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

Abstract

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 LNCaP104-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.

Androgenic Suppression of ATP-binding Cassette Transporter A1 Expression in LNCaP Human Prostate Cancer Cells

“…DNA coding for a RNAi for human ABCA1 was prepared with the following oligonucleotides: 5Ј-GATCCCCTGAGTTTAGGTATGGCGGCT-TCAAGAGAGCCGCCATACCTAAACTCATTTTTGGAAA-3Ј and 5Ј-AG-CTTTTCCAAAAATGAGTTTAGGTATGGCGGCTCTCTTGAAGCCGCC-ATACCTAAACTCAGGG-3Ј. These 64-mer oligonucleotides were annealed and ligated into the pH1RP vector (10), and the construct was verified by sequencing. The ABCA1-RNAi expression plasmid was stably transfected into 104-S cells with Effectene and selection for G418 resistance.…”

“…Cell number was analyzed by measuring DNA content with fluorescent dye Hoechst 33258 as described previously (10).…”

Role of Polyamines Derived from Arginine in Differentiation and Proliferation of Human Blood Cells

“…13) The cellular polyamines are thought to be supplied through de novo synthesis from L-arginine and transport, while the mammalian polyamine transporter gene has not been identified, 14,15) unlike bacterial and/or fungal polyamine transporter. 10,16) De novo polyamine synthesis is governed in part by the activity of ornithine decarboxylase (ODC), which catalyzes the conversion of the amino acid, L-ornithine to the diamine and putrescine.…”

Antiproliferative Effect of Liver X Receptor Agonists on LNCaP Human Prostate Cancer Cells

“…DNA coding for an RNA interference for human p27 was prepared using the following oligonucleotides: 5Ј-GATCCCCGCACTGCA-GAGACATGGAATTCAAGAGATTCCATGTCTCTGCAGTGCTTTTTG-GAAA-3Ј and 5Ј-AGCTTTTCCAAAAAGCACTGCAGAGACATGGAA-TCTCTTGAATTCCATGTCTCTGCAGTGCGGG-3Ј. These 64-mer oligonucleotides were annealed and ligated into the pH1RP vector (12). The p27-RNA interference expression plasmid was stably transfected into 104-S cells using Effectene (Qiagen) and selection for G418 resistance.…”