Ferroptosis is involved in alcohol-induced cell death in vivo and in vitro.

A critical pathogenic factor in the development of lethal liver failure is cell death induced by the accumulation of lipid reactive oxygen species. In this study, we discovered and illuminated a new mechanism that led to alcoholic liver disease via ferroptosis, an iron-dependent regulated cell death. Study in vitro showed that both necroptosis inhibitor and ferroptosis inhibitors performed significantly protective effect on alcohol-induced cell death, while apoptosis inhibitor and autophagy inhibitor had no such effect. Our data also indicated that alcohol caused the accumulation of lipid peroxides and the mRNA expression of prostaglandin-endoperoxide synthase 2, reduced the protein expression of the specific light-chain subunit of the cystine/glutamate antiporter and glutathione peroxidase 4. Importantly, ferrostatin-1 significantly ameliorated liver injury that was induced by overdosed alcohol both in vitro and in vivo. These findings highlight that targeting ferroptosis serves as a hepatoprotective strategy for alcoholic liver disease treatment.

Caffeine Protects Skin from Oxidative Stress-Induced Senescence through the Activation of Autophagy.

Skin cells are vulnerable to oxidative stress-induced senescence, which may lead to abnormal aging or aging-related disorders. Therefore, strategies that can ameliorate oxidative stress-induced senescence are expected to protect skin from damage, holding the promise of treating skin diseases in the clinic. This study aims to investigate whether caffeine, a well-known purine alkaloid, is able to prevent skin from oxidative stress-induced senescence, and to explore the underlying molecular mechanisms. Methods: A free radical inducer 2,2'-Azobis (2-amidinopropane) dihydrochloride (AAPH) was used to induce oxidative stress and cellular senescence in both transformed skin cells and in normal human epidermal keratinocytes (NHEKs). Ultraviolet (UV) irradiation was established as the in vivo oxidative stress model in mouse skin tissues. Cellular senescence was determined by SA ß-galactosidase staining, immunofluorescence and western blotting. Activation of autophagy was confirmed by western blotting, immunofluorescence, and transmission electron microscopy. Reactive oxygen species (ROS) detection by commercial kits, gene knockdown by RNA interference (RNAi) and receptor activation/inactivation by agonist/antagonist treatment were applied in mechanistic experiments. Results: We report that AAPH induced senescence in both transformed skin cells and in NHEKs. Similarly, UV irradiation induced senescence in mouse skin tissues. Remarkably, low dose of caffeine (<10 µM) suppressed cellular senescence and skin damage induced by AAPH or UV. Mechanistically, caffeine facilitated the elimination of ROS by activating autophagy. Using a combination of RNAi and chemical treatment, we demonstrate that caffeine activates autophagy through a series of sequential events, starting from the inhibition of its primary cellular target adenosine A2a receptor (A2AR) to an increase in the protein level of Sirtuin 3 (SIRT3) and to the activation of 5' adenosine monophosphate-activated protein kinase (AMPK). Oral administration of caffeine increased the protein level of SIRT3, induced autophagy, and reduced senescence and tissue damage in UV-irradiated mouse skin. On the other hand, co-administration with autophagy inhibitors attenuated the protective effect of caffeine on UV-induced skin damage in mice. Conclusion: The results reveal that caffeine protects skin from oxidative stress-induced senescence through activating the A2AR/SIRT3/AMPK-mediated autophagy. Our study not only demonstrated the beneficial effect of caffeine using both in vitro and in vivo models, but also systematically investigated the underlying molecular mechanisms. These discoveries implicate the potential of caffeine in the protection of skin disease.

Inhibition effect of cypermethrin mediated by co-regulators SRC-1 and SMRT in interleukin-6-induced androgen receptor activation.

It is hypothesized that the pesticide cypermethrin may induce androgen receptor (AR) antagonism via ligand-independent mechanisms. The Real-Time Cell Analysis (RTCA) iCELLigence system was used to investigate the inhibitory effect of cypermethrin on interleukin-6 (IL-6)-induced ligand-independent LNCaP cell growth. Then, the mammalian two-hybrid assays were applied to clarify whether the mechanism of IL-6-induced AR antagonism of cypermethrin was associated with the interactions of the AR and co-activator steroid receptor co-activator-1 (SRC-1) and co-repressor silencing mediator for retinoid and thyroid hormone receptors (SMRT). Cypermethrin inhibited the LNCaP cell growth induced by IL-6. The interactions of AR-SRC-1 and AR-SMRT mediated by IL-6 were suppressed by cypermethrin. The results indicate that the IL-6-mediated AR antagonism induced by cypermethrin is related to repress the recruitment of co-regulators SRC-1 and SMRT to the AR in a ligand-independent manner. Inhibition of the interactions of AR-SRC-1 and AR-SMRT mediated by IL-6 contributes to the AR antagonism induced by cypermethrin.

Ischemic preconditioning protects the brain against injury via inhibiting CaMKII-nNOS signaling pathway.

