Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Health System, 1500 W Medical Center Drive, 3916 Taubman Center, Ann Arbor, MI, 48109-0360, USA.
Sci Rep. 2020 Dec 4;10(1):21231. doi: 10.1038/s41598-020-77601-1.
Forkhead box F1 (FOXF1) is a lung embryonic mesenchyme-associated transcription factor that demonstrates persistent expression into adulthood in mesenchymal stromal cells. However, its biologic function in human adult lung-resident mesenchymal stromal cells (LR-MSCs) remain to be elucidated. Here, we demonstrate that FOXF1 expression acts as a restraint on the migratory function of LR-MSCs via its role as a novel transcriptional repressor of autocrine motility-stimulating factor Autotaxin (ATX). Fibrotic human LR-MSCs demonstrated lower expression of FOXF1 mRNA and protein, compared to non-fibrotic controls. RNAi-mediated FOXF1 silencing in LR-MSCs was associated with upregulation of key genes regulating proliferation, migration, and inflammatory responses and significantly higher migration were confirmed in FOXF1-silenced LR-MSCs by Boyden chamber. ATX is a secreted lysophospholipase D largely responsible for extracellular lysophosphatidic acid (LPA) production, and was among the top ten upregulated genes upon Affymetrix analysis. FOXF1-silenced LR-MSCs demonstrated increased ATX activity, while mFoxf1 overexpression diminished ATX expression and activity. The FOXF1 silencing-induced increase in LR-MSC migration was abrogated by genetic and pharmacologic targeting of ATX and LPA1 receptor. Chromatin immunoprecipitation analyses identified three putative FOXF1 binding sites in the 1.5 kb ATX promoter which demonstrated transcriptional repression of ATX expression. Together these findings identify FOXF1 as a novel transcriptional repressor of ATX and demonstrate that loss of FOXF1 promotes LR-MSC migration via the ATX/LPA/LPA1 signaling axis.
叉头框转录因子 F1（FOXF1）是一种与肺胚胎间充质相关的转录因子，在间充质基质细胞中持续表达至成年期。然而，其在人肺固有间充质基质细胞（LR-MSCs）中的生物学功能仍有待阐明。在这里，我们证明 FOXF1 的表达通过作为自分泌运动刺激因子 Autotaxin（ATX）的新型转录抑制因子来限制 LR-MSCs 的迁移功能。与非纤维化对照相比，纤维化的人 LR-MSCs 表现出 FOXF1 mRNA 和蛋白表达降低。LR-MSCs 中的 RNAi 介导的 FOXF1 沉默与调节增殖、迁移和炎症反应的关键基因的上调有关，并且在 FOXF1 沉默的 LR-MSCs 中通过 Boyden 室证实了显著更高的迁移。ATX 是一种分泌型溶脂酶 D，主要负责细胞外溶血磷脂酸（LPA）的产生，并且是 Affymetrix 分析中上调的前 10 个基因之一。FOXF1 沉默的 LR-MSCs 表现出 ATX 活性增加，而 mFoxf1 过表达则降低 ATX 表达和活性。通过 ATX 和 LPA1 受体的遗传和药理学靶向，FOXF1 沉默诱导的 LR-MSC 迁移增加被消除。染色质免疫沉淀分析鉴定了 ATX 启动子中三个推定的 FOXF1 结合位点，该结合位点显示 ATX 表达的转录抑制。这些发现共同确定 FOXF1 是 ATX 的新型转录抑制剂，并证明 FOXF1 的缺失通过 ATX/LPA/LPA1 信号轴促进 LR-MSC 迁移。
