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Tensor decompositionbased unsupervised feature extraction identified the universal nature of sequencenonspecific offtarget
regulation of mRNA mediated by microRNA transfection
Yh. Taguchi
Department of Physics, Chuo UniversityTokyo, Japan
Bian and Sun, “Noncoding RNAs in Neural Stem Cell Development” in “ Neural Stem Cells and Therapy”
What is miRNAs?
DICERDICER
Many miRNA transfection experimentsPrincipal Purpose
Identification of mRNAs targeted by transfected miRNAs
On the other hands, there are many mRNAs associated with gene expression alteration caused by miRNA transfection, but not targeted by but not targeted by transfected miRNA.transfected miRNA. sequencenonspecific →
offtarget regulation of mRNA mediated by microRNA
mRNA
Mechanism of sequencenonspecific offtarget regulation
Protein
TransfectedmiRNAs
Disfunction
miRNAs
Method = identification of commonly altered mRNAs
miRNA 1
Offtarget
Transfected
miRNA 2
miRNA 4
miRNA 5
miRNA 6
miRNA 3
mRNA
target
commonly altered mRNAs
How to identify commonly altered mRNAsHow to identify commonly altered mRNAs
Tensor decomposition (TD) unsupervised feature extraction (FE)
Q:What is TD?
A: Extension of matrix factorization to tensor.
xijk = ∑l1,l2,l3 G(l1,l2,l3)xl1i xl2j xl3k
ik j
xijk
Tensor
l2
l1
l3
GCore tensor ixl1i
j
xl2j
k xl3kSingular
value matrix
miR
NA
(M)
Contr ol
Treated
N0---2
N0---2
miRNA nonspecific regulation
miRNA specific regulation
Expression tensor
R N M 2
TD Control
Treated
miRNA independent expression
mRNA (N
)
1P
Pvalues computed with assuming Gaussian for mRNA singular value vector
Synthetic dataSynthetic data
Successful identification of commonly regulated mRNAs
What is PCA based unsupervised FE?
N features
Categorical multiclasses
In contrast to usual usage of PCA, not samples but features are embedded into Q dimensional space.
PC
A
PC1
samplesPC Loadings
M samplesN × M Matrix X (numerical values)
PC2
PC1
PC Score
++ ++ +
+++
++ ++ ++
+
No distinction between classes
Synthetic example
10 samples10 samples
90 features 10 featuresN(0)N()
[N()+N(0)]/2
+:Top 10 outliersThus, extracting outliers selects features distinct between two classes in an unsupervised way.Accuracy:(100 trials)Accuracy:(100 trials) 89.5% ( 52.6% (
PC1
PC2
Normal μ:mean Distribution ½ :SD
Real data (from gene expression omnibus)Real data (from gene expression omnibus)Transfected miRNAcell lines (cancer)
Results for exp 4Results for exp 4
Cont rol
Treated
miRNA independent expression
Results for exp 1Results for exp 1
Gens singular value vectorsfirst
second
miRNA nonspecific regulation
miRNA specific regulation
Genes (~102) selected in each of eleven experiments are significantly overlappedPvalue
Odds ratio
Genes (~102) selected in each of eleven experiments share significantly the TF target genes.
Genes selected in each of eleven experiments
TFs whose target genes are enriched in selected genes
TF
Genes (~102) selected in each of eleven experimentsare enriched in common KEGG [(i)~(x)] pathways
10 KEGG pathways 10 KEGG pathways (i) Ribosome:hsa03010, (ii) Alzheimer’s disease:hsa05010, (iii) Parkinson’s disease:hsa05012, (iv) Oxidative phosphorylation:hsa00190, (v) Pathogenic Escherichia Coli infection:hsa05130,(vi) Huntington’s disease:hsa05016, (vii) Cardiac muscle contraction:hsa04260,(viii) Nonalcoholic fatty liver disease (NAFLD):hsa04932, (ix) Protein processing in endoplasmic reticulum:hsa04141, (x) Proteoglycans in cancer:hsa05205.
Although more biological validations were performed, they are omitted here because of lack of time. Anyway, selected genes are obviously biologically similar.
Number of experiments →
Number of miRNAs Rank
Although there are no direct evidences that selected genes are really regulated by sequencenonspecific offtarget effects, there are some indirect evidences.
Genes selected more frequently among eleven experiments are targeted by more miRNAs
Genes targeted by more miRNAs are more likely affected by sequencenonspecific offtarget effect
Genes selected in eleven experiments are significantly overlapped with ….. Upper : genes whose expression is reported to be altered by 16 DICER KO experiments in Enrichr.Lower: genes that bind to DICER (IP experiments).
Conclusions
We have identified mRNAs regulated by sequencenonspecific offtarget effect mediated by microRNA transfection, over eleven experiments.
They are significantly overlapped with one another over eleven experiments.
They are enriched in various biological terms and concepts.
They are overlapped with genes associated with altered expression by DICER KO and genes that bind to DICER.