Transcriptional regulation of APOBEC3G, a cytidine deaminase that hypermutates human immunodeficiency virus.
Apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like 3G (APOBEC3G) is an antiretroviral deoxycytidine deaminase that lethally hypermutates human immunodeficiency virus type 1 (HIV-1) but is itself neutralized by the HIV-1-encoded viral infectivity factor. Accordingly, APOBEC3G occurs specifically in human T lymphocytic cell lines that contain this antiviral defense, including H9. Since the substrate specificities of related cytidine deaminases are strongly influenced by their intracellular quantities, we analyzed the factors that control APOBEC3G expression. The levels of APOBEC3G mRNA and protein were unaffected by treatment of proliferating H9 cells with interferons or tumor necrosis factor-alpha but were enhanced up to 20-fold by phorbol myristate acetate. This induction was mediated at the transcriptional level by a pathway that required activation of the protein kinase Calpha/betaI isozyme (PKC), mitogen-activated protein kinase kinase (MEK) 1 and 2, and extracellular signal-regulated kinase (ERK). Correspondingly, induction of APOBEC3G was blocked by multiple inhibitors that act at diverse steps of this pathway. The PKCalpha/betaI/MEK/ERK pathway also controlled basal levels of APOBEC3G mRNA and protein, which consequently declined when cells were treated with these inhibitors or arrested in the G(0) state of the cell cycle by serum starvation. We conclude that expression of the antiviral APOBEC3G editing enzyme is dynamically controlled by the PKCalpha/betaI/MEK/ERK protein kinase cascade in human T lymphocytes.
Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon 97239-3098, USA.
Kristine M
KM
Rose
Mariana
M
Marin
Susan L
SL
Kozak
David
D
Kabat
D000071480:APOBEC-3G Deaminase; D002460:Cell Line; D003564:Cytidine Deaminase / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology; D015497:HIV-1 / Q000235:genetics; D006801:Humans; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D009700:Nucleoside Deaminases; D014176:Protein Biosynthesis; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D011505:Protein-Tyrosine Kinases; D011506:Proteins / Q000235:genetics / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis; D012097:Repressor Proteins; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000031:analogs & derivatives* / Q000494:pharmacology; D014158:Transcription, Genetic; D015854:Up-Regulation
D011506:Proteins; D012333:RNA, Messenger; D012097:Repressor Proteins; C016658:phorbolol myristate acetate; C482128:MAP2K2 protein, human; D011505:Protein-Tyrosine Kinases; C496628:PRKCA protein, human; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; C482125:MAP2K1 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases; D009700:Nucleoside Deaminases; D000071480:APOBEC-3G Deaminase; C464924:APOBEC3G protein, human; D003564:Cytidine Deaminase; D013755:Tetradecanoylphorbol Acetate