MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, China.
J Cell Physiol. 2013 May;228(5):1045-59. doi: 10.1002/jcp.24252.
Low-power laser irradiation (LPLI) has been shown to exert promotive effects on cell survival and proliferation through activation of various signaling pathways. Estrogen receptors (ERs, ERα, and ERβ) are ligand-activated transcription factors, which regulate target gene expression, promote cell proliferation, and resist apoptosis. However, it is unclear whether LPLI could induce ligand-independent activation of ERs. In the present study, we investigated the subcellular pools, nuclear redistribution, and transcriptional activity of ERs under LPLI (1.2 J/cm(2), 633 nm) treatment using single-molecule fluorescence imaging and dual-luciferase reporter assay. We found that ERs were not only localized to nucleus, but also existed in mitochondria. Moreover, we found that LPLI induced nuclear redistribution and transcriptional activity of ERs in a ligand-independent manner. Our further investigation showed that PI3-K/Akt signaling cascade was involved in LPLI-induced activation of ERs. Wortmannin, a PI3-K inhibitor, or triciribine (API-2), a specific Akt inhibitor, potently suppressed the nuclear redistribution and transcriptional activity of ERs induced by LPLI, revealing that PI3-K/Akt signaling cascade was required for the activation of ERs induced by LPLI. Collectively, we demonstrated the first time that LPLI induced the ligand-independent nuclear redistribution and transcriptional activity of ERs, which were dependent on the activity of PI3-K/Akt. Our findings provide direct evidence for the molecular mechanisms of LPLI-induced transcription factor activation.
低强度激光照射（LPLI）已被证明通过激活多种信号通路对细胞存活和增殖发挥促进作用。雌激素受体（ERs，ERα 和 ERβ）是配体激活的转录因子，可调节靶基因表达，促进细胞增殖并抵抗细胞凋亡。然而，目前尚不清楚 LPLI 是否可以诱导 ERs 的非配体依赖性激活。在本研究中，我们使用单分子荧光成像和双荧光素酶报告基因检测研究了 LPLI（1.2 J/cm²，633nm）处理下 ERs 的亚细胞池、核重定位和转录活性。我们发现 ERs 不仅定位于细胞核，还存在于线粒体中。此外，我们发现 LPLI 以非配体依赖性方式诱导 ERs 的核重定位和转录活性。我们进一步的研究表明，PI3-K/Akt 信号级联参与了 LPLI 诱导的 ERs 激活。PI3-K 抑制剂wortmannin 或 Akt 特异性抑制剂 triciribine（API-2）可强烈抑制 LPLI 诱导的 ERs 核重定位和转录活性，表明 PI3-K/Akt 信号级联对于 LPLI 诱导的 ERs 激活是必需的。总之，我们首次证明 LPLI 诱导了 ERs 的非配体依赖性核重定位和转录活性，这依赖于 PI3-K/Akt 的活性。我们的研究结果为 LPLI 诱导转录因子激活的分子机制提供了直接证据。
