loss of cl leads to perturbation of mitochondrial fe-s … · 2017. 10. 17. · x-linked disorder...
TRANSCRIPT
![Page 1: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/1.jpg)
Loss of cardiolipin leads to perturbation of mitochondrial and
cellular iron homeostasis
Miriam L. Greenberg
Wayne State University
Detroit, MI USA
![Page 2: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/2.jpg)
Barth syndrome – a life-threatening
X-linked disorder
• cardioskeletal myopathy
• growth retardation
• neutropenia
Barth et al., 1983. An X-linked mitochondrial disease affecting cardiac
muscle, skeletal muscle and neutrophil leucocytes. J. Neurol. Sci.
62:327-355.
Peter Barth
THE DISORDER
![Page 3: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/3.jpg)
Bione et al., 1996. A novel X-linked gene, G4.5, is responsible
for Barth syndrome. Nat. Genet. 12:385-389.
G4.5 (tafazzin) is responsible for Barth
syndrome
THE GENE
![Page 4: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/4.jpg)
• Decreased CL
• Increased MLCL (monolyso-CL)
• Decreased unsaturated fatty acyl CL species
Barth syndrome is a disorder of
cardiolipin remodeling
Vreken et al., 2000. Defective remodeling of cardiolipin and phosphatidylglycerol in Barth syndrome. Biochem. Biophys. Res. Comm. 279:378-382.
THE BIOCHEMICAL DEFECT
![Page 5: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/5.jpg)
L4-CL deficiency in Barth syndrome
Schlame et al. 2002. Deficiency of tetralinoleoyl-cardiolipin in Barth
syndrome. Ann. Neurol. 51: 634-7
THE BIOCHEMICAL DEFECT
![Page 6: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/6.jpg)
Clinical phenotypes vary widely in Barth syndrome
asymptomatic death in infancy
TAZ
MOLECULAR BASIS OF THE PATHOLOGY?
RELATIONSHIP OF GENOTYPE TO PHENOTYPE?
![Page 7: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/7.jpg)
Molecular mechanisms underlying monogenic diseases
• “There are major problems associated with dissecting the molecular basis of even simple monogenic diseases caused by mutations in a single gene.
• Principal among these are the modifying effects of other genes… This results in marked variations in the symptoms of patients with the same disease.
• Of the 1500 or so monogenic diseases for which the mutated gene has been identified, there are only a few where the effects of other genes on disease pathogenesis have been studied.”
Peltonen and McKusick Science 2001 291:1224-1229
![Page 8: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/8.jpg)
Functions of cardiolipin may elucidate mechanisms underlying the pathology and
identify physiological modifiers
![Page 9: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/9.jpg)
PGP PGS1
CDP-DG PG CL (premature) CRD1
MLCL CL (mature) TAZ1 P
CLD1
GEP4
Advantages of the yeast model
Yeast mutants are available for all yeast genes, including every step of CL synthesis. The pathway is conserved. Yeast are amenable to genetic and genomic analyses.
![Page 10: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/10.jpg)
• Decreased CL
• Increased MLCL (monolyso-CL)
• Decreased unsaturated fatty acyl CL species
Barth syndrome is a disorder of
cardiolipin remodeling
Vreken et al., 2000. Defective remodeling of cardiolipin and phosphatidylglycerol in Barth syndrome. Biochem. Biophys. Res. Comm. 279:378-382.
THE BIOCHEMICAL DEFECT
![Page 11: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/11.jpg)
Functions of CL may elucidate mechanisms underlying pathology and identify physiological modifiers
vacuolar function
PKC signaling
mitochondrial protein import
life span/stress response
cell integrity cell division
mitochondrial fusion
mitochondrial bioenergetics
iron homeostasis
![Page 12: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/12.jpg)
Vishal Gohil Vinay Patil
![Page 13: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/13.jpg)
Microarray analysis: Increased expression of iron regulon genes in crd1D
Gene crd1Δ Cellular function
FIT1 3.07 Retention of siderophore-iron
FIT2 17.57 Retention of siderophore-iron
FIT3 33.84 Retention of siderophore-iron
FET3 6.94 High-affinity iron uptake
FTR1 2.50 High affinity iron permease
ARN1 2.72 Transporter of siderophore-iron chelates
ARN4 2.29 Ferric enterobactin transporter
TIS11 2.95 Degradation of mRNA upon iron starvation
![Page 14: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/14.jpg)
FIT1-3
FRE1-4
Fe (III)
Siderophore
Fe (III)
Fe (II)
Mitochondrion
Fe (II)
Vacuole
The iron regulon controls cellular iron homeostasis Siderophores
bind iron
Reductases reduce
ferric to ferrous iron
Permeases transport
iron
![Page 15: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/15.jpg)
Fold
ch
ange
/AC
T1
AFT1 regulated iron regulon is up-regulated in crd1Δ
0
1
2
3
4
5
6
7
8
9
10
11
12
AFT1 FIT1 FIT2 FIT3 ARN1 ARN2 ARN3 FET3 FTR1
WT
crd1Δ
![Page 16: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/16.jpg)
Does loss of CL lead to defective iron homeostasis?
