Expression of Viral and Human dUTPase in Epstein-Barr Virus -Associated Diseases.

Deoxyuridine triphosphatase (dUTPase) catalyses the hydrolysis of dUTP to dUMP and pyrophosphate thus preventing the incorporation of uracil into replicating DNA. Previous studies of several virus models have suggested that viral dUTPases may be required for virus replication in resting cells whereas in proliferating cells cellular dUTPase may substitute for a mutant viral protein. Using monoclonal antibodies and immunohistochemistry, Epstein-Barr virus-associated nonneoplastic and neoplastic diseases were studied for the expression of viral and human dUTPases. Oral hairy leukoplakia, an AIDS-associated lesion of the tongue, is known to support EBV replication in the upper epithelial cell layers. In agreement with this, strong focal expression of EBV dUTPase was detected in the upper epithelial cell layers of oral hairy leukoplakia whereas expression of human dUTPase was confined to the basal proliferative cell compartment. Furthermore, in infectious mononucleosis tonsils, rare scattered small lymphoid cells expressed EBV dUTPase, consistent with the expression pattern of other EBV lytic cycle antigens. These findings are in agreement with the notion that EBV replicates in resting cells. Three EBV-associated tumours, Hodgkin lymphoma, Burkitt lymphoma and nasopharyngeal carcinoma, lacked detectable expression of EBV dUTPase, in agreement with the notion that EBV infection is largely latent in these tumours. By contrast, expression of human dUTPase was observed regularly in these tumours. These results suggest that EBV dUTPase may be a suitable target for anti-viral therapy and that inhibitors of human dUTPase should prove useful for the treatment of human tumours, including EBV-associated cancers

A new strategy for the development of monoclonal antibodies for the determination of human procalcitonin in serum samples.

Procalcitonin (PCT)-a diagnostic serum parameter for bacterial infection and sepsis-is of great interest in the field of biosensors for point-of-care testing. Its detection needs specific biological recognition elements, such as antibodies. Herein, we describe the development and characterization of rat monoclonal antibodies (mAbs) for PCT, and their application in enzyme-linked immunosorbent assays (ELISAs) for the determination of PCT in patient serum samples. From about 50 mAbs, two mAbs, CALCA 2F3 and CALCA 4A6, were selected as a pair with high affinity for PCT in sandwich immunoassays. Both mAbs could be used either as capture or as detection mAb. They were Protein G-purified and biotinylated when used as detection mAb. The setup of two sandwich ELISAs with standards of human recombinant (hr) PCT, using either CALCA 2F3 (assay A) or CALCA 4A6 (assay B) as capture mAbs and the biotinylated mAbs CALCA 4A6 or CALCA 2F3, respectively, as detection mAbs, led to highly specific determinations of PCT without cross-reactivity to calcitonin and katacalcin. Test midpoints (IC(50)) of both assays were determined for hrPCT standards in 4% (w/v) human serum albumin and found with 2.5 (assay A) and 2.7 μg L(-1) (assay B). With both sandwich ELISAs a collection of eight patient serum samples have been determined in comparison to the determination by the Elecsys BRAHMS PCT assay. Good correlations between our prototype ELISAs and the BRAHMS assay could be demonstrated (R (2): assay A, 0.996 and assay B, 0.990). The use of these newly developed anti-PCT mAbs should find broad applications in immunosensors for point-of-care diagnostics of sepsis and systemic inflammation processes

Np9, a cellular protein of retroviral ancestry restricted to human, chimpanzee and gorilla, binds and regulates ubiquitin ligase MDM2.

Humans and primates are long-lived animals with long reproductive phases. One factor that appears to contribute to longevity and fertility in humans, as well as to cancer-free survival, is the transcription factor and tumor suppressor p53, controlled by its main negative regulator MDM2. However, p53 and MDM2 homologs are found throughout the metazoan kingdom from Trichoplacidae to Hominidae. Therefore the question arises, if p53/MDM2 contributes to the shaping of primate features, then through which mechanisms. Previous findings have indicated that the appearances of novel p53-regulated genes and wild-type p53 variants during primate evolution are important in this context. Here, we report on another mechanism of potential relevance. Human endogenous retrovirus K subgroup HML-2 (HERV-K(HML-2)) type 1 proviral sequences were formed in the genomes of the predecessors of contemporary Hominoidea and can be identified in the genomes of Nomascus leucogenys (gibbon) up to Homo sapiens. We previously reported on an alternative splicing event in HERV-K(HML-2) type 1 proviruses that can give rise to nuclear protein of 9 kDa (Np9). We document here the evolution of Np9-coding capacity in human, chimpanzee and gorilla, and show that the C-terminal half of Np9 binds directly to MDM2, through a domain of MDM2 that is known to be contacted by various cellular proteins in response to stress. Np9 can inhibit the MDM2 ubiquitin ligase activity towards p53 in the cell nucleus, and can support the transactivation of genes by p53. Our findings point to the possibility that endogenous retrovirus protein Np9 contributes to the regulation of the p53-MDM2 pathway specifically in humans, chimpanzees and gorillas

Antibodies against the mono-methylated arginine-glycine repeat (MMA-RG) of the Epstein-Barr virus nuclear antigen 2 (EBNA2) identify potential cellular proteins targeted in viral transformation.

