小柯机器人

美国哈佛医学院丹娜-法伯癌症研究所和波士顿儿童医院Stuart H. Orkin课题组在研究中取得进展。他们发现转录因子通过竞争结合γ-球蛋白的启动子区域调控血红蛋白转换。2021年3月1日出版的《自然-遗传学》发表了这项成果。

为了揭示BCL11A如何发挥抑制功能，研究人员使用CRISPR–Cas9、dCas9、dCas9-KRAB和dCas9-VP64筛选来区分γ-球蛋白的启动子，并在BCL11A结合位点附近鉴定到新的激活因子。使用CUT＆RUN和碱基编辑，研究人员发现近端CCAAT盒被激活因子NF-Y占据。 BCL11A通过位阻与NF-Y竞争结合启动子，从而开启阻抑。在BCL11A缺失后，NF-Y在启动子区的结合增加，并先于γ-球蛋白抑制和基因座控制区（LCR）-球蛋白环形成。

该发现表明，在> 50-kb β-球蛋白基因簇内从胎儿到成人球蛋白基因表达的转换，是由阶段选择性阻遏物与γ-球蛋白启动子在离散区域内普遍存在的激活因子竞争造成的。

研究人员表示，在成年血红蛋白（HbA，α2β2）转换过程中，胎儿血红蛋白（HbF，α2γ2）的主要调控因子BCL11A通过直接与启动子结合来抑制成年红系细胞中γ-球蛋白的表达。

附：英文原文

Title: Transcription factor competition at the γ-globin promoters controls hemoglobin switching

Author: Nan Liu, Shuqian Xu, Qiuming Yao, Qian Zhu, Yan Kai, Jonathan Y. Hsu, Phraew Sakon, Luca Pinello, Guo-Cheng Yuan, Daniel E. Bauer, Stuart H. Orkin

Issue&Volume: 2021-03-01

Abstract: BCL11A, the major regulator of fetal hemoglobin (HbF, α2γ2) level, represses γ-globin expression through direct promoter binding in adult erythroid cells in a switch to adult hemoglobin (HbA, α2β2). To uncover how BCL11A initiates repression, we used CRISPR–Cas9, dCas9, dCas9-KRAB and dCas9-VP64 screens to dissect the γ-globin promoters and identified an activator element near the BCL11A-binding site. Using CUT&RUN and base editing, we demonstrate that a proximal CCAAT box is occupied by the activator NF-Y. BCL11A competes with NF-Y binding through steric hindrance to initiate repression. Occupancy of NF-Y is rapidly established following BCL11A depletion, and precedes γ-globin derepression and locus control region (LCR)–globin loop formation. Our findings reveal that the switch from fetal to adult globin gene expression within the >50-kb β-globin gene cluster is initiated by competition between a stage-selective repressor and a ubiquitous activating factor within a remarkably discrete region of the γ-globin promoters.

DOI: 10.1038/s41588-021-00798-y

Source: https://www.nature.com/articles/s41588-021-00798-y

Nature Genetics：《自然—遗传学》，创刊于1992年。隶属于施普林格·自然出版集团，最新IF：41.307
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投稿链接：https://mts-ng.nature.com/cgi-bin/main.plex