Aging is associated with increased brain iron through cortex-derived hepcidin expression

  1. Tatsuya Sato
  2. Jason Solomon Shapiro
  3. Hsiang-Chun Chang
  4. Richard A Miller
  5. Hossein Ardehali  Is a corresponding author
  1. Feinberg Cardiovascular and Renal Research Institute, Northwestern University School of Medicine, United States
  2. Department of Pathology, University of Michigan School of Medicine, United States
3 figures, 1 table and 1 additional file

Figures

Non-heme iron is increased in the cytosol and mitochondria of the brain cortex with aging.

Liver non-heme (A) and heme (B) iron in young (4 months old) and old (22 months old) mice from the cytosol and mitochondria (n=6). Gastrocnemius non-heme (C) and heme (D) iron in young and old mice from the cytosol and mitochondria (n=6). Outliers in non-heme iron in the cytosol (n=1) and in the mitochondria (n=2) were excluded. Mitochondrial heme iron in gastrocnemius muscle was not detectable in our studies. Brain non-heme (E) and heme (F) iron in young and old mice from the cytosol and mitochondria (n=6). (G) Immunoblots of mitochondrial and cytosolic markers, confirming the purity of mitochondrial isolation in the brain cortex tissue. W = whole cell lysate, Cyt = cytosolic fraction, Mit = mitochondrial fraction, SDHA = Succinate Dehydrogenase Complex Flavoprotein Subunit A, HPRT = hypoxanthine phosphoribosyltransferase. (H) Immunoblots of FTN and IRP2 in the brain of young and aged mice (n=4). FTN = ferritin, IRP2 = iron regulatory protein 2, H = heavy chain, L = light chain. Densitometric quantification of light and heavy chain FTN (I) and IRP2 (J) in the brain of young and aged mice. * p<0.05.

Figure 1—source data 1

Full-length images of immunoblots shown in Figure 1.

https://cdn.elifesciences.org/articles/73456/elife-73456-fig1-data1-v1.pptx
Figure 1—source data 2

Iron measurement – Original data of iron measurements shown in Figure 1.

https://cdn.elifesciences.org/articles/73456/elife-73456-fig1-data2-v1.xlsx
Figure 1—source data 3

Densitometry – Original data of densitometric quantifications of immunoblots shown in Figure 1.

https://cdn.elifesciences.org/articles/73456/elife-73456-fig1-data3-v1.xlsx
Hepcidin protein expression is significantly increased in the aged brain cortex.

mRNA levels of proteins involved in iron regulation in the liver (A) and brain (B) in young (4 months old) and old (22 months old) mice (n=10/group). Means and SEM are indicated as horizontal and vertical bars, respectively. An undetected measurement (n=1) in the brain Fech and undetected measurements (n=2) and an outlier (n=1) in the brain Hamp1 were excluded. Tfr1 = transferrin receptor 1, Tfr2 = transferrin receptor 2, Dmt1 = divalent metal transporter 1, Fpn1 = ferroportin 1, Pcbp1 = Poly(RC) Binding Protein 1, Steap3 = Metalloreductase Six-Transmembrane Epithelial Antigen Of Prostate 3, Sec15l1 = exocyst complex component 6, Mfrn2 = mitoferrin 2, Abcb7 = ATP-binding cassette sub-family B member 7, Abcb8 = ATP-binding cassette sub-family B member 8, Alr1 = augmenter of liver regeneration, Cp = ceruloplasmin, Fxn = frataxin, Ttp = tristetraprolin, Lias = tristetraprolin, Hmox1 = heme oxygenase 1, Hmox2 = heme oxygenase 2, Alas1 = 5′-aminolevulinate synthase 1, Alas2 = 5′-aminolevulinate synthase 2, Fech = ferrochelatase, Alad = aminolevulinate dehydratase, Pbgd = porphobilinogen deaminase, Uros = uroporphyrinogen III synthase, Urod = uroporphyrinogen decarboxylase, Ppox = protoporphyrinogen oxidase, Abcb10 = ATP-binding cassette, sub-family B member 10, Hamp1 = hepcidin1, Bmp6 = bone morphogenetic protein 6, Hfe = homeostatic iron regulator, Ftmt = mitochondrial ferritin. (C) Representative immunoblot for hepcidin1 in the brain (n=6). (D) Summary of densitometry analysis of panel (C). (E) Representative immunohistochemistry of hepcidin1 (Red = anti-hepcidin1, blue = DAPI) in the brain frontal cortex of young and aged mice. Scale bar=200 µm. * p<0.05.

Figure 2—source data 1

Full-length images of immunoblots shown in Figure 2.

https://cdn.elifesciences.org/articles/73456/elife-73456-fig2-data1-v1.pptx
Figure 2—source data 2

qRT-PCR liver – Original data of qRT-PCR in the liver shown in Figure 2.

https://cdn.elifesciences.org/articles/73456/elife-73456-fig2-data2-v1.xlsx
Figure 2—source data 3

qRT-PCR brain – Original data of qRT-PCR in the brain shown in Figure 2.

https://cdn.elifesciences.org/articles/73456/elife-73456-fig2-data3-v1.xlsx
Figure 2—source data 4

Densitometry – Original data of densitometry quantifications of immunoblots shown in Figure 2.

https://cdn.elifesciences.org/articles/73456/elife-73456-fig2-data4-v1.xlsx
FPN1 protein level is decreased while its poly-ubiquitination is increased in the brain cortex of aged mice.

