Proteasome-ubiquitin pathway in
pathology
• Nikolajs Sjakste, Faculty of
Medicine, University of Latvia
• Genetic and Environmental
Influence of Bronchial Asthma in
Taiwan, Latvia and Lithuania,
• Tainan, 02.11.12
Proteasomes
How the proteasome acts
“E3-diseases”
•
•
•
•
•
•
•
There is only one E1 enzyme
About 10 E2 enzymes
1000 E3 enzymes
E3 enzymes are divided in 3 classes
RING
U-box
HECT-domain E3 ligases
What happens if a E3
enzyme gene of the
proteasome-ubiquitin
system gene is
completely deleted?
• Subtelomeric region of
Chromosome 15 harbours
UBE3A gene which encodes
Ubiquitin-protein ligase
E3A (UBE3A)
Inheritance of the deletion from the mother on chromosome 15
produces Angelman syndrome
• AS is characterized by intellectual and
developmental delay, speech impediment,
sleep disturbance, unstable jerky gait,
seizures, hand flapping movements, frequent
laughter/smiling and usually a happy
demeanour. AS is a classic example of genetic
imprinting caused by deletion or inactivation
of critical genes on the maternally inherited
chromosome 15.
• Angelman syndrome can also be the result of mutation of a
single gene. This gene (Ube3a) part of the ubiquitin pathway) is
present on both the maternal and paternal chromosomes, but
differs in the pattern of methylation (Imprinting). The paternal
silencing of the Ube3a gene occurs in a brain region-specific
manner; the maternal allele is active almost exclusively in the
hippocampus and cerebellum. The most common genetic
defect leading to Angelman syndrome is an ~4Mb (mega base)
maternal deletion in chromosomal region 15q11-13 causing an
absence of Ube3a expression in the maternally imprinted brain
regions. Ube3a codes for an E6-AP ubiquitin ligase, which
chooses its substrates very selectively and the four identified
E6-AP substrates have shed little light on the possible molecular
mechanisms underlying the human Angelman syndrome
mental retardation state.
E3 neurodevelopmental diseases
Disease
UPS component
affected
Function
Angelman syndrome
UBE3A
E3 ligase
Williams-Beuren syndrome
TRIM50
E3 ligase
Intellectual disability not
otherwise specified
CUL4B
E3 ligase
HUWE1
E3 ligase. Suppresses
N-Myc-DLl3 cascade, stops
proliferation enables neuronal
differentiation
A girl with Williams syndrome, illustrating typical facial features: broad forehead,
short palpebral fissures, low nasal bridge, anteverted nostrils, long filtrum, full cheeks,
and relatively large and often downturned mouth
E3 neurodevelopmental diseases 2
Autism spectrum
disorders
Johanson-Blizzard
syndrome
UBE3A
E3 ligase
PARK2
E3 ligase
RFWD2
E3 ligase
FBXO40
Constitutes one of the
four subunits of the
ubiquitin protein ligase
complex called SCFs
(SKP1-cullin-F-box),
E3 ligase
UBR1
Johanson-Blizzard syndrome
• Ectodermal displasia:
•
•
•
•
•
•
Abnormal development of the pancreas
Nose
Scalp
Mental retardaton
Hearing loss
Growth failure
E3 neurodegenerative diseases
Parkinson disease
Parkin
(PARK2)
E3-ligase
Machado-Joseph
disease
ATXN3
Ataxin-3 interacts with
ubiquitinated proteins,
can bind the proteasome,
when the gene harbors an
expanded repeat length, can
interfere with the degradation
substrates. Associates with
the ubiquitin- and
proteasome-binding factors
Rad23 and valosin-containing
protein (VCP/p97). proteins.
E3 in inherited cancer syndromes
• Von Hippel-Lindau syndrome
• Adenomatous polyposis coli
Von Hippel-Lindau syndrome
pVHL is an E3 ligase
Deubiqitination diseases
Disease
UPS component
affected
Function
Ataxia
USP-14
Ubiquitin
carboxylterminal
hydrolase 14
Parkinson
disease
UCH-L1
(PARK5)
Ubiquitin carboxyterminal hydrolase
L1
Immunoproteasomes
• IFN-gamma induces the synthesis of three active
site−containing beta-subunits as well as the synthesis of the
proteasome maturation protein (POMP).
