TATA-binding Protein-associated Factor 7 Regulates Polyamine Transport Activity and Polyamine Analog-induced Apoptosis

• Published in: The Journal of biological chemistry 2004-07, Vol.279 (29), p.29921-29929
• Main Authors: Fukuchi, Junichi, Hiipakka, Richard A, Kokontis, John M, Nishimura, Kazuhiro, Igarashi, Kazuei, Liao, Shutsung
• Format: Article
• Language: English
• Subjects: Animals; Antineoplastic Agents - pharmacology; Apoptosis; Base Sequence; Biological Transport; Blotting, Northern; Blotting, Southern; Blotting, Western; Caspase 3; Caspases - metabolism; Cell Division; CHO Cells; Cinnamates - pharmacology; Cricetinae; Dose-Response Relationship, Drug; Genes, Reporter; Humans; Hygromycin B - analogs & derivatives; Hygromycin B - pharmacology; JNK Mitogen-Activated Protein Kinases; Mitogen-Activated Protein Kinases - metabolism; Mitoguazone - pharmacology; Molecular Sequence Data; Phenotype; Plasmids - metabolism; Polyamines - chemistry; Polyamines - metabolism; Reverse Transcriptase Polymerase Chain Reaction; RNA Interference; Spermine - metabolism; TATA-Binding Protein Associated Factors - metabolism; TATA-Binding Protein Associated Factors - physiology; Time Factors; Transcription Factor TFIID - metabolism; Transcription Factor TFIID - physiology; Transcription, Genetic; Transcriptional Activation
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M401078200

Identification of the polyamine transporter gene will be useful for modulating polyamine accumulation in cells and should be a good target for controlling cell proliferation. Polyamine transport activity in mammalian cells is critical for accumulation of the polyamine analog methylglyoxal bis(guanylhydrazone) (MGBG) that induces apoptosis, although a gene responsible for transport activity has not been identified. Using a retroviral gene trap screen, we generated MGBG-resistant Chinese hamster ovary (CHO) cells to identify genes involved in polyamine transport activity. One gene identified by the method encodes TATA-binding protein-associated factor 7 (TAF7), which functions not only as one of the TAFs, but also a coactivator for c-Jun. TAF7-deficient cells had decreased capacity for polyamine uptake (20% of CHO cells), decreased AP-1 activation, as well as resistance to MGBG-induced apoptosis. Stable expression of TAF7 in TAF7-deficient cells restored transport activity (55% of CHO cells), AP-1 gene transactivation (100% of CHO cells), and sensitivity to MGBG-induced apoptosis. Overexpression of TAF7 in CHO cells did not increase transport activity, suggesting that TAF7 may be involved in the maintenance of basal activity. c-Jun NH 2 -terminal kinase inhibitors blocked MGBG-induced apoptosis without alteration of polyamine transport. Decreased TAF7 expression, by RNA interference, in androgen-independent human prostate cancer LN-CaP104-R1 cells resulted in lower polyamine transport activity (25% of control) and resistance to MGBG-induced growth arrest. Taken together, these results reveal a physiological function of TAF7 as a basal regulator for mammalian polyamine transport activity and MGBG-induced apoptosis.