(A) Immunoblots of iron transporting proteins TfR1 and FPN1 in the brain cortex of young and aged mice (n=3). (B) Summary of densitometric analysis of panel (A). (C) Poly-ubiquitination levels of FPN1, as assessed by immunoprecipitation, in the brain cortex of young and aged mice (n=3). (D) Summary of the densitometric analysis of panel (C). (E) Fe-S cluster containing aconitase enzyme activity, a marker of cellular oxidative stress, in the brain cortex of young and aged mice (n=4). c-aconitase = cytosolic aconitase (ACO1), m-aconitase = mitochondrial aconitase (ACO2). * p<0.05.

Figure 3—source data 1

Full length images of immunoblots shown in Figure 3.

https://cdn.elifesciences.org/articles/73456/elife-73456-fig3-data1-v1.pptx
Figure 3—source data 2

Densitometry – Original data of densitometry quantifications of immunoblots shown in Figure 3.

https://cdn.elifesciences.org/articles/73456/elife-73456-fig3-data2-v1.xlsx
Figure 3—source data 3

Aconitase assay – Original data of aconitase enzyme activities shown in Figure 3.

https://cdn.elifesciences.org/articles/73456/elife-73456-fig3-data3-v1.xlsx

Tables

Key resources table
Reagent type (species) or resourceDesignationSource or referenceIdentifiersAdditional information
Strain, strain background(Mus musculus, female, C57BL/6)UM-HET3Dr. Miller labHarrison et al., 2021 (cited in the paper)
Strain, strain background(M. musculus, female, C57BL/6)Wild typeJackson Laboratories
AntibodyRabbit polyclonal anti-HPRT antibodyProteinTech150-59-1-APWB (1:5000)
AntibodyRabbit polyclonal anti-SDHA antibodyInvitrogen45-920-0WB (1:1000)
AntibodyRabbit polyclonal anti-FTN antibodySigma-ArdrichF5012WB (1:1000)
AntibodyRabbit polyclonal anti-IRP2 antibodySigma-ArdrichSAB2101174WB (1:500)
AntibodyRabbit polyclonal anti-TFR1 antibodyProteinTech100-84-2-APWB (1:1000)
AntibodyRabbit polyclonal anti-FPN1 antibodyNovus BiologicalsNBP1-21502WB (1:1000)
AntibodyRabbit monoclonal anti-Hepcidin antibodyAbcam190775WB (1:200)IH (1:20)
AntibodyMouse polyclonal anti-ubiquitin antibodyCell Signaling Technologies3933SWB (1:1000)
AntibodyMouse monoclonal anti-GAPDH antibodyProteinTech60004-1-IgWB (1:5000)
AntibodyRabbit polyclonal anti-α-Tubulin antibodyProteinTech66031-1-IgWB (1:5000)
AntibodyHRP-conjugated donkey polyclonal anti-rabbit IgG antibodyJackson ImmunoResearch711-035-152WB (1:5000)
AntibodyHRP-conjugated donkey polyclonal anti-mouse IgG antibodyJackson ImmunoResearch715-035-150WB (1:5000)
AntibodyAlexa Fluor 594 goat polyclonal anti-rabbit IgGJackson ImmunoResearch111-585-144IH (1:200)
Chemical compound, drug3-(2-Pyridyl)–5,6-di(2-furyl)–1,2,4-triazine-5′,5″-disulfonic acid disodium salt(Ferrozine)Sigma-Aldrich82940
Chemical compound, drugTrichloroacetic acidSigma-AldrichT6399
Chemical compound, drugThioglycolic acidSigma-AldrichT3758
Chemical compound, drugHeminSigma-AldrichH9039
Chemical compound, drugRNA-STAT60TeltestCs-502
Chemical compound, drugGlycogenLife TechnologiesAM9510
Chemical compound, drugParaformaldehydeThermo Fisher ScientificAC416780250
Chemical compound, drugRIPA BufferThermo Fisher Scientific89901
Commercial assay or kitProteaseArrest Protease InhibitorG-Biosciences786-437
Commercial assay or kitqScript cDNA Synthesis KitQuanta95047-500
Commercial assay or kitPerfeCTa SYBR Green FastMixQuanta95074-05K
Commercial assay or kitSuperSignal West Pico PLUS Chemiluminescent SubstratePierce34579
Commercial assay or kitDynabeads Protein G for ImmunoprecipitationInvitrogen10003D
Commercial assay or kitBCA Protein Assay KitPierce23225
Commercial assay or kitMitochondria Isolation Kit for TissuePierce89801
Commercial assay or kitAconitase Activity Assay KitAbcamAb109712
Commercial assay or kitOTC compoundSakura Finetek4583
Sequence-based reagentPrimers for qRT-PCRThis manuscriptN/AIncluded in the next table
Software, algorithmGraphPad PrismGraphPadVersion 9
Software, algorithmImageJNIH1.53c

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  1. Tatsuya Sato
  2. Jason Solomon Shapiro
  3. Hsiang-Chun Chang
  4. Richard A Miller
  5. Hossein Ardehali
(2022)
Aging is associated with increased brain iron through cortex-derived hepcidin expression
eLife 11:e73456.
https://doi.org/10.7554/eLife.73456