Hepcidin Mediates Transcriptional Changes in Ferroportin mRNA in Differentiated Neuronal-Like PC12 Cells Subjected to Iron Challenge

Abstract

Ferroportin is the only known iron exporter, and its regulation seems to be controlled at both transcriptional, post-transcriptional, and post-translational levels. The objective of the current work was to investigate how cellular iron status affects the expression of the ferroportin gene Fpn under the influence of hepcidin, known to post-translational lower the available ferroportin protein. Nerve growth factor-beta (NGF-β)-differentiated PC12 cells, used as a model of neuronal cells, were evaluated in terms of their viability and expression of ferroportin after inducing cellular iron overload with ferric ammonium citrate (FAC) or hepcidin, iron deficiency with deferoxamine (DFO), or hepcidin in combination with FAC or DFO. Ferritin mRNA was significantly upregulated following treatment with 20 mM FAC. The viability of the differentiated PC12 cells was significantly reduced after treatment with 30 mM FAC or 1.0 μM hepcidin, but when combining FAC and hepcidin treatment, the cells remained unaffected. The expression of Fpn was concurrently upregulated after treatment with FAC in combination with hepcidin. Fifty millimolar DFO also increased Fpn. Together, these data point towards a transcriptional induction of Fpn in response to changes in cellular iron levels. Epigenetic regulation of Fpn may also occur as changes in genes associated with epigenetic regulation of Fpn were demonstrated.

Brain iron transport

“…Fpn1 is the only known cellular iron exporter which has been demonstrated to be expressed in neurons (Burdo et al, ; Wu et al, ; Du et al, ; Urrutia et al, ; Zarruk et al, ), astrocytes (Wu et al, ; Pelizzoni et al, ; Rathore et al ., ; Urrutia et al, ; Zarruk et al, ; Xu et al, ), oligodendrocytes (Wu et al, ; Zarruk et al, ) and microglia (Pelizzoni et al, ; Rathore et al ., ; Urrutia et al, ; Xu et al, ; Zarruk et al, ; Xu et al, ). Transcriptional changes in Fpn1 mRNA were found to be mediated by hepcidin in differentiated neuronal‐like PC12 cells subjected to iron challenge (Helgudottir et al, ), and iron export through Fpn1 is modulated by the iron chaperone poly(rC)‐binding protein 2 (PCBP2) (Yanatori et al, ). CP, a critical ferroxidase, has been found in neurons (Loeffler et al, ; Loeffler, Sima & LeWitt, ) and astrocytes (Klomp et al, ; Klomp & Gitlin, ; Loeffler et al, ; Loeffler, Sima, & Lewitt, ; Jeong & David, , ), while another ferroxidase Heph is expressed in neurons (Hudson et al, ; Ji et al, ), oligodendrocytes (Schulz et al, ; Zarruk et al, ) and microglia (Zarruk et al, ).…”

Cardiomyocyte‐specific overexpression of FPN1 diminishes cardiac hypertrophy induced by chronic intermittent hypoxia

“…In the control group, cells were cultivated under normal oxygen conditions 28 . The cells were treated with hepcidin, FAC and DFO 29 . At the end of the treatment, cell viability, protein blot analysis and other assays were performed.…”

“…28 The cells were treated with hepcidin, FAC and DFO. 29 At the end of the treatment, cell viability, protein blot analysis and other assays were performed.…”

Iron role paradox in nerve degeneration and regeneration

“…However, considering iron accumulation after PNI (Martinez‐Vivot et al., 2015; Raivich et al., 1991), it can be thought that Fer levels are increased. Ferric ammonium citrate (FAC)‐induced iron overload in differentiated PC12 cells increases the expression of Fer subunits mRNA (Helgudottir et al., 2019). Ablation of Fer reduces embryonic SC proliferation, maturation, and postnatal myelination.…”

“…SCs express Fpn and Cp, two proteins that partner to efflux iron from SCs (Camborieux et al., 1998; Schulz, 2011). The expression of Fpn mRNA is greater in differentiated PC12 cells than in undifferentiated cells (Helgudottir et al., 2019). Up‐regulation of Fpn has been shown after sciatic nerve crush injury (Schulz, 2011).…”