• Perturbation of mitochondrial iron levels?
• Decreased growth on media with high iron?
• Sensitivity to ROS inducing agents?
![Page 17: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/17.jpg)
crd1Δ has increased mitochondrial iron levels
0
20
40
60
80
100
120
140
160
WT crd1Δ
Mit
och
on
dri
al ir
on
leve
ls
% o
f W
T *
crd1Δ
![Page 18: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/18.jpg)
crd1Δ is sensitive to iron
WT crd1Δ
0
2
5
7
FeSO4
(mM)
glycerol/ethanol 30˚C
10
![Page 19: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/19.jpg)
crd1Δ is sensitive to hydrogen peroxide
H2O2
(mM)
0.2 0.25 0.275
0.3
0.325
0
WT crd1Δ
![Page 20: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/20.jpg)
Loss of CL leads to defective iron homeostasis
• Perturbation of mitochondrial metal levels
• Decreased growth on media with high iron
• Sensitivity to ROS inducing agents
What is the mechanism linking loss of CL to
defective iron homeostasis?
![Page 21: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/21.jpg)
Factors that cause increased expression of the iron regulon
• Iron starvation
• Iron-sulfur (Fe-S) biogenesis defects
![Page 22: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/22.jpg)
Iron-sulfur (Fe-S) clusters
[3Fe-4S] [2Fe-2S]
[4Fe-4S] Cluster
disassembly
Cluster interconversion
Rouault Cell 2005
![Page 23: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/23.jpg)
Fe-S clusters are essential co-factors in energy metabolism
Rouault Cell 2008
![Page 24: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/24.jpg)
Mitochondrion
Nfs1/Isd11
Ala Cys
pmf
Iron (Fe2+)
Isu1/2 Isu1/2 Scaffold
Mrs3/4
Ssq1-ATP, Jac1
Grx5
Yah1
NADH
Yfh1
Mitochondrial Fe/S proteins
Holo
Apo
Aconitase, [4Fe-4S]
From Roland Lill
Mge1 Respiratory complexes
Fe-S cluster biogenesis
Step 1: synthesis of the Isu/Fe-S scaffold
Step 2: transfer of Fe-S cluster to apoenzyme
![Page 25: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/25.jpg)
Atm1 mediates the export of Fe-S co-factors for cytoplasmic Fe-S biosynthesis
ISC
as
sem
bly
Fe
S2- Atm1
From Roland Lill
Cytoplasmic Fe-S biosynthesis
![Page 26: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/26.jpg)
Cardiolipin stimulates ATPase activity of Atm1
Kunhke Mol Memb Biol 2006
a
![Page 27: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/27.jpg)
Is perturbation of iron homeostasis in crd1D due to decreased Atm1 activity?
Prediction:
• Overexpression of Atm1 rescues the iron-associated defects in crd1D
![Page 28: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/28.jpg)
0
0.5
1
1.5
2
2.5
3
WT+empty WT+ ATM1 crdΔ1+ empty crd1Δ+ ATM1
FET3
FIT2
FIT3
Fold
ch
ange
/AC
T1
Overexpression of ATM1 does NOT restore WT iron regulon levels to crd1Δ
+ vector + ATM1 + vector + ATM1
WT crd1Δ
![Page 29: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/29.jpg)
Is perturbation of iron homeostasis in crd1D due to defects in mitochondrial Fe-S cluster biogenesis?
