Translocation Of FoxO1 Research Articles

MSC-secreted TGF-\u03b2 regulates lipopolysaccharide-stimulated macrophage M2-like polarization via the Akt/FoxO1 pathway

BackgroundAn uncontrolled inflammatory response is a critical pathophysiological feature of sepsis. Mesenchymal stem cells (MSCs) induce macrophage phenotype polarization and reduce inflammation in sepsis. MSC-secreted transforming growth factor beta (TGF-β) participated in the immune modulatory function of MSCs. However, the underlying mechanism of MSC-secreted TGF-β was not fully elucidated in regulation macrophage M2-like polarization.MethodsThe paracrine effects of MSCs on macrophage polarization were studied using a co-culture protocol with LPS-stimulated RAW264.7 cells/mouse peritoneal macrophages and MSCs. The effect of TGF-β in the co-culture system was blocked by the TGF-β receptor inhibitor. To determine the role of MSC-secreted TGF-β, we used recombinant TGF-β to culture with LPS-stimulated RAW264.7 cells. In addition, we employed antibody microarray analysis to determine the mechanisms of MSC secreted TGF-β on LPS-stimulated RAW264.7 cell/mouse peritoneal macrophage M2-like polarization. Furthermore, we used an Akt inhibitor and a FoxO1 inhibitor to inhibit the Akt/FoxO1 pathway. The nuclear translocation of FoxO1 was detected by Western blot.ResultsMSCs induced LPS-stimulated RAW264.7 cell/mouse peritoneal macrophage polarization towards the M2-like phenotype and significantly reduced pro-inflammatory cytokine levels via paracrine, which was inhibited by TGF-β receptor inhibitor. Furthermore, we found that MSC-secreted TGF-β enhanced the macrophage phagocytic ability. The antibody microarray analysis and Western blot verified that TGF-β treatment activated the Akt/FoxO1 pathway in LPS-stimulated macrophages, TGF-β-induced FoxO1 nuclear translocation and obviously expressed in the cytoplasm, the effects of TGF-β regulatory effects on LPS-stimulated macrophage were inhibited by pre-treatment with Akt inhibitor and FoxO1 inhibitor.ConclusionsTGF-β secreted by MSCs could skew LPS-stimulated macrophage polarization towards the M2-like phenotype, reduce inflammatory reactions, and improve the phagocytic ability via the Akt/FoxO1 pathway, providing potential therapeutic strategies for sepsis.

PRMT5 Inhibition Drives Therapeutic Vulnerability to BCL-2 Inhibition with Venetoclax and Provides Rationale for Combination Therapy in Mantle Cell Lymphoma

