Regulation of CDKN2B expression by interaction of Arnt with Miz-1 - a basis for functional integration between the HIF and Myc gene regulatory pathways

Molecular Cancer

Research

Marit Bakke¹  Kathrine S Aasrud¹  Reidun Aesoy¹  Erling A Hoivik¹  Katarina Gradin²  Lorenz Poellinger³  Jorge L Ruas⁴ 

[1] Department of Biomedicine, University of Bergen, Jonas Lies vei 91, N-5009, Bergen, Norway;Department of Cell and Molecular Biology, Karolinska Institutet, S-171 77, Stockholm, Sweden;Department of Cell and Molecular Biology, Karolinska Institutet, S-171 77, Stockholm, Sweden;Cancer Science Institute Singapore, National University of Singapore, 117456, Singapore, Republic of Singapore;Department of Cell and Molecular Biology, Karolinska Institutet, S-171 77, Stockholm, Sweden;Department of Physiology and Pharmacology, Karolinska Institutet, S-171 77, Stockholm, Sweden;

关键词: Helix-loop-helix transcription factors;    Hypoxia;    Hypoxia-inducible factor (HIF);    Myc;    Arnt;    CDKN2B;    Miz-1;   

DOI  :  10.1186/1476-4598-13-54

 received in 2013-08-22, accepted in 2014-03-04,  发布年份 2014

来源: Springer

【 摘 要 】

BackgroundHypoxia- and Myc-dependent transcriptional regulatory pathways are frequently deregulated in cancer cells. These pathways converge in many cellular responses, but the underlying molecular mechanisms are unclear.MethodsThe ability of Miz-1 and Arnt to interact was identified in a yeast two-hybrid screen. The mode of interaction and the functional consequences of complex formation were analyzed by diverse molecular biology methods, in vitro. Statistical analyses were performed by Student’s t-test and ANOVA.ResultsIn the present study we demonstrate that the aryl hydrocarbon receptor nuclear translocator (Arnt), which is central in hypoxia-induced signaling, forms a complex with Miz-1, an important transcriptional regulator in Myc-mediated transcriptional repression. Overexpression of Arnt induced reporter gene activity driven by the proximal promoter of the cyclin-dependent kinase inhibitor 2B gene (CDKN2B), which is an established target for the Myc/Miz-1 complex. In contrast, mutated forms of Arnt, that were unable to interact with Miz-1, had reduced capability to activate transcription. Moreover, repression of Arnt reduced endogenous CDKN2B expression, and chromatin immunoprecipitation demonstrated that Arnt interacts with the CDKN2B promoter. The transcriptional activity of Arnt was counteracted by Myc, but not by a mutated variant of Myc that is unable to interact with Miz-1, suggesting mutually exclusive interaction of Arnt and Myc with Miz-1. Our results also establish CDKN2B as a hypoxia regulated gene, as endogenous CDKN2B mRNA and protein levels were reduced by hypoxic treatment of U2OS cells.ConclusionsOur data reveal a novel mode of regulation by protein-protein interaction that directly ties together, at the transcriptional level, the Myc- and hypoxia-dependent signaling pathways and expands our understanding of the roles of hypoxia and cell cycle alterations during tumorigenesis.

【 授权许可】

CC BY   
© Aesoy et al.; licensee BioMed Central Ltd. 2014