[Gene expression in normal and virally transformed erythroid cells and the effect of stress factors]

The globin gene expression in normal and Rauscher virus-transformed murine erythroid cells and the effect of heatshock and cycloheximide (CHI) were investigated. The hybridization analysis of RNA transcripts synthesized using erythroid cell chromatin as a template with globin cDNA demonstrated the disturbance of globin gene transcription in transformed erythroblasts. Using the Northern hybridization analysis of poly(A) +RNA with pCR1 beta MG9 as a probe, the presence of a rather broad RNA set (from approximately 1500 to 450 nucleotides) in these cells was discovered, while hemoglobin was not synthesized. This indicated that the processing of globin mRNA was probably also disturbed. As a result of heatshock, the RNA set approached that in normal erythroid cells (500-650 nucleotides), and the proteins corresponding to globins were synthesized. The stable appearance of low molecular weight proteins and the irregular synthesis of HSP-90 and HSP-70 in response to heat shock were the characteristic features of transformed erythroblasts. After CHI treatment, the content of globin sequences in RNA of transformed erythroblasts increased and beta-globin protein chains appeared.