LOCAL-SOURCES OF RETINOIC ACID COINCIDE WITH RETINOID-MEDIATED TRANSGENE ACTIVITY DURING EMBRYONIC-DEVELOPMENT
LOCAL-SOURCES OF RETINOIC ACID COINCIDE WITH RETINOID-MEDIATED TRANSGENE ACTIVITY DURING EMBRYONIC-DEVELOPMENT
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DOI：
10.1073/pnas.90.14.6572
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发表时间：
1993-07-15
影响因子：
11.1
通讯作者：
LAMANTIA, AS
中科院分区：
文献类型：
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作者：
COLBERT, MC;LINNEY, E;LAMANTIA, AS
我们已经评估了维甲酸(RA)是来自当地还是广泛用于激活胚胎中的基因表达。我们使用了一个RA反应指示细胞系L-C2A5来定位RA来源。在这些细胞中，我们以前用来产生指示性转基因小鼠的RA敏感启动子/LacZ报告结构被RA在介质中全局或局部诱导，RA从AG-1x2树脂珠中以生理浓度(1 NM)释放。此外，细胞对低浓度的9-顺式和全反式维甲酸异构体有不同的反应。使用具有相同启动子/报告结构的指示性转基因小鼠来鉴定RA介导的基因激活区域。在胚胎指示性小鼠的颈髓和腰髓中有明显的LacZ表达区域。这种模式可能反映了RA来源的局限性或RA受体、结合蛋白或其他因素的时空表达受限。为了解决这个问题，我们比较了与正常胚胎脊髓共培养的指示细胞单层和转基因脊髓中的转基因激活模式。外植体在L-C2A5细胞中诱导了报告基因的表达，其模式与转基因小鼠相同：颈髓和腰髓的翼区呈阳性，而胸段和腰椎的区域不呈阳性。我们的结论是，在发育中的脊髓中，RA的有限来源介导了RA诱导基因的局部激活。因此，胚胎中的区域特异性基因激活可以由精确定位的诱导分子来源如RA介导。
We have assessed whether retinoic acid (RA) comes from local sources or is available widely to activate gene expression in embryos. We used an RA-responsive indicator cell line, L-C2A5, to localize RA sources. In these cells, an RA-sensitive promoter/lacZ reporter construct used previously by us to produce indicator transgenic mice is induced globally by RA in medium or locally by RA released at physiological concentrations (1 nM) from AG-1X2 resin beads. Furthermore, the cells are differentially responsive to the 9-cis and all-trans isomers of RA at low concentrations. Indicator transgenic mice with the same promoter/reporter construct were used to identify regions of RA-mediated gene activation. There are distinct domains of lacZ expression in the cervical and lumbar spinal cords of embryonic indicator mice. This pattern might reflect localized RA sources or restricted spatial and temporal expression of RA receptors, binding proteins, or other factors. To resolve this issue we compared the pattern of transgene activation in indicator cell monolayers cocultured with normal embryonic spinal cords with that in transgenic spinal cords. The explants induced reporter gene expression in L-C2A5 monolayers in a pattern identical to that in transgenic mice: alar regions of the cervical and lumbar cord were positive whereas those in the thoracic and sacral regions were not. We conclude that restricted sources of RA in the developing spinal cord mediate the local activation of RA-inducible genes. Thus, region-specific gene activation in embryos can be mediated by precisely localized sources of inductive molecules like RA.