL54 or UL112/113 E promoters.
Cell clones derived from a stably transfected human cell line permissive to HCMV replication showed a specific and inducible dose- and time-dependent EGFP response to HCMV infection. The sensitivity of these indicator cells for detecting infectious particles of clinical isolates of HCMV was comparable to that of a conventional plaque assay. The HCMV-induced EGFP expression was completely prevented by treatment of indicator cells with fomivirsen, an antisense oligodeoxynucleotide designed to block IE2 expression, and this inhibitory activity was also observed when the IE2 protein alone was constitutively expressed in EGFP indicator cells.
The EGFP-based cell assays have proved to be a rapid, sensitive, quantitative and specific system for detection of HCMV and selection of antivirals.
These new cell-based assays can be exploited as functional assays to detect infectious HCMV particles, as well as to screen antiviral compounds that interfere with IE2 activity.
Journal of Applied Microbiology 01/2009; 105(6):1791-801. · 2.34 Impact Factor
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ABSTRACT: To investigate whether the expression of interferon (IFN)-inducible gene IFI16 is inversely related to proliferative activity in vivo, we compared immunohistochemical reactivity of IFI16 in a series of head and neck squamous cell carcinomas (HNSCCs) with their proliferation index and the cell cycle regulator pRb. As human papillomavirus (HPV) infection is manifested by changes in the function or expression level of host genes such as IFN-inducible genes, we also investigated the presence of HPV DNA to determine whether head and neck cancers associated with HPV DNA can be distinguished from tumours that are presumably transformed by other mechanisms.
Thirty-six HNSCCs were evaluated for IFI16, pRb and Ki67 expression by immunohistochemistry. The presence of HPV was also detected by polymerase chain reaction. Nine tumours were located in the oropharynx (tonsillar area) and 27 in the larynx.
HPV DNA was found in 14 of 25 (56%) laryngeal SCCs and in five of nine (56%) tonsillar SCC specimens examined; 17 out of the 19 HPV-DNA-positive cases showed high-grade IFI16 expression. Overall, proliferative activity was significantly related to tumour differentiation and histological grading. IFI16 protein expression was significantly inversely correlated with Ki67 (P = 0.039). Low-proliferating tumours positive for IFI16 staining showed a marked expression of pRb and a better prognosis than those whose tumours had low IFI16, pRb levels and a high proliferation index.
To our knowledge, this is the first expression analysis of the IFN-inducible IFI16 gene in HNSCC. Low-proliferating tumours positive for IFI16 staining showed a marked expression of pRb and a better prognosis than those whose tumours had low IFI16, pRb levels and a high proliferation index.
Histopathology 01/2005; 45(6):560-72. · 3.08 Impact Factor
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ABSTRACT: Antibodies (Abs) against the structure specific recognition protein 1 (SSRP1) were reported in a small systemic lupus erythematosus (SLE) series but not in other systemic autoimmune diseases. The aim of the study was to confirm the selective presence of anti-SSRP1 Abs in a larger SLE series and to evaluate their relationship with disease activity and other immune markers. Anti-SSRP1 Abs were investigated by a 'home made' ELISA in: 120 SLE, 65 rheumatoid arthritis (RA), 51 systemic sclerosis (SSc), 23 Churg-Strauss syndrome (CSS) and 40 idiopathic autoimmune urticaria (IAU) patients and 190 healthy controls. Sera from MRL lpr/lpr and Balb-c mice were also tested. Anti-SSRP1 Abs were detected in 43 SLE (35.8%), nine SSc (17.6%), eight RA (12.3%), six IAU (15%), three CSS (13%) patients and five healthy controls (2.6%). Antibody prevalence and titers were significantly higher in SLE patients than in sera from both normal and disease controls. Anti-SSRP1 Ab activity was also detected in sera from MRL lpr/lpr but not Balb-c mice. The antibodies did not correlate with the disease activity evaluated as the ECLAM index score and were more prevalent in patients without renal involvement. No correlation was found with other serum autoantibodies. Our results confirm that anti-SSRP1 Abs are associated with but not specific for the lupus disease.
