NDAL’s Research Activities A. Nazlı BAŞAK http://www.ndal.boun.edu.tr/posters.php
Neurodegenerative Diseases • have tremendous adverse effects on the aging population..... • people of all nations, races, ethnicity are affected..... GREAT BURDEN ! GREAT BURDEN ! • 120.000 new cases appear every year...
AD, PD, HD, ALS, SBMA, Ataxias... • loss of memory and decrease in cognitive function: dementia • deterioration in muscle coordination: ataxia • involuntary movements: chorea • tremor, rigidity, bradykinesia • behavioural abnormalities • paralysis There are no effective treatments for these disorders yet...
NDAL’s Aims: Genetic approaches: • determine mutations and genes leading to disease • develop methods for early diagnosis Molecular and cell biology approaches: • investigate mechanisms leading to neurodegeneration • halt/prevent disease at early stages • develop molecular treatment modalities
YÜKSEK LİSANS ÖĞRENCİLERİ Abdülkadir ÖZKAN Didem ERUSLU Suna LAHUT Gülçin VARDAR Merve KILINÇ
Why Genetics? • Genetics plays a major role in any disease; – cardiovascular disease, cancer, diabetes, infection, neurological/mental disorders • It is a person’s genetic makeup, which affects – susceptibility to disease, disease course, response to treatment • Understanding these genetic contributions is the first step toward understanding disease mechanisms.
Common Mechanisms: The specific molecular events and selectivity of neuronal death are still unclear, but damage to neurons seems to occur through a combination of several different mechanisms
Selective vulnerability of neurons specific for each disease HMND Bertram and Tanzi, 2005
ALS as MODEL DISEASE
Jean-Martin Charcot (1825-1893) French Neurobiologist • Charcot, J.M. & Joffroy, A. ”Deux cas d’atrophie musculaire progressive avec lesions de la substance grise et des faisceaux antero-lateraux de la moelle epiniere” Arch. Physiol. Neurol. Pathol. 2, 744- 754 (1869)
ALS: S: Most Common Motor Neuron Most Common Motor Neuron AL Disease Disease • Fatal within 1-5 years Fatal within 1-5 years • Incidence: 1-2.5/100 000 Incidence: 1-2.5/100 000 • Prevalence: 4-8 / 100 000 Prevalence: 4-8 / 100 000 • Lou Gehrig Lou Gehrig: : “A bad break’’ A bad break’’ “ “I am so tired, and I simply cannot play well anymore…” I am so tired, and I simply cannot play well anymore…” “
AMYOTROPHIC LATERAL SCLEROSIS • A: Absence of Weakness and • Myo: Muscle atrophy of muscles • Trophic: Nourishment Sclerosis (hardening) • Lateral: Side (ofspine) observed in the • Sclerosis: Hardening or lateral parts of the spinal cord during scarring autopsy
ALS progressively weakens and paralyses the muscles, controling voluntary movement
HALLMARKS of ALS • Degeneration and death of upper and lower lower motor neurons upper in the brain and spinal cord • Progressive muscle weakness • Atrophy and spasticity • Total paralysis • Denervation of the respiratory muscles and diaphragm is the fatal event • “Dying back” of the MN: – Degeneration begins at the ends of the axon, proceeding back to cell body.
Neighbours matter..... • A paradigm shift in our thinking about the nature of ALS has occurred in the last decade. • ALS is now considered a multisystem neurodegenerative disease: – voluntary motor pathways are the first, but not the only (CNS) structures involved – microglia, astrocytes, skeletal muscle are active co-players
The most devastating aspect of ALS... • Cognitive functions of the brain remain undamaged • Sensory nerves are spared, too... • Patients are obliged to Stephen watch the demise of Hawking their own bodies.
Most ALS Cases Are Isolated Incidences Familial ALS : fALS % 10 % 10 (Mendel gen.: AD/AR inh.) Sporadic ALS : sALS % 90 % 90 (no documented family history, genetic contribution?) fALS sALS fALS and sALS are clinically similar!!
The development of ALS probably probably reflects an interplay reflects an interplay The development of ALS between environmental and genetic factors, between environmental and genetic factors, influenced by aging influenced by aging. . SOD1 High ? retrovirus Environment ? pesticides Genes Risk Risk smoking high glut diet Low Aging Age Risk Youth
Seven genes involved in fALS SOD1 Alsin Senataxin VAPB Dynactin TDP-43 FUS
fALS genes encode proteins • Involved in a diverse range of cellular processes: – dismutation – RNA processing – axonal transport – angiogenesis – vesicle transport – endosomal trafficking – DNA/RNA binding • This diversity indicates that the pathogenesis of ALS is probably associated with several different processes – leading to a cascade of neurodegeneration.
