RGD Reference Report - Silencing the Menkes copper-transporting ATPase (Atp7a) gene in rat intestinal epithelial (IEC-6) cells increases iron flux via transcriptional induction of ferroportin 1 (Fpn1). - Rat Genome Database

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Silencing the Menkes copper-transporting ATPase (Atp7a) gene in rat intestinal epithelial (IEC-6) cells increases iron flux via transcriptional induction of ferroportin 1 (Fpn1).

Authors: Gulec, S  Collins, JF 
Citation: Gulec S and Collins JF, J Nutr. 2014 Jan;144(1):12-9. doi: 10.3945/jn.113.183160. Epub 2013 Oct 30.
RGD ID: 11341686
Pubmed: PMID:24174620   (View Abstract at PubMed)
PMCID: PMC3861793   (View Article at PubMed Central)
DOI: DOI:10.3945/jn.113.183160   (Journal Full-text)

The Menkes copper-transporting ATPase (Atp7a) gene is induced in rat duodenum during iron deficiency, consistent with copper accumulation in the intestinal mucosa and liver. To test the hypothesis that ATP7A influences intestinal iron metabolism, the Atp7a gene was silenced in rat intestinal epithelial (IEC-6) cells using short hairpin RNA (shRNA) technology. Perturbations in intracellular copper homeostasis were noted in knockdown cells, consistent with the dual roles of ATP7A in pumping copper into the trans-Golgi (for cuproenzyme synthesis) and exporting copper from cells. Intracellular iron concentrations were unaffected by Atp7a knockdown. Unexpectedly, however, vectorial iron ((59)Fe) transport increased ( approximately 33%) in knockdown cells grown in bicameral inserts and increased further ( approximately 70%) by iron deprivation (compared with negative control shRNA-transfected cells). Additional experiments were designed to elucidate the molecular mechanism of increased transepithelial iron flux. Enhanced iron uptake by knockdown cells was associated with increased expression of a ferrireductase (duodenal cytochrome b) and activity of a cell-surface ferrireductase. Increased iron efflux from knockdown cells was likely mediated via transcriptional activation of the ferroportin 1 gene (by an unknown mechanism). Moreover, Atp7a knockdown significantly attenuated expression of an iron oxidase [hephaestin (HEPH); by approximately 80%] and membrane ferroxidase activity (by approximately 50%). Cytosolic ferroxidase activity, however, was retained in knockdown cells (75% of control cells), perhaps compensating for diminished HEPH activity. This investigation has thus documented alterations in iron homeostasis associated with Atp7a knockdown in enterocyte-like cells. Alterations in copper transport, trafficking, or distribution may underlie the increase in transepithelial iron flux noted when ATP7A activity is diminished.



Gene Ontology Annotations    Click to see Annotation Detail View

Biological Process

  
Object SymbolSpeciesTermQualifierEvidenceWithNotesSourceOriginal Reference(s)
Atp7aRatnegative regulation of iron ion transmembrane transport  IMP  RGD 

Objects Annotated

Genes (Rattus norvegicus)
Atp7a  (ATPase copper transporting alpha)


Additional Information