Human T-cell leukemia virus types I and II exhibit different DNase I protection patterns.
Human T-cell leukemia virus types I (HTLV-I) and II (HTLV-II) are human retroviruses which normally infect T-lymphoid cells. HTLV-I infection is associated with adult T-cell leukemia-lymphoma, and HTLV-II is associated with an indolent form of hairy-cell leukemia. To identify potential transcriptional regulatory elements of these two related human retroviruses, we performed DNase I footprinting of both the HTLV-I and HTLV-II long terminal repeats (LTRs) by using extracts prepared from uninfected T cells, HTLV-I and HTLV-II transformed T cells, and HeLa cells. Five regions of the HTLV-I LTR and three regions of the HTLV-II LTR showed protection by DNase I footprinting. All three of the 21-base-pair repeats previously shown to be important in HTLV transcriptional regulation were protected in the HTLV-I LTR, whereas only one of these repeats was protected in the HTLV-II LTR. Several regions exhibited altered protection in extracts prepared from lymphoid cells as compared with HeLa cells, but there were minimal differences in the protection patterns between HTLV-infected and uninfected lymphoid extracts. A number of HTLV-I and HTLV-II LTR fragments which contained regions showing protection in DNase I footprinting were able to function as inducible enhancer elements in transient CAT gene expression assays in the presence of the HTLV-II tat protein. The alterations in the pattern of the cellular proteins which bind to the HTLV-I and HTLV-II LTRs may in part be responsible for differences in the transcriptional regulation of these two related viruses.
Altman
R
R
Department of Medicine, University of California, Los Angeles School of Medicine 90024.
Harrich
D
D
Garcia
J A
JA
Gaynor
R B
RB
D001483:Base Sequence; D002460:Cell Line; D004262:DNA Restriction Enzymes; D004268:DNA-Binding Proteins / Q000032:analysis*; D017977:Deltaretrovirus / Q000235:genetics*; D003850:Deoxyribonuclease I; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D012045:Regulatory Sequences, Nucleic Acid; D012091:Repetitive Sequences, Nucleic Acid; D014158:Transcription, Genetic; D014162:Transfection
D004268:DNA-Binding Proteins; D004262:DNA Restriction Enzymes; D003850:Deoxyribonuclease I