title: Differential effect of heat shock on RNA metabolism in human Burkitt's lymphoma B-cell lines.
abstract: Thermal stress induces expression of a family of heat shock proteins which may regulate the synthesis of various cellular genes. We investigated the effect of heat shock on polyadenylation in Epstein-Barr Virus (EBV) negative and EBV transformed human Burkitt's lymphoma (BL) B-cell lines. Incubation of the BL B-cell line P3HR-1, carrying the defective EBV genome [EBV nuclear antigen-2 gene deletion] at 46 degrees C for 15 min increased nuclear poly(A) polymerase (PAP) activity. Thereafter, enzymatic activity declined and at 60 min it was reduced to about 50% of that observed in cells incubated at 37 degrees C. In contrast, no significant increase in PAP activity was observed at 15 min or thereafter in an EBV- BL cell line, ST-486, in response to elevated temperature. Furthermore, no heat shock mediated change in nuclear poly(A)-specific endonuclease activity was observed in either P3HR-1 or ST-486 cells suggesting a specific effect on PAP activity. However, thermal stress dependent increase in c-myc expression was detected only in P3HR-I cells. These results suggest an association between EBV transformation and enhanced expression of c-myc and PAP activity. To further determine the role of EBV, and EBV- BL cell line, BL-30, and BL-30 cells infected in vitro with a wild type strain of EBV, BL-30/B95-8, were investigated. BL-30/B-95-8, unlike the parental BL-30 cells, exhibited c-myc and PAP gene upregulation at 15 min but were downregulated at 60 min following exposure of cells to elevated temperatures. These results suggest that infection of human B-cells with EBV is associated with their ability to respond to thermal stress by increased PAP activity which may stabilize mRNA through enhanced polyadenylation.
authors.affiliation: Department of Virology, Children's Hospital of Eastern Ontario, Ottawa, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Kumar
authors.forename: R N
authors.initials: RN
authors.lastname: Kurl
authors.forename: M
authors.initials: M
authors.lastname: Kryworuchko
authors.forename: F
authors.initials: F
authors.lastname: Diaz-Mitoma
authors.forename: S
authors.initials: S
authors.lastname: Sharma
mesh_terms: D002051:Burkitt Lymphoma / Q000201:enzymology / Q000378:metabolism* / Q000821:virology; D002472:Cell Transformation, Viral; D004720:Endonucleases / Q000378:metabolism; D015870:Gene Expression; D016259:Genes, myc; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics; D004854:Herpesvirus 4, Human; D006358:Hot Temperature; D006801:Humans; D011062:Polynucleotide Adenylyltransferase / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012334:RNA, Neoplasm / Q000378:metabolism*
chemical_list: D018840:HSP70 Heat-Shock Proteins; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D011062:Polynucleotide Adenylyltransferase; D004720:Endonucleases