Lupus 02/2004; 13(6):463-8. · 2.34 Impact Factor
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ABSTRACT: Two different isozymes (Iso A and Iso B) of catechol 1,2 dioxygenase (C1,2O) were isolated from cultures of A. radioresistens grown in two different media, containing phenol and benzoate respectively. In the phenol medium the bacteria expressed about 90% of Iso A, whereas in the benzoate medium the Iso A/Iso B ratio was 40:60. The two proteins have different molecular masses, isoelectric points and N-terminal sequences that are not consistent with simple post-translational modifications. Furthermore, their behaviour differs at high temperatures (42 degrees C-47 degrees C) and at moderately acidic pH (pH 6.0): Iso A proved to be the more stable under conditions of environmental stress. Hybridisation analysis with an A. calcoaceticus catA-derived probe revealed that A. radioresistens C1,2O proteins are encoded by two chromosomally located genes. Bidimensional electrophoresis (2DE) maps of crude extracts of cells grown in different carbon sources (phenol, benzoate and acetate) clearly demonstrated a differential induction pattern for the two proteins. The hypothesis of a double set of genes, one for benzoate catabolism and the other for phenol catabolism, is discussed, and analogies are drawn with other known C1,2Os.
Biological Chemistry 09/2001; 382(8):1253-61. · 2.96 Impact Factor
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ABSTRACT: Infection of cells with viable or UV-inactivated murine cytomegalovirus (MCMV) increased the IFN-inducible 204 gene at both the mRNA and the protein levels. The activity of a reporter gene driven by the mouse Ifi204 promoter induced following virus infection showed that this increase was due to transcriptional activation. Moreover, FACS analysis of infected mouse embryo fibroblasts (MEF) stably transfected with a p204-dominant-negative mutant (p204dmMEF) revealed that they do not accumulate at the G1/S border in the same way as infected MEF transfected with the empty vector (neoMEF). MCMV DNA synthesis is significantly delayed (144 h in p204dmMEF vs 72 h in neoMEF), due to retarded expression of viral genes, namely, IE1 and DNA polymerase, as shown by Western blot comparison of p204dmMEF and neoMEF extracts. These results demonstrate that MCMV may exploit the Ifi204 gene to regulate the cell cycle and enhance its DNA synthesis.
Virology 09/2001; 286(2):249-55. · 3.35 Impact Factor
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ABSTRACT: The course of mouse cytomegalovirus (MCMV) infection was compared between mutant C57BL/6 (B6) mice deficient in either perforin (perf-/-), or perforin, granzyme A and B (perfxgzmAxB-/-), and B6 gld mice lacking functionally active Fas ligand to elucidate the contribution of the two main cytolytic pathways in the early control of MCMV infection. At 15 and 30 days post infection (p.i.) virus titers were elevated in salivary glands of perf-/- and perfxgzmAxB-/-, but almost undetectable in those of mutant gld and C57BL/6 wild-type mice. No virus was detectable in lung and spleen tissues of the mutant or B6 mice at the time points tested. At 15 days p.i., scanty lymphocytic periductal infiltration was seen in salivary glands of perf-/- and perfxgzmAxB-/; these pathological alterations were minimal at 30 days p.i.. In contrast, no pathological alterations were seen in the respective organs of infected B6 and gld mice at the two time points p.i.. At 15 days p.i., reactive follicles were observed in the white pulp of spleen tissues from both mutant and B6 mice, but at 30 days p.i. only in those of mutant mice. No inflammatory responses were seen in the lung tissues of any of the four mouse strains tested. Together with previous observations (Riera et al.. 2000), the results demonstrate that both perforin and granzymes A/B, but not the FasL/Fas system are critical for viral elimination in salivary glands during the acute phase of infection. However, for the long-term control of MCMV infection, neither of the two cytolytic pathways seem to be necessary.
