Regulation of C‐FGR proto‐oncogene expression in epstein‐barr virus infected B‐cell lines

Abstract

We and others have previously shown that in vitro conversion of Epstein-Barr virus (EBV)-negative Burkitt lymphoma (BL) cell lines with the immortalizing B95-8 strain of EBV results in a marked elevation in levels of c-fgr proto-oncogene mRNA. We now show, using a nuclear run-off assay, that this induction results from an increase in the rate of transcription of the c-fgr gene. We also show that BL cell lines freshly converted with the non-immortalizing HR-I strain of EBV do not accumulate higher levels of c-fgr mRNA, suggesting that EBNA-2 and/or LMP, the genes which are deleted in the HR-I strain, may be involved in the pathway which leads to changes in c-fgr gene expression. In order to assess the generality of a role for the c-fgr gene in the response of B-lymphocytes to EBV-infection, which is controversial, we have analysed c-fgr expression in 6 freshly immortalized cell lines established by EBV (B95-8) infection of B-lymphocytes from the peripheral blood of normal adults and of adults with rheumatoid arthritis, from cord blood, and from foetal liver. All 6 cell lines expressed c-fgr mRNA at elevated levels compared to EBV-negative BL cell lines.

Transgenic mice carrying the guinea-pig α-lactalbumin gene transcribe milk protein genes in their sebaceous glands during lactation

“…1. An 848 bp RsaI-HpaII fragment from the 5' end of the gene was endlabelled using T4 polynucleotide kinase (BCL) and [y-32P]ATP (3000 Ci/mmol; New England Nuclear) as described by Patel et al (1990). A 20 ,ug portion of total RNA and 104 c.p.m.…”

“…of the probe were co-precipitated and the washed pellet was redissolved in 20 ,ul of SI hybridization buffer [80 % (v/v) deionized formamide, 50 mM-Pipes, pH 6.4, 400 mM-NaCl and 1 mm-EDTA, pH 8.0]. After 15 min at 90 'C, the mixture was incubated at 52 'C for 15 h. Samples were then treated with SI nuclease and the digestion products were analysed by 6 % polyacrylamide/urea gel electrophoresis as previously described (Patel et al, 1990). An M13mpl8 sequencing ladder was used as a size marker.…”

The <i>c-fgr</i>Proto-Oncogene: Expression in Epstein-Barr-Virus-Infected B Lymphocytes and in Cells of the Myelomonocytic and Granulocytic Lineages

“…EBV-negative BL biopsies and cell lines established from them contain low levels of c-fgr mRNA, but these levels increase 10-to 30-fold following EBV conversion with B95-8 ( fig. 1) as a result of an increase in the rate of transcription of the c-fgr gene [15]. In contrast, EBV con version of EBV-negative BL cell lines with the non immortalising mutant HR-1 strain of EBV does not result in an elevation of c-fgr mRNA levels ( fig.…”

“…In contrast, EBV con version of EBV-negative BL cell lines with the non immortalising mutant HR-1 strain of EBV does not result in an elevation of c-fgr mRNA levels ( fig. 1) [13,15]. Since the HR-1 strain of EBV lacks the genes encod ing EBNA-2 and EBNA-LP, this implicates one or both of these proteins in the pathway leading to c-fgr gene regulation by EBV.…”

“…However, the viral protein EBNA-2 is sufficient by itself to induce proliferation and immortalisation, although the efficiency of immortalisation is increased by other, unidentified, viral functions [12], Infection of human peripheral-blood B lymphocytes in vitro with the immortalising B95-8 strain of EBV results in the accumulation of high levels of c-fgr mRNA [13], and established B-LCL derived from such cultures invariably contain high levels of c-fgr mRNA [13][14][15]. EBV-negative BL biopsies and cell lines established from them contain low levels of c-fgr mRNA, but these levels increase 10-to 30-fold following EBV conversion with B95-8 ( fig.…”