RNA revolution?

A protein-centric perspective has long ruled the classical model of molecular biology. In this model RNA molecules are fully described and characterized in terms of their actual contribution to protein synthesis. In the composite, yet linear, chain going from genes to proteins, in fact, RNA molecules play important intermediary roles. As such, there are three main types of ‘standard’ RNA: messenger RNAs (mRNAs), transfer RNAs (tRNAs), and ribosomal RNAs (rRNAs). As sketchy as it might be, this picture shows the epistemological frame in which the characterization of gene regulation has long been embedded. In the last decade the biological world has been taken by storm. The discovery that small RNA molecules (∼ 22 nucleotides long) can regulate gene expression, by the cleavage of their mRNA targets (short interfering RNA, siRNA) or by repressing translation (microRNA, miRNA), has been considered as a significant breakthrough calling for a serious epistemological reconsideration of gene regulation. Following the wave of excitement that usually accompanies the scientific community dealing with a new discovered mechanism, someone has not hesitated to announce an “RNA revolution”. Along the lines of this paper, we attempt to elucidate the new layer of complexity added by miRNA in life sciences. mRNAs show that RNA molecules do play a much more relevant role than the one assigned in the classical, linear model DNA→ RNA → protein. A role that is itself highly regulated, and whose mechanisms as well as possible applications in therapies scientists have been attempting to uncover in detail. In particular, we will argue that “revolution” is not the correct metaphor for describing the new role played by RNA in gene regulation. In a kuhnian sense, a scientific revolution occurs when normal science – with its fundamental dogmas, accepted ways of solving problems, and set of practices – is radically challenged by a rival program with new dogmas, problems, etc. In the kuhnian picture, different paradigms are incommensurable because they put forwards radically different conceptual frameworks, terminologies, and ways of solving puzzles. In this respect, theory-change is, at the bottom, an all or nothing affair: only one paradigm survives to the normal science stage. We will argue that this picture is not operating with respect to the so-called ‘RNA revolution’. We will show that miRNA research has not challenged at the basis previous researches, nor it has proposed a conceptual framework incommensurable with previous knowledge of gene regulation. Certainly it has offered new ways to look at things. Now introns are not merely non-coding parts of pre-mRNA, but putative sites where miRNA can be found. Still, biological work has not changed in its basics experimental practices. As opposite to it, we will argue that the patchwork view of research, as Rheinberger has put it forward, is a more apt metaphor. Specifically, we will argue that biology does not derive its coherence by an axiomatic structure. It is instead piecemeal constructed around diverse research attractors, such as experimental systems, continuously reshaping the boundaries of their research objects in a fuzzy, yet consistent, manner.