Pax6 and SOX2 form a co-DNA-binding partner complex that regulates initiation of lens development
Pax6 and SOX2 form a co-DNA-binding partner complex that regulates initiation of lens development
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DOI：
10.1101/gad.887101
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发表时间：
2001-05-15
影响因子：
10.5
通讯作者：
Kondoh, H
中科院分区：
文献类型：
--
作者：
Kamachi, Y;Uchikawa, M;Kondoh, H
Pax 6是眼发育，特别是透镜发育中的关键转录因子，但其分子作用尚不清楚。我们证明Pax 6通过与晶状体特异性增强子元件上的SOX 2形成分子复合物来启动透镜发育，例如，δ-晶状体蛋白最小增强子DC 5。DC 5显示出与Pax 6的结合共有序列有限的相似性，并且仅与Pax 6结合不良。然而，Pax 6与SOX 2协同结合到DC 5序列，导致在体外形成高迁移率形式的三元复合物，这与体内增强子激活相关。我们观察到Pax 6和SOX 2相互依赖的因子在体内染色质环境中占据DC 5，提供了Pax 6和SOX 2协同激活的分子基础。DC 5的Pax 6结合位点序列或结合位点间距离的细微改变减少了合作结合，并导致形成非功能性低迁移率形式的复合物，这表明DNA序列引导和蛋白质相互作用诱导的Pax 6蛋白的构象变化。当Pax 6和SOX 2在胚胎外胚层异位表达时，联合激活δ-晶状体蛋白基因并诱导透镜基板发育，表明Pax 6和SOX 2在特定DNA序列上形成的复合物是启动透镜分化的遗传开关。
Pax6 is a key transcription factor in eye development, particularly in lens development, but its molecular action has not been clarified. We demonstrate that Pax6 initiates lens development by forming a molecular complex with SOX2 on the lens-specific enhancer elements, e.g., the delta -crystallin minimal enhancer DC5. DC5 shows a limited similarity to the binding consensus sequence of Pax6 and is bound poorly by Pax6 alone. However, Pax6 binds cooperatively with SOX2 to the DC5 sequence, resulting in formation of a high-mobility form of ternary complex in vitro, which correlates with the enhancer activation in vivo. We observed Pax6 and SOX2-interdependent factor occupancy of DC5 in a chromatin environment in vivo, providing the molecular basis of synergistic activation by Pax6 and SOX2. Subtle alterations of the Pax6-binding-site sequence of DC5 or of the inter-binding-sites distance diminished the cooperative binding and caused formation of a non-functional low-mobility form complex, suggesting DNA sequence-guided and protein interaction-induced conformation change of the Pax6 protein. When ectopically expressed in embryo ectoderm, Pax6 and SOX2 in combination activate delta -crystallin gene and elicit lens placode development, indicating that the complex of Pax6 and SOX2 formed on specific DNA sequences is the genetic switch for initiation of lens differentiation.