Transcriptional Regulation of the Menkes Copper ATPase ( Atp7a ) Gene by Perturbations of Iron and Copper in Intestinal Epithelial Cells

Divalent metal transport 1 ( Dmt1 ) and duodenal cytochrome B ( DcytB ) are regulated by HIF‐2α during iron deficiency in the mammalian intestine. Our previous work demonstrated that Atp7a is strongly upregulated in the duodenum of iron‐deficient rats while hypoxia also occurs. Further study demonstrated that Atp7a is also upregulated by HIF‐2α in intestinal epithelial (IEC‐6) cells either with CoCl 2 treatment or under 1% O 2 , while the effect of HIF‐1α on Atp7a expression level is not significant. In the present study, we sought to test whether both iron and copper are involved in the regulation of Atp7a mRNA and protein expression levels by HIF‐2α independent mechanisms. To mimic iron deficiency in vitro, pre‐confluent IEC‐6 cells were treated with deferoxamine (DFO) and additional Cu was also added with DFO. There was no change in HIF‐2α protein level, however, both Atp7a mRNA and protein were induced for ~1.5‐ and 3‐fold with DFO and DFO+Cu treatment, respectively. To further evaluate the hypothesis that iron deficiency and HIF‐2α regulate Atp7a expression by distinct molecular mechanisms, we are going to pursue further mechanism studies designed to define Atp7a gene regulation during low iron conditions. Grant Funding Source : 1R01 DK074867