The new microbiologica: official journal of the Italian Society for Medical, Odontoiatric, and Clinical Microbiology (SIMMOC) 08/2001; 24(3):231-8. · 1.00 Impact Factor
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ABSTRACT: Cytomegalovirus (CMV) replication in non-proliferating cells requires the coordinated expression of the host enzymes responsible for deoxyribonucleotide synthesis. Thymidylate synthase (TS) is an essential cellular enzyme that catalyzes de novo synthesis of thymidylic acid (dTMP). In this report we show that murine CMV (MCMV) replication and DNA synthesis are inhibited in quiescent 3T6 fibroblasts by raltitrexed, a quinazoline-based folate analog that specifically inhibits TS. This antiviral activity was abrogated in LU3-7 cells, a 3T6 derivative that overproduces TS by about 50-fold. These observations indicate that the anticytomegaloviral activity of raltitrexed is associated with TS inhibition and suggest that cellular TS activity is required for efficient CMV replication in quiescent cells.
Virus Research 02/2001; 73(1):57-65. · 2.94 Impact Factor
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ABSTRACT: Cytomegalovirus (CMV) infection stimulates the expression of cellular enzymes involved in the biosynthesis of DNA precursors. Among them, dihydrofolate reductase (DHFR) and thymidylate synthase (TS) require folate as coenzymes. In growing cells, folates are readily converted to polyglutamated forms by the cellular enzyme folylpolyglutamate synthetase (FPGS). Polyglutamated folates are selectively retained within the cell and have an increased affinity for DHFR and TS. Here we report that murine CMV (MCMV) increases the levels of the FPGS mRNAs as well as the enzymatically active FPGS protein through a mechanism that requires viral gene expression. FPGS induction by MCMV would provide the necessary supply of polyglutamated folates to the cellular enzymes involved in the biosynthesis of deoxyribonucleotides, enabling viral DNA replication to take place in quiescent cells.
Intervirology 02/2001; 44(4):224-6. · 2.34 Impact Factor
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ABSTRACT: Ribonucleotide reductase (RNR) is an essential enzyme for the de novo synthesis of both cellular and viral DNA and catalyzes the conversion of ribonucleoside diphosphates into the corresponding deoxyribonucleoside diphosphates. The enzyme consists of two nonidentical subunits, termed R1 and R2, whose expression is very low in resting cells and maximal in S-phase cells. Here we show that murine cytomegalovirus (MCMV) replication depends on ribonucleotide reduction since it is prevented by the RNR inhibitor hydroxyurea. MCMV infection of quiescent fibroblasts markedly induces both mRNA and protein corresponding to the cellular R2 subunit, whereas expression of the cellular R1 subunit does not appear to be up-regulated. The increase in R2 gene expression is due to an increase in gene transcription, since the activity of a reporter gene driven by the mouse R2 promoter is induced following virus infection. Cotransfection experiments revealed that expression of the viral immediate-early 1 protein was sufficient to mediate the increase in R2 promoter activity. It was found that the viral gene M45, encoding a putative homologue of the R1 subunit, is expressed 24 and 48 h after infection. Meanwhile, we observed an expansion of the deoxyribonucleoside triphosphate pool between 24 and 48 h after infection; however, neither CDP reduction nor viral replication was inhibited by treatment with 10 mM thymidine. These findings indicate the induction of an RNR activity with an altered allosteric regulation compared to the mouse RNR following MCMV infection and suggest that the virus R1 homologue may complex with the induced cellular R2 protein to reconstitute a new RNR activity.