Mantle cell lymphoma (MCL) is an incurable B cell malignancy, defined by the t(11;14) translocation and comprises 3-6% of non-Hodgkin lymphomas diagnosed annually. MCL is associated with a poor prognosis due to emergence of resistance to immuno-chemotherapy and targeted agents. Due to the late median age of diagnosis, aggressive chemotherapy and stem cell transplantation are often not realistic options. The average overall survival of patients with MCL is 5 years and for the majority of patients who progress on targeted agents like ibrutinib, survival remains at a dismal 3-8 months. There is a major unmet need to identify new therapeutic approaches that are well tolerated by elderly patients to improve treatment outcomes and quality of life. Our group has identified the type II protein arginine methyltransferase enzyme, PRMT5, to be dysregulated in MCL and to promote growth and survival by supporting the cell cycle, PRC2 activity, and signaling via the BCR and PI3K/AKT pathways. We have developed first-in-class selective inhibitors of PRMT5 and, in collaboration with Prelude Therapeutics, we have demonstrated that novel SAM-competitive PRMT5 inhibitors provide potent anti-tumor activity in aggressive preclinical models of human MCL. Selective inhibition of PRMT5 in these models and MCL cell lines leads to disruption of constitutive PI3K/AKT signaling, dephosphorylation and nuclear translocation of FOXO1, and enhanced recruitment of this tumor suppressor protein to chromatin. We identified 136 newly emerged FOXO1-bound genomic loci following 48 hours of PRMT5 inhibition in the CCMCL1 MCL line by performing chromatin immunoprecipitation-seq analysis. These genes were markedly upregulated in CCMCL1 cells treated with the PRMT5 inhibitor PRT382 as determined by RNA-seq analysis. Among those genes, we identified and confirmed FOXO1 recruitment to the promoter of BAX, a pro-apoptotic member of the BCL2 family of proteins. Treatment of MCL cell lines (Granta-519, CCMCL1, Z-138, and SEFA) with the selective PRMT5 inhibitor PRT382 (10, 100nM) led to upregulation of BAX protein levels and induction of programmed cell death as measured by annexin V/PI staining and flow cytometry. We hypothesized that induction of BAX would trigger a therapeutic vulnerability to the BCL2 inhibitor venetoclax, and that combination PRMT5/BCL2 inhibitor therapy would drive synergistic cell death in MCL. Single agent and combination treatment with venetoclax and PRT382 was performed in eight MCL lines including a new cell line generated from our ibrutinib-refractory PDX model (SEFA) and IC50 and synergy scores were calculated. The Z-138 line was most sensitive to venetoclax (IC50<10nM) while CCMCL-1, SP53, JeKo-1, and Granta-519 demonstrated relative resistance (IC50>1uM). All lines reached an IC50 <1uM when co-treated with PRT382, with IC50 values ranging from 20 - 500nM. Combination treatments showed high levels of synergy (scores > 20) in 4 lines and moderate synergy (scores 10-20) in 2 lines. The two lines with the highest levels of synergy, Z-138 and SEFA, express high levels of BCL-2 and are Ibrutinib resistant. Overall there was a strong positive correlation between BCL2 expression and synergy score (r=0.707), and no correlation between PRMT5 expression and synergy score (r=0.084). In vivo evaluation in two preclinical MCL models (Granta-519 NSG mouse flank and an ibrutinib-resistant MCL PDX) showed therapeutic synergy with combination venetoclax/PRT382 treatment. In both models, mice were treated with sub-therapeutic doses of venetoclax and/or PRT543 (Granta) or PRT382 (IR-MCL PDX) and tumor burden assessed weekly via flank mass measurement (Granta) or flow cytometry (IR-MCL-PDX). Combination treatment with well-tolerated doses of venetoclax and PRMT5 inhibitors in both MCL in vivo models showed synergistic anti-tumor activity without evidence of toxicity. This preclinical data provides mechanistic rationale while demonstrating therapeutic synergy and lack of toxicity in this preclinical study and justifies further consideration of this combination strategy targeting PRMT5 and BCL2 in MCL in the clinical setting. PRT543, a selective PRMT5 inhibitor, has been advanced into clinical studies for the treatment of patients with solid tumors and hematologic malignancies, including MCL (NCT03886831). Disclosures Zhang: Prelude Therapeutics: Employment. Vaddi:Prelude Therapeutics: Employment. Scherle:Prelude Therapeutics: Employment. Baiocchi:Prelude: Consultancy.

Interaction of Mantle Cell Lymphoma with the Microenvironment Induces Phospho Akt-Mediated Resistance Against BTK Inhibition and Can be Overcome By Co-Treatment with a Specific Akt Inhibitor (MK-2206)

