A couple of weeks ago I spent a few days at the 71st Cold Spring Harbor symposium, this one on regulatory RNAs. I don’t have to tell this audience that the emergence in the last few years of a remarkable diversity of functions for small RNAs is one of the most exciting developments in contemporary genetics and molecular biology. If anything, the results presented at the symposium will only serve to heighten enthusiasm for the importance of this incredibly flexible molecule. In regard to microRNAs, David Bartel probably said it best when he noted:

When considering the widespread conserved targeting and targeting avoidance, together with species-specific targeting, it is hard to escape the conclusion that microRNAs are influencing the expression and/or evolution of most mammalian protein-coding genes.

A few other thoughts from the meeting:

The first task is obviously to identify the small RNAome (forgive me), and in that regard it’s clear that several groups are proceeding with deep 454-based sequencing in order to do this.

You can tell that an area of research is beginning to mature when good old-fashioned genetics is consistently being applied to it, and that’s the case with many aspects of the small RNA world. Large-scale genetic screens are being carried out to identify all of the RNA and protein components that regulate several features of small RNA metabolism.

A debate is emerging as to whether microRNAs largely act by fine-tuning gene expression, or whether they may have central roles in cellular differentiation events. Early data suggest some of both, but it’s too early to say whether one role will dominate.

The bulk of the ENCODE data will soon see the light of day in formal publications, and a preview given by Tom Gingeras was rather remarkable. There may be as many as 450,000 small RNAs transcribed in the human genome, and the overall complexity of the genome is much deeper than had been anticipated. It’s also clear that the exact number of protein-coding genes is irrelevant as a metric for complexity. Alternative splicing, overlapping sense-antisense transcripts, small RNAs, and exon-exon fusions mean that the genome’s functional output is truly staggering.

You can listen to interviews with leading scientists working on small RNAs here.

I also must mention our new supplement on microRNAs, which is freely available, and contains perspectives and reviews on miRNAs covering discovery, target prediction, miRNA function, their roles in development, viral miRNAs, and roles in plants. It’s all freely available. Enjoy.