• The immunosubunits 1i, 2i and 5i are preferentially
incorporated into the 20S core after de novo synthesis to form
the immunoproteasome.
• In addition, IFN-gamma induces synthesis of PA28. Three
PA28 and four P28 subunits form heptameric rings that can
bind to the two outer alpha-rings of the 20S constitutive
proteasome as well as the 20S immunoproteasome and
activate the enzyme complex by opening the central gate.
Immunoproteasomes
“Immunoproteasome” diseases
• Nakajo-Nishimura syndrome
• JMP syndrome
• CANDLE syndrome
Nakajo-Nishimura syndrome
•
•
•
•
an autoinflammatory disorder
pernio-like rashes
progressive partial lipodystrophy
homozygous mutation c.224C > T in exon
2 the PSMB8 gene, which encodes the β5i
subunit of immunoproteasome is
responsible for development of the disease
JMP syndrome
• Recessive autoinflammatory syndrome
characterized by joint contractures, muscle
atrophy, microcytic anemia, and panniculitisinduced lipodystrophy (JMP)
• Caused by homozygous missense mutation
c.224C>T (p.Thr75Met) in the PSMB8
CANDLE syndrome
• Chronic atypical neutrophilic dermatosis with
lipodystrophy and elevated temperature is an
autoinflammatory syndrome recently
described in children.
CANDLE syndrome is caused by mutations
in PSMB8
• One patient was homozygous for a novel
nonsense mutation in PSMB8 (c.405C>A),
suggesting a protein truncation;
• 4 patients were homozygous and 2 were
heterozygous for a previously reported
missense mutation (c.224C>T)
Pathologies of “bad substrates” for
proteasomes
Polyglutamine (PolyQ) Diseases
Disease
Gene
DRPLA
ATN1 or
(Dentatoru DRPLA
bropallidolu
ysian
atrophy)
Normal
number of
repeats
Pathologic
number of
repeats
between 6
and 35
copies of
CAG
between 49
and 88
copies
Polyglutamine (PolyQ) Diseases 2
HD
HD
(Huntington's
disease)
between 10
and 35
copies of
CAG
more than 35
copies
SBMA
(Spinobulb
ar muscular
atrophy or
Kennedy
disease)
between 9
and 36
copies of
CAG
between 38
and 62
copies
AR Androgen
receptor on
the X
chromosom
e
Models of Poly Q diseases
Silica NPs
• Aggregation-prone
proteins
• Amyloid formation
• Insoluble aggregates
Liddle syndrome
• severe hypertension, hypokalemia, and
metabolic alkalosis.
• In contrast to hyperaldosteronism, which can
result in similar symptoms, low aldosterone
and renin levels
• The gene responsible for Liddle syndrome was
actually identified as a mutation in the beta subunit
of the renal epithelial sodium channel (ENaC) . The
site of the mutation is located in its binding site to
Nedd4 (E3 ubiquitin ligase) .
• Because Nedd4 cannot recognize the channel and
target it for degradation,it accumulates. Thus, the
mutation leads to excessive re-absorption of Na+
accompanied by water.
Alzheimer’s disease
• Mutated ubiquitin
• Impaired proteasome function
• More immunoproteasomes
Ubiquitination sites on amino terminally processed tau.
Ihara Y et al. Cold Spring Harb Perspect Med 2012;2:a006361
©2012 by Cold Spring Harbor Laboratory Press
Dysfunction of autophagic and endocytic pathways to lysosomes driven by relevant genes and other risk
factors in Alzheimer disease (left side of the diagram) causes or promotes pathophysiology critical to the
development and progression of Alzheimer disease...
Ihara Y et al. Cold Spring Harb Perspect Med 2012;2:a006361
©2012 by Cold Spring Harbor Laboratory Press
Schematic illustrating the endocytic and the autophagic pathways to the lysosome.