Journal of Virology 01/2001; 74(24):11557-65. · 5.40 Impact Factor
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ABSTRACT: We have previously demonstrated that overexpression of p204, a member of the Ifi 200 gene family, inhibits growth, delays G0/G1 progression into S phase, and impairs E2F-mediated transcriptional activity. In this study, we show that p204 directly binds the retinoblastoma protein (pRb) in vivo to exert its activity. Transient p204 overexpression in Rb+/+ mouse embryo fibroblasts (MEF) inhibits cell proliferation, but does not affect cell growth in MEF derived from Rb-/- mice. Two human cell lines, Saos2 and C33A, bearing an inactive pRb, but not primary human embryo fibroblasts, are resistant to the p204 antiproliferative activity. p204 contains two 200 amino acid motifs, designated as type a or b domains, each containing a canonical Rb binding motif (LXCXE). When dominant-negative mutants at the Rb binding motif were transfected in Rb+/+ MEF, p204 lost its ability to inhibit cell growth, delay cell transition from G1 to S phase, and impair DNA synthesis. Moreover p204 overexpression in Rb+/+ MEF led to a significant decrease of both DHFR and PCNA proteins, two S phase markers. By contrast, this effect was not observed when Rb+/+ MEF were transfected with a p204 mutated at both Rb binding sites. Finally, overexpression of the LXCXE p204 mutant rendered Rb+/+ MEF resistant to the IFN-alpha antiproliferative activity, in comparison to the untransfected Rb+/+ MEF. As expected, Rb-/- cells were unsensitive to the IFN-alpha induced growth inhibition. Taken as a whole, these results suggest that (i) p204 contributes to the IFN-alpha antiproliferative activity and (ii) the primary target of p204 leading to efficient G1 arrest as well as to blockade of DNA replication from G1 phase is the pRb regulatory system.
Oncogene 08/2000; 19(32):3598-608. · 6.37 Impact Factor
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ABSTRACT: Tomudex (ZD1694) is a quinazoline-based folate analog and a powerful inhibitor of cellular thymidylate synthase and is approved in Europe for use in oncology. Here the first evidence of its activity against murine and human cytomegalovirus (MCMV and HCMV) is reported. ZD1694 irreversibly inhibited the replication and DNA synthesis of both viruses in quiescent fibroblasts. The corresponding 50% effective concentrations were 0.006 and 0.002 microM respectively, whereas the 50% cytotoxic concentration was >10 microM for both murine and human quiescent fibroblasts. A similar antiviral effect was observed against two ganciclovir-resistant HCMV strains isolated from AIDS patients. Taken as a whole these results demonstrate that cellular thymidylate synthase plays an essential role in viral replication and that ZD1694 merits further investigation as anticytomegaloviral agent.
Antiviral Research 08/2000; 47(2):111-20. · 4.30 Impact Factor
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ABSTRACT: Herpesviruses accomplish DNA replication either by expressing their own deoxyribonucleotide biosynthetic genes or by stimulating the expression of the corresponding cellular genes. Cytomegalovirus (CMV) has adopted the latter strategy to allow efficient replication in quiescent cells. In the present report, we show that murine CMV (MCMV) infection of quiescent fibroblasts induces both mRNA and protein corresponding to the cellular thymidylate synthase (TS) gene, which encodes the enzyme that catalyzes the de novo synthesis of thymidylic acid. The increase in TS gene expression was due to an increase in gene transcription, since the activity of a reporter gene driven by the mouse TS promoter was induced following MCMV infection. Mutagenesis of the potential E2F-responsive element immediately upstream from the TS essential promoter region abolished the virus-mediated stimulation of the TS promoter, suggesting that the transactivating activity of MCMV infection was E2F dependent. Cotransfection experiments revealed that expression of the viral immediate-early 1 protein was sufficient to mediate the increase in TS promoter activity. Finally, MCMV replication and viral DNA synthesis were found to be inhibited by ZD1694, a quinazoline-based folate analog that inhibits TS activity. These results demonstrate that upregulation of cellular TS expression is required for efficient MCMV replication in quiescent cells.
Journal of Virology 07/2000; 74(11):4979-87. · 5.40 Impact Factor
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ABSTRACT: The course of mouse cytomegalovirus (MCMV) infection was compared between wild-type and mutant C57BL / 6 (B6) mice deficient in either RAG-2, perforin, granzyme A, granzyme B or combinations thereof at two time points post infection (p. i.). At day 15 p. i., virus titers were similarly elevated in salivary glands of all mutant, but not wild-type B6 mice and undetectable in lung and spleen tissues of any of the mouse strains. Significant pathological alterations were only seen in salivary glands and spleen from RAG2(- / -), but not in those from other mice whereas few inflammatory foci were observed in lung tissues of all mice except B6. At day 30 p. i., elevated virus titers were observed only in salivary glands, lung and spleen from RAG2(- / -), but in none of the other mice, and were accompanied by extended pathological alterations in all three organs. The data extend previous reports on the critical role of NK / CD8(+) T cells in the early control of MCMV infection by showing that both perforin and granzymes A / B contribute to viral elimination in salivary glands; however, neither of the three molecules alone seem to be indispensable for the final control of infection.