SOD1: the first and major gene 1993( Rosen et al . ) chromosome 21 SOD1 accounts for 20% of all familial forms (and for 2 % of all ALS cases). All the other genes account for 11% (blue), leaving 69% (green) undefined.
SOD1 catalyzes the conversion of superoxide to SOD1 catalyzes the conversion of superoxide to oxygen and hydrogen peroxide. oxygen and hydrogen peroxide. • extremely stable dimer: 153 aa/monomer • Cu catalytic, Zn structural • ubiquitously expressed • present in all organisms above bacteria • aminoacid sequence is highly conserved – crucial funtion in cellular homeostasis
All 133 SOD1 mutations result in typical ALS! • Alsin, SETX, DCTN1, VAPB Atypical ! Mutations confer a destructive property to SOD1: • Gain of a novel toxic function! • Autosomal dominant inheritance! • How such a diverse range of mutations can result in a novel function – producing the same relatively homogeneous phenotype is still a mystery!
Mt SOD1 impairs multiple cellular functions, leading to death of MNs Passinelli & Brown, 2006
ALS in Turkey ????
192 ALS patients from different regions of Turkey • FALS: 32 patients * – 6 families/ 15 members – 17 single cases • Juvenile: 11 patients – 1 family/ 2 children – 9 single cases • SALS: 149 apparently sporadic cases *ALS was classified as familial, when at least two members were clinically affected in the same pedigree.
Clinical Characteristics of Patients FALS SALS # of patients* 32 (15 fam.) 149 Gender (Male/Female) 13 / 19 93 / 56 Ratio 1 : 1. 5 1.6 : 1 Age of onset (years) 39.3 47.5 Mean Range 16-68 18-79 * Juvenile cases not included
SOD1 Results • FALS: 5mut/32 patients: 15.6% – H71Y – N86S* * recessive inheritance – D90A* – L144F – A4S – IVS-III-34 (A:C) • SALS: – 6 cases: IVS-III-34 (A:C)
NORTH-SOUTH gradient in the frequency of SOD1 mutations across Europe.
EUROPE: SOD1 mts in FALS 23% 23% 50% 50% 13% 13% 20% 20% 64% 64% 15% 15% 15.6% 15.6% 16% 16%
D90A, N86S autosomal recessive behaviour • Evidence for a cis-acting regulatory polymorphism as disease modifier? – decreases ALS susceptibility in heterozygotes – slows disease progression in homozygotes • Comparative haplotype analysis
Genome-wide Association Studies in ALS (Collaboration Brown Lab) • Aim: to identify genetic variants associated with – Susceptibility for sALS – phenotypes in SALS • site of onset • age of onset • risk of disease • duration of disease • Materials: 1821 SALS DNA + 2258 Control DNA – 288,357 SNPs
Reduced Expression of the Kinesin-Associated Protein 3 (KIFAP3) Gene Increases Survival in SALS Landers et al, 2009, PNAS in print • A single SNP (rs1541160) in the noncoding region of KIFAP3 showed significant value, regarding the disease duration in ALS. • Genetic factors modify phenotypes in sALS • Cellular motor proteins are determinants of motor neuron viability.
From SOD1 to GWAS in ALS • Aslıhan Özoğuz, PhD Thesis – Altar Sorkaç • Collaboration with Brown’s Lab – John Landers • Collaboration with Andersen’s Lab • Tubitak SBAG 1001
Alsin in the pathology of ALS Alsin mutations lead to related, but clinically distinct motor neuron degenerative diseases: ALS ALS PLS HSP SMA Alsin May be an important molecule in the elucidation of a common May be an important molecule in the elucidation of a common mechanism for MN degeneration! mechanism for MN degeneration!
Alsin Protein ( G nt exchange factor ) Ubiquitously expressed and abundant in neurons Function not fully understood Many interacting domains Investigations on Alsin may be crucial for the elucidation of a common mechanism for MND
Yeast-2-Hybrid screen • Alsin is known to inhibit the neurotoxicity of mt SOD1; its SOD1 interacting region is DH/PH. • the DH/PH region of Alsin revealed 6 novel i.a, – UXT Xp11 – PMM1 22q13 – PCMB4 1q21 – SRPK2 7q22-q31.1 – NDUFV1 11q13 – VARSL 6p21 • These proteins are expected to give clues about the function of Alsin.
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