Lepper Christoph, Fan Chen-Ming
Department of Embryology, Carnegie Institution, Baltimore, Maryland, USA.
Genesis. 2010 Jul;48(7):424-36. doi: 10.1002/dvg.20630.
We have generated a mouse strain carrying a Cre-ER(T2) knock-in allele at the Pax7 locus, the Pax7(CE) allele (Lepper et al., 2009, Nature 460:627-631). Combining Pax7(CE) and the R26R(LacZ) Cre reporter allele, here we describe temporal-specific tamoxifen (tmx)-inducible lineage tracing of embryonic Pax7-expressing cells. In particular, we focus on the somitic lineage. Tmx-inducible Cre activity directed by the Pax7(CE) allele is similar to the endogenous Pax7 expression pattern. The somitic Pax7-expressing cells selectively marked at embryonic day 9.5 (E9.5) give rise to dorsal dermis and brown adipose tissue, in addition to dorsal aspects of trunk muscles and the diaphragm muscle. However, they do not contribute to ventral body wall and limb muscles. After E12.5, marked Pax7-expressing cells become lineage restricted to muscles. Descendants of these early marked Pax7-expressing cells begin to occupy sublaminal positions associated with the myofibers around E16.5, characteristic of embryonic satellite cells. Furthermore, they contribute to adult myofibers and regeneration competent satellite cells in the tibialis anterior muscle, providing evidence that some adult satellite cells are of embryonic origin.
我们构建了一种小鼠品系，其在Pax7基因座携带一个Cre-ER(T2)敲入等位基因，即Pax7(CE)等位基因（Lepper等人，2009年，《自然》460:627-631）。将Pax7(CE)与R26R(LacZ) Cre报告基因等位基因相结合，在此我们描述了胚胎期表达Pax7的细胞的时间特异性他莫昔芬（tmx）诱导的谱系追踪。特别地，我们关注体节谱系。由Pax7(CE)等位基因指导的tmx诱导的Cre活性与内源性Pax7表达模式相似。在胚胎第9.5天（E9.5）选择性标记的表达Pax7的体节细胞，除了产生躯干肌肉和膈肌的背侧部分外，还产生背侧真皮和棕色脂肪组织。然而，它们对腹侧体壁和肢体肌肉没有贡献。在E12.5之后，标记的表达Pax7的细胞在谱系上局限于肌肉。这些早期标记的表达Pax7的细胞的后代在E16.5左右开始占据与肌纤维相关的板下层位置，这是胚胎卫星细胞的特征。此外，它们对成年肌纤维和胫骨前肌中具有再生能力的卫星细胞有贡献，这证明一些成年卫星细胞起源于胚胎。
