NEUROECTODERMAL AUTONOMY OF HOX-2.9 EXPRESSION REVEALED BY RHOMBOMERE TRANSPOSITIONS
NEUROECTODERMAL AUTONOMY OF HOX-2.9 EXPRESSION REVEALED BY RHOMBOMERE TRANSPOSITIONS
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DOI：
10.1038/356157a0
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发表时间：
1992-03-12
期刊：
影响因子：
64.8
通讯作者：
LUMSDEN, A
中科院分区：
文献类型：
--
作者：
GUTHRIE, S;MUCHAMORE, I;LUMSDEN, A
Hox基因与果蝇的同源选择基因序列相似，基因组组织与表达位点之间保持共线关系，以及突变分析1-5表明Hox基因参与脊椎动物体轴的区域规范。脊椎动物胚胎后脑神经上皮向谱系室6（菱形室7,8）的细分是神经元分化的节段模式的基础9。菱形球边界划定了Hox基因10-12的表达域，被认为是菱形球表型的决定因素，这表明Hox基因赋予位置价值13；在菱形体4 （r4）形成之后，在其范围内强烈表达Hox-2.9。如果Hox基因是决定因素，它们的表达应该是自主的，从区域承诺成为固定和不可逆转的发育阶段。我们将未来的r4区域（来自状态-9的鸡胚胎）移植到r2的更前位置，并探索了Hox-2.9转录本。我们在这里报道了Hox-2.9在异位r4中的表达与在正常r4中的表达一样强烈，而未来r2到r4位置的反向移植物不表达Hox-2.9。异位菱形球的表型根据其原始位置发展，如脑神经传出核的逆行示踪所证明。早在9 -期（6个体），Hox-2.9的表达和片段识别在鸡胚后脑中是独立的，不依赖于神经上皮的位置和来自下层中胚层的信号。
INVOLVEMENT of the Hox genes in regional specifications of the vertebrate body axis is suggested by sequence similarity with the homeotic selector genes of Drosophila, the conservation of a collinear relationship between genomic organization and site of expression, and mutational analysis 1-5. Subdivision of vertebrate embryo hindbrain neuroepithelium into lineage compartments 6 (rhombomeres 7,8) underlies segmental patterning of neuronal differentiation 9. The rhombomere boundaries delimit domains of expression of Hox genes 10-12, presumed to be determinants of rhombomere phenotype, suggesting that Hox genes confer positional value 13; the formation of rhombomere 4 (r4) is followed by strong expression of Hox-2.9 within its confines 14. If the Hox genes are determinants, their expression should be autonomous from the developmental stage at which regional commitment becomes fixed and irreversible. We have transplanted the future r4 region (from state-9-chick embryos) into the more anterior position of r2 and probed for Hox-2.9 transcripts. We report here that Hox-2.9 was expressed in the ectopic r4 as strongly as in the normal r4, whereas reciprocal grafts of future r2 to r4 position did not express Hox-2.9. The phenotype of ectopic rhombomeres developed according to their original position, as demonstrated by retrograde tracing of efferent cranial nerve nuclei. As early as stage-9 - (six somites), both Hox-2.9 expression and segment identity are autonomous in the chick embryo hindbrain, independent both of position in the neuroepithelium and of signals from the underlying mesoderm 15.