Mantle cell lymphoma (MCL) is a distinct lymphoma subtype representing 6-8% of non-Hodgkin's lymphoma (NHL). Although with current standard therapy high initial response rates can be achieved, early relapses and rapid disease progression determine the clinical course of most MCL patients. Recently, Bruton´s tyrosine Kinase (BTK) inhibitors have been introduced with highly promising clinical activity. Nevertheless, interindividual responsiveness is heterogenous and primary and secondary resistance has been reported. However, molecular mechanisms driving resistance to BTK inhibition are not well understood yet. Among other factors, interactions between the tumor and its microenvironment have been proposed to play an important role in response to targeted therapy. In this study, we investigated the influence of tumor cell interaction with its microenvironment on sensitivity to the BTK inhibitor CC292 in vitro. MCL cell lines JeKo-1, Z-138 and Granta-519 were treated with 5 µM of CC292 alone or in co-culture with human bone marrow stromal cells (HS-5) and cell death induction and proliferation were assessed. Expression of proteins involved in BCR signaling and other tumor-promoting pathways was analyzed by Western Blot. Co-cultured MCL cells settled within the stromal cell layer were separated using MACS Feeder removal microbeads prior to Western Blot analysis. In all cell lines, direct interaction with the microenvironment markedly reduced sensitivity towards CC292 treatment (by 22% (JeKo-1), 33% (Granta) and 64 % (Z-138)). Importantly, cell-cell contact was shown to play a crucial role for mediating resistance to CC292 as only those MCL cells settled within the stromal cell layer proved to be significantly less vulnerable to the inhibitor compared to MCL cells co-cultured with HS-5 but separated by a transwell insert. Western Blot analysis showed a reduction of protein levels of phBTK upon treatment with CC292 in both, mono- and co-cultured cells. Interestingly, direct interaction of MCL cells with the microenvironment strongly induced protein expression of phAkt. Accordingly, phosphorylation (inactivation) of the pro-apoptotic FoxO1, a downstream-target of phAkt, was increased and its translocation to the nucleus was decreased in those cells. We could show that the effect of microenvironment interaction on sensitivity towards CC292 is mediated by Akt as knockdown of Akt using siRNA restored sensitivity to the drug. Furthermore, co-treatment of MCL cells with CC292 and the specific Akt inhibitor MK-2206 hampered upregluation of phAkt in co-cultivated cells and prevented Akt-mediated sequestration of FoxO1 in the cytoplasm, resulting in translocation of FoxO1 to the nucleus. Thus, combination with MK-2206 could significantly overcome microenvironment-mediated protection from growth inhibition and apoptosis induction upon CC292 treatment. Moreover, combination of the BTK inhibitor CC292 and the Akt inhibitor MK-2206 proved to act synergistically in MCL cells in all dose combinations tested (Combination index 0,73-0,93 in Z-138; 0,47-0,78 in JeKo-1). Taken together, cell-cell-interaction of MCL cells with their microenvironment protected them from CC292-induced cell death. This effect was mediated by increased phAkt expression resulting in inhibition of pro-apoptotic signaling and could effectively be overcome by combination with the specific Akt inhibitor MK-2206. Furthermore, CC292 and MK-2206 acted synergistically in MCL cells. Our results indicate that co-targeting the PI3K/Akt-pathway might be a promising strategy to overcome resistance to BTK inhibition mediated by interaction with the microenvironment. Disclosures Dreyling: Sandoz: Other: Scientific advisory board; Roche: Other: Scientific advisory board, Research Funding, Speakers Bureau; Novartis: Other: Scientific advisory board; Mundipharma: Other: Scientific advisory board, Research Funding; Janssen: Other: Scientific advisory board, Research Funding, Speakers Bureau; Gilead: Other: Scientific advisory board, Speakers Bureau; Celgene: Other: Scientific advisory board, Research Funding, Speakers Bureau; Bayer: Other: Scientific advisory board, Speakers Bureau; Acerta: Other: Scientific advisory board.

Advanced Glycation End-Products and Hyperglycemia Increase Angiopoietin-2 Production by Impairing Angiopoietin-1-Tie-2 System.

