The putative heme transporter HCP1 is expressed in cultured astrocytes and contributes to the uptake of hemin

Dang, Theresa N. T.; Bishop, Glenda M.; Dringen, Ralf; Robinson, Stephen R.

doi:10.1002/glia.20901

Cited by 50 publications

(46 citation statements)

References 41 publications

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“…First, PCFT was initially described as HCP1, a low-affinity heme carrier protein (15). Recent studies suggest that some heme transport may possibly occur via HCP1/PCFT (SLC46A1) (43,44). Interestingly, heme biosynthesis involves interlinked reactions occurring both in the mitochondria and cytosol (45,46), primarily of erythrocytes that by themselves are extremely dependent on folate cofactors for erythropoiesis (47).…”

Section: Discussionmentioning

confidence: 99%

The Obligatory Intestinal Folate Transporter PCFT (SLC46A1) Is Regulated by Nuclear Respiratory Factor 1

Gonen

Assaraf

2010

Journal of Biological Chemistry

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Folates are essential vitamins that play a key role as onecarbon donors in a spectrum of biosynthetic pathways including RNA and DNA synthesis. The proton-coupled folate transporter (PCFT/SLC46A1) mediates obligatory intestinal folate absorption. Loss-of-function mutations in PCFT result in hereditary folate malabsorption, an autosomal recessive disorder characterized by very low folate levels in the blood and cerebrospinal fluid. Hereditary folate malabsorption manifests within the first months after birth with anemia, immune deficiency, and neurological deficits. Here we studied the role of inducible trans-activators of PCFT gene expression. Bioinformatics identified three putative nuclear respiratory factor 1 (NRF-1) binding sites in the minimal promoter. The following evidence establish that PCFT is an NRF-1-responsive gene; electrophoretic mobility shift assay showed NRF-1 binding to native but not mutant NRF-1 sites, whereas antibody-mediated supershift analysis and chromatin immunoprecipitation revealed NRF-1 binding to its consensus sites within the PCFT promoter. Moreover, mutational inactivation of individual or all NRF-1 binding sites resulted in 40 -60% decrease in luciferase reporter activity. Consistently, overexpression of NRF-1 or a constitutively active NRF-1 VP-16 construct resulted in increased reporter activity and PCFT mRNA levels. Conversely, introduction of a dominant-negative NRF-1 construct markedly repressed reporter activity and PCFT mRNA levels; likewise, introduction of NRF-1 siRNA duplexes to cells resulted in decreased PCFT transcript levels. Moreover, NRF-1 silencing down-regulated genes encoding for key folate transporters and enzymes in folate metabolism. These novel findings identify NRF-1 as a major inducible transcriptional regulator of PCFT gene expression. The implications of this linkage between folate transport and metabolism with mitochondria biogenesis and respiration are discussed.

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Section: Discussionmentioning

confidence: 99%

The Obligatory Intestinal Folate Transporter PCFT (SLC46A1) Is Regulated by Nuclear Respiratory Factor 1

Gonen

Assaraf

2010

Journal of Biological Chemistry

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“…This decrease could be explained by the depletion of the regulatory pool and heme from cellular storage. Such heme storage was demonstrated in astrocytes and involved a reputed heme transporter HCP1 (Dang et al, 2010). It is plausible that core functions using cofactor heme (e.g., respiratory chain in mitochondrial cytochromes) would be protected by homeostatic mechanisms.…”

Section: Discussionmentioning

confidence: 99%

Early Failure ofN-Methyl-d-aspartate Receptors and Deficient Spine Formation Induced by Reduction of Regulatory Heme in Neurons