Predictions:
• crd1D exhibits decreased activity of Fe-S enzymes
• crd1D is sensitive to further perturbation of Fe-S synthesis
• crd1D exhibits up-regulation of Fe-S scaffold (characteristic of Fe-S perturbation)
![Page 30: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/30.jpg)
Is perturbation of iron homeostasis in crd1D due to defects in mitochondrial Fe-S cluster biogenesis?
Predictions:
• crd1D exhibits decreased activity of Fe-S enzymes
• crd1D is sensitive to further perturbation of Fe-S synthesis
• crd1D exhibits up-regulation of Fe-S scaffold (characteristic of Fe-S perturbation)
![Page 31: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/31.jpg)
0
20
40
60
80
100
120
WT crd1Δ
Act
ivit
y (%
of
WT)
Succinate dehydrogenase Ubiquinol-cytochrome c oxidoreductase Aconitase
crd1Δ WT
crd1Δ has decreased activities of mitochondrial Fe-S enzymes
* *
*
![Page 32: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/32.jpg)
0
20
40
60
80
100
120
WT crd1Δ
Act
ivit
y %
of
WT
Isopropylmalate isomerase
Sulfite reductase
crd1Δ
crd1Δ has decreased activities of cytoplasmic Fe-S enzymes
* *
WT
![Page 33: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/33.jpg)
Decreased cytoplasmic Fe-S enzyme activities lead to amino acid auxotrophies in crd1Δ
• sulfite reductase (Met5, Met10) - methionine synthesis
• isopropylmalate isomerase (Leu1) - leucine synthesis
![Page 34: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/34.jpg)
crd1Δ WT
35°C
SD-g
luco
se
+Met
hio
nin
e
-Me
thio
nin
e
crd1Δ shows methionine auxotrophy at elevated temperature
![Page 35: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/35.jpg)
crd1Δ WT
37°C
SD-g
luco
se +L
eu
cin
e
-Le
uci
ne
crd1Δ shows leucine auxotrophy at elevated temperature
![Page 36: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/36.jpg)
Is perturbation of iron homeostasis in crd1D due to defects in mitochondrial Fe-S cluster biogenesis?
Predictions:
• crd1D DOES exhibit decreased activity of Fe-S enzymes
• crd1D is sensitive to further perturbation of Fe-S synthesis – synthetic genetic interaction with Isu
• crd1D exhibits up-regulation of Fe-S scaffold (characteristic of Fe-S perturbation)
![Page 37: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/37.jpg)
Mitochondrion
Nfs1/Isd11
Ala Cys
pmf
Iron (Fe2+)
Isu1/2 Isu1/2 Scaffold
Mrs3/4
Ssq1-ATP, Jac1
Grx5
Yah1
NADH
Yfh1
Mitochondrial Fe/S proteins
Holo
Apo
Aconitase, [4Fe-4S]
From Roland Lill
Mge1 Respiratory complexes
Fe-S (iron sulfur) cluster biogenesis
Step 1: synthesis of the Isu/Fe-S scaffold
Step 2: transfer of Fe-S cluster to apoenzyme
![Page 38: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/38.jpg)
The isu1 mutant exacerbates the growth defect of crd1D
WT
crd1
isu1
crd1isu1
![Page 39: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/39.jpg)
Is perturbation of iron homeostasis in crd1D due to defects in mitochondrial Fe-S cluster biogenesis?
Predictions:
• crd1D DOES exhibit decreased activity of Fe-S enzymes
• crd1D IS sensitive to further perturbation of Fe-S synthesis – synthetic genetic interaction with Isu
• crd1D DOES exhibit up-regulation of Fe-S scaffold (characteristic of Fe-S perturbation)
![Page 40: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/40.jpg)
Summary: Loss of CL leads to iron homeostasis defects and perturbation of Fe-S biogenesis
• Phenotypes associated with altered Fe levels – Increased mitochondrial Fe
– Sensitivity to iron
– Sensitivity to peroxide
• Fe-S associated defects – Decreased activities of mitochondrial and cytoplasmic
Fe-S enzymes
– Synthetic interaction with Fe/S scaffold mutant Isu1
– Phenotypes associated with Fe-S defects (increased expression of Isu1)
![Page 41: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/41.jpg)
Nucleus
Cytosol
Mitochondrion
Fe
Cyt Fe-S
Aft1
Aco1
III
Fe-S biogenesis
CL
Fe
Iron regulon
Aft1
II
Proposed model: Loss of CL leads to perturbation of mitochondrial and cellular iron homeostasis
![Page 42: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/42.jpg)
Cardiolipin is required for optimal mitochondrial protein import
Jiang et al. 2000. Absence of Cardiolipin in the crd1 Null Mutant Results in Decreased Mitochondrial Membrane Potential and Reduced Mitochondrial Function. J. Biol. Chem., 275, 22387-22394.
