Las Computadoras

Defining Temporal and Spatial Enhancer Elements in C. elegans mir-48/mir-241 Locus
Authors: Dianarys Hernandez-Aquino and Ann Rougvie
University: University of Minnesota, Collegeof Biological Sciences

C. elegans is a powerful model organism for the study of genetics and developmental biology. It was in this nematode that microRNAs (miRNAs) were discovered.miRNAs are small RNA molecules that work as post-transcriptional negative regulators of gene expression. mir-48 and mir-241 are co-transcribed miRNAs that play important roles in thecontrol of developmental timing in C. elegans. When these miRNAs are deleted, early epidermal fates are inappropriately repeated during later developmental stages; when they areover-expressed, late fates occur too early. mir-48/mir-241 are members of an important miRNA family that is conserved in humans. Our research focuses on identifying enhancer elementsrequired for full function and expression of the mir-48/mir-241 locus. This study was accomplished by generating transgenic nematodes expressing a series of mir-48/mir-241 promoter:gfp(green fluorescent protein) gene fusions containing different regions of the mir-48/mir-241 promoter. Transgenic strains were generated that express these gfp fusions, and theiranalysis revealed sequences required for the proper spatial expression of the mir-48/mir-241 locus. Expression was observed in several cell types including epidermal seam cells, distal tipcells, gonadal sheath cells, body wall muscle and many neurons. The seam cell expression is most relevant to the developmental timing function of mir-48/mir-241, and a seam cellenhancer was localized to a 753 bp fragment residing approximately 2.0 kb upstream of mir-241. This enhancer is located in a region known to be required for in vivo function of the locus.