Activation of a diphtheria toxin A gene by expression of human immunodeficiency virus-1 Tat and Rev proteins in transfected cells.
Expression of a gene encoding the diphtheria toxin A (DT-A) fragment, controlled by tissue specific regulatory elements, has previously been used to kill selected cell populations. Here, we have examined the feasibility of controlling DT-A expression using regulatory systems from the human immunodeficiency virus (HIV-1) genome. Plasmids were constructed which express either DT-A or, as a model system, the luciferase (luc) reporter gene, under control of HIV-1 long terminal repeat (LTR) sequences (-167 to +80). While trans-activation by expression of the viral protein Tat was demonstrated, significant basal expression was observed. To reduce basal expression, cis-acting negative regulatory elements from the env region of the HIV-1 genome were inserted in the 3' untranslated region of both the luc and DT-A constructs. This dramatically reduced basal expression from the HIV LTR, and now both viral regulatory proteins Tat and Rev were required for maximal trans-activation. Such regulation of DT-A expression might be therapeutically applied to selectively kill HIV-infected cells in acquired immunodeficiency syndrome (AIDS) and AIDS-related complex (ARC).
Harrison
G S
GS
Division of Medical Oncology, University of Colorado Health Sciences Center, Denver 80262.
Maxwell
F
F
Long
C J
CJ
Rosen
C A
CA
Glode
L M
LM
Maxwell
I H
IH
D004167:Diphtheria Toxin / Q000096:biosynthesis / Q000235:genetics*; D015967:Gene Expression Regulation, Viral; D015694:Gene Products, rev / Q000502:physiology*; D015696:Gene Products, tat / Q000502:physiology*; D015316:Genetic Therapy; D005822:Genetic Vectors; D015658:HIV Infections / Q000628:therapy; D016325:HIV Long Terminal Repeat; D015497:HIV-1 / Q000235:genetics*; D006801:Humans; D008156:Luciferases / Q000096:biosynthesis / Q000235:genetics; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000235:genetics; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured; D054321:rev Gene Products, Human Immunodeficiency Virus; D054322:tat Gene Products, Human Immunodeficiency Virus
D004167:Diphtheria Toxin; D015694:Gene Products, rev; D015696:Gene Products, tat; D011993:Recombinant Fusion Proteins; D054321:rev Gene Products, Human Immunodeficiency Virus; D054322:tat Gene Products, Human Immunodeficiency Virus; D008156:Luciferases