Ihara Y et al. Cold Spring Harb Perspect Med 2012;2:a006361
©2012 by Cold Spring Harbor Laboratory Press
Frontotemporal dementias
• Ubiquitinylated TAR DNA-binding protein
(TDP-43) accumulates
• Ubiquilin 2 – involved in transport of
ubiquinylated proteins to proteasome
• FUS protein
Amyotrophic lateral sclerosis
• Ubiquitinylated TAR DNA-binding protein
(TDP-43) accumulates
Parkinson disease
• Degradation of aplha-synuclein is a crucial
question for Parkinson’s disease
• Ubiquitin proteasomal system is defective in
SN affected neurons
• Autophagy-lysosomal pathway is also affected
Parkinson disease
(non-monogenic)
• Dysfunction of the UPS
• Reduced proteasome activity in the substantia nigra
• Reduced expression of proteasomal subunits in the subsatntia
nigra
• Reduced proteasome activity and expression of UPS-related
proteins in peripheral blood mononuclear cells
• Altered proteasome function in toxin-based models of PD
• Altered proteasome function in alpha -synuclein
overexpressing rodents
• Mutated PSMC1 subunit of ATPase in a rodent model
SKP1A protein interacting E3 ligase is down-regulated in
PD
E2
Cullin
Ub
Early PD
Late PD
• Enahncement of autophagy by rapamycin (inhibitor
of mTOR) is prospective for tratment of
neurodeganerative diseases
Autoimmune diseases
•
•
•
•
•
•
Autonatibodies to proteasomes in
Sjogren’ s syndrome
SLE
Rheumatoid arthritis
Autoimmune myositis
Result in decreased proteasomal activity
Inflammatory response
Inflammatory disease
• Inflammatory arthritis. Proteasome inhibition
improves the arhritis score.
• Psoriasis. T-cell mediated disease, related to
activation of NF-kappa. Proteasome inhibition
reduces lesions.
Asthma and allergy
• Abnormal activation of of Type 2 helper cells.
E3 ubiquitin ligase Itch maintains immune
tolerance. Itch-deficient mice fail to block
development of airway inflamamation.
Cell proliferation and cancer
Proteasomes regulate density of
cardiac ion channels
• Mutations in SCNA5 gene encoding Nav1.5
channel hindering its interactions with E3
(Nedd4-2) cause arrhythmias and conduction
defects
• Mutations in the gene hERG1 (K+ channel)
resulting in its rapid decay cause the long QT
syndrome
Heart diseases
Ub mRNA
E2 mRNA
Atrophy/
Unloading
Hypertrophy
Hypoxemia
Heart
failure
Increased
Increased
Increased
_
Increased
Increased
_
Heart diseases 2
Atrophy/
Unloading
Hypertrophy
Hypoxemia
Heart
failure
E3 mRNA
Atrogin 1
Decreased
Increased
Increased
_
E3 mRNA
MuRF1
Decreased
Increased
Increased
_
Heart diseases 3
Atrophy/
Unloading
Hypertrophy
Hypoxemia
Heart
failure
Proteasome
proteolytic
Activity
Decreased
Decreased
Decreased
PSMB4
mRNA
Increased
Increased
Increased
Heart diseases 4
Atrophy/
Unloading
Deubiquitination
enzymes
Hypertrophy
Hypoxemia
Heart
failure
Increased
Proteasome inhibitors
• Cancer treatment
• Antiinflammatory action
Funding
• Joint research project “Genetic studies of human diseases and
longevity in Latvian population”, sub-project “Genome-wide
scanning of proteasomal gene polymorphisms and their
association with autoimmune diseases” - No 10.0010/09
• National Reserach Program 2010.10.-4/VPP4 „Creation of
novel means and methods for prophylaxis, treatment and
diagnostics, elaboration of biomedical Technologies for
improvement of social health“
• ERAF project ESS2010/110 „Creation of a method for early
diagnostics of autoimmune diseases”
• Joint LV-LT-TW project “Proteasomal gene alleles as risk
factors for bronchial asthma in Latvian, Lithuanian and
Taiwanese populations”
Ieguldījums Jūsu nākotnē