Although studies have shown that cerebral ischemic preconditioning (IPC) can ameliorate ischemia/reperfusion (I/R) induced brain damage, but its precise mechanisms remain unknown. Therefore, the aim of this study was to investigate the neuroprotective mechanisms of IPC against ischemic brain damage induced by cerebral I/R and to explore whether the Calcium/calmodulin-dependent protein kinase II (CaMKII)-mediated up-regulation of nNOS ser847-phosphorylation signaling pathway contributed to the protection provided by IPC. Transient global brain ischemia was induced by 4-vessel occlusion in adult male Sprague-Dawley rats. The rats were pretreated with 3 min of IPC alone or KN62 (selective antagonist of CaMKII) treatment before IPC, after reperfusion for 3 days, 6 min ischemia was induced. Cresyl violet staining was used to examine the survival of hippocampal CA1 pyramidal neurons. Immunoblotting was performed to measure the phosphorylation of CaMKII, nNOS, c-Jun and the expression of FasL. Immunoprecipitation was used to examine the binding between PSD95 and nNOS. The results showed that IPC could significantly protect neurons against cerebral I/R injury, furthermore, the combination of PSD95 and nNOS was increased, coinstantaneously the phosphorylation of CaMKII and nNOS (ser847) were up-regulated, however the activation of c-Jun and FasL were reduced. Conversely, KN62 treatment before IPC reversed all these effects of IPC. Taken together, the results suggest that IPC could diminish ischemic brain injury through CaMKII-mediated up-regulation of nNOS ser847-phosphorylation signaling pathway.

The co-regulators SRC-1 and SMRT are involved in interleukin-6-induced androgen receptor activation.

BACKGROUND: The androgen receptor (AR) can be stimulated by interleukin-6 (IL-6) in the absence of androgens to induce prostate cancer progression. The purpose of this study was to investigate whether the co-activator steroid receptor coactivator-1 (SRC-1) and co-repressor silencing mediator for retinoid and thyroid hormone receptors (SMRT) are involved in IL-6-induced AR activation. METHODS: The effects of IL-6 on LNCaP cell proliferation were monitored using real-time cell analysis (RTCA) iCELLigence system. The impacts of IL-6 on the association of the AR with SRC-1 and SMRT were investigated using the mammalian two-hybrid assay. RESULTS: IL-6 increased the proliferation of LNCaP cells with maximal induction at 50 ng/mL. The AR-SRC-1interaction was enhanced by IL-6, with maximal induction at the concentration of 50 ng/mL (P<0.05). IL-6 decreased the AR-SMRT interaction and a marked reduction was detected at 50 ng/mL (P<0.05). CONCLUSIONS: IL-6 enhances LNCaP cells proliferation, which suggests that IL-6 might cause AR-positive prostate cancer growth through activation of the AR. The mechanism of IL-6-induced AR activation is mediated through enhancing AR-SRC-1 interaction and inhibiting AR-SMRT interaction. We have shown a significant role for SRC-1 and SMRT in modulating IL-6-induced AR transactivation.

Antagonism effects of cypermethrin on interleukin-6-induced androgen receptor activation.

To identify whether androgen receptor (AR) antagonism by cypermethrin involves interleukin-6 (IL-6)-induced ligand-independent AR signaling, we have developed the AR reporter gene assay. The reporter gene plasmid pMMTV-chloramphenicol transferase (CAT) was transfected into LNCaP cells. IL-6 increased expression of MMTV-CAT significantly (P<0.05). Cypermethrin decreased CAT reporter expression induced by IL-6 (50 ng/ml), and the significant inhibition was detected at 10(-5)M (P<0.05). IL-6 induces ligand-independent activation of AR. Cypermethrin exhibits inhibitory effects on IL-6-induced ligand-independent AR signaling. We provide a novel insight into cypermethrin-mediated antagonism of the IL-6-mediated ligand-independent activation of the AR.

nNOS downregulation attenuates neuronal apoptosis by inhibiting nNOS-GluR6 interaction and GluR6 nitrosylation in cerebral ischemic reperfusion.

Glutamate receptor 6 (GluR6) is well documented to play a pivotal role in ischemic brain injury, which is mediated by the GluR6·PSD95·MLK3 signaling module and subsequent c-Jun N-terminal kinase (JNK) activation. Our recent studies show that GluR6 is S-nitrosylated in the early stages of ischemia-reperfusion. NO (Nitric Oxide) is mainly generated from neuronal nitric oxide synthase (nNOS) in cerebral neurons during the early stages of reperfusion. Here, the effect of nNOS downregulation on GluR6 S-nitrosylation and GluR6-mediated signaling was investigated in cerebral ischemia and reperfusion. Administration of nNOS oligonucleotides confirmed that GluR6 nitrosylation is induced by nNOS-derived endogenous NO and further activates the GluR6·PSD95·MLK3 signaling module and JNK signaling pathway. Moreover, this study revealed for the first time that nNOS can bind with GluR6 during ischemic reperfusion, and PSD95 is involved in this interaction. In summary, our results suggest that nNOS binds with GluR6 via PSD95 and then produces endogenous NO to S-nitrosylate GluR6 in cerebral ischemia-reperfusion, which provides a new approach for stroke therapy.

Inhibition of cerebral ischemia/reperfusion-induced injury by adenovirus expressed C-terminal amino acids of GluR6.

GluR6 kainate receptor subunit is largely expressed in hippocampus of brain regions and plays an important role in brain ischemia/reperfusion-mediated neuronal cell death. Our previous researches have shown that cerebral ischemia/reperfusion could facilitate the assembly of GluR6 and postsynaptic density protein 95(PSD95) as well as mixed lineage kinase 3(MLK3) and further induce the activation of c-Jun NH2-terminal kinase 3(JNK3), leading to neuronal death of hippocampal CA1. Here, we show that over-expression of C-terminal amino acids of GluR6 can interrupt the combination of GluR6 with PSD95, inhibit the assembly of GluR6.PSD-95.MLK3 signaling module, suppress the activation of JNK3 and the downstream signaling pathway. Thus, our results imply that over-expression of C-terminal amino acids of GluR6 induce neuroprotection against ischaemic brain injury in rat hippocampal CA1 region via suppressing proapoptosis signaling pathways, which can be an experimental foundation for gene therapy of stroke.