Mohapatra Bhopal, Zutshi Neha, An Wei, Goetz Benjamin, Arya Priyanka, Bielecki Timothy A, Mushtaq Insha, Storck Matthew D, Meza Jane L, Band Vimla, Band Hamid
Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198, USA.
Department of Biochemistry & Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA.
Development. 2017 Mar 15;144(6):1072-1086. doi: 10.1242/dev.138164. Epub 2017 Jan 18.
The ubiquitin ligases CBL and CBL-B are negative regulators of tyrosine kinase signaling with established roles in the immune system. However, their physiological roles in epithelial tissues are unknown. Here, we used MMTV-Cre-mediated gene deletion on a null background, as well as a tamoxifen-inducible mammary stem cell (MaSC)-specific and double knockout ( DKO) using Lgr5-EGFP-IRES-CreERT2, to demonstrate a mammary epithelial cell-autonomous requirement of CBL and CBL-B in the maintenance of MaSCs. Using a newly engineered tamoxifen-inducible and deletion model with a dual fluorescent reporter (), we show that DKO in mammary organoids leads to hyperactivation of AKT-mTOR signaling with depletion of MaSCs. Chemical inhibition of AKT or mTOR rescued MaSCs from DKO-induced depletion. Our studies reveal a novel, cell-autonomous requirement of CBL and CBL-B in epithelial stem cell maintenance during organ development and remodeling through modulation of mTOR signaling.
泛素连接酶CBL和CBL - B是酪氨酸激酶信号传导的负调节因子，在免疫系统中具有既定作用。然而，它们在上皮组织中的生理作用尚不清楚。在此，我们在无背景的情况下使用MMTV - Cre介导的基因缺失，以及使用Lgr5 - EGFP - IRES - CreERT2进行他莫昔芬诱导的乳腺干细胞（MaSC）特异性双敲除（DKO），以证明CBL和CBL - B在维持MaSC方面对乳腺上皮细胞具有自主性需求。使用新设计的具有双荧光报告基因的他莫昔芬诱导和缺失模型，我们表明乳腺类器官中的DKO会导致AKT - mTOR信号过度激活以及MaSC耗竭。对AKT或mTOR的化学抑制可使MaSC从DKO诱导的耗竭中恢复。我们的研究揭示了在器官发育和重塑过程中，CBL和CBL - B通过调节mTOR信号，对上皮干细胞维持具有新的细胞自主性需求。
