title: Regeneration and maintenance of the planarian midline is regulated by a slit orthologue.
abstract: Several families of evolutionarily conserved axon guidance cues orchestrate the precise wiring of the nervous system during embryonic development. The remarkable plasticity of freshwater planarians provides the opportunity to study these molecules in the context of neural regeneration and maintenance. Here we characterize a homologue of the Slit family of guidance cues from the planarian Schmidtea mediterranea. Smed-slit is expressed along the planarian midline, in both dorsal and ventral domains. RNA interference (RNAi) targeting Smed-slit results in the collapse of many newly regenerated tissues at the midline; these include the cephalic ganglia, ventral nerve cords, photoreceptors, and the posterior digestive system. Surprisingly, Smed-slit RNAi knockdown animals also develop morphologically distinguishable, ectopic neural structures near the midline in uninjured regions of intact and regenerating planarians. These results suggest that Smed-slit acts not only as a repulsive cue required for proper midline formation during regeneration but that it may also act to regulate the behavior of neural precursors at the midline in intact planarians.
authors.affiliation: Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, B107 Chemical and Life Sciences Laboratory, 601 South Goodwin Avenue, Urbana, IL 61801, USA.
authors.forename: Francesc
authors.initials: F
authors.lastname: Cebrià
authors.forename: Tingxia
authors.initials: T
authors.lastname: Guo
authors.forename: Jessica
authors.initials: J
authors.lastname: Jopek
authors.forename: Phillip A
authors.initials: PA
authors.lastname: Newmark
mesh_terms: D000818:Animals; D019521:Body Patterning / Q000235:genetics; D002490:Central Nervous System / Q000254:growth & development / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D015801:Helminth Proteins / Q000235:genetics / Q000502:physiology; D017403:In Situ Hybridization; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000502:physiology; D010932:Planarians / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012038:Regeneration / Q000235:genetics / Q000502:physiology*
chemical_list: D015801:Helminth Proteins; D036341:Intercellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger