A novel gene, BENI is required for the convergent extension during Xenopus laevis gastrulation.
Activin-like signaling plays an important role in early embryogenesis. Activin A, a TGF-beta family protein, induces mesodermal/endodermal tissues in animal cap assays. In a screen for genes expressed early after treatment with activin A, we isolated a novel gene, denoted as BENI (Brachyury Expression Nuclear Inhibitor). The BENI protein has a conserved domain at the N-terminus that contains a nuclear localization signal (NLS), and two other NLSs in the C-terminal domain. BENI mRNA was localized to the animal hemisphere at the gastrula stages and to ectoderm except for neural regions at stage 17; expression persisted until the tadpole stage. The overexpression of BENI caused gastrulation defects and inhibition of elongation of activin-treated animal caps with reduction of Xbra expression. Moreover, whole-mount in situ hybridization revealed reduced expression of Xbra in BENI mRNA-injected regions of gastrula embryos. Functional knockdown of BENI using an antisense morpholino oligonucleotide also resulted in an abnormal phenotype of embryos curling to the dorsal side, and excessive elongation of activin-treated animal caps without altered expression of mesodermal markers. These results suggested that BENI expression is regulated by activin-like signaling, and that this regulation is crucial for Xbra expression.
Homma
Motohiro
M
Department of Life Sciences (Biology), Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan.
Inui
Masafumi
M
Fukui
Akimasa
A
Michiue
Tatsuo
T
Okabayashi
Koji
K
Asashima
Makoto
M
D028341:Activins / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019521:Body Patterning / Q000235:genetics / Q000502:physiology*; D002467:Cell Nucleus / Q000378:metabolism; D017931:DNA Primers; D005697:Galactosides; D005775:Gastrula / Q000502:physiology*; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D005822:Genetic Vectors; D017403:In Situ Hybridization; D007211:Indoles; D008969:Molecular Sequence Data; D009841:Oligonucleotides; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D020825:T-Box Domain Proteins / Q000235:genetics / Q000378:metabolism*; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis / Q000196:embryology* / Q000235:genetics*
D017931:DNA Primers; D005697:Galactosides; D007211:Indoles; D009841:Oligonucleotides; D020825:T-Box Domain Proteins; C116765:TBXT protein, Xenopus; D029867:Xenopus Proteins; C518634:ZNF750 protein, Xenopus; D028341:Activins; C044888:5-bromo-4-chloro-3-indolyl beta-galactoside