The angiopoietin-Tie-2 system plays a crucial role in the maintenance of endothelial integrity. Hyperglycemia and advanced glycation end-products (AGEs) are involved in endothelial cell dysfunction responsible of the pathogenesis of microvascular complications of diabetes. Here, we investigated whether glycated serum (GS) or hyperglycemia (HG) affect the angiopoietin-Tie-2 system in the microvascular endothelial cells HMEC-1. We found that culture for 5 days in the presence of AGEs and HG (alone or in combination) decreased cell proliferation, increased reactive oxygen species (ROS) production, and reduced ratio between the oxidized and the reduced form of glutathione. Since angiopoietin-1 (Ang-1) signaling regulates angiopoietin-2 (Ang-2) expression through inactivation of the forkhead transcription factor FoxO1, we investigated intracellular signaling of Ang-1 and expression of Ang-2. HG and AGEs reduced phosphorylation of Akt and abrogated phosphorylation of FoxO1 induced by Ang-1 without affecting neither Tie-2 expression nor its activation. Furthermore, AGEs and/or HG induced nuclear translocation of FoxO1 and increased Ang-2 production. In conclusion, we demonstrated that both hyperglycemia and AGEs affect the angiopoietin-Tie-2 system by impairing Ang-1/Tie-2 signaling and by increasing Ang-2 expression. These results suggest that therapeutic strategies useful in preventing or delaying the onset of diabetic vascular complications should be aimed to preserve Ang-1 signaling.

1853-P: Transforming Growth Factor Beta 1 Acts as a Hepatokine in Control of Glucose and Energy Metabolism

Liver and adipose tissue are crucial for blood glucose and energy homeostasis, while impaired regulation of hepatic glucose production (HGP) and energy expenditure contribute to hyperglycemia and excessive fat storage in type 2 diabetes mellitus. Hepatokines are proteins secreted by hepatocytes, and several hepatokines have been shown to directly affect glucose and energy expenditure. In this study, we investigated the role of transforming growth factor beta 1 (TGF-β1) in hepatocytes in regulating glucose and energy homeostasis. We generated the liver-specific TGF-β1 knockout mice and found that the mice exhibited lower blood glucose, increased hepatic insulin sensitivity compared with wild type (WT) control mice. Using the mouse primary hepatocytes, we found that TGF-β1 deletion impaired HGP and TGF-β1 treatment promoted protein kinase A (PKA) signaling and stimulated the nuclear translocation of FoxO1. Under high fat diet (HFD) treatment, hepatic TGF-β1 deficiency protected mice from HFD-induced obesity and insulin resistance, decreased HGP and improved energy expenditure. Moreover, we used hepatic insulin receptor substrate-1, 2 (IRS1, 2) knockout (DKO) mice and deleted the TGF-β1 gene in the liver of DKO mice. We found that hepatic TGF-β1 ablation prevented hyperglycemia and hyperinsulinemia in DKO mice. Deletion of TGF-β1 or neutralization of TGF-β1 with antibody significantly decreased HGP of DKO hepatocytes. Additionally, hepatic TGF-β1 ablation enhanced thermogenesis and inguinal white adipose tissue (iWAT) browning in DKO mice. These findings underscore an important role of hepatic TGF-β1 in contribution to systemic glucose and energy homeostasis. Thus, hepatic TGF-β1 may serve as a therapeutic target for control of glucose and energy homeostasis in insulin resistance and type 2 diabetes mellitus. Disclosure Q. Pan: None. Y. Chen: None. D. Kim: None. Z. Shen: None. W. Yang: None. X. Li: None. Y. Sun: None. S. Guo: None. Funding American Diabetes Association (1-15-CD-09 to S.G.)

1864-P: p38α MAPK Mediates Glucagon-Induced Hepatic Glucose Production through Phosphorylation of Foxo1 at Ser273

