Lecture 4Frontotemporal Lobar Degeneration (FTLD) &

Amyotrophic Lateral Sclerosis (ALS)

David Saffen, Ph.D.Professor/Principal Investigator

Department of Cellular and Genetic MedicineFudan University, Shanghai, China

Email: saffen@fudan.edu.cn

Pick’s disease

Arnold Pick 1851 – 1924

German neurologist

and psychiatrist

1892: identified a form of dementia characterized byatrophy of the frontal andtemporal lobes and the presence of distinctiveprotein tangles, later termed “Pick bodies,” and“ballooned” neurons,later termed “Pick cells.”

Pick bodies Pick cells

Frontotemporal lobar degeneration (FTLD)

• A set of neurodegenerative disorders characterized by degeneration of specific regions within the frontal and temporal lobes.

• Extensive heterogeneity at clinical, pathological and genetic levels

• Symptoms include disturbances of personality, behavior, emotions, social awareness and language. Collectively, FTLD-associated clinical syndromes are often called frontotemporal dementia (FTD).

• Onset is typically in middle life (45-65); survival after diagnosis: 6-8 years; incidence 3.5-4.1/100,000per year

• Family history present in about 40 – 50% of casesAbout 10% show autosomal dominant inheritance.

FTLD clinical syndromes

• Behavioral variant-frontotemporal dementia (bvFTD)-changes in personality, behavior and social awareness; impairedrecognition of emotions; impaired impulse control; stereotypic,ritualized behaviors; atrophy of right frontal and temporal lobes

• Progressive non-fluent aphasia (PNFA)-difficulties with word retrieval and language expression;preserved word comprehension; associated with asymmetricatrophy of left frontal and temporal lobes

• Semantic dementia (SD)-loss of ability to understand the meaning of words and significance of objects and faces; associated with bilateral atrophy of middle and inferior temporal cortex

Major anatomic divisions of the cerebral cortex

Brain from FTLD patient showing atrophy of frontal and anterior temporal lobes

Normal brain FTLD brain

Brain areas affected in PNFA and bvFTLD

right orbital frontal lobe:social behavior; injury causes “disinhibition”

right anterior cingulate cortex:drive, initiation of behavior;caring about what happens;

injury causes apathy & blunted emotional responses

left frontal lobe:speech production

speech; word output

Brain areas affected in patients with SD

left anterior and left posteriortemporal cortex: semantics = understanding the meanings ofwords and significance of objects

Sylvian fissure

pole of left frontal lobe

MRIs showing atrophied regions inbvFTD, PNFA and SD patients

van der Flier and Scheltens, 2005

left anteriorlobe atrophy

atrophy of frontal& temporal lobes

left sidedPerisylvian

atrophy

MRI imaging of representative patients with: bvFTD (A & B); SD (C) or PNFA (D)

Rabinovici & Miller, 2010

(A,B) atrophythroughoutmedial andfrontal cortex;preservation ofposterior areas

(C) atrophyof temporallobe poles (l>r)

(D) atrophy ofLeft inferolateral& dorsomedialfrontal cortex &anterior insula

FTLD: histopathology-based classifications

FTLD-TAU

FTLD

FTLD-U ubiquitin inclusionstau inclusions

FTLD-TDP

TDP-43inclusions

FUSinclusions

FTLD-FUS

80%

40% 60%

20%

FTLD-17 (tau)

FTLD-17 (GRN)

FTLD-TAU• The type of FTLD originally described by Pick;

still often referred to as “Pick’s” disease.

• Characterized by cytoplasmic, tau-staining Pick bodies in neurons, most commonly in dentate gyrus, hippocampus, amygdala, frontal and temporal cortex; Pick bodies contain primarily the 3R microtubule binding domain tau isoform;Pick bodies also stain positively for ubiquitin.

• Associated with bvFTFD, PNFA, and, to a lesser extent, with SD

• A familial form of FTLD where tau inclusions are present, designated FTDP-17 (frontotemporal dementia with parkinsonism linked to chromosome 17), is caused by mutations in the MAPT (tau) gene. The majority of tau-negative FTDP-17 cases are caused by mutations in the GRN (progranulin) gene (discussed below).

