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Activation of NF-kappa B/Rel by Tax involves degradation of I kappa B alpha and is blocked by a proteasome inhibitor. 1995

S B Maggirwar, and E Harhaj, and S C Sun
Department of Microbiology and Immunology, Pennsylvania State University College of Medicine, Hershey Medical Center, Hershey 17033, USA.

The tax gene product of the human T-cell leukemia virus type I (HTLV-I) induces the nuclear expression and biological function of the NF-kappa B/Rel family of host transcription factors although the underlying mechanism remains unclear. In the present study, we demonstrate that Tax-mediated activation of NF-kappa B/Rel can be inhibited by a proteasome inhibitor, suggesting the involvement of proteolytic reactions in this Tax-specific activation pathway. Transient transfection and reporter gene assays have revealed that Tax overrides the inhibitory function of I kappa B alpha in both F9 embryonal cells and Jurkat T cells. Moreover, Tax-mediated inactivation of I kappa B alpha requires a 16 amino acid sequence element located at the N-terminal region (amino acid 21-36) of I kappa B alpha, which is also required for tumor necrosis factor alpha-induced degradation of this inhibitory protein. We further demonstrate that the proteasome inhibitor also blocks the degradation of I kappa B alpha observed in HTLV-I-infected T cells. Interestingly, inhibition of I kappa B alpha degradation in these cells led to the accumulation of a phosphorylated form of I kappa B alpha. Together, these studies suggest that Tax activation of NF-kappa B/Rel may involve induction of phosphorylation and subsequent proteasome-mediated degradation of the inhibitor I kappa B alpha.

UI MeSH Term Description Entries
D008969 Molecular Sequence Data Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories. Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D009097 Multienzyme Complexes Systems of enzymes which function sequentially by catalyzing consecutive reactions linked by common metabolic intermediates. They may involve simply a transfer of water molecules or hydrogen atoms and may be associated with large supramolecular structures such as MITOCHONDRIA or RIBOSOMES. Complexes, Multienzyme
D010766 Phosphorylation The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety. Phosphorylations
D002460 Cell Line Established cell cultures that have the potential to propagate indefinitely. Cell Lines,Line, Cell,Lines, Cell
D003546 Cysteine Endopeptidases ENDOPEPTIDASES which have a cysteine involved in the catalytic process. This group of enzymes is inactivated by CYSTEINE PROTEINASE INHIBITORS such as CYSTATINS and SULFHYDRYL REAGENTS.
D004268 DNA-Binding Proteins Proteins which bind to DNA. The family includes proteins which bind to both double- and single-stranded DNA and also includes specific DNA binding proteins in serum which can be used as markers for malignant diseases. DNA Helix Destabilizing Proteins,DNA-Binding Protein,Single-Stranded DNA Binding Proteins,DNA Binding Protein,DNA Single-Stranded Binding Protein,SS DNA BP,Single-Stranded DNA-Binding Protein,Binding Protein, DNA,DNA Binding Proteins,DNA Single Stranded Binding Protein,DNA-Binding Protein, Single-Stranded,Protein, DNA-Binding,Single Stranded DNA Binding Protein,Single Stranded DNA Binding Proteins
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000072000 NF-KappaB Inhibitor alpha An I-kappa B protein that inhibits the activity of dimeric NF-KAPPA B P50-REL complexes, sequesters transcription factor NF-kappaB as an inactive complex in the cytoplasm; and prevents NF-kappaB nuclear translocation and DNA binding. I Kappa B-alpha Protein,IKappaB-alpha,IKappaBalpha,Major Histocompatibility Complex Enhancer-Binding Protein MAD3,p40 Protein (IKappaB-alpha),I Kappa B alpha Protein,IKappaB alpha,Inhibitor alpha, NF-KappaB,Major Histocompatibility Complex Enhancer Binding Protein MAD3,NF KappaB Inhibitor alpha,alpha, NF-KappaB Inhibitor
D000595 Amino Acid Sequence The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION. Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D015368 Human T-lymphotropic virus 1 A strain of PRIMATE T-LYMPHOTROPIC VIRUS 1 isolated from mature T4 cells in patients with T-lymphoproliferation malignancies. It causes adult T-cell leukemia (LEUKEMIA-LYMPHOMA, T-CELL, ACUTE, HTLV-I-ASSOCIATED), T-cell lymphoma (LYMPHOMA, T-CELL), and is involved in mycosis fungoides, SEZARY SYNDROME and tropical spastic paraparesis (PARAPARESIS, TROPICAL SPASTIC). ATLV,Adult T-Cell Leukemia-Lymphoma Virus I,HTLV-1,HTLV-I,Human T-Cell Leukemia Virus I,Leukemia Virus I, Human T-Cell,T-Cell Leukemia Virus I, Human,Adult T Cell Leukemia Lymphoma Virus I,Human T Cell Leukemia Virus I,Leukemia Lymphoma Virus I, Adult T Cell,Leukemia Virus I, Human T Cell,T Cell Leukemia Virus I, Human,Human T lymphotropic virus 1

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