From the Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Box 582 Biomedical Center, Uppsala University, 751 23 Uppsala, Sweden and.
the Ludwig Institute for Cancer Research, Science for Life Laboratory, Box 595 Biomedical Center, Uppsala University, 751 24 Uppsala, Sweden.
J Biol Chem. 2019 Mar 15;294(11):4119-4136. doi: 10.1074/jbc.RA118.004984. Epub 2019 Jan 8.
TGFβ signaling via SMAD proteins and protein kinase pathways up- or down-regulates the expression of many genes and thus affects physiological processes, such as differentiation, migration, cell cycle arrest, and apoptosis, during developmental or adult tissue homeostasis. We here report that NUAK family kinase 1 () and are two TGFβ target genes. NUAK1/2 belong to the AMP-activated protein kinase (AMPK) family, whose members control central and protein metabolism, polarity, and overall cellular homeostasis. We found that TGFβ-mediated transcriptional induction of and requires SMAD family members 2, 3, and 4 (SMAD2/3/4) and mitogen-activated protein kinase (MAPK) activities, which provided immediate and early signals for the transient expression of these two kinases. Genomic mapping identified an enhancer element within the first intron of the gene that can recruit SMAD proteins, which, when cloned, could confer induction by TGFβ. Furthermore, NUAK2 formed protein complexes with SMAD3 and the TGFβ type I receptor. Functionally, NUAK1 suppressed and NUAK2 induced TGFβ signaling. This was evident during TGFβ-induced epithelial cytostasis, mesenchymal differentiation, and myofibroblast contractility, in which NUAK1 or NUAK2 silencing enhanced or inhibited these responses, respectively. In conclusion, we have identified a bifurcating loop during TGFβ signaling, whereby transcriptional induction of NUAK1 serves as a negative checkpoint and NUAK2 induction positively contributes to signaling and terminal differentiation responses to TGFβ activity.
TGFβ 通过 SMAD 蛋白和蛋白激酶途径的信号转导上调或下调许多基因的表达，从而影响生理过程，如分化、迁移、细胞周期停滞和细胞凋亡，在发育或成人组织稳态中。我们在这里报告 NUAK 家族激酶 1 () 和 是 TGFβ 的两个靶基因。NUAK1/2 属于 AMP 激活的蛋白激酶 (AMPK) 家族，其成员控制中心和蛋白质代谢、极性和整体细胞稳态。我们发现 TGFβ 介导的 和 的转录诱导需要 SMAD 家族成员 2、3 和 4 (SMAD2/3/4) 和丝裂原激活蛋白激酶 (MAPK) 活性，这为这两种激酶的瞬时表达提供了即时和早期信号。基因组作图在 基因的第一个内含子中鉴定出一个增强子元件，该元件可以募集 SMAD 蛋白，当克隆时，该元件可以赋予 TGFβ 的诱导能力。此外，NUAK2 与 SMAD3 和 TGFβ 型 I 受体形成蛋白复合物。功能上，NUAK1 抑制和 NUAK2 诱导 TGFβ 信号。这在 TGFβ 诱导的上皮细胞静止、间充质分化和肌成纤维细胞收缩中很明显，其中 NUAK1 或 NUAK2 的沉默分别增强或抑制了这些反应。总之，我们已经确定了 TGFβ 信号中的一个分叉循环，其中 NUAK1 的转录诱导作为负检查点，而 NUAK2 的诱导则积极有助于 TGFβ 活性的信号转导和终末分化反应。