FTLD-TAU histopathology

Intracellular Pick bodies Tau protein accumulation in glial cells

MAPT (tau) 17q21

Tau in FTLD:~ 40 mutationsin 100 families;Mutations areautosomal dominant and highly penetrant, leading to disease onset between ages 40 and 60, with 8- 10 year survival

Six brain tau isoforms generatedby alternative splicing(352-441 amino acids)

Tauisoformsfound in Pickbodies

FTLD: histopathology-based classifications

FTLD-TAU

FTLD

FTLD-U ubiquitin inclusionstau inclusions

FTLD-TDP

TDP-43inclusions

FUSinclusions

FTLD-FUS

80%

40% 60%

20%

FTLD-17 (tau)

FTLD-17 (GRN)

FTLD-U

Ubiquitin immunohistochemistry of familial FTLD-U brains demonstrates staining of:

(a) neurites and neuronal cytoplasmicinclusions in the superficial cerebralneocortex

(b) neuronal cytoplasmic inclusions in hippocampal dentate granule cells

(c) lenticular neuronal intranuclearinclusions in the cerebral neocortex(arrows)

Scale bars: (a) and (b) 40 mm, (c) 25 mm; insert 6 mm

FTLD-TDP subtypes

C9orf72?

FTLD-FUS

VCP

FTLD-TDP

FTLD-U

GRN

Type: 1 2 3 4

FTLD-17 (GRN)

=

FTLD-TDP• Most common form of FTLD, accounting for ~50% of cases

• Characterized by presence of tau-negative immunoreactive inclusions that stain positively for ubiquitin and TAR DNA binding protein-43 (TDP-43); absence of Pick bodies and Pick cells

• Inclusions are found in both neurons and glial cells with highest concentrations in the dentate gyrus and layer II neurons in frontal and temporal cortex.

• TDP-43 is a ubiquitously expressed nuclear protein that plays a role in DNA transcription and splicing. Mutations in TDP-43 are also linked to autosomal dominant ALS, where the suspected disease mechanism is toxic gain-of-function (see below).

• Familial forms of FTLD-TDP are linked to autosomal dominantmutations in the progranulin gene (GRN: FTLD-17), the recentlyidentified C9orf72 gene (9p12-p21), more rarely the valosin-containing protein (VCP).

Characteristics of FTLD-TDP subtypes

Mackenzieet al, 2010

(C9orf72)

(FTLD-17)

GRN (progranulin) 17q21

Progranulin is a secreted growth factor; highly expressed in pyramidal cells in the hippocampus and cortex. About 70 pathogenic mutations have been identified in 210 families; nearly all are non-sense or missense mutations that producenon-functional proteins; two recent studies have also linked hemizygous deletions ofGRN gene to FTLD; collectively, these studies strongly suggest that the disease mechanism is “haploinsufficiency.”

C9orf72 (9p21.2) Atypical translation of intronic RNA containing expansions of GGGGCC-repeat sequences produce aggregating dipeptide-repeat (DPR) proteins

(< 23 repeats: normal; > 30 repeats: pathogenic) Detected in 12% familial FTD and 29% sporadic FTD (Finnish population)

repeat

Note: translation is initiated in the absence of a AUG codon[aka: repeat-associated non-AUG (RAN) translation]

Most inclusions contain poly-GA and to a lesser extent poly-GP and poly-GA

VCP (valosin-containing protein) 9p13

VCP is a member of the ATPase associated with diverse cellular activities (AAA) gene superfamily. N-terminal domain binds phosphoinositides; phosphorylated by the protein kinase AKT.

Mutations in VCP have been linked to “Multisystem Proteinopathy” (MSP) a dominantly inherited, pleiotropic, degenerative disorder that can affect muscle, bone and/or the CNS.

In one subtype of MSP, IBMPFD (inclusion body myopathy associatedwith Paget’s disease of bone and frontotemporal dementia), VPC mutations interfere with proteosome-dependent degradation of unbiquitinated proteins, including TDP43, resulting in the formation ofubiquitin-positive TDP43 inclusions in the cytoplasm and nucleus.

