SMAD1 signaling is critical for initial commitment of germ cell lineage from mouse epiblast
SMAD1 signaling is critical for initial commitment of germ cell lineage from mouse epiblast
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DOI：
10.1016/s0925-4773(02)00237-x
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发表时间：
2002-10-01
影响因子：
2.6
通讯作者：
Kitamura, D
中科院分区：
文献类型：
--
作者：
Hayashi, K;Kobayashi, T;Kitamura, D
胚胎发生过程中生殖细胞谱系的定型依赖于哺乳动物合子基因的表达，但对生殖细胞形成所需的信号分子知之甚少。在这里，我们表明，细胞内信号分子SMAD 1，作用于骨形态发生蛋白（BMP）受体的下游，是必需的生殖细胞谱系的承诺，从早期小鼠胚胎的外胚层。将lacZ基因插入到Smad 1基因的外显子中，获得Smad 1纯合突变胚（Smad 1-/-）。大多数Smad 1-/-胚胎不含原始生殖细胞（PGCs），并有短的尿囊，而组织学分析和原位杂交的中胚层标记基因显示，早期中胚层诱导是正常的，在这些胚胎。Smad 1的表达观察到在上胚层和内脏内胚层在原肠胚形成，而只有少数碱性磷酸酶阳性的PGCs在7.5和8.5天后coblasts（E7.5和E8.5）表达Smad 1。磷酸化SMAD蛋白定位于E6.0-6.5的上胚层近端区域，其中PGCs和尿囊的祖细胞驻留。单细胞逆转录-聚合酶链反应分析显示Smad 1、Smad 5和Smad 8在近端上胚层细胞中呈散在表达，且相互独立。我们还发现，BMP 4诱导的PGCs体外分化的上胚层是完全依赖于磷酸化SMAD 1的存在。这些结果表明SMAD 1信号在生殖细胞谱系的初始定型中具有关键和非冗余的功能。(C)2002爱思唯尔科学爱尔兰有限公司保留所有权利。
Commitment of the germ cell lineage during embryogenesis depends on zygotic gene expression in mammals, but little is known about the signaling molecules required for germ cell formation. Here we show that the intracellular signaling molecule SMAD1, acting downstream of bone morphogenetic protein (BMP) receptors, is required for the commitment of germ cell lineage from epiblast in early mouse embryos. Smad1 homozygous mutant embryos (Smad1 -/-) were generated by in-frame insertion of lacZ gene into an exon of the Smad1 gene. Most of the Smad1 -/- embryos contained no primordial germ cells (PGCs) and had short allantois, while histological analysis and in situ hybridization for the mesoderm marker genes revealed that early mesoderm induction was normal in those embryos. Smad1 expression was observed in epiblast and in visceral endoderm during gastrulation, while only a few alkaline phosphatase-positive PGCs at 7.5 and 8.5 days post coitum (E7.5 and E8.5) expressed Smad1. Phosphorylated SMAD proteins were localized in the proximal region of epiblast at E6.0-6.5, where the progenitors of PGCs and of allantois reside. Single-cell reverse transcription-polymerase chain reaction analysis revealed that the expression of Smad1, -5 and -8 were sporadic and mutually independent in proximal epiblast cells. We also found that BMP4-induced differentiation of PGCs from epiblast in vitro was fully dependent on the existence of phosphorylated SMAD1. These results indicate that SMAD1 signaling possesses a critical and non-redundant function in the initial commitment of the germ cell lineage. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.