Glucagon is involved in glucose homeostasis via triggering gluconeogenesis and glycogenolysis. In addition to activation of protein kinase A (PKA), p38α MAPK (p38) is activated by glucagon and promotes glucagon-induced hepatic glucose production. However, underlying mechanisms by which p38 mediates the effect of glucagon are not well elucidated. Previously, we established that glucagon increases the phosphorylation of Foxo1 at Ser273 via PKA to promote hepatic glucose production. In this study, we investigated the potential role of p38 in the action of glucagon by phosphorylation of Foxo1 at Ser273. Using the mouse primary hepatocytes, we showed that activation of p38 by glucagon promoted phosphorylation of Foxo1 at Ser273, which results in both increased stability and nuclear translocation of Foxo1. In vivo kinase assay shows that the active p38 enzyme increased the phosphorylation of Foxo1 at Ser273. Moreover, p38 promoted glucagon-induced PKA activity to increase the phosphorylation of Foxo1 at Ser273. Suppression of p38 by siRNA and SB203580 decreased hepatic glucose production by glucagon in control mouse primary hepatocytes; however, such an effect was diminished in the hepatocytes isolated from the Foxo1-S273D knock-in mice, where Foxo1-Ser273 was replaced by the aspartate mutation (D). In mice, we further showed that injection of p38 inhibitor SB203580 decreased the fasting blood glucose and hepatic glucose production in wild type control mice, while this effect was not observed in Foxo1-S273D mice. These results revealed the novel role of p38 in control of Foxo1 phosphorylation at Ser273 to regulate the action of glucagon in glucose homeostasis. Disclosure W. Yang: None. W. Ai: None. X. Li: None. Q. Pan: None. Z. Shen: None. Y. Chen: None. Y. Sun: None. S. Guo: None. Funding American Diabetes Association (1-15-CD-09 to S.G.); National Institutes of Health (R01DK095118)

FoxK1 and FoxK2 in insulin regulation of cellular and mitochondrial metabolism

A major target of insulin signaling is the FoxO family of Forkhead transcription factors, which translocate from the nucleus to the cytoplasm following insulin-stimulated phosphorylation. Here we show that the Forkhead transcription factors FoxK1 and FoxK2 are also downstream targets of insulin action, but that following insulin stimulation, they translocate from the cytoplasm to nucleus, reciprocal to the translocation of FoxO1. FoxK1/FoxK2 translocation to the nucleus is dependent on the Akt-mTOR pathway, while its localization to the cytoplasm in the basal state is dependent on GSK3. Knockdown of FoxK1 and FoxK2 in liver cells results in upregulation of genes related to apoptosis and down-regulation of genes involved in cell cycle and lipid metabolism. This is associated with decreased cell proliferation and altered mitochondrial fatty acid metabolism. Thus, FoxK1/K2 are reciprocally regulated to FoxO1 following insulin stimulation and play a critical role in the control of apoptosis, metabolism and mitochondrial function.

Epigallocatechin Gallate Inhibits Hepatic Glucose Production in Primary Hepatocytes via Downregulating PKA Signaling Pathways and Transcriptional Factor FoxO1.

Forkhead/winged helix transcription factor O-class member 1 (FoxO1) is a key mediator of insulin and glucagon signaling in control of glucose homeostasis. Although epigallocatechin gallate (EGCG) has attracted interest owing to its potential to combat hyperglycemic diabetes, molecular mechanisms underlying its antihyperglycemic effect, in particular the effect on FoxO1, is poorly understand. This study aims to assess the impact of EGCG on the glucagon signaling pathway in regulating glucose metabolism. Primary hepatocytes from wild-type (WT), liver-specific FoxO1 knock out (FKO), and FoxO1-S273D knock-in (KI) mice were isolated, cultured, and treated with EGCG and/or glucagon. Our data showed the treatment of 10 μM EGCG for 6 h decreased hepatic glucose production by 20 and 23% in WT and FKO primary hepatocytes, respectively. EGCG repressed both gluconeogenesis and glycogenolysis in primary hepatocytes, coupled with activating AMPK. In addition, EGCG decreased mitochondrial oxygen consumption. We further investigated the effects of EGCG on glucagon-stimulated cAMP/PKA signaling pathway. EGCG reduced p-PKA-T197/T-PKA and p-CREB-S133/T-CREB levels by 39 and 20%, blocked p-FoxO1-S273, and suppressed nuclear FoxO1 translocation, suggesting that FoxO1 and CREB were possible downstream targets. A novel mechanism of EGCG in restraining hepatic glucose production (HGP) is through antagonizing glucagon signaling and suppressing FoxO1 via Ser273. EGCG may serve as a promising compound for regulating glucose homeostasis.

