title: Expression and cellular localization of hepcidin mRNA and protein in normal rat brain.
abstract: BACKGROUND
  Hepcidin is a peptide hormone belonging to the defensin family of cationic antimicrobial molecules that has an essential role in systemic iron homeostasis. The peptide is synthesised by hepatocytes and transported in the circulation to target tissues where it regulates the iron export function of the ferrous iron permease, ferroportin. In the brain hepcidin protein has been identified using immuno-histochemistry and mRNA by real-time PCR but not by in situ hybridisation raising the question of whether there is measurable transcription of the hepcidin gene in the central nervous system. Alternatively hepcidin could be transported as a hormone to the brain via the circulation.
  
  
  RESULTS
  By RT-PCR hepcidin mRNA was present at low level throughout normal rat brain while in situ hybridisation to detect low-abundant mRNA revealed that transcripts were restricted to endothelium of blood vessels and choroid plexus. In contrast, hepcidin protein analysed by immuno-histochemistry was highly expressed in blood vessels, in endothelium and in pericytes. Hepcidin was also present in glial cells and in the olfactory bulb, sub-ventricular zone and dentate gyrus, areas where neurogenesis and synaptic plasticity are maintained throughout adult life. The hepcidin species identified by Western blotting in sub-ventricular zone, cortex and hippocampus migrated as a ~2.8 kDa band, identical in size to hepcidin present in normal rat serum suggesting that hepcidin in brain was the full-length biologically active 25 amino acid peptide. Hepcidin co-localised with ferroportin in ependymal cells of the sub-ventricular zone and in the corpus callosum consistent with a regulatory role in iron metabolism at these sites.
  
  
  CONCLUSIONS
  Hepcidin protein was widely expressed in brain parenchyma while levels of hepcidin gene transcription appeared to be below the limits of detection of the in situ hybridisation probes. This disparity suggests that not all hepcidin in the brain is transcribed in situ and may originate in part outside the brain. The properties of hepcidin as a cationic peptide hormone are reflected in the finding of hepcidin in the walls of blood vessels and in pericytes and glia, cells that may be involved in transporting the peptide into brain interstitium.
authors.affiliation: John Van Geest Centre for Brain Repair, Department of Clinical Neuroscience, University of Cambridge, Cambridge, UK. rr224@cam.ac.uk.
authors.forename: Ruma
authors.initials: R
authors.lastname: Raha-Chowdhury
authors.affiliation: John Van Geest Centre for Brain Repair, Department of Clinical Neuroscience, University of Cambridge, Cambridge, UK. alex.raha@icloud.com.|Institute of Liver Studies, King's College Hospital, London, UK. alex.raha@icloud.com.
authors.forename: Animesh Alexander
authors.initials: AA
authors.lastname: Raha
authors.affiliation: Department of Neuroscience Institute of Experimental Medicine Academy of Sciences of the Czech Republic, Prague, Czech Republic. serhiy.forostyak@biomed.cas.cz.
authors.forename: Serhiy
authors.initials: S
authors.lastname: Forostyak
authors.affiliation: John Van Geest Centre for Brain Repair, Department of Clinical Neuroscience, University of Cambridge, Cambridge, UK. jingweizhao@fudan.edu.cn.
authors.forename: Jing-Wei
authors.initials: JW
authors.lastname: Zhao
authors.affiliation: John Van Geest Centre for Brain Repair, Department of Clinical Neuroscience, University of Cambridge, Cambridge, UK. ss2060@cam.ac.uk.
authors.forename: Simon Russell William
authors.initials: SR
authors.lastname: Stott
authors.affiliation: Institute of Liver Studies, King's College Hospital, London, UK. Adrian.bomford@kcl.ac.uk.
authors.forename: Adrian
authors.initials: A
authors.lastname: Bomford
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D001774:Blood Chemical Analysis; D001921:Brain / Q000098:blood supply / Q000378:metabolism*; D002648:Child; D042783:Endothelial Cells / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D064451:Hepcidins / Q000378:metabolism*; D006801:Humans; D017403:In Situ Hybridization; D008875:Middle Aged; D009457:Neuroglia / Q000378:metabolism; D020286:Pericytes / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D017207:Rats, Sprague-Dawley; D060888:Real-Time Polymerase Chain Reaction; D055815:Young Adult
chemical_list: C578702:HAMP protein, human; C578703:Hamp protein, rat; D064451:Hepcidins; D012333:RNA, Messenger