Forkhead Box O3 Transcription Research Articles

Expression of Foxo3a Transcription Factor in Alzheimer?s Rat Brain

This paper aims to research the expression of forkhead box O3 transcription factor in the brain of Alzheimer’s rats. First, the rats were selected as subjects and divided into Alzheimer’s disease group and normal control group to establish the Alzheimer model. Then the positive forkhead box O3 immunoreactivity was observed in the posterior thalamus, cortex and hippocampus of rats, together with the changes of positive neurons in these locations. Results have shown that the number of positive cells in the cortex, thalamus and hippocampus of the experimental group was significantly higher than that of the control group, and the difference between the groups was statistically significant (p<0.05). Also, the optical density of the experimental group in the carbonic anhydrase 2, cortex, and carbonic anhydrase 1 regions was significantly higher than that of the control group, with the inter-group of statistical significance (p<0.05). It is concluded that forkhead box O3 is highly related to Alzheimer’s disease. The expression of forkhead box O3, whether leading to endoplasmic reticulum protein apoptosis or protection, will affect Alzheimer’s disease.

Knockdown of NIR Suppresses Breast Cancer Cell Proliferation via Promoting FOXO3.

BackgroundNovel inhibitor of histone acetyltransferase repressor (NIR), a corepressor with a novel inhibitor of histone acetyltransferase (INHAT) activity, has been reported to be a negative modulator of p53 and a regulator of the cell cycle in cancer cells. However, the role of NIR in the progression of breast cancer remains elusive.Materials and MethodsOncomine database was used to analyze the mRNA levels and prognosis value of NIR in breast cancer. We performed loss-of-function and gain-of-function studies using lentivirus expressing shRNA targeting NIR, enhancer of zeste homolog 2 (EZH2) and forkhead box O3 (FOXO3) or lentivirus expressing NIR or FOXO3, respectively. Cell proliferation and colony formation assays were performed. Co-immunoprecipitation (Co-IP) and immunoprecipitation (IP) were performed to identify the interaction between NIR and polycomb repressive complex 2 (PRC2) subunits. ChIP assay was used to identify the enrichment of NIR, EZH2, H3K27ac and H3K27me3 at the FOXO3 promoter region and the regulation of H3K27 modification at the FOXO3 promoter by NIR.ResultsHigh levels of NIR expression were correlated with poor prognosis in breast cancer patients. Knockdown of NIR suppressed the proliferation of breast cancer cells. Mechanically, NIR was recruited by EZH2 to the promoter vicinity of FOXO3 via direct protein–protein interaction. Silencing NIR increased H3K27ac and decreased H3K27me3 levels at the FOXO3 promoter, resulting in enhancing FOXO3 expression. In accordance with this, growth inhibition of breast cancer cells caused by silencing of NIR could be reversed by FOXO3 knockdown.ConclusionNIR knockdown inhibited proliferation by switching the H3K27me3 and H3K27ac marks at the FOXO3 promoter to promote FOXO3 transcription, and this effect depends on the physical interaction between NIR and PRC2 in breast cancer cells. Our results suggest that NIR might be a potential target for breast cancer treatment.

Altered FoxO3 expression and apoptosis in granulosa cells of women with polycystic ovary syndrome.

To determine the level of apoptosis, and alteration of FoxO3 (forkhead box O3 transcription factor) expression and phosphorylation in human granulosa cells amongst polycystic ovary syndrome (PCOS) patients and control group. We recruited infertile women with PCOS (n=14) and compared them with infertile women due to tubal blockage or male factor infertility (n=14, controls). GnRH agonist and gonadotropins were used for ovarian stimulation. Follicular fluids from large follicles (>16mm) were pooled and granulosa cells (GCs) were isolated using cell strainer methodology. Apoptosis of purified GCs was measured by flow cytometry using Annexin V and propidium iodide. Quantitative real-time PCR and western blotting were performed to assess alteration of FoxO3 expression and phosphorylation in GCs. There were higher percentages of early and late apoptosis in GCs of PCOS patients than in the control group. FoxO3 mRNA level and total FoxO3 protein were significantly higher in PCOS group than in the control group. The ratio of p-FoxO3/total FoxO3 decreased significantly in PCOS than in the control group. It was inferred that unphosphorylated (active form) FoxO3 was higher in GCs of PCOS patients. Apoptosis was significantly and positively correlated with the total FoxO3 and negatively correlated with the p-FoxO3 protein levels in PCOS patients. Activation and overexpression of FoxO3 in granulosa cells of PCOS women correlated with higher apoptosis levels in these cells suggesting that FoxO3 may be a candidate for the higher apoptosis in granulosa cells from women with PCOS.

