MIR-237 is Likely a Developmental Timing Gene that Regulates the L2-to-L3 Transition in C. Elegans

MIR-237 IS LIKELY A DEVELOPMENTAL TIMING GENE THAT REGULATES THE L2-TO-L3 TRANSITION IN C. ELEGANS Xi Li, B.S. Marquette University, 2010 Development is regulated in both the spatial and temporal dimensions. The developmental timing pathway in C. elegans is the most extensively studied timing mechanism. Many components of the pathway are conserved across phyla. Postembryonic development of C. elegans is comprised of four larval stages (L1 to L4). The lin-4 microRNA regulates development from the L1 to L3 stages by repressing the expression of key developmental timing genes: lin-14 and lin-28. Another microRNA, mir-237, shares sequence similarity with lin-4 and they are grouped into one microRNA family. mir-237 and lin-4 display closely overlapped temporal expression in the hypodermis. I hypothesize that mir-237 may function in the same developmental timing pathway as lin-4. I used a genetic approach to analyze the relationship between mir-237 and other important developmental timing genes that regulate development at early stages. Data from genetic analysis suggests that mir-237 likely functions downstream of lin-14 and lin-28, and in parallel with lin-46 to control L2-to-L3 transition. mir-237 expression requires lin-4 activity. In lin-4(0) mutants, mir-237 expression is reduced. I used quantitative Real-Time PCR and a transcriptional GFP reporter transgene to analyze the mechanism for the regulation of mir-237 in lin-4(0) mutants. My data suggest that this regulation of mir-237 is largely transcriptional. lin-14 likely mediates this regulation.