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Biomedical subjects

C Sauder

Publications and source records attributed to C Sauder.

23 records · Page 2Linked to original sources
PubMed1996

Mutational analysis of the Epstein-Barr virus nuclear antigen 2 by far-Western blotting and DNA-binding studies.

We have previously shown by far-Western blotting that the Epstein-Barr virus nuclear antigen 2 (EBNA-2) both binds to a cellular protein of 130 kDa and histone H1, with the complex between EBNA-2 and p130 being tighter than between EBNA-2 and histone H1. Here we demonstrate that the N terminus of EBNA-2, which was previously shown to be necessary for transformation of B lymphocytes by EBNA-2, is essential for binding to p130. We further show data indicating that the binding of EBNA-2 to histone H1 appears not to be mediated exclusively via the basic Arg-Gly rich region in the C-terminal part of EBNA-2. With a MAb directed against the Trp-Trp322-Pro (WWP) motif of EBNA-2, which is known to be essential for the interaction of EBNA-2 with the cellular factor RBPJkappa/CBF1, we could inhibit the DNA binding of EBNA-2, providing further evidence that this region of EBNA-2 forms direct contact with RBPJkappa/CBF1.

Amino Acid Sequence↗
PubMed1996

Detection of Borna disease virus (BDV) antibodies and BDV RNA in psychiatric patients: evidence for high sequence conservation of human blood-derived BDV RNA.

In several vertebrate species, Borna disease virus (BDV), the prototype of a new group of animal viruses, causes central nervous system disease accompanied by diverse behavioral abnormalities. Seroepidemiological data indicate that BDV may contribute to the pathophysiology of certain human mental disorders. This hypothesis is further supported by the detection of both BDV antigens and BDV RNA in peripheral blood mononuclear cells (PBMCs) of patients with psychiatric disorders and the isolation of BDV from such PBMCs. Here we describe serological and molecular epidemiological studies on psychiatric patients and healthy individuals from the area of Homburg, Germany. Using a novel Western blot (immunoblot) assay, we found a BDV seroprevalence of 9.6% among 416 neuropsychiatric patients, which is significantly higher than the 1.4% found among 203 healthy control individuals. Human sera displayed a prominent immunoreactivity against the virus nucleoprotein, the p40 antigen. Reverse transcriptase-mediated PCR analysis of RNA extracted from PBMCs of a subset of 26 of the neuropsychiatric patients revealed that 50% were BDV RNA positive. Three of the 13 BDV RNA-positive patients also had BDV-positive serology, whereas one patient with serum antibodies to BDV p40 antigen did not harbor detectable BDV RNA in PBMCs. BDV p40 and p24 sequences derived from human PBMCs exhibited both a high degree of inter- and intrapatient conservation and a close genetic relationship to animal-derived BDV sequences.

Adolescent↗
PubMed1994

DNA-binding studies of the Epstein-Barr virus nuclear antigen 2 (EBNA-2): evidence for complex formation by latent membrane protein gene promoter-binding proteins in EBNA-2-positive cell lines.

The Epstein-Barr virus (EBV) nuclear antigen 2 (EBNA-2) protein is essential for the immortalization of human primary B cells by EBV. EBNA-2 trans-activates cellular and viral genes like CD23, c-fgr, latent membrane protein 1 (LMP1) and terminal protein 1 (TP1). Trans-activation of the TP1 promoter and of the BamHI C promoter has already been investigated in detail and appears to be mediated via protein-protein interactions and not by direct binding of EBNA-2 type A (of EBV type 1) to the DNA. EBNA-2 is able to trans-activate the expression of the LMP gene in several cell lines. Various reports have delineated the cis-acting elements of the LMP promoter through which EBNA-2 mediates trans-activation. To determine whether EBNA-2 also trans-activates the LMP promoter by protein-protein interactions, we performed a series of gel retardation assays and competition experiments with LMP promoter fragments of different sizes. We determined that the protein-binding region on the LMP promoter was within a 42 bp fragment encompassing nucleotides -135 to -176 relative to the LMP transcriptional start site. None of the DNA fragments investigated indicated interaction of EBNA-2 with the DNA via protein-protein interactions. No significant differences between EBNA-2-positive and EBNA-2-negative nuclear extracts could be seen in the gel retardation assay under conditions that clearly showed binding of EBNA-2A to the TP1 promoter. However, analysis of sucrose gradient fractions in the gel retardation assay provided evidence that the LMP promoter-binding proteins form a complex of higher M(r) in EBNA-2-positive cell extracts. These complexes were destroyed by detergent. We deduce from these results that EBNA-2-positive cells might indeed contain specific complexes bound to the LMP promoter which are, however, too labile to be detected in a standard gel retardation assay.

Antigens, Viral↗
PubMed1993

Immunological detection of proteins associated with the Epstein-Barr virus nuclear antigen 2A.

The Epstein-Barr virus nuclear antigen 2A (EBNA-2A) has been strongly implicated in the EBV-mediated B-cell transformation process. Since EBNA-2A might exert this function through interaction with proteins of the infected cell, we studied the association of EBNA-2A with cellular proteins. Immunoprecipitation of EBNA-2A from 32P-labeled cell extracts separated by sucrose gradient centrifugation revealed the presence of phosphoproteins complexed with the two forms of the EBNA-2A sedimenting at 13 S and 34 S. Prominent bands were observed at 250, 170, 120, 110, 105, and 95 kDa with minor species at 78, 52, 45, 31, 26, 22 and 18 kDa. By "West-Western" or "Far-Western" blotting using EBNA-2A protein from insect cells as a probe we detected binding to proteins migrating with apparent molecular masses of about 200, 130, 110, 105, 95, and 31 kDa with minor species detectable at 90, 68, 50-55, 40, and 17 kDa. The protein with an apparent molecular mass of 31 kDa was identified by competition experiments as histone H1. Some of the EBNA-2A-complexed phosphoproteins, notably the proteins of 110 and 95 kDa, comigrated with the proteins detectable by "West-Western" analysis. The binding of EBNA-2A to the 130-kDa protein was stable against up to 1.5 M NaCl and could not be competed with histone H1. In a similar experiment, the less transforming EBNA-2B which is encoded by the subtype 2 virus bound to most of the proteins detected with EBNA-2A but with strongly reduced efficiency to the protein of 130 kDa indicating that this protein might be a target for EBNA-2 during EBV-mediated transformation.

Animals↗