FTLD-U subtypes

NIFID BIBD

FTLD-FUS

aFTLD-U

FTLD-TDP

FTLD-U

FTLD-FUS

• Characterized by the absence of both tau and TDP-43 inclusions; presence of cytoplasmic inclusions containing ubiquitin and FUS (fused in sarcoma) protein

• FUS is a ubiquitously expressed DNA/RNA binding protein that regulates gene expression. Mutations in FUS are linked to familial ALS.

• Clinical phenotype of FTLD-FUS: early onset (mean age = 38); severely disturbed behavior; profound caudate atrophy.

• FTLD-FUS subtypes include: neuronal intermediate filament inclusion disease (NIFID), basophilic inclusion body disease(BIBD) and atypical FTLD-FUS (aFTLD-FUS)

FTLD-FUS histopathology

Mackenzie et al, 2010

FUS-immunoreactive inclusions detected in granule cells of dentate Gyrus (C) and cortical cells (D); “vermiform” (worm-like) intranuclear inclusions (E) and (F); basophilic inclusion body disease (BIBD) (G) andneuronal intermediate filament inclusion disease (NIFID) (H)

NIFID BIBD

?

Summary of FTLD clinical,histopathologic and genetic classifications

40% 60% cases

GRN C9orf72 VPC

PNFA bvFTLD SD

FTLD-TAU FTLD-FUSFTLD-TDP

MAPT

aFTLD-U

CHMP2B is linked to a rare form of FTLDwith inclusions lacking tau, ubiquitin, TDP-43, and FUS

FTLD-TAU

FTLD

FTLD-U

40% 60%

FTLD-UPS

CHMP2B

rare

CHMP2B 3p11.2 (charged multivesicular body protein 2B)

CHMP2B is a member of ESCRT-III (endosomal sorting complex required fortransport III), which is required for the formation of the multivesicular body, a late-endosomal structure that fuses with lysosomes to degrade endocytosed proteins.

Carboxyl-terminal truncation mutants have a dominant-negative effect on endosomal functions, resulting in cell death.

Amyotrophic lateral sclerosis (ALS)

Jean-Martin Charcot; 1825-1893French Neurologist

“Founder of Modern Neurology”first described the disorder in 1869

Lou Gehrig; 1903-1941ALS is commonly known as

“Lou Gehrig’s disease”in North America

http://en.wikipedia.org/wiki/File:Jean-Martin_Charcot.jpg

ALS [aka: Charcot’s disease; motor neuron disease (MND)]

• Progressive, fatal motor neuron disease caused by the degeneration of motor neurons in the motor cortex, brain stem and spinal cord.

• Amyotrophic = lack of trophic factor for muscles; lateral sclerosis= atrophy of myelinated axons in lateral column of the spinal cord.

• Symptoms include muscle weakness and atrophy throughout the body; muscle fasciculations, cramping and stiffness; difficulty in speaking (dysarthria) and swallowing (dysphagia).

• Preservation of eye movements and control of bladder and bowels. Preservation for sense of smell, taste, touch and hearing.

• Preservation of intellect, memory and personality.

• A small percentage (~5%) of ALS patients develop symptoms characteristic of frontotemporal lobar degeneration (ALS-FTLD). Another (~30-50% have subtle cognitive deficits).

Epidemiology

• One of the most common neuromuscular diseases worldwide; most common form of motor neuron disease (MND): incidence 2.6/100,000per year

• Commonly strikes between the ages of 40 and 60

• Sporadic in ~90 - 95% of cases (SALS)

• Familial ALS (FALS) accounts for the remaining 5-10%. About 1/5 of these are caused by a dominant mutation in the superoxide dismutase gene (SOD1) on chromosome 21. Intracellular inclusions contain SOD1.

• Mutations in TARDBP, encoding TAR DNA binding protein 43 (TDP-43), and FUS, encoding fused in sarcoma/translated in liposarcoma (FUS/TLS) protein, have been linked to rare forms of familial and sporadic ALS.

