Abstract
Hypoxia-inducible factor- 1α (HIF-1α) is an important protein involved in tumor development. Production of HIF-1α would be stimulated by the hypoxic environment in tumor and leads to tumor metastasis. Metal responsive transcription factor 1 (MTF-1), which plays an essential role in modulating the expression of genes, involves in cellular zinc homeostasis. In this study, we investigated the interaction between HIF-1α and MTF-1 by immunoprecipitation. The results revealed that HIF-1α interacts with all of the domains of MTF-1. Besides, we also expressed MTF-1 and HIF-1α with the deletion of ODD domain. The results showed that loss of ODD domain, a region responsible for protein stability, had no effect on HIF-1α and MTF-1 interaction. Noticeably, addition of zinc to cells increased MTF-1/ HIF-1α interaction in a dose-dependent manner. According to the results, addition of zinc increased the HIF-1α protein level. However, this increase was not due to the alternation of its mRNA level by enhancing protein stability through the use of cycloheximide. Analyzing the position of HIF-1α in cytoplasmic and nuclear fraction showed that the presence of MTF-1 did not affect the distribution of HIF-1α. Using reporter gene assay and siRNA to reduce the expression of MTF-1 mRNA revealed that the presence of MTF-1 would increase the transcriptional activity of HIF-1α significantly.