Abstract：
Su (var) 3-9, enhancer of seste, trithorax (SET)-domain bifurcated histone lysine methyltransferase (SETDB1) plays a crucial role in maintaining intestinal stem cell homeostasis; however, its physiological function in epithelial injury is largely unknown. In this study, we investigated the role of SETDB1 in epithelial regeneration using an intestinal ischemia/reperfusion injury (IRI) mouse model. Jejunum tissues were sampled after 75 min of ischemia followed by 3, 24, and 48 h of reperfusion. Morphological evaluations were performed using light microscopy and electron microscopy, and the involvement of SETDB1 in epithelial remodeling was investigated by immunohistochemistry. Expression of SETDB1 was increased following 24 h of reperfusion and localized in not only the crypt bottom but also in the transit amplifying zone and part of the villi. Changes in cell lineage, repression of cell adhesion molecule expression, and decreased histone H3 methylation status were detected in the crypts at the same time. Electron microscopy also revealed aberrant alignment of crypt nuclei and fusion of adjacent villi. Furthermore, increased SETDB1 expression and epithelial remodeling were confirmed with loss of stem cells, suggesting SETDB1 affects epithelial cell plasticity. In addition, crypt elongation and increased numbers of Ki-67 positive cells indicated active cell proliferation after IRI; however, the expression of PCNA was decreased compared to sham mouse jejunum. These morphological changes and the aberrant expression of proliferation markers were prevented by sinefungin, a histone methyltransferase inhibitor. In summary, SETDB1 plays a crucial role in changes in the epithelial structure after IRI-induced stem cell loss.
摘要：
Su(var)3-9，seste增强剂，三thorax(SET)-结构域分叉组蛋白赖氨酸甲基转移酶(SETDB1)在维持肠干细胞稳态中起着至关重要的作用;然而,其在上皮损伤中的生理功能尚不清楚。在这项研究中,我们使用肠缺血/再灌注损伤（IRI）小鼠模型研究了SETDB1在上皮再生中的作用。缺血75分钟，再灌注3、24和48小时后，对空肠组织进行采样。使用光学显微镜和电子显微镜进行形态学评估，并通过免疫组织化学研究了SETDB1在上皮重塑中的参与。再灌注24小时后，SETDB1的表达增加，不仅位于隐窝底部，而且位于转运扩增区和部分绒毛中。细胞谱系的变化，抑制细胞粘附分子表达，同时在隐窝中检测到组蛋白H3甲基化状态降低。电子显微镜还显示隐窝核的异常排列和相邻绒毛的融合。此外，SETDB1表达增加和上皮重塑被证实与干细胞的损失，提示SETDB1影响上皮细胞可塑性。此外,隐窝延长和Ki-67阳性细胞数量增加表明IRI后细胞增殖活跃；然而，与假小鼠空肠相比，PCNA的表达降低。这些形态学变化和增殖标志物的异常表达被sinefungin阻止，组蛋白甲基转移酶抑制剂.总之,SETDB1在IRI诱导的干细胞丢失后的上皮结构变化中起关键作用。