Chernova

Steinert²,

Richards³

et al. 2011

Mol Pharmacol

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An initial stage of many neurodegenerative processes is associated with compromised synaptic function and precedes synapse loss, neurite fragmentation, and neuronal death. We showed previously that deficiency of heme, regulating many proteins of pharmacological importance, causes neurodegeneration of primary cortical neurons via N-methyl-D-aspartate receptor (NMDAR)-dependent suppression of the extracellular signal-regulated kinase 1/2 pathway. Here, we asked whether the reduction of heme causes synaptic perturbation before neurite fragmentation in neuronal cultures and investigated molecular mechanisms of synaptic dysfunction in these cells. We showed the change in the NR2B subunit phosphorylation that correlates with compromised NMDAR function after the reduction of regulatory heme and a rapid rescue of NR2B phosphorylation and NMDAR function by exogenous heme. Electrophysiological recordings demonstrated diminished NMDAR currents and NMDAR-mediated calcium influx after 24 h of inhibition of heme synthesis. These effects were reversed by treatment with heme; however, inhibition of the Src family kinases abolished the rescue effect of heme on NMDA-evoked currents. Diminished NMDAR current and Ca 2ϩ influx resulted in suppressed cGMP production and impairment of spine formation. Exogenous heme exerted rescue effects on NR2B tyrosine phosphorylation and NMDA-evoked currents within minutes, suggesting direct interactions within the NMDAR complex. These synaptic changes after inhibition of heme synthesis occurred at this stage without apparent dysfunction of major hemoproteins. We conclude that regulatory heme is necessary in maintaining NR2B phosphorylation and NMDAR function. NMDAR failure occurs before neurite fragmentation and may be a causal factor in neurodegeneration; this could suggest a route for an early pharmacological intervention.

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“…The sections were washed in PBS and mounted using a fluorescent mounting medium (Dako). Perls' iron staining was performed in control, hypoxic, and hypoxia ϩ deferoxamine group of primary microglial cultures according to a method previously described by Dang et al (2010). The cells were then stained with lectin and processed as described above.…”

Section: Methodsmentioning

confidence: 99%

Iron and Iron Regulatory Proteins in Amoeboid Microglial Cells Are Linked to Oligodendrocyte Death in Hypoxic Neonatal Rat Periventricular White Matter through Production of Proinflammatory Cytokines and Reactive Oxygen/Nitrogen Species

Rathnasamy¹,

Ling²,

Kaur³

2011

J. Neurosci.

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This study was aimed to examine the role of iron in causing periventricular white matter (PWM) damage following a hypoxic injury in the developing brain. Along with iron, the expression of iron regulatory proteins (IRPs) and transferrin receptor (TfR), which are involved in iron acquisition, was also examined in the PWM by subjecting 1-d-old Wistar rats to hypoxia. Apart from an increase in iron levels in PWM, Perls' iron staining showed an increase of intracellular iron in the preponderant amoeboid microglial cells (AMCs) in the tissue. In response to hypoxia, the protein levels of IRP1, IRP2, and TfR in PWM and AMCs were significantly increased. In primary microglial cultures, administration of iron chelator deferoxamine reduced the generation of iron-induced reactive oxygen and nitrogen species and proinflammatory cytokines such as tumor necrosis factor-␣ and interleukin-1␤. Primary oligodendrocytes treated with conditioned medium from hypoxic microglia exhibited reduced glutathione levels, increased lipid peroxidation, upregulated caspase-3 expression, and reduced proliferation. This was reversed to control levels on treatment with conditioned medium from deferoxamine treated hypoxic microglia; also, there was reduction in apoptosis of oligodendrocytes. The present results suggest that excess iron derived primarily from AMCs might be a mediator of oligodendrocyte cell death in PWM following hypoxia in the neonatal brain.

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The putative heme transporter HCP1 is expressed in cultured astrocytes and contributes to the uptake of hemin

Cited by 50 publications

References 41 publications

The Obligatory Intestinal Folate Transporter PCFT (SLC46A1) Is Regulated by Nuclear Respiratory Factor 1

The Obligatory Intestinal Folate Transporter PCFT (SLC46A1) Is Regulated by Nuclear Respiratory Factor 1

Early Failure ofN-Methyl-d-aspartate Receptors and Deficient Spine Formation Induced by Reduction of Regulatory Heme in Neurons

Iron and Iron Regulatory Proteins in Amoeboid Microglial Cells Are Linked to Oligodendrocyte Death in Hypoxic Neonatal Rat Periventricular White Matter through Production of Proinflammatory Cytokines and Reactive Oxygen/Nitrogen Species

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