Mesodermally expressed Drosophila microRNA-1 is regulated by Twist and is required in muscles during larval growth.
Although hundreds of evolutionarily conserved microRNAs have been discovered, the functions of most remain unknown. Here, we describe the embryonic spatiotemporal expression profile, transcriptional regulation, and loss-of-function phenotype of Drosophila miR-1 (DmiR-1). DmiR-1 RNA is highly expressed throughout the mesoderm of early embryos and subsequently in somatic, visceral, and pharyngeal muscles, and the dorsal vessel. The expression of DmiR-1 is controlled by the Twist and Mef2 transcription factors. DmiR-1KO mutants, generated using ends-in gene targeting, die as small, immobilized second instar larvae with severely deformed musculature. This lethality is rescued when a DmiR-1 transgene is expressed specifically in the mesoderm and muscle. Strikingly, feeding triggers DmiR-1KO-associated paralysis and death; starved first instar DmiR-1KO larvae are essentially normal. Thus, DmiR-1 is not required for the formation or physiological function of the larval musculature, but is required for the dramatic post-mitotic growth of larval muscle.
Sokol
Nicholas S
NS
Department of Genetics, Dartmouth Medical School, Hanover, New Hampshire 03755, USA. nicholas.sokol@dartmouth.edu
Ambros
Victor
V
D000818:Animals; D004330:Drosophila; D029721:Drosophila Proteins / Q000378:metabolism*; D017353:Gene Deletion; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D007814:Larva / Q000254:growth & development; D008648:Mesoderm / Q000378:metabolism*; D035683:MicroRNAs / Q000096:biosynthesis* / Q000235:genetics; D008938:Mitosis / Q000502:physiology; D024510:Muscle Development / Q000502:physiology*; D009132:Muscles / Q000196:embryology; D018006:Myogenic Regulatory Factors / Q000378:metabolism; D014158:Transcription, Genetic / Q000502:physiology
D029721:Drosophila Proteins; C499409:Mef2 protein, Drosophila; D035683:MicroRNAs; D018006:Myogenic Regulatory Factors