Gebert et al., 2009. Mitochondrial Cardiolipin Involved in
Outer Membrane Protein Biogenesis: Implications for Barth Syndrome. Current Biol. 19, 2133-2139.
Possible mechanism linking cardiolipin to defective iron homeostasis - defective import of proteins involved in Fe-S biogenesis
![Page 43: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/43.jpg)
What are the consequences of Fe-S defects?
![Page 44: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/44.jpg)
TCA Cycle
Succinate dehydrogenase
Aconitase
Perturbation of the TCA cycle
Pyruvate
THE CELL, 4th edition
![Page 45: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/45.jpg)
TCA Cycle
Succinate dehydrogenase
Aconitase
Secondary metabolic effects Alanine
Cysteine
Glycine
Serine
Threonine
Tryptophan
Pyruvate
Aspartate
Asparagine
Aspartate
Phenylalanine
Tyrosine
Isoleucine
Methionine
Threonine
Valine
Isoleucine
Leucine
Tryptophan
Glutamate
Glutamine
Histidine
Proline Arginine
THE CELL, 4th edition
![Page 46: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/46.jpg)
TCA Cycle
Succinate dehydrogenase
Aconitase
Secondary metabolic effects
Pyruvate
Glutamate
THE CELL, 4th edition
![Page 47: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/47.jpg)
Supplementation of glutamate restores growth of crd1Δ at elevated temperature
![Page 48: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/48.jpg)
Aberrant plasma TCA cycle intermediates in BTHS patients
Data from Richard Kelley
![Page 49: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/49.jpg)
Aberrant plasma amino acids in BTHS patients
Data from Richard Kelley
![Page 50: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/50.jpg)
ISCU (iron sulfur cluster assembly protein) mutation in humans leads to myopathy
• Clinical Manifestation and a New ISCU Mutation in Iron–Sulfur Cluster Deficiency Myopathy (Kollberg Brain 2009).
• Splice Mutation in the Iron-Sulfur Cluster Scaffold Protein ISCU Causes
Myopathy with Exercise Intolerance (Mochel Amer J Hum Gen 2008). • Myopathy with Lactic Acidosis is Linked to Chromosome 12q23.3–24.11
and Caused by an Intron Mutation in the ISCU Gene Resulting in a Splicing Defect (Olsson Human Molec Gen 2008).
• Reversal of Iron-Induced Dilated Cardiomyopathy During Therapy With
Deferasirox in Beta-Thalassemia (Trad Pediat Blood Cancer 2008). • Mitochondrial Myopathy with Succinate Dehydrogenase and Aconitase
Deficiency Abnormalities of Several Iron-Sulfur Proteins (Hall J Clin Inv 1993).
![Page 51: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/51.jpg)
Loss of cardiolipin
defective Fe-S biogenesis
perturbation of the TCA cycle
secondary metabolic dysfunction
MOLECULAR BASIS OF THE PATHOLOGY?
RELATIONSHIP OF GENOTYPE TO PHENOTYPE?
![Page 52: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/52.jpg)
Future directions
• Elucidate mechanisms linking cardiolipin to Fe-S biogenesis
• Determine consequences of TCA cycle perturbation in cardiolipin deficient cells
• Characterize role of cardiolipin in acetyl CoA synthesis and b-oxidation
![Page 53: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/53.jpg)
Acknowledgements
Collaborators:
Dennis R. Winge
Jennifer L. Fox
Vinay Patil
Vishal Gohil
Support:
NIH
Barth Syndrome Foundation
![Page 54: Loss of CL leads to perturbation of mitochondrial Fe-S … · 2017. 10. 17. · X-linked disorder • cardioskeletal myopathy • growth retardation • neutropenia Barth et al.,](https://reader031.vdocuments.mx/reader031/viewer/2022011915/5fcb7a5267d22057f7438d12/html5/thumbnails/54.jpg)