Setiawan Jajar, Kotani Takenori, Konno Tasuku, Saito Yasuyuki, Murata Yoji, Noda Tetsuo, Matozaki Takashi
Division of Molecular and Cellular Signaling, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe, Japan.
Department of Physiology, Faculty of Medicine, Public Health, and Nursing, Universitas Gadjah Mada, Yogyakarta, Indonesia.
Kobe J Med Sci. 2019 Apr 12;64(6):E200-E209.
Mammalian target of rapamycin complex 1 (mTORC1), a protein complex containing the serine/threonine kinase mTOR, integrates various growth stimulating signals. mTORC1 is expressed in intestinal epithelial cells (IECs), whereas the physiological roles of this protein complex in homeostasis of IECs remain virtually unknown. We here generated mice, in which tuberous sclerosis complex 2 (Tsc2), a negative regulator of mTORC1, was specifically ablated in IECs (Tsc2 CKO mice). Ablation of Tsc2 enhanced the phosphorylation of mTORC1 downstream molecules such as ribosomal S6 protein and 4E-BP1 in IECs. Tsc2 CKO mice manifested the enhanced proliferative activity of IECs in intestinal crypts as well as the promoted migration of these cells along the crypt-villus axis. The mutant mice also manifested the increased apoptotic rate of IECs as well as the increased ectopic Paneth cells, which are one of the major differentiated IECs. In addition, in vitro study showed that ablation of Tsc2 promoted the development of intestinal organoids without epidermal growth factor, while mTORC1 inhibitor, rapamycin, diminished this phenotype. Our results thus suggest that Tsc2-mTORC1 signaling regulates the proliferation, migration, and positioning of IECs, and thereby contributes to the proper regulation of intestinal homeostasis.
雷帕霉素靶蛋白复合物1(mTORC1)是一种包含丝氨酸/苏氨酸激酶mTOR的蛋白复合物,可整合各种生长刺激信号。mTORC1在肠上皮细胞(IECs)中表达,然而该蛋白复合物在IECs稳态中的生理作用几乎仍不清楚。我们在此构建了在IECs中特异性敲除mTORC1负调节因子结节性硬化复合物2(Tsc2)的小鼠(Tsc2基因敲除小鼠)。Tsc2的敲除增强了IECs中mTORC1下游分子(如核糖体S6蛋白和4E-BP1)的磷酸化。Tsc2基因敲除小鼠表现出肠隐窝中IECs增殖活性增强,以及这些细胞沿隐窝-绒毛轴的迁移促进。突变小鼠还表现出IECs凋亡率增加以及异位潘氏细胞增加,潘氏细胞是主要的分化IECs之一。此外,体外研究表明,Tsc2的敲除促进了无表皮生长因子时肠道类器官的发育,而mTORC1抑制剂雷帕霉素可减弱这种表型。因此,我们的结果表明,Tsc2-mTORC1信号传导调节IECs的增殖、迁移和定位,从而有助于肠道稳态的适当调节。