The leukemia-associated Mllt10/Af10-Dot1l are Tcf4/β-catenin coactivators essential for intestinal homeostasis.
The leukemia-associated Mllt10/Af10-Dot1l are Tcf4/β-catenin coactivators essential for intestinal homeostasis.
复制标题
DOI：
10.1371/journal.pbio.1000539
复制
发表时间：
2010-11-16
期刊：
影响因子：
9.8
通讯作者：
Clevers H
中科院分区：
文献类型：
--
作者：
Mahmoudi T;Boj SF;Hatzis P;Li VS;Taouatas N;Vries RG;Teunissen H;Begthel H;Korving J;Mohammed S;Heck AJ;Clevers H
白血病相关的Mllt10/Af10及其伴侣组蛋白甲基转移酶Dot1l被鉴定为Tcf4/β-连环蛋白共激活因子，并被证明对wnt驱动的内源性基因表达、肠道发育和体内平衡至关重要。Wnt信号通过诱导细胞核TCF4/β-连环蛋白复合物的形成，维持肠隐窝祖细胞的未分化状态。在结直肠癌中，Wnt通路组分的激活突变导致TCF4/β-catenin驱动转录的不适当激活。尽管在TCF4和β-catenin作为Wnt信号的分子效应物被发现十年之后，很少有转录激活因子被发现，这些转录激活因子对Wnt信号的调控是必不可少的和独特的。利用蛋白质组学，我们鉴定出白血病相关的Mllt10/Af10和甲基转移酶Dot1l是小鼠小肠隐窝中Tcf4/β-连环蛋白的相互作用物。转录延伸所必需的Mllt10/Af10-Dot1l以β-catenin依赖的方式被募集到Wnt靶基因上，导致结直肠癌小鼠小肠增殖隐窝和Wnt诱导的HEK293T细胞体内编码区H3K79甲基化。在大肠癌和Wnt诱导的HEK293T细胞中缺失MLLT10/AF10，通过表达阵列分析发现，MLLT10/AF10和DOT1L在很大程度上是Wnt靶基因调控的必需激活因子。相比之下，先前发表的β-catenin共激活因子p300和BRG1显示出控制Wnt和其他途径的多效性靶基因表达谱。tcf4、mllt10/af10和dot11在斑马鱼wnt驱动组织中共表达，对wnt报告活性至关重要。Apc突变斑马鱼的肠道分化缺陷可以通过缺失Mllt10和Dot1l来修复，在体内将这些基因建立为Apc下游Wnt靶基因激活的激活因子。斑马鱼中mllt10/af10-dot1l的morpholino缺失导致肠道稳态缺陷，Wnt直接靶基因在体内的表达和增殖性肠上皮细胞的数量显著减少。我们得出结论，Mllt10/Af10-Dot1l是wnt依赖性转录的重要激活因子，对维持肠道增殖和稳态至关重要。甲基转移酶DOT1L可能是结直肠癌药物靶向的一个有吸引力的候选者。典型的Wnt通路是控制肠道细胞增殖、分化和干细胞维持的关键调控通路，其失调导致哺乳动物肠道恶性肿瘤。转录因子TCF4-β-catenin作为Wnt的下游肠道分子效应因子被发现已有十年之久，但对该转录程序的调控必不可少且独特的转录激活因子却很少被发现。在这项研究中，我们使用蛋白质组学方法，鉴定了白血病相关的Mllt10/Af10及其伴侣组蛋白甲基转移酶Dot1l作为小鼠小肠上皮中Tcf4/β-catenin的相互作用物。我们证明，在肠上皮细胞中，Mllt10/ Af10-Dot1l被募集到Wnt靶基因上，并且对调节这些靶基因的表达至关重要。我们还在斑马鱼中发现了Wnt通路和Mllt10/Af10-Dot1l之间的遗传联系，并描述了它们在Wnt驱动的内源性基因表达中的重要作用。最后，我们证明了Mllt10/Af10-Dot1l在wnt驱动的肠道发育和稳态中的生理作用；在斑马鱼胚胎中，Mllt10/Af10-Dot1l的缺失模拟了tcf4缺失的表型，在这种表型中，肠道增殖缺陷显著伴随着肠道细胞总数的减少。我们得出结论，酶Dot1l可能是结肠直肠癌药物靶向的一个有吸引力的候选物。
The leukemia-associated Mllt10/Af10 and its partner the histone methyltransferase Dot1l are identified as Tcf4/β-catenin co-activators and shown to be essential for Wnt-driven endogenous gene expression, intestinal development and homeostasis. Wnt signaling maintains the undifferentiated state of intestinal crypt progenitor cells by inducing the formation of nuclear TCF4/β-catenin complexes. In colorectal cancer, activating mutations in Wnt pathway components cause inappropriate activation of TCF4/β-catenin-driven transcription. Despite the passage of a decade after the discovery of TCF4 and β-catenin as the molecular effectors of the Wnt signal, few transcriptional activators essential and unique to the regulation of this transcription program have been found. Using proteomics, we identified the leukemia-associated Mllt10/Af10 and the methyltransferase Dot1l as Tcf4/β-catenin interactors in mouse small intestinal crypts. Mllt10/Af10-Dot1l, essential for transcription elongation, are recruited to Wnt target genes in a β-catenin-dependent manner, resulting in H3K79 methylation over their coding regions in vivo in proliferative crypts of mouse small intestine in colorectal cancer and Wnt-inducible HEK293T