• Possible environmental causes suggested in certain isolated populations, including a high-incidence of “lytico-bodig” disease among the Chamorro people on the island of Guam. The symptoms of “lytico” resemble ALS and “bodig” Parkinson’s disease

Faces of ALS

Charles Mingus1922-1979

Stephen Hawkingsb1942

Jason Beckerb1969

Motor neurons affected by ALS

Atrophy of skeletal muscle in ALS

http://neuromuscular.

wustl.edu/index.htmlHematoxylin & Eosin

stained striated muscle

Small, angular-shaped muscles are atrophied

Cellular nuclei are

stained dark purple

http://neuromuscular/

Anatomical drawing from one of Charcot’s

original patients

atrophy (sclerosis)of axons in the lateral corticospinal tract(descending tract)

loss of motor neurons inthe anterior (ventral) horn

cross-section of superior cervical spinal cord

http://neuromuscular.

wustl.edu/index.html

Dorsal

Ventral

http://neuromuscular/

ALS: histopathology-based classifications

ALS-SOD

ALS ubiquitin inclusions

SOD inclusions

ALS-TDP

TDP-43inclusions

FUSinclusions

ALS-FUS

SOD1 (21q22.11)superoxide dismutase

M(n+1)+-SOD + O2− → Mn+-SOD + O2Mn+-SOD + O2− + 2H+ → M(n+1)+-SOD + H2O2

where M = Cu (n=1) ; Mn (n=2) ; Fe (n=2) ; Ni(n=2).

http://en.wikipedia.org/wiki/Copperhttp://en.wikipedia.org/wiki/Manganesehttp://en.wikipedia.org/wiki/Ironhttp://en.wikipedia.org/wiki/Nickel

TARDBP (1p36.2)

TAR DNA binding protein-43

Lagier-Tourenne et al, 2010

-TDP-43 protein (414 aa): highly conserved, widely expressed; primarily localized to cellular nucleus; can shuttle between nucleus and cytoplasm

-regulates transcription, RNA splicing and exon skipping; may also function in the cytoplasm

-Many mutations in the carboxy-terminal glycine-rich regions are linked to ALS

“prion-like domain”

Severity of TDP-43 pathology in ALS brain

Geser F et al, 2008

FUS/TLS (16p11.2) (fused in sarcoma/translocated in liposarcoma)

Lagier-Tourenne et al, 2010

Ubiquitously expressed protein belonging to the FET (FUS, EWS, TAF15) family of multifunctional DNA/RNA binding proteins. Shuttles between nucleus and cytoplasm. Originally discovered as a component of fusion oncogenes in human cancers.

Thirty autosomal dominant mutations in 4% of familial ALS and rare sporadic ALS patients have been identified.

“prion-like domain”

Proposed physiological roles of TDP-43 and FUS/TLS

Lagier-Tourenne et al, 2010

Identified mutations in SOD1,TDPDBP and FUS account

for only a small fraction of ALS cases

Gene Percent ALS

SOD1 12-23% FALS

2-3% SALS

TARDBP

(TDP-43)

4% FALS

1.5% SALS

FUS 4% FALS

0.4% SALS

FALS = familial ALS; SALS = sporadic ALS

Genes implicated in both FTLD and ALS

C90rf72

VCP

SQSTM1 (p62)

OPTN

UBQLN

C9orf72 (9p21.2) expansions of GGGGCC-repeat in intron 1

DeJesus-Hernanez et al, Neuron 72, 2011:Expansions detected in: 12% familial FTP

22% familial ALS

Renton et al, Neuron 72, 2011:Expansions detected in: 46% familial ALS

21% sporadic ALS29% sporadic FTD (Finnish population)33% sporadic ALS(wider European population)

Possible mechanisms underlying pathogenic C9orf72 hexanucleotide expansions

Taylor JP, Science, 2013

Poly:

GA

GP

GR

(sense

strand)

Poly:

GP

AP

PR

(Anti-

Sense

strand)

[loss of function] [Toxic gain-of-function]

SQSTM1 (5q35): sequestosome 1 [aka p62]Binds ubiquitin; targets ubiquitinated proteins for degradation via protosomes or autophagy;Colocalizes with ubiquitinated proteins in cytoplasmic inclusions in FTLD, ALS and many otherdisorders characterized by abnormal protein aggregation.

Recently, multiple missense or truncating mutations in SQSTM1 have been identified as possible pathogenic mutations in FTLD and ALS in European and Japanese populations [with or without concomitant Piget’s disease of bone (PDB)].

