improved anti-mirna (amos) and splice-switching oligonucleotides (ssos)
DESCRIPTION
Improved Anti-miRNA (AMOs) and Splice-Switching Oligonucleotides (SSOs), presented by Dr Mark Behlke, Chief Scientific Officer at Integrated DNA TechnologiesTRANSCRIPT
Integrated DNA Technologies
Improved Anti-miRNA (AMOs) and Splice-Switching Oligonucleotides (SSOs)Mark Behlke MD, PhD Chief Scientific Officer
Biopolis, Singapore July 26, 2013
Inhibition of miRNAs by Antisense Oligonucleotides
RISCRNA Induced
Silencing Complex
Target mRNA
Inhibit translation, mRNA cleavage …
AAAAA
Transfect AMO
miRNA
Steric blockingEventual Degradation?
2
Role of Chemical Modifications
1. Nuclease Stabilization
2. Increased binding affinitya. Tighter binding greater potencyb. Tighter binding decreased specificity
3. Compatible with invasion of RISC?
4. Assist with delivery?
3
Chemical Modifications – Sugar alterations
4
Chemical Modifications – Phosphorothioate linkage
5
Newer AMO designs
Original “antagomir”
M*M*MMMMMMMMMMMMMMMMMM*M*M*M-Chol
M = 2’OMem = 2’MOEF = 2’FD = DNAL = LNA* = PS bond
Chemistries used in anti-miRNA Oligos (AMOs)
6
DLDDLDDLDDLDDLDDLDDLDD
D*D*L*D*D*L*D*D*L*D*D*L*D*D*L*D*D*L*D*D
L*D*L*D*D*L*L*D*D*L*D*L*D*L*L
m*m*F*F*F*F*F*F*F*F*F*F*F*F*F*F*F*F*F*m*m
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM MMMMMM MMMMMM
L*L*L*L*L*L*L*L*L
Luc/Luc Assay System
One perfect match miRNA binding site was cloned
Renilla luciferase
Fireflyluciferase
miRNA
+AMO
Translation
Light
miRNA
Renilla Luciferase
miRNA Binding
Site
Transfected into Cells
+
miRNA
Degradation
Renilla Luc
No Light
Cleavage
7
Rluc/Fluc assay in HeLa cells (express miR-21)
Direct Comparison of Different AMO Chemistries for miR-21 Knockdown
0
10
20
30
40
50
60
70
80
90
100
Fold
inc
reas
e in
RL/
FL
1nM5nM10nM25nM50nM
DNA 2'OMe 2'OMePS-ends
DNA/LNA PS
2'OMe/LNA
2'OMe/LNA PS
2'FLNAends
2'FLNAends PS
HP+RC+HP2'OMe
DNA/LNA
2'OMePS
DNA PS ■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■ 2’OMe ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ 2’OMe PS-ends ■•■•■•■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■•■•■•■ 2’OMe PS ■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■
DNA/LNA ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DNA/LNA PS ■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■ 2’OMe/LNA ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ 2’OMe/LNA PS ■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■ 2’F LNAends ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ 2’F LNAends PS ■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■ HP+RC+HP 2’OMe ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■
■ = DNA bases ■ = 2’OMe bases ■ = LNA bases ■ = 2’F bases • = PS linkages
8
Unmodified DNA or 2’OMe oligos are rapidly degraded in serum – need PS modification or hairpin
(Note: unmodified 2’OMe is stable in cell extracts, even though it degrades in serum)
Stability in Serum
9
Interestingly, the DNA/LNA mixmers also require some PS modification (at least on the ends)
(Note: unmodified are all stable in cell extracts)
Stability in Serum
10
Interestingly, the DNA/LNA mixmers also require some PS modification (at least on the ends)
(Note: 2’F without PS rapidly degrades in cell extracts)
Stability in Serum
Degraded in cell extracts
11
For More Information:
12
Insertion of “ZEN” between bases increases duplex stability
Temperature (oC)
20 30 40 50 60 70 80
% m
elte
d du
plex
0
20
40
60
80
100Unmod DNAInternal ZEN
5’-ATCGTTGCTA-3’3’-TAGCAACGAT-5’
5’-ATCGTzTGCTA-3’3’-TAGCA ACGAT-5’
vs.+ ZEN
13
2’OMe RNA is:NaturalSafe / NontoxicLess expensive than LNAs or 2’F
Degraded by exonucleases in serumStable to endonucleases in cell extracts
The new napthyl-azo modification increasesTm (PS decreases Tm), blocks exonuclease action, and is compatible with RISC invasion
MzMMMMMMMMMMMMMMMMMMMMMzM
2’OMe with new napthyl-azo (“ZEN”) modifier between end bases
O P
O
O-
O3'
N
O
N
N
5'
NO2
14
miR-21 2’OMe AMOs with internal ZEN insertion