Anti-diabetic effect of loganin by inhibiting FOXO1 nuclear translocation via PI3K/Akt signaling pathway in INS-1 cell.

Objective(s):JiangTangXiaoKe (JTXK) granule, a Chinese traditional herbal formula, has been clinically used and demonstrated to be beneficial in controlling high glucose and to relieve the symptoms of Type 2 diabetes mellitus patients for decades. In this study, we explored how loganin, one of the components in JTXK granule, mediated the anti-diabetic effect.Materials and Methods:We generate a cell model with the dysfunction of insulin secretion by over-expression FOXO1 in INS-1 cells. MTT method was used to detect cytotoxicity after treated with Loganin. ELISA analysis was used to examine insulin secretion. The expression levels of FOXO1 and Akt were evaluated by Western blot.Results:Treatment with Loganin did not change the expression level of FOXO1 in INS-1 cells, but increased phosphorylation of FOXO1 and inhibited the nuclear translocation and accumulation of FOXO1, which improved the insulin secretion of the cells. Mechanistically, we found PI3K/Akt signaling pathway involved in these effects, which were blocked by an Akt inhibitor, LY294002.Conclusion:Loganin mediated the subcellular distribution of FOXO1 via PI3K/Akt signaling pathway, which protected the function of insulin secretion in islet INS-1 cells.

Paclitaxel alleviates monocrotaline-induced pulmonary arterial hypertension via inhibition of FoxO1-mediated autophagy.

It has been demonstrated that activation of autophagy is involved in the development of pulmonary arterial hypertension (PAH). Recent studies have shown that cytosolic forkhead box protein O1 (FoxO1) activates autophagy in cancer cells. Paclitaxel has been found to potentially reverse PAH progression. However, the role of FoxO1 and the effects of paclitaxel on autophagy in the pathogenesis of PAH remain unknown. PAH was generated by intraperitoneal injection of monocrotaline (MCT) to rats. The right ventricular systolic pressure (RVSP), the right ventricle hypertrophy index (RV/LV+S), and the percentage of medial wall thickness (%MT) were used to detect the development of PAH. Hematoxylin and eosin staining was performed to measure pulmonary vascular remodeling. The protein level, phosphorylation, and nucleus translocation of FoxO1 and the levels of LC3A, LC3B, and Beclin-1 were examined by immunoblotting. The results showed that in spite of reduced expression of FoxO1, elevated phosphorylation of FoxO1 caused most of FoxO1 accumulating in cytosolic fraction in MCT-PAH rats. Autophagy was also activated in the MCT-PAH group. In cultured rat pulmonary arterial smooth muscle cells (PASMCs), knockdown of FoxO1 markedly blocked autophagy activation, indicating that elevation of cytosolic FoxO1 stimulates autophagy activation. Treatment of PAH rats with paclitaxel reduced FoxO1 phosphorylation and increased FoxO1 nuclear accumulation, despite increased FoxO1 expression, therefore suppressed autophagy, finally reduced elevated RVSP, RV/LV+S, and %MT in MCT-induced PAH. Taken together, paclitaxel inhibits pulmonary vascular remodeling by FoxO1-mediated autophagy suppression, suggesting that paclitaxel might be a novel therapeutic agent for the prevention and treatment of PAH.

Interplay Among PI3K/AKT, PTEN/FOXO and AR Signaling in Prostate Cancer.

