title: Role of TSC-22 during early embryogenesis in Xenopus laevis.
abstract: Transforming growth factor-beta1-stimulated clone 22 (TSC-22) encodes a leucine zipper-containing protein that is highly conserved. During mouse embryogenesis, TSC-22 is expressed at the site of epithelial-mesenchymal interaction. Here, we isolated Xenopus laevis TSC-22 (XTSC-22) and analyzed its function in early development. XTSC-22 mRNA was first detected in the ectoderm of late blastulae. Translational knockdown using XTSC-22 antisense morpholino oligonucleotides (XTSC-22-MO) caused a severe delay in blastopore closure in gastrulating embryos. This was not due to mesoderm induction or convergent-extension, as confirmed by whole-mount in situ hybridization and animal cap assay. Cell lineage tracing revealed that migration of ectoderm cells toward blastopore was disrupted in XTSC-22-depleted embryos, and these embryos had a marked increase in the number of dividing cells. In contrast, cell division was suppressed in XTSC-22 mRNA-injected embryos. Co-injection of XTSC-22-MO and mRNA encoding p27Xic1, which inhibits cell cycle promotion by binding cyclin/Cdk complexes, reversed aberrant cell division. This was accompanied by rescue of the delay in blastopore closure and cell migration. These results indicate that XTSC-22 is required for cell movement during gastrulation though cell cycle regulation.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Hashiguchi
authors.forename: Koji
authors.initials: K
authors.lastname: Okabayashi
authors.forename: Makoto
authors.initials: M
authors.lastname: Asashima
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis; D001923:Brain Chemistry; D002465:Cell Movement / Q000235:genetics / Q000502:physiology; D047108:Embryonic Development; D005123:Eye / Q000737:chemistry; D005775:Gastrula / Q000166:cytology / Q000502:physiology*; D015870:Gene Expression / Q000187:drug effects; D016350:Leucine Zippers; D008969:Molecular Sequence Data; D020319:Oligodeoxyribonucleotides, Antisense / Q000235:genetics / Q000494:pharmacology; D012097:Repressor Proteins / Q000235:genetics / Q000502:physiology*; D015533:Transcriptional Activation; D029867:Xenopus Proteins; D014982:Xenopus laevis / Q000196:embryology* / Q000235:genetics / Q000378:metabolism
chemical_list: D020319:Oligodeoxyribonucleotides, Antisense; D012097:Repressor Proteins; C501281:TSC22D1 protein, Xenopus; D029867:Xenopus Proteins