Department of Anesthesiology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
Department of Critical Care Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
Cell Biol Int. 2018 Sep;42(10):1311-1320. doi: 10.1002/cbin.11016. Epub 2018 Jul 2.
Aberrant aggregation and activation of lung fibroblasts is a key process in pulmonary fibrosis, but the underlying mechanism remains enigmatic. Forkhead Box O3a (FoxO3a) is considered to be an important transcription factor that could regulate both cell cycle and cell viability. To investigate the role of FoxO3a on LPS-induced lung fibroblast proliferation, we transfected FoxO3a-SiRNA or FoxO3a-OE lentivirus into cultured mouse lung fibroblasts to knockdown or overexpress FoxO3a and pretreated mouse lung fibroblasts with gefitinib to enhance FoxO3a activity. The proliferation of lung fibroblasts was evaluated by CCK8 assay, the expression of FoxO3a, phosphorylated FoxO3a (p-FoxO3a) and p27 were measured by Western blot. We found that the proliferation of mouse lung fibroblasts mediated by LPS is accompanied by the inactivation of FoxO3a. The knockdown of FoxO3a could further decreased the expression of p27 mediated by LPS, while the overexpression of FoxO3a significantly increased the expression of p27 and suppressed LPS-induced lung fibroblast proliferation. Upon treating fibroblasts with gefitinib, the phosphorylation of FoxO3a was reduced and FoxO3a translocated into the nucleus, the expression of p27 was significantly increased and the proliferation of lung fibroblasts mediated by LPS could also be inhibited effectively. The results indicate that overexpression and reduced phosphatase activity of FoxO3a inhibit LPS-induced lung fibroblast proliferation through the activation of FoxO3a/p27 signaling pathways. Thus, to enhance FoxO3a activity could be a potential therapeutic target for LPS-induced pulmonary fibrosis.
异常聚集和激活肺成纤维细胞是肺纤维化的一个关键过程，但潜在的机制仍不清楚。叉头框蛋白 O3a（FoxO3a）被认为是一种重要的转录因子，它可以调节细胞周期和细胞活力。为了研究 FoxO3a 在 LPS 诱导的肺成纤维细胞增殖中的作用，我们将 FoxO3a-SiRNA 或 FoxO3a-OE 慢病毒转染到培养的小鼠肺成纤维细胞中，以敲低或过表达 FoxO3a，并使用吉非替尼预处理小鼠肺成纤维细胞以增强 FoxO3a 活性。通过 CCK8 测定法评估肺成纤维细胞的增殖，通过 Western blot 测定 FoxO3a、磷酸化 FoxO3a（p-FoxO3a）和 p27 的表达。我们发现，LPS 介导的小鼠肺成纤维细胞增殖伴随着 FoxO3a 的失活。敲低 FoxO3a 可进一步降低 LPS 介导的 p27 表达，而过表达 FoxO3a 则显著增加 p27 的表达并抑制 LPS 诱导的肺成纤维细胞增殖。用吉非替尼处理成纤维细胞后，FoxO3a 的磷酸化减少，FoxO3a 易位到细胞核中，p27 的表达显著增加，LPS 介导的肺成纤维细胞增殖也可有效抑制。结果表明，FoxO3a 的过表达和磷酸酶活性降低通过激活 FoxO3a/p27 信号通路抑制 LPS 诱导的肺成纤维细胞增殖。因此，增强 FoxO3a 活性可能是 LPS 诱导的肺纤维化的一个潜在治疗靶点。
