کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
2819469 1569921 2008 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Hypoxia induces class III beta-tubulin gene expression by HIF-1α binding to its 3' flanking region
موضوعات مرتبط
علوم زیستی و بیوفناوری بیوشیمی، ژنتیک و زیست شناسی مولکولی ژنتیک
پیش نمایش صفحه اول مقاله
Hypoxia induces class III beta-tubulin gene expression by HIF-1α binding to its 3' flanking region
چکیده انگلیسی

Class III β-tubulin (TUBB3) overexpression represents a major mechanism of drug resistance to microtubule interacting agents such as taxanes and Vinca alkaloids. Here, we tested hypoxia as a possible inducer of TUBB3. The effects of hypoxia on TUBB3 expression were monitored at mRNA and protein level in A2780, in its paclitaxel-resistant counterpart (TC1) and in HeLa cells. Hypoxia was a strong inducer of TUBB3 in A2780, but not in TC1 and HeLa cells. In A2780 HIF-1α was knocked down using RNA interference and TUBB3 expression was assessed in normoxia and hypoxia. The silencing abolished the hypoxia-dependent increase of TUBB3, thereby demonstrating that HIF-1α mediates TUBB3 induction in hypoxia. To investigate this phenomenon, the 5' flanking region of human TUBB3 was cloned upstream GFP as a reporter. This region contained the promoter gene, but activity of the reporter was unaffected by hypoxia. Thus, we looked at the 3' flanking region and, at + 168 nucleotides from the stop codon, an HIF-1α binding site was proven to be active in hypoxia, using a construct in which the site was cloned downstream GFP as reporter gene. Deletion of the site in the construct abolished GFP enhancement upon hypoxia. Chromatin immunoprecipitation revealed the engagement by HIF-1α of this site in hypoxia. Methylation analysis of this 3' enhancer showed that it was free of methylation in 70% of cells in A2780, while in less than 16% in both TC1 and HeLa cells, thereby suggesting that TUBB3 increase upon hypoxia is abolished through methylation of the 3' enhancer.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Gene - Volume 409, Issues 1–2, 15 February 2008, Pages 100–108
نویسندگان
, , , , , , , , ,