Emerging paradigms of regulated microRNA processing

MicroRNAs (miRNAs) modulate a broad range of gene expression patterns during development and tissue homeostasis, and in the pathogenesis of disease. The exquisite spatio-temporal control of miRNA abundance is made possible, in part, by regulation of the miRNA biogenesis pathway. In this review, we discuss two emerging paradigms for post-transcriptional control of miRNA expression. One paradigm centers on the Microprocessor, the protein complex essential for maturation of canonical miRNAs. The second paradigm is specific to miRNA families, and requires interaction between RNA-binding proteins and cis-regulatory sequences within miRNA precursor loops.