SIRT6 suppresses isoproterenol-induced cardiac hypertrophy through activation of autophagy

Reduction in autophagy has been reported to contribute to the pathogenesis of cardiac hypertrophy. However, the molecular pathways leading to impaired autophagy at the presence of hypertrophic stimuli remain to be elucidated. The present study aimed to investigate the role of sirtuin 6 (SIRT6), a sirtuin family member, in regulating cardiomyocyte autophagy, and its implication in prevention of cardiac hypertrophy. Primary neonatal rat cardiomyocytes (NRCMs) or Sprague-Dawley (SD) rats were submitted to isoproterenol (ISO) treatment, and then the hypertrophic responses and changes in autophagy activity were measured. The influence of SIRT6 on autophagy was observed in cultured NRCMs with gain- and loss-of-function approaches to regulate SIRT6 expression, and further confirmed invivo by intramyocardial delivery of an adenovirus vector encoding SIRT6 cDNA. In addition, the involvement of SIRT6-mediated autophagy in attenuation of cardiomyocyte hypertrophy induced by ISO was determined basing on genetic or pharmaceutical disruption of autophagy, and the underlying mechanism was preliminarily explored. ISO-caused cardiac hypertrophy accompanying with a significant decrease in autophagy activity. SIRT6 overexpression enhanced autophagy in NRCMs and in rat hearts, whereas knockdown of SIRT6 by RNA interference led to suppression of cardiomyocyte autophagy. Furthermore, the protective effect of SIRT6 against ISO-stimulated hypertrophy was associated with induction of autophagy. SIRT6 promoted nuclear retention of forkhead box O3 transcription factor possibly via attenuating Aktsignaling, which was responsible for autophagy activation. Our findings revealedthat SIRT6 positively regulates autophagy in cardiomyocytes, which may help to ameliorate ISO-induced cardiac hypertrophy.

Wnt activation protects against neomycin-induced hair cell damage in the mouse cochlea.

Recent studies have reported the role of Wnt/β-catenin signaling in hair cell (HC) development, regeneration, and differentiation in the mouse cochlea; however, the role of Wnt/β-catenin signaling in HC protection remains unknown. In this study, we took advantage of transgenic mice to specifically knockout or overactivate the canonical Wnt signaling mediator β-catenin in HCs, which allowed us to investigate the role of Wnt/β-catenin signaling in protecting HCs against neomycin-induced damage. We first showed that loss of β-catenin in HCs made them more vulnerable to neomycin-induced injury, while constitutive activation of β-catenin in HCs reduced HC loss both in vivo and in vitro. We then showed that loss of β-catenin in HCs increased caspase-mediated apoptosis induced by neomycin injury, while β-catenin overexpression inhibited caspase-mediated apoptosis. Finally, we demonstrated that loss of β-catenin in HCs led to increased expression of forkhead box O3 transcription factor (Foxo3) and Bim along with decreased expression of antioxidant enzymes; thus, there were increased levels of reactive oxygen species (ROS) after neomycin treatment that might be responsible for the increased aminoglycoside sensitivity of HCs. In contrast, β-catenin overexpression reduced Foxo3 and Bim expression and ROS levels, suggesting that β-catenin is protective against neomycin-induced HC loss. Our findings demonstrate that Wnt/β-catenin signaling has an important role in protecting HCs against neomycin-induced HC loss and thus might be a new therapeutic target for the prevention of HC death.

Gossypol Acetic Acid Prevents Oxidative Stress-Induced Retinal Pigment Epithelial Necrosis by Regulating the FoxO3/Sestrin2 Pathway.

The late stage of dry age-related macular degeneration (AMD), or geographic atrophy (GA), is characterized by extensive retinal pigment epithelial (RPE) cell death, and a cure is not available currently. We have recently demonstrated that RPE cells die from necrosis in response to oxidative stress, providing a potential novel mechanism for RPE death in AMD. In this study, we screened U.S. Food and Drug Administration-approved natural compounds and identified gossypol acetic acid (GAA) as a potent inhibitor of oxidative stress-induced RPE cell death. GAA induces antioxidative response and inhibits accumulation of excessive reactive oxygen species in cells, through which it prevents the activation of intrinsic necrotic pathway in response to oxidative stress. Sestrin2 (SESN2) is found to mediate GAA function in antioxidative response and RPE survival upon oxidative stress. Moreover, Forkhead box O3 transcription factor (FoxO3) is further found to be required for GAA-mediated SESN2 expression and RPE survival. Mechanistically, GAA promotes FoxO3 nuclear translocation and binding to the SESN2 enhancer, which in turn increases its transcriptional activity. Taken together, we have identified GAA as a potent inhibitor of oxidative stress-induced RPE necrosis by regulating the FoxO3/SESN2 pathway. This study may have significant implications in the therapeutics of age-related diseases, especially GA.

Upregulation of forkhead box O3 transcription is involved in C2-ceramide induced apoptosis and autophagy in ovarian cancer cells in vitro.

