title: An epidermal signal regulates Lmx-1 expression and dorsal-ventral pattern during Xenopus limb regeneration.
abstract: The results of recent studies have supported the idea that the ability to organize the formation of axes such as the anteroposterior and proximodistal axes corresponds to limb regeneration ability in Xenopus. In this study, we investigated the mechanism by which the dorsoventral (D-V) axis of regenerating Xenopus limbs is established and the relationships between D-V patterning and regenerative ability. Transplantation experiments were performed to study which epidermis or mesenchyme is responsible for the D-V patterning in regenerating limbs. Naked mesenchyme of a donor limb was rotated and implanted on a host opposite-side limb stump to make a reversed recombination about the D-V axis. The resultant regenerates had a normal-looking D-V pattern, including Lmx-1 expression, muscle pattern, and joints, in stage 52 recombinants and a reversed D-V pattern in stage 55 recombinants. Further experiments in recombination at stage 52 and stage 55 showed that the epidermal signal is responsible for producing the D-V pattern in the regenerating blastema. These results, together with the finding that Lmx-1 expression is absent in the froglet forelimb blastema, suggest that D-V axis formation is a key step in understanding the loss of regenerative ability.
authors.affiliation: Biological Institute, Graduate School of Science, Tohoku University, Aoba-yama Aoba-ku, Sendai, 980-8578, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Matsuda
authors.forename: H
authors.initials: H
authors.lastname: Yokoyama
authors.forename: T
authors.initials: T
authors.lastname: Endo
authors.forename: K
authors.initials: K
authors.lastname: Tamura
authors.forename: H
authors.initials: H
authors.lastname: Ide
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019521:Body Patterning / Q000502:physiology*; D002645:Chickens; D006224:Cricetinae; D000078404:Epidermal Cells; D004817:Epidermis / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D006801:Humans; D060850:LIM-Homeodomain Proteins; D018878:Limb Buds / Q000502:physiology*; D008648:Mesoderm / Q000166:cytology / Q000502:physiology*; D051379:Mice; D008969:Molecular Sequence Data; D010802:Phylogeny; D012038:Regeneration / Q000235:genetics*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors; D014184:Transplantation, Homologous; D029867:Xenopus Proteins; D014982:Xenopus laevis / Q000196:embryology / Q000502:physiology*
chemical_list: D018398:Homeodomain Proteins; D060850:LIM-Homeodomain Proteins; C489695:LMX1A protein, Xenopus; C078021:LMX1A protein, human; C489692:Lmx1a protein, mouse; D014157:Transcription Factors; D029867:Xenopus Proteins