Heat shock protein 70 (Hsp70)-stimulated deoxycytidine deaminases from a human lymphoma cell but not the activation-induced cytidine deaminase (AID) from Ramos 6.4 human Burkitt's lymphoma cells.
Deoxycytidine deaminase enzyme activity was reduced in lysates of human leukemic THP1 cells 24 h after transfection with siRNA designed to inhibit cell synthesis of heat shock protein 70 (Hsp70)1a and Hsp701b. The cytidine deaminase enzyme activity from the cell lysates was purified from an affinity column which contained bound single-stranded oligodeoxycytidylic acid. Deficient enzyme activity in certain elution fractions from the siRNA-transfected cells was restored by including recombinant HSP 70 in the assays. Enzyme activity in some other fractions was increased after siRNA transfection. Activation-induced cytidine deaminase (AID) is a central factor in the immune response. A more specific assay for AID was used to study the influence of Hsp70 on AID activity. Unlike Hsp70's ability to stimulate certain enzymes of DNA base excision repair and other cytidine deaminases, it had little effect on AID activity in vitro, or was weakly inhibitory.
Bases
Robert
R
Radiology and Radiation Oncology, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, NY 10467, USA. rbases@verizon.net
D002051:Burkitt Lymphoma / Q000201:enzymology; D045744:Cell Line, Tumor; D003564:Cytidine Deaminase / Q000378:metabolism*; D004260:DNA Repair; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D016393:Lymphoma, B-Cell / Q000201:enzymology; D009700:Nucleoside Deaminases / Q000378:metabolism*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D013997:Time Factors; D000098830:AICDA (Activation-Induced Cytidine Deaminase)
D018840:HSP70 Heat-Shock Proteins; D034741:RNA, Small Interfering; D000098830:AICDA (Activation-Induced Cytidine Deaminase); D009700:Nucleoside Deaminases; D003564:Cytidine Deaminase; C011530:deoxycytidine deaminase