Decoding genetic circuits for developmental timing and stem cell fate

Real-time live-imaging and analysis of pulsatile microRNA transcription in the C. elegans hypodermis

Visualizing transcription in real time, using the MS2 tethering system in the C. elegans larva. (A) Schematics of the MS2 labeling system. The incorporation of an array of RNA stem loops from the phage MS2 into the 5' end of gene expressed in the presence of a fusion of the stem loop binding protein (MCP) with GFP allows for the direct visualization and quantification of nascent RNAs as…

The four larval stages of C. elegans are characterized by stage-specific patterns of cell division, cell differentiation, and cuticle formation that occur during intermolt periods. Classical forward genetic approaches have identified several highly conserved temporal selector genes that combinatorially program stage-specific patterns of cell fate specification during post-embryonic development. Transitions through successive stage-specific developmental cell fate programs are mediated by the accumulation of several microRNAs (miRNAs) that post-transcriptionally regulate the expression of their temporal selector gene targets.

Our team is interested in the mechanisms that determine miRNA transcriptional dosage and the strategy by which stem cells in the C. elegans hypodermis acquire their temporal identities based on the temporal gradients of miRNA target genes.