TATA-binding protein-associated factor 7 regulates polyamine transport activity and polyamine analog-induced apoptosis.
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 NH2-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.
Fukuchi
Junichi
J
Ben May Institute for Cancer Research and the Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois 60637, USA.
Hiipakka
Richard A
RA
Kokontis
John M
JM
Nishimura
Kazuhiro
K
Igarashi
Kazuei
K
Liao
Shutsung
S
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis; D001483:Base Sequence; D001692:Biological Transport; D015152:Blotting, Northern; D015139:Blotting, Southern; D015153:Blotting, Western; D016466:CHO Cells; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002455:Cell Division; D002934:Cinnamates / Q000494:pharmacology; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D017930:Genes, Reporter; D006801:Humans; D006921:Hygromycin B / Q000031:analogs & derivatives* / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008935:Mitoguazone / Q000494:pharmacology; D008969:Molecular Sequence Data; D010641:Phenotype; D010957:Plasmids / Q000378:metabolism; D011073:Polyamines / Q000737:chemistry / Q000378:metabolism*; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013096:Spermine / Q000378:metabolism; D035381:TATA-Binding Protein Associated Factors / Q000378:metabolism / Q000502:physiology*; D013997:Time Factors; D035362:Transcription Factor TFIID / Q000378:metabolism / Q000502:physiology*; D014158:Transcription, Genetic; D015533:Transcriptional Activation
D000970:Antineoplastic Agents; D002934:Cinnamates; D011073:Polyamines; C091537:TAF7 protein, human; D035381:TATA-Binding Protein Associated Factors; D035362:Transcription Factor TFIID; D013096:Spermine; D006921:Hygromycin B; C026273:hygromycin A; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D008935:Mitoguazone