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Céline Cluzeau, Ph.D. Postdoctoral Visiting Fellow Biological pathways influencing Purkinje cell survival in Niemann- Pick disease type C1.

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Presentation on theme: "Céline Cluzeau, Ph.D. Postdoctoral Visiting Fellow Biological pathways influencing Purkinje cell survival in Niemann- Pick disease type C1."— Presentation transcript:

1 Céline Cluzeau, Ph.D. Postdoctoral Visiting Fellow Biological pathways influencing Purkinje cell survival in Niemann- Pick disease type C1

2 A fatal, autosomal recessive neurodegenerative disease Characterized by the accumulation of unesterified cholesterol and glycosphingolipids in the endosomal/lysosomal system Prevalence: 1/100,000-1/150,000 (Western Europe) Due to mutations in the NPC1 (95%) or NPC2 genes NPC1 encodes a large transmembraneous lysosomal protein NPC2 encodes a small soluble protein able to bind cholesterol Niemann-Pick Disease, Type C (NPC)

3 Large variation in age of onset, and severity Clinical presentation includes: -Hepatosplenomegaly -Liver disease: cholestasis, elevated plasma enzymes -Neurological symptoms: Ataxia Progressive dementia Gelastic cataplexy/Seizures Vertical gaze palsy No FDA approved therapy for NPC Miglustat approved in EU: slow progression Ongoing clinical trials: 2-hydroxypropyl-  -cyclodextrin (phase I) and vorinostat (HDAC inhibitor; in preparation) NPC Clinical Presentation

4 1 wk3 wks5 wks7 wks9 wks11 wks TerminalAtaxia, weight lossTremorsPre-symptomatic Animal models Mouse model (BALB/cNctr-Npc1 m1N /J) Anteroposterior gradient of Purkinje cells degeneration in NPC1 cerebellum (from lobule I-II to X) Lobule X genuinely resistant to Purkinje cells death even in late stages Other early pathological signs present in lobule X (axonal degeneration, microgliosis) but progression seems to stop in this posterior lobule Axonal degeneration Microgliosis AstrogliosisOnset of Purkinje cells loss Lysosomal accumulation of lipids

5 Goals Identify the differentially expressed genes between lobules with preserved Purkinje neurons versus lobules with early and late loss of Purkinje cells Study the relevance of the genes associated with a different Purkinje cell survival rate to NPC1 pathology

6 RNAseq outline RNA extraction Enrichment in mRNA Library building Preparation of pools of barcoded libraries Templated bead preparation and sequencing Bioinformatics analysis Tissue/sample collection

7 Preliminary test Lobules very small: how many animals do we need? SOLID library building protocol: -200 to 500ng rRNA-depleted RNA rRNA content: 90-95% of total RNA -Need 10  g total RNA RNA extraction from lobule X of one animal: ~1.7  g total RNA - Pool lobules from 6 animals

8 Preliminary test: rRNA depletion Run a Bioanalyzer chip to determine the quality of rRNA-depleted RNA (RNA pico kit, Agilent) Bioanalyzer profile after 1 st depletion Bioanalyzer profile after 2nd depletion Total RNA bioanalyzer profile

9 Sample collection Sacrifice of one-month-old Npc1 +/+ and Npc1 -/- mice (N=24 for each genotype) Cardiac perfusion with cold 1x PBS/0.6% glucose solution with RNase inhibitors (1/10,000; Protector RNase inhibitor, Roche Diagnostics) Dissection of cerebellum, and isolation of vermis Microdissection of each lobule (I-II, III, IV, V-VI, VII, VIII, IX and X) Lobules flash-frozen and kept at -80°C separately

10 RNA extraction Pool lobules from 6 mice (3 males and 3 females) for RNA extraction: - Lobule III (3 pools; early degeneration) - Lobule V-VI (3 pools; intermediate degeneration) - Lobule X (4 pools; resistant lobule) RNA extraction with TRIzol (Life technologies) followed by purification on Qiagen columns (Rneasy Mini kit): - Good yield and quality

11 RNA extraction RNA extraction with TRIzol followed by purification on Qiagen columns: Autoclaved disposable tips OMNI Inc. Tissue homogenizer TRIzol Transfer upper phase in new tube Add ethanol On-column DNase I digestion 2x

12 RNA extraction RNA concentration measured with Nanodrop (Thermo Sci.) Sample ID Mean RNA concentration (ng/  L) Total quantity of RNA (  g) WT lobule III57117.1 WT lobule V-VI83024.9 WT lobule X37411.2 Mutant lobule III52915.9 Mutant lobule V-VI56316.9 Mutant lobule X33410 10  g used for rRNA depletion

13 rRNA depletion 1 st step with 2x 5  g total RNA using RiboMinus TM Eukaryote Kit v2 (Ambion) 2 nd step with 1  g of rRNA-depleted RNA from 1 st step using Low Input RiboMinus TM Eukaryote Kit v2 (Ambion) Alternatives: –RiboZero rRNA removal kits (Illumina) –poly(A) selection

14 rRNA depletion Sample ID Quantity of rRNA- depleted RNA (  g) % of starting material WT lobule III0.383.8 % WT lobule V-VI0.393.9 % WT lobule X0.424.2 % Mutant lobule III0.464.6 % Mutant lobule V-VI0.404.0 % Mutant lobule X0.383.8 % Slightly less than 5 % of starting material, but within 200-500ng range required for library building

15 rRNA depletion Run a Bioanalyzer chip to determine the quality of rRNA-depleted RNA (RNA pico kit, Agilent)


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