MicroRNAs are small noncoding RNAs that regulate genes post- transciptionally by binding and degrading target eukaryotic mR- NAs . We use a quantitative model to study gene regulation by  microRNAs and compare it to gene regulation by prokaryotic small non-coding RNAs (sRNAs). Our model uses a combina- tion of analytic techniques as well as computational simulations to calculate the mean-expression and noise profiles of genes regu- lated by both sRNAs and microRNAs . We find that despite very different molecular machinery and modes of action (catalytic vs stoichiometric), the mean expression levels and noise profiles of microRNA-regulated genes are almost identical to genes regu- lated by prokaryotic sRNAs. MicroRNAs suppress noise when proteins are expressed at low levels but substantially increase noise at intermediate and high expression levels. This suggests that microRNAs and sRNAs may represent an example of con- vergent evolution . We extend our model to study crosstalk be- tween multiple mRNAs that are regulated by a single microRNA and show that noise is a sensitive measure of microRNA-mediated interaction between mRNAs. This suggests a new experimental strategy for uncovering the microRNA-mRNA interactions and testing the competing endogenous RNA (ceRNA) hypothesis.
MicroRNAs are small noncoding RNAs that regulate genes post-transciptionally by binding and degrading target eukaryotic mRNAs . We use a quantitative model to study gene regulation by inhibitory microRNAs and compare it to gene regulation by prokaryotic small non-coding RNAs (sRNAs). Our model uses a combination of analytic techniques as well as computational simulations to calculate the mean-expression and noise profiles of genes regulated by both microRNAs and sRNAs . We find that despite very different molecular machinery and modes of action (catalytic vs stoichiometric), the mean expression levels and noise profiles of microRNA-regulated genes are almost identical to genes regulated by prokaryotic sRNAs. This behavior is extremely robust and persists across a wide range of biologically relevant parameters . We extend our model to study crosstalk between multiple mRNAs that are regulated by a single microRNA and show that noise is a sensitive measure of microRNA-mediated interaction between mRNAs. We conclude by discussing possible experimental strategies for uncovering the microRNA-mRNA interactions and testing the competing endogenous RNA (ceRNA) hypothesis.
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post- transciptionally
post-transciptionally
R
mR- NAs
mRNAs
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inhibitory
R
combina- tion
combination
R
regu- lated by both sRNAs and microRNAs
regulated by both microRNAs and sRNAs
R
regu- lated
regulated
R
MicroRNAs suppress noise when proteins are expressed at low levels but substantially increase noise at intermediate and high expression levels. This suggests that microRNAs and sRNAs may represent an example of con- vergent evolution
This behavior is extremely robust and persists across a wide range of biologically relevant parameters
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be- tween
between
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This suggests a new experimental strategy
We conclude by discussing possible experimental strategies