OPTN (10p13) optineurin

Rare null /nonsense or missense mutations have been shown to cause both recessive and dominant ALS with or without FTLD; GWAS also link OPTN to PDB in individuals free of SQSTM1 mutations. Distinct OPTN mutations also implicated as a cause of adult-onset glaucoma.

Similar to SQSTM1/p62, optineurin binds ubiquitin andmediates protein clearance via autophagy.

CC = coiled coil domains; LZ = leucine zipper; LIR = LC3 interacting region UBD = ubiquitin binding domain; ZF = zinc finger

UBQLN2 (ubiquitin-like protein, ubiquitin 2)Mutations cause dominant X-linked juvenile and

adult-onset ALS and ALS/dementia

Deng HX, et al, Nature 477, 2011

UBL = ubiquitin-like domain, STI1 = heat shock chaperone binding motif, XXP repeats (12),

ubiquitin-associated domain

Guerriro R, Bras J and Hardy J, SnapShot:

Genetics of ALS and FTD, Cell 160, February 12, 2015

References

• Warren JD, et a;, Frontotemporal dementia (Clinical Review), BMJ 347, f4827, 2013

• Neary D et al, Frontotemporal dementia, Lancet Neurology 4, 771-780, 2005

• Rabinovici GD and Miller BL, Frontotemporal lobar degeneration: Epidemiology, pathophysiology, diagnosis and management, CNS Drugs 24, 375-398, 2010

• Sleegers K et al, Molecular Pathways of frontotemporal degeneration, Annual Reviews Neuroscience 33, 71-88, 2010

• Van der Flier WM & Scheltens P, Use of laboratory and imaging investigations in dementia, Journal of Neurological and Neuro-Neurosurgical Psychiatry 76, v45-v52, 2005

• Ballatore C et al, Tau-mediated neurodegeneration in Alzheimer’s disease and related disorders, Nature Reviews Neuroscience 8, 663-672, 2007

• Orr HT, FTD and ALS: Genetic ties that bind, Neuron 72, 189-190, 2011

References• Neumann M et al. Ubiquitinated TDP-43 in frontotemporal lobar

degeneration and amyotrophic lateral sclerosis, Science 314, 131-134, 2006

• Geser F et al, Evidence of multisystem disorder in whole-brain map of pathological TDP-43 in amyotrophic lateral sclerosis, Archives of Neurology 65, 636-641, 2008

• Lagier-Tourenne C et al, TDP-43 and FUS/TLS: emerging roles in RNA processing and neurodegeneration, Human Molecular Genetics 19, R46-R54, 2010

• Mackenzie et al, TDP-43 and FUS in amyotrophic lateral sclerosis and frontotemporal dementia, Lancet Neurology 9, 995-1007, 2010

• Ling SC, et al, Converging mechanisms in ALS and FTD: Disrupted RNA and protein homeostasis, Neuron 79, 416-438, 2013

• DeJesus-Hernandez M et al, Expanded GGGCC hexanucleotide repeat in noncoding region of C9orf72 causes chromosome 9p-linked TFD and ALS, Neuron 72, 245-256, 2011

• Lattante S et al, Defining the genetic connection linking ALS and FTD,Trends in Genetics 31, 263-273, 2015

References• Renton AE et al, A hexanucleotide repeat expansion in C90rf72 is the cause

of chromosome 9p21-linked ALF-FTD, Neuron 72, 257-268, 2011

• Deng Han-Xiang et al, Mutations in UBQLN2 cause dominant X-linked juvenile and adult-onset ALS and ALS/dementia, Nature 477, 211-215, 2011

• Lashley T, Hardy J and Isaacs AM, Ranting about C90rf72, Neuron 77, 597-598, 2013

• Taylor JP, RNA that gets RAN in Neurodegeneration, Science 339, 1282-1283, 2013

• Mori K et al, The C9orf72 GGGGCC repeat is translated into aggregating dipeptide-repeat proteins in FTLD/ALS, Science 339, 1335-1338, 2013

• Roher JD et al, C9orf72 expansions in frontotemporal dementia and amytophic lateral sclerosis, Lancet Neurology 14, 291-301, 2015

• Rovelet-Lecrux A et al, Frontotemporal dementia phenotype associated with MAPT gene duplication, Journal of Alzheimer’s Disease 21, 897-902, 2010

• Hardy J and Rogaeva E, Motor neuron disease and frontotemporal dementia: sometimes related, sometimes not, Experimental Neurology, 2013

Journal presentation

• Background article

Christensen T, Human endogenous retroviruses in

neurologic disease, APMIS 124, 2016

• Research article

Li W, et al, Human endogenous retrovirus-K contributes

to motor neuron disease, Science Translational Medicine7, 2015.

