title: Ouro proteins are not essential to tail regression during Xenopus tropicalis metamorphosis.
abstract: Tail regression is one of the most prominent transformations observed during anuran metamorphosis. A tadpole tail that is twice as long as the tadpole trunk nearly disappears within 3 days in Xenopus tropicalis. Several years ago, it was proposed that this phenomenon is driven by an immunological rejection of larval-skin-specific antigens, Ouro proteins. We generated ouro-knockout tadpoles using the TALEN method to reexamine this immunological rejection model. Both the ouro1- and ouro2-knockout tadpoles expressed a very low level of mRNA transcribed from a targeted ouro gene, an undetectable level of Ouro protein encoded by a target gene and a scarcely detectable level of the other Ouro protein from the untargeted ouro gene in tail skin. Furthermore, congenital athymic frogs were produced by Foxn1 gene modification. Flow cytometry analysis showed that mutant frogs lacked splenic CD8(+) T cells, which play a major role in cytotoxic reaction. Furthermore, T-cell-dependent skin allograft rejection was dramatically impaired in mutant frogs. None of the knockout tadpoles showed any significant delay in the process of tail shortening during the climax of metamorphosis, which shows that Ouro proteins are not essential to tail regression at least in Xenopus tropicalis and argues against the immunological rejection model.
authors: Division of Embryology and Genetics, Institute for Amphibian Biology, Graduate School of Science, Hiroshima University, Higashihiroshima, 739-8526, Japan.
authors: Yuya
authors: Y
authors: Nakai
authors: Division of Embryology and Genetics, Institute for Amphibian Biology, Graduate School of Science, Hiroshima University, Higashihiroshima, 739-8526, Japan.
authors: Keisuke
authors: K
authors: Nakajima
authors: Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, 14642, NY, USA.
authors: Jacques
authors: J
authors: Robert
authors: Division of Embryology and Genetics, Institute for Amphibian Biology, Graduate School of Science, Hiroshima University, Higashihiroshima, 739-8526, Japan.
authors: Yoshio
authors: Y
authors: Yaoita
mesh_terms: D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000378:metabolism; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D007633:Keratins / Q000235:genetics / Q000378:metabolism*; D008675:Metamorphosis, Biological / Q000235:genetics*; D013950:Thymus Gland / Q000166:cytology / Q000378:metabolism; D014981:Xenopus; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D051858:Forkhead Transcription Factors; C544963:Ouro1 protein, Xenopus; C544964:Ouro2 protein, Xenopus; C090140:Whn protein; D029867:Xenopus Proteins; D007633:Keratins