Arabidopsis WUSCHEL Is a Bifunctional Transcription Factor That Acts as a Repressor in Stem Cell Regulation and as an Activator in Floral Patterning
Arabidopsis WUSCHEL Is a Bifunctional Transcription Factor That Acts as a Repressor in Stem Cell Regulation and as an Activator in Floral Patterning
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DOI：
10.1105/tpc.109.069997
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发表时间：
2009-11-01
期刊：
影响因子：
11.6
通讯作者：
Ohme-Takagi, Masaru
中科院分区：
文献类型：
--
作者：
Ikeda, Miho;Mitsuda, Nobutaka;Ohme-Takagi, Masaru
大多数转录因子作为激活子或抑制子，并没有这样的因子具有双重功能已明确确定和植物中的特点。我们在这里证明，拟南芥蛋白质WUSCHEL（WUS），它调节茎分生组织中的干细胞群体的维持，是一个双功能转录因子，主要作为一个阻遏物，但成为激活剂时，参与AGAMOUS（AG）基因的调控。我们表明，WUS框，这是保守的WOX基因之间，是域，是必不可少的所有活动的WUS，即，调节干细胞的身份和大小的花分生组织。通过突变WUS盒消除了WUS的所有已知活性，包括WUS诱导AG表达的能力。WUS盒的突变通过外源阻遏结构域的融合来补充，从而诱导根中的体细胞胚胎发生和花分生组织的扩张，如在WUS的异位表达后所观察到的。相比之下，外源激活结构域的融合并没有导致扩大花分生组织，但诱导的花类似于由AG的异位表达诱导的花。我们的研究结果表明，WUS的行为主要是作为一个阻遏物，其功能的变化，从一个阻遏物的情况下，AG的表达调控的激活剂。
Most transcription factors act either as activators or repressors, and no such factors with dual function have been unequivocally identified and characterized in plants. We demonstrate here that the Arabidopsis thaliana protein WUSCHEL (WUS), which regulates the maintenance of stem cell populations in shoot meristems, is a bifunctional transcription factor that acts mainly as a repressor but becomes an activator when involved in the regulation of the AGAMOUS (AG) gene. We show that the WUS box, which is conserved among WOX genes, is the domain that is essential for all the activities of WUS, namely, for regulation of stem cell identity and size of floral meristem. All the known activities of WUS were eliminated by mutation of the WUS box, including the ability of WUS to induce the expression of AG. The mutation of the WUS box was complemented by fusion of an exogenous repression domain, with resultant induction of somatic embryogenesis in roots and expansion of floral meristems as observed upon ectopic expression of WUS. By contrast, fusion of an exogenous activation domain did not result in expanded floral meristems but induced flowers similar to those induced by the ectopic expression of AG. Our results demonstrate that WUS acts mainly as a repressor and that its function changes from that of a repressor to that of an activator in the case of regulation of the expression of AG.