European Journal of Immunology 06/2000; 30(5):1350-5. · 5.10 Impact Factor
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ABSTRACT: Interferon-alpha (IFN) plays a role in the management of different neoplasias, particularly those of hematological origin. The mechanisms of action of IFN are still poorly understood and the individual response is unpredictable. In the present study, the pattern of intracellular gene expression following in vitro and in vivo exposure of chronic myeloid leukemia (CML) cells to IFN was evaluated and correlated with the response to in vivo treatment with IFN.
CML patients in different phases of the disease were studied. The pattern of expression of two IFN-inducible proteins involved in IFN-mediated biological activities, the p91 and p84 proteins (STAT1alpha and STAT1beta), components of the IFN-stimulated gene factor 3 (ISGF3) complex and the enzyme 2'-5' oligoadenylate synthetase (2'-5' OASE) were investigated by Western blot in peripheral blood mononuclear cells stimulated or not in vitro by IFN.
In 6/9 patients evaluated before starting treatment, STAT1 was expressed either constitutively or after in vitro stimulation by IFN. In three cases, STAT1 remained negative even after in vitro activation. The pattern of protein expression correlated with the subsequent hematological response to prolonged in vivo IFN administration: the presence of STAT1 being associated with the clinical response to IFN and the absence and non-inducibility of STAT1 with resistance to IFN. This was further substantiated by studies carried out in ten patients analyzed at the time of a documented clinico-hematological response or resistance to the in vivo administration of IFN. Finally, in order to establish whether the pattern of response to IFN treatment could be predicted at diagnosis, cells cyropreserved at diagnosis from patients with a documented complete response, confirmed also by cytogenetic negativity, or resistance, were studied. While complete responders proved STAT1 positive, none of the four resistant cases ever expressed STAT1. The expression of 2'-5' OASE did not correlate with the clinical response to IFN. This study documents the pivotal role of STAT1 in the in vitro and in vivo responses of CML cells to IFN. The constitutive or induced presence or absence of STAT1 shows a predictive correlation with the response or resistance to treatment with IFN and could be utilized to identify, at diagnosis, resistant patients who may be spared an expensive and unnecessary prolonged IFN administration.
The Hematology Journal 02/2000; 1(1):7-14. · 1.86 Impact Factor
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ABSTRACT: To examine whether Ifi 200 genes are involved in antiviral state induction by IFNs we expressed mutant forms capable of inactivating the endogenous p204 and analyzed replication of both RNA and DNA viruses following IFN-alpha treatment. Inactivation of p204 does not impair replication of vesicular stomatitis virus, encephalomyocarditis virus, ectromelia virus, and herpes simplex virus 1 and does not alter an IFN-alpha induced antiviral state. By contrast, in cells lacking functional p204, mouse cytomegalovirus (MCMV) replication is strongly inhibited and is not further modulated by IFN-alpha. These results suggest that p204, a member of the Ifi 200 gene family, is not involved in the IFN-alpha-induced antiviral activity against some RNA or DNA viruses, but is required by MCMV for its replication.
