LST-1 is a bifunctional regulator that feeds back on Notch-dependent transcription to regulate C. elegans germline stem cells.
LST-1 is a bifunctional regulator that feeds back on Notch-dependent transcription to regulate C. elegans germline stem cells.
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DOI：
10.1073/pnas.2309964120
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发表时间：
2023-09-26
影响因子：
11.1
通讯作者：
Kimble, Judith
中科院分区：
文献类型：
--
作者：
Ferdous, Ahlan S.;Lynch, Tina R.;Dos Santos, Stephany J. Costa;Kapadia, Deep H.;Crittenden, Sarah L.;Kimble, Judith
Notch信号控制着动物胚胎发育中的干细胞，当不受调节时可能导致肿瘤。线虫Notch激活两种有效的干细胞调节因子LST-1和SYGL-1的转录。以前的工作建立了LST-1和SYGL-1作为转录后调节因子，在过表达时对自我更新和致癌至关重要。在这里，我们报告说，LST-1也反馈Notch依赖的转录，以限制自我更新。LST-1使用C-末端锌指来削弱Notch强度并降低lst-1和sygl-1表达，而它使用N-末端PUF相互作用基序来抑制RNA。LST-1作为一种双功能调节剂出现，与苍蝇和哺乳动物调节剂具有有趣的相似之处。从蠕虫到人类的保守主题是PUF介导的RNA抑制与同一蛋白质中的Notch反馈的偶联。Notch信号在动物胚胎发育中调节干细胞。C.线虫Notch信号激活两个基因lst-1和sygl-1的转录，这两个基因编码生殖系干细胞的有效调节因子。LST-1蛋白以两种不同的方式调节干细胞：它在转录后促进自我更新，并通过一种知之甚少的机制限制自我更新。其自我更新促进活性存在于其N-末端区域，而其自我更新限制活性存在于其C-末端区域并且需要Zn指。在这里，我们报告LST-1通过下调Notch依赖性转录来限制自我更新。我们在细胞核中检测到LST-1，除了其先前已知的细胞质定位。LST-1降低lst-1和sygl-1基因座的新生转录水平，但不降低Notch非依赖性基因座let-858的水平。LST-1还降低了Notch激活复合物的两个关键组分LAG-1 DNA结合蛋白和Notch胞内结构域（NICD）的水平。在遗传学上，LST-1锌指突变体增加了功能获得性和功能丧失性GLP-1/Notch受体突变体中的Notch信号强度。在生物化学上，LST-1与来自线虫提取物的LAG-1共免疫沉淀，表明直接作用。因此，LST-1是一种双功能调节因子，在单个蛋白质中协调转录后和转录机制。这种LST-1双功能性依赖于其二分蛋白质结构，并通过产生两种LST-1同种型（一种专门用于Notch下调）来支持。从蠕虫到人类的保守主题是PUF介导的RNA抑制与同一蛋白质中的Notch反馈的偶联。
Notch signaling controls stem cells across animal phylogeny and when unregulated can cause tumors. Nematode Notch activates transcription of two potent stem cell regulators, LST-1 and SYGL-1. Previous work established LST-1 and SYGL-1 as posttranscriptional regulators essential for self-renewal and oncogenic when overexpressed. Here, we report that LST-1 also feeds back on Notch-dependent transcription to limit self-renewal. LST-1 uses a C-terminal Zinc finger to weaken Notch strength and lower lst-1 and sygl-1 expression, whereas it uses N-terminal PUF-interacting motifs to repress RNAs. LST-1 emerges as a bifunctional regulator with intriguing parallels to fly and mammalian regulators. A conserved theme from worms to human is the coupling of PUF-mediated RNA repression together with Notch feedback in the same protein. Notch signaling regulates stem cells across animal phylogeny. C. elegans Notch signaling activates transcription of two genes, lst-1 and sygl-1, that encode potent regulators of germline stem cells. The LST-1 protein regulates stem cells in two distinct ways: It promotes self-renewal posttranscriptionally and also restricts self-renewal by a poorly understood mechanism. Its self-renewal promoting activity resides in its N-terminal region, while its self-renewal restricting activity resides in its C-terminal region and requires the Zn finger. Here, we report that LST-1 limits self-renewal by down-regulating Notch-dependent transcription. We detect LST-1 in the nucleus, in addition to its previously known cytoplasmic localization. LST-1 lowers nascent transcript levels at both lst-1 and sygl-1 loci but not at let-858, a Notch-independent locus. LST-1 also lowers levels of two key components of the Notch activation complex, the LAG-1 DNA binding protein and Notch intracellular domain (NICD). Genetically, an LST-1 Zn finger mutant increases Notch signaling strength in both gain- and loss-of-function GLP-1/Notch receptor mutants. Biochemically, LST-1 co-immunoprecipitates with LAG-1 from nematode extracts, suggesting a direct effect. LST-1 is thus a bifunctional regulator that coordinates posttranscriptional and transcriptional mechanisms in a single protein. This LST-1 bifunctionality relies on its bipartite protein architecture and is bolstered by generation of two LST-1 isoforms, one specialized for Notch downregulation. A conserved theme from worms to human is the coupling of PUF-mediated RNA repression together with Notch feedback in the same protein.
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