Duodenal cytochrome b (Cybrd1) ferric reductase functional studies in cells

Abstract

Dietary non-heme ferric iron is reduced by the ferric reductase enzyme, duodenal cytochrome b (Dcytb), before absorption by the divalent metal transporter 1 (DMT1). A single nucleotide polymorphism (SNP rs10455 mutant) that is located in the last exon of the Dcytb gene was reported in C282Y haemochromatosis HFE subjects. The present work therefore investigated the phenotype of this mutant Dcytb in Chinese hamster ovary (CHO) cells. These cultured cells were transfected with either wild type (WT) or the SNP vector plasmids of Dcytb. Ferric reductase assays were performed in Dcytb transgenic CHO cells using the ferrozine spectrophometric assay protocol. The Dcytb SNP rs10455 showed a gain-of-function capability since ferric reductase activity increased significantly (p < 0.01) in the transgenic cells. Varying ferric reductase activity was found when CHO cells were pretreated with modulators of Dcytb protein expression. Although ferric reductase in endogenous CHO cells increased with deferoxamine or CoCl, iron loading with ferric ammonium citrate (FAC) had the opposite effect. Taken together, the study reveals a gain-of-function phenotype for Dcytb rs10455 mutation that could be a putative modifier of colorectal cancer risk, with attendant variability in penetrance among human HFE C282Y homozygotes.

Upregulated Expression of CYBRD1 Predicts Poor Prognosis of Patients with Ovarian Cancer

“…CYBRD1 is a ferrous ion-regulated reductase that activates multiple intracellular signaling pathways involved in transmembrane ferric ion transport [ 12 ]. CYBRD1 comprises 286 amino acid residues and six membrane-spanning domains [ 12 ].…”

“…CYBRD1 is a ferrous ion-regulated reductase that activates multiple intracellular signaling pathways involved in transmembrane ferric ion transport [ 12 ]. CYBRD1 comprises 286 amino acid residues and six membrane-spanning domains [ 12 ]. The amino acid sequence of CYBRD1 is 45%–50% similar to that of cytochrome b561, which facilitates electron transport across the membrane [ 25 ].…”

“…Cytochrome b reductase 1 (CYBRD1) is an iron-regulated ferric reductase that mediates iron-regulated signaling pathways [ 11 ] by catalyzing the conversion of ferric to ferrous ion during iron absorption [ 12 ]. Ferrous iron promotes DNA damage and participates in the pathogenesis and progression of cancer by inducing the production of reactive oxygen species [ 13 , 14 ].…”

Integrated analysis of a lncRNA‑mRNA network reveals a potential mechanism underlying necrotizing enterocolitis

“…as a member of the cytochrome family, cYBrd1 encodes an iron-regulated protein and exhibits ferric reductase activity (40). Furthermore, cYBrd1 has been demonstrated to serve a key role in dietary iron absorption (41). it has been shown that nec may affect the expression of cYBrd1 in the duodenal brush border membrane and contributes to the severe anemia associated with nec (42).…”

Iron Metabolism and Ferroptosis in Epilepsy

“…However, heme is rapidly catabolized by HO-1 to release the iron (Daher et al, 2017). Fe 3+ can be reduced into the Fe 2+ form by DCYTB, and Fe 2+ is imported by the apical DMT1 (Schlottmann et al, 2017). In the basolateral membrane of intestinal epithelial cells, ferritin (FPN) is the main iron exporter, transporting Fe 2+ .…”