Milano Istituto Nazionale Neurologico C. Besta Mutazioni primarie del mtDNA Massimo Zeviani IUSS,...
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Transcript of Milano Istituto Nazionale Neurologico C. Besta Mutazioni primarie del mtDNA Massimo Zeviani IUSS,...
Milano
www.mitopedia.org
Istituto Nazionale Neurologico “C. Besta”
Mutazioni primarie del mtDNAMassimo Zeviani
IUSS, Medicina Mitocondriale
mtDNA mutations
•Heteroplasmic mutations
•Homoplasmic mutations
•Single-Nucleotide Polymorphisms
homoplasmic mother
her offspring
(usually) healthy (usually) sick
Mutation is necessary but not sufficient to produce the disease phenotype
Homoplasmicpoint mutationeg, LHON
mitochondrial bottleneck
mitochondrialproliferation
her oogonia
the A1555G affects the aminoglycoside binding site of 12S rRNA
• Secondary structure of decoding site of small ribosomal RNAs. The A site of E. coli 16 S rRNA oligonucleotide showing the DMS footprints, observed in the presence of the aminoglycosides neomycin and paromomycin, is marked with a dot (A). The corresponding region of S. cerevisiae mt-15S rRNA and human mt-12S rRNA is shown as the wild type version (B and E) and in the version containing the PR454 (C) and A1555G mutation (F), respectively.
modifier loci/genes
Sequence alignment of human Mto1p with its homologs
MTO1 COX1 overlap
Leber’s Hereditary Optic Neuropathy (LHON)
Leber, T. : Ueber hereditaere und congenital angelegte Sehnervenleiden. Graefes Arch. Ophthal. 17: 249-291, 1871.
Homoplasmic point mutations Homoplasmic point mutations e.g. Leber’s Hereditary Optic Neuropathy 11778G->Ae.g. Leber’s Hereditary Optic Neuropathy 11778G->A
blindhealthy
mutantwt
Homoplasmic point mutations Homoplasmic point mutations e.g. Leber’s Hereditary Optic Neuropathy 11778G->Ae.g. Leber’s Hereditary Optic Neuropathy 11778G->A
F
V
LUUR
T
PE
LCUN
SAGY
H
ND5ND6
ND4
ND4L
ND3R
COIII
G
ATPase6/8KCOIID
SUCN
COI
A NC Y
W
ND2
IM
Q
ND1
16S
12S
D-loop Cyt.b
LHON/14484C26%
LHON/11778A58%
LHON/3460A16%
Hudson et al, Am J Hum Genet 2007
Am J Hum Genet 2007
Hudson et al, Am J Hum Genet 2007
F
V
LUUR
T
PE
LCUN
SAGY
H
ND5ND6
ND4
ND4L
ND3R
COIII
G
ATPase6/8KCOIID
SUCN
COI
A NC Y
W
ND2
IM
Q
ND1
16S
12S
D-loop Cyt.b
SNHL/1555G
LHON/14482G/ALHON/14485CLHON14495GLHON/14568T
LHON/11778A
LHON/3460ALHON/4171A
LHON/10663C
Homoplasmic mutations
syndromic SNHL/7472insC
aminoglycoside-induced SNHL/delT961
neonatal death-Leigh s./16427T
SNHL/7445CSNHL/7510CSNHL/7511C
MIHC/9997CMIHC/4300G
Leigh s./9537insC
Encephalopathyobesity/4290C
hypertensionhyperchol.hypoMg++/4291C
Published online: 22 January 2002, doi:10.1038/ng819volume 30 no. 2 pp 145 - 146
Multiple neonatal deaths due to a homoplasmic mitochondrial DNA mutationRobert McFarland1, Kim M. Clark1, Andrew A.M. Morris2, Robert W. Taylor1, Sheila Macphail3, Robert N. Lightowlers1 & Douglass M. Turnbull1
C1624T
230 bp
201 bp
154 bp
47 bp
II-1
mu
scle
II-1
blo
od
I-2
blo
od
III-
6 b
ucc
al
III-
9 p
lace
nta
cont
rol 1
blo
od
un
dig
est
ed
cont
rol 2
ca
rdia
c
III-
10 b
lood
III-
10m
uscl
e
III-
10ca
rdia
c
un
dig
est
ed
Rsa I Digestion
21h
pH
Alive
Leigh s.
