Cell autonomous specification of temporal identity by Caenorhabditis elegans microRNA lin-4

MicroRNAs provide developing systems with substantial flexibility in posttranscriptional gene regulation. Despite advances made in understanding microRNA structure and function, the relationships between their site-of-synthesis and site-of-action ("autonomy" versus "non-autonomy") remain an open question. Given the well-defined role of microRNA lin-4 in a reproducible series of time-specific developmental switches, lin-4 is an excellent candidate for understanding whether microRNAs and the resulting heterochronic regulatory pathway have the potential to act cell autonomously. By monitoring temporal development and reporter activity in animals where lin-4 is modulated, we have demonstrated that lin-4 acts cell autonomously to specify temporal identity. This work (i) provides an example of cell autonomy in microRNA functions, and (ii) reveals a cell autonomous component of temporal regulation in C. elegans.