2’OMe ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ 2’OMe 3PSends ■•■•■•■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■•■•■•■ 2’OMe PS ■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■
HP+RC+HP 2’OMe ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ 2’OMe 3’-Z ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■z■ 2’OMe 5’-Z ■z■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ 2’OMe 2-Z ■z■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■z■ 2’OMe 2-Z-PS ■z■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■z■ 2’OMe 3-Z ■z■ ■ ■ ■ ■ ■ ■ ■ ■ ■z■ ■ ■ ■ ■ ■ ■ ■ ■ ■z■ DNA LNA PS ■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■ 2’OMe LNA PS ■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■
■ = DNA bases ■ = 2’OMe bases ■ = LNA bases • = PS linkages z = ZEN mod
Tm 72.7 72.2 68.1 76.3 71.4 74.5 87.3DTm +0.5 -- -4.1 +4.1 -0.8 +2.3 +15.1
15
Small DTm can result in large DKa at 37oC
16
DNA t c a a c a t c a g t c t g a t a a g c t a 56.3 -16.4 -18.7 1.5 x1013
2 OMe′ U C A A C A U C A G U C U G A U A A G C U A 72.7 - -26.9 9.4 x1018
2 OMe 3PSends′ U*C*A*A C A U C A G U C U G A U A A G*C*U*A 72.2 -0.5 -26.4 4.3 x1018
2 OMe 5 inZEN,3 ZEN′ ′ ′ UzC A A C A U C A G U C U G A U A A G C U Az 76.3 3.6 -30.6 3.8 x1021
K a(37°C) (mol/L)-1Name miR-21 AMO Sequences (5 to 3 )′ ′ T m (°C) ΔT m (°C) ΔG o
37 (kcal/mol)
A 4.1oC increase in Tm between the 2’OMe-PSends AMO and the ZEN-AMO results in an 880-fold increase in the
binding affinity (Ka) at 37oC
Importance of binding affinity for AMO potency
17
• It is generally accepted that high binding affinity improves potency for all steric blocking antisense applications (AMO, SSO, mRNA …)
• miRNAs reside in RISC (complexed to protein) and can be stable for weeks. It is critical to be able to invade RISC and inactivate these miRNAs
• miRNAs start as dsRNAs and get reduced to ssRNA form in RISC – thus RISC has machinery that renders the miRNA duplex single-stranded : the AMO must overcome these natural pathways so it does not get treated like a passenger strand• Nuclease “slicer” function in Ago2• Helicase “unwinding” of duplexes in Ago1, Ago2, Ago3, Ago4
• Thus the AMOs need to be nuclease resistant (cannot be cut by Ago2)
• Thus the AMOs need high enough binding affinity to overcome helicase activity• After you reach the “threshold Tm” where helicase can no longer unwind the AMO from
the miRNA guide strand, then increases in binding affinity mostly serve to make cross-reactivity for mismatches worse
miR-21 AMO length walk
18
For the miR-21 AMO with ZEN-2’OMe chemistry, the binding affinity threshold to escape helicase unwinding must lie between the 14mer & 15mer
Specificity comparison of AMO chemistries
19
Mutant Type
Wildtype MUT 1 MUT 2 MUT 3
a Mutations are notated as blue nucleotides enclosed in red boxes
U C A A C A U C A G U C U G A U A A G C U AU C A A C A U C A G U C A G A U A A G C U AU C A A C C U C A G U C A G A U A A G C U AU C A A C C U C A G U C A G A U A A C C U A
miR-21 AMO Sequences (5′ to 3 )′ a
ZEN-2’OMe DNA/LNA-PS 2’OMe/LNA-PS2’OMe-PSends“Antagomir”
ZEN is non-toxic, whereas PS mod and LNA mod show toxicity
2’OMe 2-Z ■Z■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■Z■ 2’OMe 3PS-ends ■•■•■•■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■•■•■•■ DNA PS ■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■ DNA/LNA PO ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DNA/LNA PS ■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■ 2’OMe/LNA PO ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ 2’OMe/LNA PS ■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■•■
■ = DNA bases ■ = 2’OMe bases ■ = LNA bases Z = ZEN mod • = PS linkages
20
Se-ries1
0
20
40
60
80
100
120
Cytotoxicity Data of "NC1" AMOs transfected into HeLa Cells for 24hrs with INTERFERin™
50nM100nM
% V
iabl
e Ce
lls
2'OMe 2-Z
Reagent Only
2'OMe3PSends
DNA/LNA PS
PS DNA/LNA PO
2'OMeLNA PS
2'OMe/LNA PO
Stauro-sporine
Pos Cont
21
30 nM
100 nM
10 nM
DNA/LNA-PS 2’OMe-ZEN 2’OMe-3PSends 2’OMe2’OMe/LNA-PS
Potency differences do not relate to transfection efficiency
22
Different AMOs were transfected at 30 nM.
