Germ cell development in the XXY mouse: Evidence that X chromosome reactivation is independent of sexual differentiation
Germ cell development in the XXY mouse: Evidence that X chromosome reactivation is independent of sexual differentiation
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DOI：
10.1006/dbio.1998.9160
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发表时间：
1999-03-01
影响因子：
2.7
通讯作者：
Hunt, PA
中科院分区：
文献类型：
--
作者：
Mroz, K;Carrel, L;Hunt, PA
在进入减数分裂之前，胎儿卵巢中的XX生殖细胞经历X染色体再激活。重新激活的信号被认为是从生殖嵴发出的，但尚不清楚它是否特异于发育中的卵巢。为了确定这些信号是否存在于发育中的睾丸和卵巢中，我们检测了XXY雄性小鼠生殖细胞中X连锁基因的表达。为了便于这项分析，我们产生了XXY和XX胎儿携带X染色体的差异标记和非随机失活。这种非随机失活的模式在体细胞中得以维持，但在XX和XXY胎儿中，两种亲本等位基因都在生殖细胞富集的细胞群中表达。由于睾丸分化是时间和形态正常的XXY睾丸，因为所有的生殖细胞走上了男性的发展途径，这些结果提供了令人信服的证据，X染色体在胎儿生殖细胞的再激活是独立的性分化的体细胞事件。适当的X染色体剂量对于雄性哺乳动物的正常生育力是必不可少的，并且在X重新激活的几天内，XXY睾丸中的生殖细胞发育异常是明显的。对出生后XXY睾丸中存活的特殊生殖细胞的研究表明，存活的生殖细胞仅为XY细胞，并且是由罕见的非分离事件引起的，这些事件引起XY细胞的克隆。(C)北京：科学出版社.
Prior to entry into meiosis, XX germ cells in the fetal ovary undergo X chromosome reactivation. The signal for reactivation is thought to emanate from the genital ridge, but it is unclear whether it is specific to the developing ovary. To determine whether the signals are present in the developing testis as well as the ovary, we examined the expression of X-linked genes in germ cells from XXY male mice. To facilitate this analysis, we generated XXY and XX fetuses carrying X chromosomes that were differentially marked and subject to nonrandom inactivation. This pattern of nonrandom inactivation was maintained in somatic cells but, in XX as well as XXY fetuses, both parental alleles were expressed in germ cell-enriched cell populations. Because testis differentiation is temporally and morphologically normal in the XXY testis and because all germ cells embark upon a male pathway of development, these results provide compelling evidence that X chromosome reactivation in fetal germ cells is independent of the somatic events of sexual differentiation. Proper X chromosome dosage is essential for the normal fertility of male mammals, and abnormalities in germ cell development are apparent in the XXY testis within several days of X reactivation. Studies of exceptional germ cells that survive in the postnatal XXY testis demonstrated that surviving germ cells are exclusively XY and result from rare nondisjunctional events that give rise to clones of XY cells. (C) 1999 Academic Press.