cells. Depletion of MLLT10/AF10 in colorectal cancer and Wnt-inducible HEK293T cells followed by expression array analysis identifies MLLT10/AF10 and DOT1L as essential activators to a large extent dedicated to Wnt target gene regulation. In contrast, previously published β-catenin coactivators p300 and BRG1 displayed a more pleiotropic target gene expression profile controlling Wnt and other pathways. tcf4, mllt10/af10, and dot1l are co-expressed in Wnt-driven tissues in zebrafish and essential for Wnt-reporter activity. Intestinal differentiation defects in apc-mutant zebrafish can be rescued by depletion of Mllt10 and Dot1l, establishing these genes as activators downstream of Apc in Wnt target gene activation in vivo. Morpholino-depletion of mllt10/af10-dot1l in zebrafish results in defects in intestinal homeostasis and a significant reduction in the in vivo expression of direct Wnt target genes and in the number of proliferative intestinal epithelial cells. We conclude that Mllt10/Af10-Dot1l are essential, largely dedicated activators of Wnt-dependent transcription, critical for maintenance of intestinal proliferation and homeostasis. The methyltransferase DOT1L may present an attractive candidate for drug targeting in colorectal cancer. The canonical Wnt pathway is a key regulatory pathway controlling intestinal cell proliferation, differentiation, and stem cell maintenance, and its deregulation leads to malignancies in the mammalian gut. A decade has passed since the discovery of the transcription factors TCF4-β-catenin as the downstream intestinal molecular effectors of Wnt, but few transcriptional activators essential and unique to the regulation of this transcription program have been found. In this study, using a proteomics approach, we identify the leukemia-associated Mllt10/Af10 and its partner the histone methyltransferase Dot1l as interactors with Tcf4/β-catenin in the mouse small intestinal epithelium. We demonstrate that Mllt10/Af10–Dot1l are recruited to Wnt target genes in intestinal epithelial cells and are essential to regulate expression of these targets. We also show a genetic link between the Wnt pathway and Mllt10/Af10-Dot1l in zebrafish and delineate their essential role in Wnt-driven endogenous gene expression. Finally, we demonstrate the physiological role of Mllt10/Af10-Dot1l in Wnt-driven intestinal development and homeostasis; depletion of Mllt10/Af10-Dot1l in zebrafish embryos mimics the Tcf4-depleted phenotype in which significant intestinal proliferation defects accompany a decrease in total number of intestinal cells. We conclude that the enzyme Dot1l may present an attractive candidate for drug targeting in colorectal cancer.
登录
查看更多内容
影响因子：
64.5
作者：
Kramps, T;Peter, O;Basler, K
通讯作者：
Basler, K
影响因子：
56.9
作者：
Behrens, J;Jerchow, BA;Birchmeier, W
通讯作者：
Birchmeier, W
影响因子：
11.4
作者：
Hecht, A;Vleminckx, K;Kemler, R
通讯作者：
Kemler, R
影响因子：
2.7
作者：
Dorsky, RI;Sheldahl, LC;Moon, RT
通讯作者：
Moon, RT
影响因子：
16
作者：
Buratowski S
通讯作者：
Buratowski S