AMO transfection efficiency was assessed using ISH (in situ hybridization).
Cells were fixed and hybridized with a Dig-probe and detected with an A647-anti-Dig antibody
Final design rules
MzMMMMMMMMMMMMMMMMMMMMz (N-1)-length
MzMMMMMMMMMMMMMMMMMMMMzM Full-length
Either during transfection (in serum) or exposure to cytoplasmic nucleases, the first AMO gets degraded to the second AMO. Positioning the ZEN at the
3’-end removes most of the Nearest Neighbor effects and avoids any degradation. Making the final AMO be 1 base shorter than the miRNA target
can also slightly increase potency.
23
For more information:
24
Molecular Therapy Nucleic Acids, 2013
Insulin Regulation in Pancreatic Islets
Eran HornsteinWeizmann Institute
• Investigated a possible role for miRNAs in the regulation of insulin secretion
• Dicer1 conditional KO using tamoxifen inducible Cre recombinase with rat insulin promoter
• Examine changes in insulin levels and glucose regulation with miRNA production disrupted
• Identified SOX6 and Bhlhe22 as negative regulators of insulin secretion, with miRNAs 22, 24, 148, and 182 regulating expression of these genes, thereby indirectly regulating insulin secretion
25
Knockout of Dicer leads to reduction in miRNA levels
Studied in isolated islets; b-cells comprise ~50-60% of cell mass
26
Dicer mutants have elevated glucose, decreased insulin
27
Up-regulation of transcription repressors in Dicer mutants
Sox6 and Bhlhe22 are repressors of insulin transcription. Increased levels of repressors lower insulin and raise glucose levels.
28
miRNA regulation of Sox6 and Bhlhe22?
• miRNA expression in pancreatic islets was examined using microarrays
• Potential binding sites for several highly expressed miRNAs were found in the 3’-UTRs of Sox6 and Bhlhe22
• AMOs were synthesized to specifically suppress these miRNAs to investigate the role of these species in normal cells (not Dicer mutants)
29
AMOs increase SOX6 and Bhlhe22 levels, lowering glucose
30
miRNA regulatory pathway for Insulin secretion
31
For more information:
32
Regulation of Cystic Fibrosis (CFTR)
33
• Investigated role of miRNAs in regulation of CFTR expression and found a major role for miR-138
• miR-138 does not directly regulate CFTR but instead acts as a suppressor of SIN3A, which is a suppressor of CFTR transcription
• miR-138 AMO increases SIN3A levels which lowers CFTR levels
• miR-138 mimic lowers SIN3A levels which raises CFTR levels (same effect is seen using anti-SIN3A siRNA)
• Not just transcription/translation effect – salvages D508 mutants!
Paul McCrayUniversity of Iowa
Effect of miR-138 AMO vs. miR-mimic on WT CFTR
34
SIN3A knockdown rescues CFTR D508 expression on cell surface
35
The D508 mutant retains Cl- channel activity, but is degraded in the EPR and never reaches the cell surface; SIN3A knockdown not only increases
CFTR expression, it alters processing and permits the semi-functional mutant CFTR protein to reach the cell surface.
miR-138 mimic restores Cl- conductance in CF airway cells
36
A new target for CF therapy?
For more information, see:
37
Use of the ZEN modification: Splice Switching Oligos (SSOs)
Another use for this kind of antisense technology: SSOs • Steric blocking mechanism of action
• 2’OMe RNA, LNA, PMO, PNA
• Bypass stop codon or other errors present by causing splicing to shift and deleting the affected mutation. Many diseases exist which could be treated by this mechanism, including DMD, SMA, b-Thalassemia, and many more
38
Duchenne Muscular Dystrophy (DMD)
Genetics – An X-linked recessive disorder affecting approx 1 in 3500 boys
Cause - An absence of dystrophin, a protein that helps keep muscle cells intact.
Onset - Early childhood - about 2 to 6 years.
Symptoms - Generalized weakness and muscle wasting first affecting the muscles of the hips, pelvic area, thighs and shoulders. Loss of ambulation, development of respiratory problems (diaphragm), cardiomyopathy and death in 20’s/30’s.
