Activation of nuclear estrogen receptors induced by low‐power laser irradiation via PI3‐K/Akt signaling cascade

Abstract

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.

MicroRNA‐221 targeting PI3‐K/Akt signaling axis induces cell proliferation and BCNU resistance in human glioblastoma

“…Proteins were extracted from cells using lysis buffer (20 mmol/L Tris, PH 7.4, 150 mmol/L NaCl, 2 mmol/L EDTA, 2 mmol/L ethyleneglycoltetraacetic acid(EGTA), 1 mmol/L sodium orthovanadate, 50 mmol/L sodium fluoride, 1% TritonX‐100, 0.1% SDS and 100 mmol/L phenylmethylsulfonyl fluoride). Western blot analysis was performed as previously described . Briefly, the extracts were mixed with Laemmli sample buffer (2% SDS) and placed in boiling water for 5 min.…”

Photoactivation of Akt1/GSK3β Isoform‐Specific Signaling Axis Promotes Pancreatic β‐Cell Regeneration

“…In order to isolate cytosolic and nuclear extracts, RIN‐m cells, INS‐1 cells, and primary islets were washed twice with ice‐cold PBS and added with 250 µl of lysis buffer (10 mM Tris, pH 7.5, 10 mM NaCl, 3 mM MgCl 2 , 0.05% Nonidet P‐40, 1 mM EGTA, 1 mM sodium orthovanadate, 50 mM sodium fluoride, 100 µM phenylmethylsulfonyl fluoride, 10 µg/ml leupeptin, 10 µg/ml aprotinin, 5 µg/ml pepstatin A, and 1 nM okadaic acid). Cytosolic and nuclear extracts were obtained as described previously [Huang et al, ].…”

“…Light energy is absorbed by intracellular chromophores, which accelerate electron transfer reactions, leading to increase the intracellular levels of Ca 2+ and reactive oxygen species as versatile second messengers [Lan et al, ]. The current studies have shown that LPLI is involved in multiple cellular physiological functions, including gene transcription and protein expression [Huang et al, ], cytoskeleton reorganization [Ricci et al, ], and cell migration [Karunarathne et al, ]. In addition, it has been widely employed in neck pain care [Chow et al, ], skin anti‐aging [Ling et al, ], and wound healing [Ozcelik et al, ].…”

Photo-enhancement of macrophage phagocytic activity via Rac1-mediated signaling pathway: Implications for bacterial infection

“…A growing body of experimental and clinical studies has demonstrated that LPLI may regulate cell survival, proliferation, and differentiation by triggering a series of complex intracellular signaling events (Feng et al , 2012, Huang et al , 2013, Liang et al , 2012, Ling et al , 2014, Meng et al , 2013. This has attracted the interest of researchers to study the effect and molecular mechanism of LPLI on the broad spectrum of cellular processes.…”