85h
pH
30h
pH
26h
pH
2h
pH
12h
pH
Control
mother Patient III-10
HeteroplasmictRNA mutation
Cytochrome c oxidase activitySkeletal muscle Cardiac mitochondria
Healthy
Ataxia, dystonia, tetraparesis, optic atrophy, DM, obesity
Same as older sister.Deceased at 16 yrs.
Deceased at 1 yr. Necrotizing encephalopathy
Activities in the living proband(fibroblasts)
CI/CS CIV/CS0
10
20
30
40
50
60
70
80
0
20
40
60
80
100
120
140
160
180
PP
CC
controlcomplex Icomplex IV
Respiratory Chain Activities in Cybrids
nm
ol/
min
/mg
pro
tein
p1 p2 p3 p1 p2 p3
CI/CS CIV/CS
0
10
20
30
40
50
60
70
80
0
20
40
60
80
100
120
140
160
180
P1: motherP2, P3: patients
I-2
II-2
C
2D-BNE on complex IV
WT
IV-1
WT II-1
ND5COIND4cyt bND2ND1COIIICOII
ATP6
ND6
ND3
ND4L
ATP8
Mito-specific protein synthesis
T4291C
Familial hypomagnesemia, hypertension, and hypercholesterolemia
F
V
LUUR
T
PE
LCUN
SAGY
H
ND5ND6
ND4
ND4L
ND3R
COIII
G
ATPase6/8KCOIID
SUCN
COI
A NC Y
W
ND2
IM
Q
ND1
16S
12S
D-loop Cyt.b
LHON/14484Chaplo J100%
LHON/11778Ahaplo J
p .02
LHON/3460Ahaplo K
p 2.3x10-3
haplo J-> cyt. b L236Ihaplo J1c-> cyt. b F18Lhaplo J2b-> cyt. b D171N
cyt. b V356M
haplo K-> cyt. b F18L
Increased penetrance of LHON mutations in Increased penetrance of LHON mutations in haplogroups J and Khaplogroups J and K
mtDNA mutations
•Heteroplasmic mutations
•Homoplasmic mutations
•Single-Nucleotide Polymorphisms
F
V
LUUR
T
PE
LCUN
SAGY
H
ND5ND6
ND4
ND4L
ND3R
COIII
G
ATPase6/8KCOIID
SUCN
COI
A NC Y
W
ND2
IM
Q
ND1
16S
12S
D-loop Cyt.b
What is the impact of mildly pathogenic mtDNA mutations or haplotypes?
- haplogroup distribution during human migrations- haplogroup J vs. H in LHON- haplogroup H vs. T in asthenozoospermia- haplogroup K vs. H in Parkinson's Disease
mtDNA haplotypes
Gene products present in mammalian mitochondria
Genetic classification of OXPHOS disease mutations
Defects of Mitochondrial DNA
• Protein synthesis genes (rRNAs, tRNAs)• Protein-encoding OXPHOS subunit genes• Large deletions
Nuclear DNA mutations
• Protein-encoding OXPHOS subunit genes• Genes encoding OXPHOS assembly factors• Genes encoding factors affecting mtDNA maintenance• Mitochondrial protein synthesis genes• Genes encoding biosynthetic enzymes for lipids or cofactors• Genes involved in mitochondrial biogenesis
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Chemiosomosis
• Chemiosmosis is the name given to the generation of ATP from a proton gradient. It occurs in all living things
Chemiosomosis
• photosynthetic archaea
Chemiosomosis
• purple proteobacteria
Chemiosomosis
• mitochondria
Chemiosomosis
• Chloroplasts