Department of Pediatrics, Division of Gastroenterology and Nutrition, Mattel Children's Hospital and the David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095.
Department of Medicine, Medical Sciences Building, University of Toronto, Toronto, Ontario M5S 1A8, Canada.
J Biol Chem. 2019 Oct 11;294(41):15182-15192. doi: 10.1074/jbc.RA119.008926. Epub 2019 Jul 24.
Neurogenin-3 (NEUROG3) is a helix-loop-helix (HLH) transcription factor involved in the production of endocrine cells in the intestine and pancreas of humans and mice. However, the human NEUROG3 loss-of-function phenotype differs subtly from that in mice, but the reason for this difference remains poorly understood. Because expression precedes exit of the cell cycle and the expression of endocrine cell markers during differentiation, we investigated the effect of lentivirus-mediated overexpression of the human gene on the cell cycle of BON4 cells and various human nonendocrine cell lines. overexpression induced a reversible cell cycle exit, whereas expression of a neuronal lineage homolog, , had no such effect. In endocrine lineage cells, the cellular quiescence induced by short-term expression required cyclin-dependent kinase inhibitor 1A (CDKN1A)/p expression. Expression of endocrine differentiation markers required sustained expression in the quiescent, but not in the senescent, state. Inhibition of the phosphatase and tensin homolog (PTEN) pathway reversed quiescence by inducing cyclin-dependent kinase 2 (CDK2) and reducing p21 and NEUROG3 protein levels in BON4 cells and human enteroids. We discovered that expression stimulates expression of CDKN2a/p and (), with the latter limiting expression of the former, delaying the onset of CDKN2a/p -driven cellular senescence. Furthermore, NEUROG3 bound to the promoters of both and genes, and BMI1 attenuated NEUROG3 binding to the / promoter. Our findings reveal how human NEUROG3 integrates inputs from multiple signaling pathways and thereby mediates cell cycle exit at the onset of differentiation.
神经元素 3（NEUROG3）是一个螺旋-环-螺旋（HLH）转录因子，参与人类和小鼠肠道和胰腺内分泌细胞的产生。然而，人类 NEUROG3 功能丧失表型与小鼠略有不同，但这种差异的原因仍知之甚少。由于 表达先于细胞周期退出和内分泌细胞标志物在分化过程中的表达，我们研究了慢病毒介导的人 基因过表达对 BON4 细胞和各种人非内分泌细胞系细胞周期的影响。过表达诱导可逆的细胞周期退出，而神经元谱系同源物 的表达则没有这种作用。在内分泌谱系细胞中，由短期 表达诱导的细胞静止需要细胞周期蛋白依赖性激酶抑制剂 1A（CDKN1A）/p 的表达。内分泌分化标志物的表达需要在静止状态下而不是衰老状态下持续表达。磷酸酶和张力蛋白同源物（PTEN）途径的抑制通过诱导细胞周期蛋白依赖性激酶 2（CDK2）和降低 BON4 细胞和人类类器官中的 p21 和 NEUROG3 蛋白水平来逆转静止状态。我们发现 表达刺激 CDKN2a/p 和 （）的表达，后者限制前者的表达，从而延迟 CDKN2a/p 驱动的细胞衰老的发生。此外，NEUROG3 结合到 和 基因的启动子上，BMI1 减弱了 NEUROG3 与 / 启动子的结合。我们的研究结果揭示了人类 NEUROG3 如何整合来自多个信号通路的输入，从而在分化开始时介导细胞周期退出。