Virology 10/1999; 262(1):1-8. · 3.35 Impact Factor
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ABSTRACT: Recent evidence has shown that human papillomavirus (HPV) is involved in both the development of carcinoma and in premalignant mucosal lesions of the oral cavity. This study examined the relationship of HPV infection to some pathological features in precancerous lesions of the larynx, not examined extensively so far. Fifty formalin-fixed paraffin-embedded tissue sections containing human laryngeal precancerous lesions were screened for the presence of HPV infection by polymerase chain reaction, and for capsid protein expression by immunohistochemistry with polyclonal antibody directed against the L1 protein. The presence of HPV DNA was detected in 28 of 50 specimens (56%), including 9/12 cases with mild dysplasia (75%), 3/6 cases with moderate dysplasia (50%), and 7/11 cases with severe dysplasia (64%). Multiple HPV infections, containing two or three types, were detected in 17 of the 28 HPV-positive lesions (60%). Of 21 cases with keratosis and no dysplasia, 11 were positive for HPV DNA (52%) and 4 showed L1 staining (36%). By contrast, L1 positivity was revealed only in two lesions with moderate dysplasia, confirming that fully productive HPV infection is strictly dependent on epithelial differentiation and surface keratinization. The probability that HPV is a cofactor in the malignant progression of these lesions is suggested by the fact that 3/4 patients who developed cancer within 50 months were positive for HPV DNA.
Journal of Medical Virology 10/1999; 59(1):110-6. · 2.82 Impact Factor
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ABSTRACT: Interferon-inducible proteins, p200, have a modular organization consisting of one (p203) or two (p202 and p204) 200 amino acid motifs, designated as type a or b domains. The relationship between this domain organization and the antiproliferative activity was investigated by generating a hybrid protein with the 204 a domain upstream from the 203 b domain. This 204a/203b protein inhibits the proliferation of transfected cells, delays G0/G1 progression into S phase following serum restimulation, and inhibits the E2F-mediated transcriptional activity. These results demonstrate for the first time that both a and b domains are needed for inhibition of proliferation by the Ifi 200 proteins.
FEBS Letters 08/1999; 456(1):31-6. · 3.54 Impact Factor
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ABSTRACT: The interferon (IFN)-inducible protein family 200 is encoded by structurally related genes located on mouse chromosome 1. The encoded proteins so far characterized and designated p202, p204, and pD3 contain at least one copy of a conserved 200 amino acid domain in addition to other regions that are different or missing among the various family members. We have recently characterized a cDNA clone (203 cDNA) encoding a 408 amino acid protein bearing structural similarities to p202 and p204. Here, we report its pattern of expression in vitro and in vivo. In vitro, the mRNA and protein encoded by the 203 gene were increased by IFN-alpha in several cell lines of different histologic origin. By contrast, no significant induction was observed in vivo in mice from C57BL/6 and BALB/c strains even after treatment with the IFN-inducer poly rI:rC. In addition, the constitutive expression of 203 gene was restricted to some myeloid and lymphoid tissues, namely, thymus, bone marrow, and spleen. Comparison of the expression pattern of the 203 and 202 genes in three mouse strains revealed that they exhibit a differential inducibility by IFN and a reciprocal expression pattern. The 203 mRNA was constitutively expressed in C57BL/6 and BALB/c mice and undetectable in the spleen of DBA/2 mice. The 202 mRNA was strongly induced by poly rI:rC in the spleen of DBA/2 and BALB/c mice but absent in C57BL/6 mice. Southern analysis revealed a restriction fragment length polymorphism in the 203 locus. Taken as a whole, these results demonstrate a remarkable difference in the in vivo IFN responsiveness of two members belonging to the same gene family with a similar degree of IFN inducibility in vitro. Moreover, the reciprocal expression pattern in C57BL/6 and DBA/2 mice could mean that p203 and p202 play the same role in a mouse strain in which only one of them is expressed.
Journal of Interferon & Cytokine Research 03/1999; 19(2):129-36. · 3.06 Impact Factor
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ABSTRACT: Cytomegalovirus (CMV) stimulates numerous cellular pathways upon infection. One of these pathways involves activation of dihydrofolate reductase (DHFR), an essential enzyme in the biosynthesis of purines and thymidylate. Here we report that methotrexate (MTX), an inhibitor of DHFR, suppresses murine CMV replication at the level of DNA synthesis in quiescent NIH 3T3 cells. However, MTX has no antiviral activity in NIH 3T3 sublines resistant to MTX due to DHFR overexpression. These results directly link MTX antiviral activity to DHFR and demonstrate that DHFR plays an essential role for CMV replication in quiescent cells.
Archives of Virology 02/1999; 144(7):1397-403. · 2.11 Impact Factor
