Zebrafish pou5f1/pou2, Homolog of Mammalian Oct4, Functions in the Endoderm Specification Cascade

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• 作者：Karen Lunde ; Heinz-Georg Belting ; Wolfgang Driever
• 关键词：CELLBIO ; DNA ; RNA
• 刊名：Current Biology
• 出版年：2004
• 出版时间：6 January 2004
• 年：2004
• 卷：14
• 期：1
• 页码：48-55
• 全文大小：501 K

文摘

pou5f1, also known as Oct4, is required to establish the pluripotent cell population necessary for embryogenesis in mouse [1]. Additional roles during development, including endoderm formation, have been proposed [2 and 3]. In zebrafish, the zygotic pou5f1/pou2 mutant spiel ohne grenzen (spg) [4, 5 and 6] shows neural plate patterning defects and reduced endoderm at the tailbud stage [7]. To investigate the function of maternal and early zygotic pou5f1 expression, we rescued zygotic spg_m793 mutants by injecting pou5f1 mRNA at the one-cell stage and raised them into fertile homozygous spg_m793 adults that mate to produce maternal-zygotic spg (MZspg) mutant embryos. Although neurectoderm, mesoderm, and germ cells develop in MZspg mutants, gastrulation is delayed and proceeds abnormally. Further, MZspg mutants do not maintain expression of sox32/casanova, express little or no sox17, and fail to develop endodermal tissue. Constitutively active Nodal receptor TARAM-A or sox32 overexpression induces ubiquitous sox17 expression in wild-type embryos [8, 9 and 10], but not in MZspg mutants. Overexpression of a Pou5f1-VP16 activator fusion protein can rescue gastrulation and endodermal tissues in MZspg mutants. We propose that pou5f1 plays an activating role in zebrafish endodermal development, where it maintains sox32 expression during gastrulation and acts with sox32 to induce sox17 expression in endodermal precursor cells.