Internet resources

• The Association for Frontotemporal Dementias (AFTD): http://www.ftd-picks.org/

• Frontier Frontotemporal dementia research group: http://www.ftdrg.org/

• FTD mutation database: http://www.molgen.ua.ac.be/FTDmutations/

• National Institute of Neurological Disorders and Stroke (NIH) Amyotrophic lateral sclerosis fact sheet: http://www.ninds.nih.gov/disorders/amyotrophiclateralsclerosis/detail_amyotrophiclateralsclerosis.htm/

• The Whole Brain Atlas (Harvard Medical School): http://www.med.harvard.edu/AANLIB/home.html

http://www.ftd-picks.org/http://www.ftd-picks.org/http://www.ftd-picks.org/http://www.ftdrg.org/http://www.ninds.nih.gov/disorders/amyotrophiclateralsclerosis/detail_amyotrophiclateralsclerosis.htm/http://www.ninds.nih.gov/disorders/amyotrophiclateralsclerosis/detail_amyotrophiclateralsclerosis.htm/http://www.med.harvard.edu/AANLIB/home.html

Additional Slides

FTLD-TDP histopathology

Neumann M et al, 2006UBIs = ubiquitin body inclusionsHDDD2 = hereditary dysphasic disinhibition dementia 2

Genetic heterogeneity of FTLD-17

MAPT17p21.1

FTLD-17

FTLD-TAU FTLD-TDP

GRN17p21.32

Note: both genes map to the same region of chromosome 17

Familial FTLD linkedto chromosome 17

Early onset FTD phenotype is associated with MAPT gene duplication

Rovelet-Lecruxet al, 2010

Computed tomography (CT) scans show atrophy of frontal and temporal regions

Summary of ALS histopathologic and genetic classifications

ALS-SOD

ALS

SOD1

ALS-TDP

TARDBP FUS

ALS-FUS

Pathologicalfeatures

in ALS-TPDand FTLD-

TDP

Mackenzieet al, 2010

TDP-43 immunostaining:A & B: ALS-TDP(motor neurons): C - H: FTLD-TDP(C-G: brain neurons;H: brain glial cells)

I: western blot:*25KDa TDP-43arrow: 45 KDa TDP-43**phosphorylated TDP***high molecularweight smear of TDP-43-immuno-reactive material

Type 1 Type 2

Type 3 Type 4

Pathological features in ALS-FUS and FTLD-FUS

Mackenzie et al, 2010

A & B: ALS-FUS;C-H: FTLD-FUSI: coexistence of FUS (red) and a–internexin1 (green) inclusions in NIMFIDJ: FUS inclusions in glial cells (observed in both ALS-FUS and FTLD=-FUS)

ALS signature detected by MRI

MRI (parasagittal FLAIR) demonstrates increased T2signal within the posterior part of the internal capsule and can be tracked to the subcortical white matter of the motor cortex, outliningthe corticospinal tract,consistent with the clinical diagnosis of ALS.

FLAIR = fluid attenuation inversion recovery

TDP-43 and FUS “proteinopathies” in FTLD and ALS

Mackenzieet al, 2010

FTLD-TDP: Type 1 GRN mutations

Type 2 ?

Type 3 C9orf72 repeat expansions

Type 4 VCP mutations

SummaryHardy J and Rogaeva E, Experimental Neurology, 2013

aIn general, inclusions are ubiquitin-positive and contain the ubiquitin binding protein p62 (SQSTM1).

Abbreviations:FTD (frontotemporal dementia)

ALS (amyotrophic lateral sclerosis)

IBMPFD = inclusion bodies associated with myopathy with PDB and frontodementia

PDB (Paget’s disease of bone)

SP (spastic paraplegia)

MS (multiple sclerosis)

CLN11 (neuronal ceroid lipofusinosis-11)

GWAS (genome-wide association study)

~80%