title: The mitochondrial protein frataxin is downregulated in hemodialysis patients.
abstract: BACKGROUND
  The mitochondrial protein frataxin regulates iron metabolism for heme and iron sulfur cluster synthesis in the mitochondria and could be associated with the regulation of oxidative stress. To clarify the expression of frataxin and its association with uremia, we evaluated the mRNA and protein levels of frataxin in the polymorphonuclear leukocytes (PMNLs) of patients on hemodialysis (HD).
  
  
  METHODS
  Uremic patients on HD (n = 18) and healthy control subjects (n = 18) were investigated. PMNLs were isolated by differential centrifugation. The mRNA levels of frataxin in isolated leukocytes were quantified by TaqMan real-time polymerase chain reaction. Frataxin protein expression in the cell lysate was evaluated using SDS-polyacrylamide gel electrophoresis and Western blotting.
  
  
  RESULTS
  The frataxin/glyceraldehyde-3-phosphate dehydrogenase mRNA ratio in PMNLs from uremic patients was significantly lower than that in control subjects. Frataxin protein expression in uremic patients was also significantly lower than that in controls. Multiple regression analysis showed that frataxin mRNA levels were independently associated with the serum levels of both the oxidative stress marker malondialdehyde and the proinflammatory cytokine tumor necrosis factor-α.
  
  
  CONCLUSIONS
  The downregulation of frataxin seems to be linked with uremic status, which is usually associated with chronic inflammation and the acceleration of oxidative stress. Mitochondrial iron regulation may play a role in several comorbidities and in the poor prognosis in uremic patients. Further investigation is needed to elucidate whether reduced frataxin levels are linked to the pathological status of uremic patients and whether uremic substances affect frataxin expression.
authors.affiliation: Division of Kidney and Dialysis, Department of Internal Medicine, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, 663-8501, Japan. cherry39@hyo-med.ac.jp
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Hasuike
authors.forename: Takanori
authors.initials: T
authors.lastname: Nagai
authors.forename: Soshi
authors.initials: S
authors.lastname: Yorifuji
authors.forename: Saiko
authors.initials: S
authors.lastname: Tanaka
authors.forename: Ayako
authors.initials: A
authors.lastname: Matsumoto
authors.forename: Mana
authors.initials: M
authors.lastname: Yahiro
authors.forename: Shoji
authors.initials: S
authors.lastname: Kaibe
authors.forename: Aritoshi
authors.initials: A
authors.lastname: Kida
authors.forename: Masanori
authors.initials: M
authors.lastname: Tokuyama
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Nagasawa
authors.forename: Yoshinaga
authors.initials: Y
authors.lastname: Otaki
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kuragano
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nakanishi
mesh_terms: D000368:Aged; D015536:Down-Regulation; D005260:Female; D006801:Humans; D033862:Iron-Binding Proteins / Q000096:biosynthesis*; D007676:Kidney Failure, Chronic / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D024101:Mitochondrial Proteins / Q000378:metabolism; D009504:Neutrophils / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D006435:Renal Dialysis; D014409:Tumor Necrosis Factor-alpha / Q000097:blood; D014511:Uremia / Q000378:metabolism*; D000096923:Frataxin
chemical_list: D033862:Iron-Binding Proteins; D024101:Mitochondrial Proteins; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D000096923:Frataxin