The Epstein-Barr virus is a human herpes virus with oncogenic potential. The virus-encoded nuclear antigen 2 (EBNA2) is a key mediator of viral tumorigenesis. EBNA2 features an arginine-glycine (RG) repeat at amino acids (aa)339-354 that is essential for the transformation of lymphocytes and contains symmetrically (SDMA) and asymmetrically (ADMA) di-methylated arginine residues. The SDMA-modified EBNA2 binds the survival motor neuron protein (SMN), thus mimicking SMD3, a cellular SDMA-containing protein that interacts with SMN. Accordingly, a monoclonal antibody (mAb) specific for the SDMA-modified RG repeat of EBNA2 also binds to SMD3. With the novel mAb 19D4 we now show that EBNA2 contains mono-methylated arginine (MMA) residues within the RG repeat. Using 19D4, we immune-precipitated and analysed by mass spectrometry cellular proteins in EBV-transformed B-cells that feature MMA motifs that are similar to the one in EBNA2. Among the cellular proteins identified, we confirmed by immunoprecipitation and/or Western blot analyses Aly/REF, Coilin, DDX5, FXR1, HNRNPK, LSM4, MRE11, NRIP, nucleolin, PRPF8, RBM26, SMD1 (SNRDP1) and THRAP3 proteins that are either known to contain MMA residues or feature RG repeat sequences that probably serve as methylation substrates. The identified proteins are involved in splicing, tumorigenesis, transcriptional activation, DNA stability and RNA processing or export. Furthermore, we found that several proteins involved in energy metabolism are associated with MMA-modified proteins. Interestingly, the viral EBNA1 protein that features methylated RG repeat motifs also reacted with the antibodies. Our results indicate that the region between aa 34-52 of EBNA1 contains ADMA or SDMA residues, while the region between aa 328-377 mainly contains MMA residues

Downregulation of Sec23A protein by miRNA-375 in prostate carcinoma.

Prostate carcinoma (CaP) is a leading cause of cancer-related death in men. We have previously determined the microRNA (miRNA) profile of primary CaP in comparison with nontumor prostate tissue. miRNAs are small, noncoding RNAs that inhibit protein synthesis on a posttranscriptional level by binding to the 3'-untranslated region (3'-UTR) of their target genes. In primary CaP tissue, we have previously found by miRNA sequencing that miR-375 and miR-200c were upregulated 9.1- and 4.5-fold, respectively. A computational analysis predicted the 3'-UTR of the SEC23A gene as a potential target for both miR-375 and miR-200c. Here, we show that the 3'-UTR of SEC23A mRNA is indeed a target for miR-375 and miR-200c and that both miRNAs downregulate Sec23A protein expression when ectopically expressed in human 293T cells. In primary samples of CaP, we found a direct correlation between reduction of SEC23A mRNA and overexpression of miR-375 but not of miR-200c. The reduced levels of Sec23A protein were inversely correlated to the increased amount of miR-375 in the LNCaP and DU145 CaP cell lines when compared with normal prostate fibroblasts. In primary CaP, we also detected decreased amounts of Sec23A protein when compared with corresponding normal prostate tissue. Ectopically overexpressed Sec23A in LNCaP and DU145 CaP cells significantly reduced the growth properties, indicating that Sec23A might play a role in the induction or growth of prostate carcinoma. Sec23A overexpression reduced cell growth but did not induce apoptosis, whereas inhibition of Sec23A stimulated cell proliferation

The antibody 2B4 directed against the Epstein-Barr virus (EBV)-encoded nuclear antigen I (EBNA I) detects MAGE-4: Implications for studies on the EBV association of human cancers.

We have previously developed two monoclonal antibodies against the Epstein-Barr Virus (EBV) nuclear antigen 1 (EBNA1), designated 1H4 and 2B4. Both detect EBNA1 by in situ staining in established EBV-positive tumours, e.g. Hodgkin's lymphoma and nasopharyngeal carcinoma. An association of EBV with other tumours, notably breast carcinomas, has been reported but remains controversial. Using the antibody 2B4, a nuclear protein has been detected in breast carcinomas that were EBV-negative by other methods, suggesting cross-reactivity with a cellular protein. Furthermore, an association of EBV with various other carcinomas has been reported on the basis of 2B4 immunohistochemistry. Here we show that 2B4 also binds to MAGE-4, a cancer testis antigen expressed in a variety of tumour cells, including breast carcinoma, seminoma and EBV-negative cases of Hodgkin's lymphoma. We conclude that the 2B4 antibody is not suitable for the detection of EBV infection but that additional techniques, particularly in situ hybridization for the detection of the EBV-encoded RNAs (EBERs), should be employed to confirm the presence of EBV. Our results add to the evidence indicating that breast cancer is not an EBV-associated disease

Characterization of DP103, a Novel DEAD Box Protein that Binds to the Epstein-Barr Virus Nuclear Proteins EBNA2 and EBNA3C.

The Epstein-Barr virus-encoded nuclear antigens EBNA2 and EBNA3C both interact with the cellular transcription factor RBP-Jkappa and modulate the expression of several shared target genes, suggesting a tight cooperation in latently infected cells. In a survey for additional cellular factors that bind to EBNA2 as well as EBNA3C, we have isolated and characterized DP103, a novel human member of the DEAD box family of putative ATP-dependent RNA helicases. The interaction with DP103 is mediated by amino acids (aa) 121-213 of EBNA2 and aa 534-778 of EBNA3C, regions that are not involved in binding of the viral proteins to RBP-Jkappa. The DP103-cDNA encodes a protein of 824 aa that harbors all of the common DEAD box motifs. Monoclonal antibodies raised against DP103 detect a protein of 103 kDa in mammalian cells that resides in high molecular weight complexes in vivo. We have detected an ATPase activity intrinsic to or closely associated with DP103. By subcellular fractionation, we find DP103 in both a soluble nuclear fraction as well as in the insoluble skeletal fraction. Whereas the protein and its mRNA are uniformly expressed in all tested cell lines, we observed differential expression of the mRNA in normal human tissues