Pituitary gland function is regulated by the activity of various transcription factors that control cell fate decisions leading to cellular differentiation and hormone production. FOXO1 is necessary for normal somatotrope differentiation and function. Recent in vivo data implicate FOXO1 in the regulation of genes important for somatotrope differentiation including Gh1, Neurod4, and Pou1f1. In the current study, the somatotrope-like cell line GH3 was treated with a FOXO1 inhibitor, resulting in significant reduction in Neurod4 and Gh1 expression. Consistent with these findings, CRISPR/Cas9-mediated deletion of Foxo1 in GH3 cells significantly reduced expression of Gh1 and Neurod4. Chromatin immunoprecipitation sequencing identifies novel FOXO1 binding sites associated with the Neurod4, Gh1, and Pou1f1 genes. The FOXO1 binding site in the Neurod4 gene exhibits enhancer activity in somatotrope-like cells but not in gonadotrope-like cells. These data strongly suggest FOXO1 directly contributes to the transcriptional control of genes important for somatotrope differentiation.

垂体功能受各种转录因子的活性调节，这些转录因子控制细胞命运决定，从而导致细胞分化和激素产生。FOXO1 对于正常生长激素的分化和功能是必需的。最近的体内数据表明 FOXO1 参与调节对生长激素分化重要的基因，包括Gh1、Neurod4和Pou1f1 。在当前的研究中，用 FOXO1 抑制剂处理生长激素样细胞系 GH3，导致Neurod4和Gh1表达显着减少。与这些发现一致，GH3 细胞中 CRISPR/Cas9 介导的Foxo1缺失显着降低了Gh1和Neurod4的表达。染色质免疫沉淀测序鉴定了与Neurod4、Gh1和Pou1f1基因相关的新 FOXO1 结合位点。Neurod4基因中的 FOXO1 结合位点在生长激素样细胞中表现出增强子活性，但在促性腺激素样细胞中则不然。这些数据强烈表明 FOXO1 直接有助于生长激素分化重要基因的转录控制。