IEO European Institute of Oncology IRCCS, Department of Experimental Oncology, Via Adamello 16, 20139 Milan, Italy.
University of Milan, Department of Health Sciences, Via A. di Rudinì, 8, 20142 Milan, Italy.
Nucleic Acids Res. 2021 Jan 25;49(2):791-804. doi: 10.1093/nar/gkaa1228.
The proteolytic cleavage of histone tails, also termed histone clipping, has been described as a mechanism for permanent removal of post-translational modifications (PTMs) from histone proteins. Such activity has been ascribed to ensure regulatory function in key cellular processes such as differentiation, senescence and transcriptional control, for which different histone-specific proteases have been described. However, all these studies were exclusively performed using cell lines cultured in vitro and no clear evidence that histone clipping is regulated in vivo has been reported. Here we show that histone H3 N-terminal tails undergo extensive cleavage in the differentiated cells of the villi in mouse intestinal epithelium. Combining biochemical methods, 3D organoid cultures and in vivo approaches, we demonstrate that intestinal H3 clipping is the result of multiple proteolytic activities. We identified Trypsins and Cathepsin L as specific H3 tail proteases active in small intestinal differentiated cells and showed that their proteolytic activity is differentially affected by the PTM pattern of histone H3 tails. Together, our findings provide in vivo evidence of H3 tail proteolysis in mammalian tissues, directly linking H3 clipping to cell differentiation.
组蛋白尾部的蛋白水解裂解，也称为组蛋白剪接，被描述为从组蛋白蛋白中永久去除翻译后修饰（PTMs）的一种机制。这种活性被认为可以确保分化、衰老和转录控制等关键细胞过程中的调节功能，为此已经描述了不同的组蛋白特异性蛋白酶。然而，所有这些研究都仅在体外培养的细胞系中进行，尚未有明确的证据表明组蛋白剪接在体内受到调节。在这里，我们显示组蛋白 H3 N 端尾部在小鼠肠道上皮的绒毛分化细胞中经历广泛的切割。通过结合生化方法、3D 类器官培养和体内方法，我们证明了肠道 H3 剪接是多种蛋白水解活性的结果。我们鉴定了胰蛋白酶和组织蛋白酶 L 作为在小肠分化细胞中活跃的特定 H3 尾部蛋白酶，并表明它们的蛋白水解活性受到组蛋白 H3 尾部 PTM 模式的差异影响。总之，我们的研究结果提供了哺乳动物组织中 H3 尾部蛋白水解的体内证据，直接将 H3 剪接与细胞分化联系起来。
