Institute of Biology, Genetics Department 190g, University of Hohenheim, Garbenstr. 30, D-70599 Stuttgart, Germany.
Biozentrum, University of Basel, Spitalstrasse 41, CH-4056 Basel, Switzerland.
Genes (Basel). 2023 Jan 13;14(1):205. doi: 10.3390/genes14010205.
Cellular differentiation relies on the highly conserved Notch signaling pathway. Notch activity induces gene expression changes that are highly sensitive to chromatin landscape. We address Notch gene regulation using as a model, focusing on the genetic and molecular interactions between the Notch antagonist Hairless and the histone chaperone Asf1. Earlier work implied that Asf1 promotes the silencing of Notch target genes via Hairless (H). Here, we generate a novel allele by genome engineering. Phenotypically, behaves as a Hairless gain of function allele in several developmental contexts, indicating that the conserved CT domain of H has an attenuator role under native biological contexts. Using several independent methods to assay protein-protein interactions, we define the sequences of the CT domain that are involved in Hairless-Asf1 binding. Based on previous models, where Asf1 promotes Notch repression via Hairless, a loss of Asf1 binding should reduce Hairless repressive activity. However, tissue-specific Asf1 overexpression phenotypes are increased, not rescued, in the background. Counterintuitively, Hairless protein binding mitigates the repressive activity of Asf1 in the context of eye development. These findings highlight the complex connections of Notch repressors and chromatin modulators during Notch target-gene regulation and open the avenue for further investigations.
细胞分化依赖于高度保守的 Notch 信号通路。Notch 活性诱导的基因表达变化对染色质景观高度敏感。我们使用 作为模型来解决 Notch 基因调控问题，重点研究 Notch 拮抗剂 Hairless 和组蛋白伴侣 Asf1 之间的遗传和分子相互作用。早期的工作表明，Asf1 通过 Hairless (H) 促进 Notch 靶基因的沉默。在这里，我们通过基因组工程生成了一个新的 等位基因。表型上，在几种发育背景下， 表现为 Hairless 功能获得性等位基因，表明 H 的保守 CT 结构域在天然生物背景下具有衰减子作用。使用几种独立的方法来检测蛋白-蛋白相互作用，我们定义了参与 Hairless-Asf1 结合的 CT 结构域的序列。基于之前的模型，其中 Asf1 通过 Hairless 促进 Notch 抑制，Asf1 结合的缺失应该降低 Hairless 的抑制活性。然而，在 背景下，组织特异性的 Asf1 过表达表型增加，而不是被挽救。与预期相反，在眼睛发育的情况下，Hairless 蛋白结合减轻了 Asf1 的抑制活性。这些发现强调了 Notch 抑制剂和染色质调节剂在 Notch 靶基因调控过程中的复杂联系，并为进一步的研究开辟了途径。