Ceramide is a bioactive lipid which functions as a tumor suppressor, mediating processes such as apoptosis, growth arrest, senescence and differentiation. The effects of ceramide in ovarian cancers have not been well established. The objective of the present study was to investigate the effects of C2‑ceramide treatment in A2780 ovarian cancer cells and its possible molecular mechanism. C2‑ceramide-induced proliferation inhibition was analyzed using an MTT assay and Trypan blue test. Flow cytometry and terminal deoxynucleotidyl transferase dUTP nick end labeling were used to identify the induction of apoptosis. Transmission electron microscopy was used to confirm the formation of autophagosomes. Quantitative polymerase chain reaction was performed to analyze the messenger RNA expression of the autophagy and cell death associated genes and western blotting was used to analyze the protein expression of beclin 1, LC3, Akt, forkhead box O3 (FOXO3) and adenosine monophosphate-activated protein kinase in ovarian cancer cells. It was found that C2‑ceramide inhibited A2780 cell proliferation in a time‑ and dose‑dependent manner and C2‑ceremide induced A2780 cell apoptosis and autophagy. However, C2‑ceramide‑induced autophagy did not result in cell death, but instead protected ovarian cancer cells from apoptosis. Akt inhibition and FOXO3 activation were implicated in C2‑ceramide‑treated ovarian cancer cells. Furthermore, FOXO3 target genes, which were associated with autophagy (MAP1LC3, GABARAP and GABARAPL1) and cell death (BNIP3, BNIP3L, BIM and PUMA), were upregulated. The present study has shown that C2‑ceramide induced apoptosis and autophagy in ovarian cancer cells. FOXO3 transcription was upregulated, which may contribute to C2‑ceramide‑induced apoptosis and autophagy.

Forkhead box O3 (FOXO3) transcription factor mediates apoptosis in BCG-infected macrophages

Enhanced apoptosis of BCG-infected macrophages has been shown to induce stronger dendritic cell-mediated cross-priming of T cells, leading to higher protection against tuberculosis (TB). Uncovering host effectors underlying BCG-induced apoptosis may then prove useful to improve BCG efficacy through priming macrophage apoptosis. Her we report that BCG-mediated apoptosis of human macrophages relies on FOXO3 transcription factor activation. BCG induced a significant apoptosis of THP1 (TDMs) and human monocytes (MDMs)-derived macrophages when a high moi was used, as shown by annexin V/7-AAD staining. BCG-induced apoptosis was associated with dephosphorylation of the prosurvival activated threonine kinase (Akt) and its target FOXO3. Cell fractionation and immunofluorescence microscopy showed translocation of FOXO3 to the nucleus in BCG-infected cells, concomitantly with an increase of FOXO3 transcriptional activity. Moreover, FOXO3 expression knock-down by small interfering RNA (siRNA) partially inhibited the BCG-induced apoptosis. Finally, real-time quantitative PCR (qRT-PCR) analysis of the expression profile of BCG-infected macrophages showed an upregulation of two pro-apoptotic targets of FOXO3, NOXA and p53 upregulated modulator of apoptosis (PUMA). Our results thus indicate that FOXO3 plays an important role in BCG-induced apoptosis of human macrophages and may represent a potential target to improve vaccine efficacy through enhanced apoptosis-mediated cross-priming of T cells.

Association between FOXO3A gene polymorphisms and human longevity: a meta-analysis

Numerous studies have shown associations between the FOXO3A gene, encoding the forkhead box O3 transcription factor, and human or specifically male longevity. However, the associations of specific FOXO3A polymorphisms with longevity remain inconclusive. We performed a meta-analysis of existing studies to clarify these potential associations. A comprehensive search was conducted to identify studies of FOXO3A gene polymorphisms and longevity. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by comparing the minor and major alleles. A total of seven articles reporting associations of FOXO3A polymorphisms with longevity were identified and included in this meta-analysis. These comprised 11 independent studies with 5241 cases and 5724 controls from different ethnic groups. rs2802292, rs2764264, rs13217795, rs1935949 and rs2802288 polymorphisms were associated with human longevity (OR = 1.36, 95% CI = 1.10–1.69, P = 0.005; OR = 1.20, 95% CI = 1.04–1.37, P = 0.01; OR = 1.27, 95% CI = 1.10–1.46, P = 0.001; OR = 1.14, 95% CI = 1.01–1.27 and OR = 1.24, 95% CI = 1.07–1.43, P = 0.003, respectively). Analysis stratified by gender indicated significant associations between rs2802292, rs2764264 and rs13217795 and male longevity (OR = 1.54, 95% CI = 1.33–1.79, P < 0.001; OR = 1.38, 95% CI = 1.15–1.66, P = 0.001; and OR = 1.39, 95% CI = 1.15–1.67, P = 0.001), but rs2802292, rs2764264 and rs1935949 were not linked to female longevity. Moreover, our study showed no association between rs2153960, rs7762395 or rs13220810 polymorphisms and longevity. In conclusion, this meta-analysis indicates a significant association of five FOXO3A gene polymorphisms with longevity, with the effects of rs2802292 and rs2764264 being male-specific. Further investigations are required to confirm these findings.