39
Collaboration with the Wood lab to study SSO in “mdx” mouse
C57BL/10ScSn-Dmdmdx/J mouse• Stop codon in Exon 23• Develops DMD phenotype• Salvage with exon skipping SSOs = skip exon 23 and
you get an in-frame semi-functional dystrophin protein• PCR assay:
• Full length = 1kb product• Skip exon 23 = 700 bp product• Skip exons 22+23 = 550 bp product
Samir EL AndaloussiSuzan HammondGraham McCloreyMatthew Wood
40
H2k (myoblast) cell culture
• H2k cells were grown at 33°C in 10% CO2 atmosphere using DMEM media supplemented with 20% FBS and 0.5% chick embryo serum; grown on gelatinised plates.
• After 24 h, cells were moved to 37°C in 5% CO2 and media is replaced with differentiation media (DMEM with 5% horse serum). Myotubes form within 3-5 days. These are very difficult to transfect compared to the undifferentiated myoblasts.
• Cells were transfected with LF2000 at the indicated concentrations or naked SSOs are added at 2-4 µM concentration and cells were incubated for 48-96 h in optiMEM.
41
PS linkage is important for function (not just nuclease stability)
80 40 20 10 80 40 20 10 U
PS20 EndPS
nM
Myoblasts, lipid transfection, studied at 48h
SSO-EndPSmG*mG*mC*mC mA mA mA mC mC mU mC mG mG mC mU mU mA*mC*mC*mU SSO-PSmG*mG*mC*mC*mA*mA*mA*mC*mC*mU*mC*mG*mG*mC*mU*mU*mA*mC*mC*mU 42
Unlike AMOs, PS linkage is important for function in ZEN SSOs
Myoblasts, lipid transfection, studied at 48h
SSO-ZENmGzmG mC mC mA mA mA mC mC mU mC mG mG mC mU mU mA mC mCzmU SSO-ZEN-PSmGzmG mC*mC*mA*mA*mA*mC*mC*mU*mC*mG*mG*mC*mU*mU*mA*mC mCzmU
80 40 20 10 80 40 20 10 U
ZEN-PO ZEN-PS
nM
43
Pilot study: direct intramuscular injection in “mdx” mice
2’OMePS ZENPS
SSO-PSmG*mG*mC*mC*mA*mA*mA*mC*mC*mU*mC*mG*mG*mC*mU*mU*mA*mC*mC*mU SSO-ZEN-PSmGzmG mC*mC*mA*mA*mA*mC*mC*mU*mC*mG*mG*mC*mU*mU*mA*mC mCzmU
• IM injection of 30 µg SSO
• Harvest muscle at day 14
• Immunohistochemical visualization of dystrophin protein
44
Functional testing in “mdx” mice
• Plan: 50 mg/kg IV weekly for 8 weeks
• Reality: 50 mg/kg IV 2x weekly for 4 weeks 1 week off 50 mg/kg IP 2x weekly for 4 weeks Study phenotype for a week, then collect tissue
• 4 cohorts, WT untreated, “mdx” untreated, “mdx” 2’OMe-PS, “mdx” ZEN
• Study animals for functional activity
The monitoring system provides an assessment of the motor activity and behavior of the mice, measuring both anxiety-related behavior and locomotor behavior associated with muscle strength. IR beams of light pass through the cage. When the mouse crosses a beam, the light is broken and this is recorded in the software, Digiscan. The system measures 22 forms of activity including rearing, active time, static time as well as distance travelled.
• Examine muscles for dystrophin protein and mRNA splice forms
45
Functional testing in “mdx” mice
• Expt was not optimal – think that the IV phase worked but IP did not
• No splice-shifted mRNA was detected (short half life)
• Dystrophin protein was present (long half life)
• Repeating with a 4 week IV regimen
46
New ZEN (napthyl-azo) modifier inserted between the terminal bases of a steric-blocking antisense oligo improves nuclease stability and increases binding affinity
Particularly useful when used with 2’OMe RNA; anti-miRNA (AMO; PO form) and splice switching (SSO; PS form) applications; more?
The designs show excellent mismatch specificity, similar to low potency unmodified 2’OMe AMOs, yet achieve the high level of potency normally associated with use of more toxic DNA/LNA-PS mixmers
Both ZEN-AMOs and ZEN-SSOs are being tested in mice now
Available now “off catalog” – just call IDT Tech Support. Full product line in catalog will be available later this year.
Summary
47
Integrated DNA TechnologiesKim LennoxScott RoseRichard OwczarzyYong YouMike MarvinAnton HoletsJess AlexanderJoseph WalderMark Behlke
Weizmann InstituteTal Melkman-ZehaviSharon Kredo-RussoAmitai MandelbaumEran Hornstein
Thanks to all the scientists whose work was discussed today!
University of IowaShyam RamachandramMichael WelchPaul McCrayBev Davidson
48
University of OxfordSamir EL AndaloussiSuzan HammondGraham McCloreyMatthew Wood