title: BMP signaling regulates the dorsal planarian midline and is needed for asymmetric regeneration.
abstract: Planarians can be cut into irregularly shaped fragments capable of regenerating new and complete organisms. Such regenerative capacities involve a robust ability to restore bilateral symmetry. We have identified three genes needed for bilaterally asymmetric fragments to regenerate missing body parts. These genes are candidate components of a signaling pathway that controls the dorsal-ventral patterning of many animal embryos: a BMP1/Tolloid-like gene (smedolloid-1), a SMAD4-like gene (smedsmad4-1), and a BMP2/4/DPP-like gene (smedbmp4-1). BMP signaling was involved in the formation of new tissues at the midline of regeneration, the dorsal-ventral patterning of new tissues, and the maintenance of the dorsal-ventral pattern of existing adult tissue in homeostasis. smedbmp4-1 was normally expressed at the dorsal midline. Asymmetric fragments lacking a midline displayed new smedbmp4-1 expression prior to formation of a regenerative outgrowth (blastema). Asymmetric fragments containing the midline displayed expanded smedbmp4-1 expression towards the wound. We suggest injured animals that lack left-right symmetry reset their midline through modulation of BMP activity as an early and necessary event in regeneration.
authors.affiliation: MIT Biology, Whitehead Institute, 9 Cambridge Center, Cambridge, MA 02138, USA.
authors.forename: Peter W
authors.initials: PW
authors.lastname: Reddien
authors.forename: Adam L
authors.initials: AL
authors.lastname: Bermange
authors.forename: Adrienne M
authors.initials: AM
authors.lastname: Kicza
authors.forename: Alejandro
authors.initials: A
authors.lastname: Sánchez Alvarado
mesh_terms: D000818:Animals; D019521:Body Patterning / Q000235:genetics; D019485:Bone Morphogenetic Proteins / Q000235:genetics / Q000502:physiology*; D004625:Embryo, Nonmammalian; D008954:Models, Biological; D010932:Planarians / Q000196:embryology* / Q000235:genetics / Q000502:physiology*; D034622:RNA Interference; D012038:Regeneration / Q000235:genetics* / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology
chemical_list: D019485:Bone Morphogenetic Proteins