MicroRNA Biogenesis and Function: An overview

In: Regulation of microRNAs Ed: H Grosshans Landes Bioscience and Springer.

Semiconserved regulation of mesendoderm differentiation by microRNAs.

MicroRNAs are known to play important roles in many different processes. However, their roles in shaping the early steps in embryogenesis have remained largely hidden. In this issue of Developmental Cell, Rosa et al. show that the miR-430/427/302 family of microRNAs has a distinct effect on Nodal signaling, affecting mesendoderm differentiation in Xenopus embryos and human embryonic cell lines.

Semiconserved regulation of mesendoderm differentiation by microRNAs.

MicroRNAs are known to play important roles in many different processes. However, their roles in shaping the early steps in embryogenesis have remained largely hidden. In this issue of Developmental Cell, Rosa et al. show that the miR-430/427/302 family of microRNAs has a distinct effect on Nodal signaling, affecting mesendoderm differentiation in Xenopus embryos and human embryonic cell lines

PIWI-interacting RNAs: from generation to transgenerational epigenetics

Small-RNA-guided gene regulation is a recurring theme in biology. Animal germ cells are characterized by an intriguing small-RNA-mediated gene-silencing mechanism known as the PIWI pathway. For a long time, both the biogenesis of PIWI-interacting RNAs (piRNAs) as well as their mode of gene silencing has remained elusive. A recent body of work is shedding more light on both aspects and implicates PIWI in the establishment of transgenerational epigenetic states. In fact, the epigenetic states imposed by PIWI on targets may actually drive piRNA production itself. These findings start to couple small RNA biogenesis with small-RNA-mediated epigenetics

Dcr1 tracked down

RNAi is essential for pericentromeric heterochromatic formation in S. pombe, and although Dcr1, the initiator protein of this process, has been biochemically well described, its subcellular localization has remained elusive. In this issue of Developmental Cell, Emmerth et al. now show that Dcr1 is dynamically shuttling between nucleus and cytoplasm, adding new insight into the subcellular mechanics of RNAi.

The role of small non-coding RNAs in genome stability and chromatin organization

Small non-coding RNAs make up much of the RNA content of a cell and have the potential to regulate gene expression on many different levels. Initial discoveries in the 1990s and early 21st century focused on determining mechanisms of post-transcriptional regulation mediated by small-interfering RNAs (siRNAs) and microRNAs (miRNAs). More recent research, however, has identified new classes of RNAs and new regulatory mechanisms, expanding the known regulatory potential of small non-coding RNAs to encompass chromatin regulation. In this Commentary, we provide an overview of these chromatin-related mechanisms and speculate on the extent to which they are conserved among eukaryotes.