As cell biologist, when working in labs I have in the past witnessed several “X-files” in a flask of cells along my way: all cells of an established cell line are supposed to have the same genetic background and to respond similarly to the same stimuli… but sometimes this is simply not what happens!
I would not risk saying that it all comes down to epigenetics, but much of this “unexpected” behaviour is governed at mRNA level independently of the genetic background. “Cell personality” is then defined at several levels: genetic background, epigenetics, mRNA modulation and protein/lipid content.
It’s a sophisticated web of positive/negative signals that governs cell fate and behavior. But how do cells cope with this complicated issue?
They use several tools, and some of the most important ones are micro (mi)RNAs. As you are probably aware, miRNAs are short single-stranded RNA molecules, which possess the ability to hybridize to numerous mRNAs via imperfect base pairing. Unlike siRNAs, which are perfectly complementary to target mRNAs and mediate mRNA cleavage, miRNAs base pairing to target mRNAs leads to their translational repression and initiates mRNA destabilization. Moreover, whereas a single siRNA binding a target mRNA is sufficient to bring about mRNA cleavage, multiple miRNAs are often need to target a single transcript in order to ‘silence’ it.
So, what tools do we have to decipher the action of miRNA and its downstream consequences on gene expression?
Today’s arsenal of laboratory tools can allow a cell biologist to investigate the impact of any given miRNA expression on cell fate. These techniques include:
- MicroRNA detection
- MicroRNA overexpression
- MicroRNA inhibition
- MicroRNA target (mRNA) detection
- Global MiRNA profiling
Over the coming weeks, I’d like to introduce a variety of tools tailored to provide accurate information at any of these five steps.