The PI3K signaling pathway is activated in a majority of cancer types. It promotes tumorigenesis by regulating nutrient metabolism, cell proliferation, survival, migration, and angiogenesis. The underlying mechanisms of PI3K/AKT activation are mainly due to deletions or mutations in its key negative regulator gene-PTEN. However, mutations in other pathway genes, such as the tumor suppressor gene SPOP, may contribute indirectly to the activation of this pathway. Interestingly, a mutually exclusive relationship exists between genomic alterations in PTEN and mutations in SPOP in prostate cancer patients, suggesting that altered functions of these two tumor suppressors might share similar or at least partially overlapping mechanisms in tumorigenesis. Activated AKT can phosphorylate directly a number of downstream effectors and thereby inhibit or activate their functions. An important target of PI3K/AKT signaling is FOXO1 protein that can be phosphorylated directly by AKT leading to translocation of FOXO1 from the cytoplasm to the nucleus. This not only impairs FOXO1 activities on transactivation of downstream target genes, but also abolishes its transcriptional activity-independent inhibitory effect on other targetssuch as AR, ERG and RUNX2. Interestingly, heterozygous deletion of Pten, or mutation of Spop alone has minimal effects on tumorigenesis in the mouse prostate, suggesting that PI3K/AKT pathway interacts with other pathways to drive prostate cancer progression. Indeed, the cross talk between PI3K/AKT and other pathways, such as AR, WNT, and ERK signaling pathways is known to play essential roles in disease progression and drug resistance in prostate cancer. Therefore, co-targeting the PI3K/AKT signaling pathway and its cooperating pathways may be critical for improving the anti-cancer efficacy of PI3K/AKT inhibitors in the clinic.

Decreased PKG transcription mediated by PI3K/Akt/FoxO1 pathway is involved in the development of nitroglycerin tolerance

Phosphoinositide 3-kinase (PI3K)/Akt plays a pivotal role in the vascular response. The present study is to determine whether PI3K/Akt pathway in vascular smooth muscle cells is involved in nitroglycerin (NTG) tolerance and the underlying mechanism. Nitrate tolerance of porcine coronary arteries in vitro was induced by incubation of NTG (10−5 M) for 24 h. Nitrate tolerance in vivo was obtained by subcutaneous injection of mice with NTG (20 mg kg−1, tid, 3 days) and the aortas were used. Protein levels of total and phosphorylated Akt, forkhead box protein O1 (FoxO1), and cGMP-dependent protein kinase (PKG) were determined by western blot analysis. Isometric vessel tension was recorded by organ chamber technique. PKG mRNA was determined by real-time PCR. The cellular translocation of FoxO1 was observed by immunofluorescence. Reactive oxygen species (ROS) level was measured by DHE staining. The vascular relaxation to NTG was significantly inhibited in in vivo and in vitro NTG tolerant arteries. Meanwhile, the protein level of phosphorylated Akt at Ser473 was increased in the tolerant arteries. The attenuated relaxation and the augmented Akt-p were ameliorated by LY294002, a specific inhibitor of PI3K. The protein and mRNA expression of PKG were significantly down-regulated in NTG tolerant arteries, which were reversed by LY294002. The level of phosphorylated FoxO1 at Ser256 and its translocation from the nucleus to the cytosol were both increased in NTG tolerance and were also inhibited by LY294002. ROS production was significantly increased in NTG tolerant arteries, which was not be affected by LY294002 but inhibited by N-acetyl-L-cysteine. In conclusion, the present study suggests that PI3K/Akt in vascular smooth muscle is involved in the development of NTG tolerance via inhibiting PKG transcription and the effect is mediated by FoxO1.

Novel MEIS1-FOXO1 Fusion Gene in a Case of Pediatric B-Cell Precursor Acute Lymphoblastic Leukemia

Background: Thanks to the total therapy and systemic basic-translation research, the overall survival rate in children with acute lymphoblastic leukemia (ALL) has dramatically improved to almost 90% over these past few decades. FOXO1 gene belongs to the forkhead family of transcription factors, which play roles in myogenic growth and differentiation. Translocation of FOXO1 with PAX3 has been reported in pediatric alveolar rhabdomyosarcoma. In B-cell precursor ALL, two cases with FOXO1 fusions have been identified already, while its function on ALL remains unknown. Here, we report a novel MEIS1-FOXO1 fusion gene in a case with B-ALL. Methods: Flowcytometery, karyotype, RT-PCR and fluorescence in were employed, MEIS1-FOXO1 was identified as novel fusion gene in a case of pediatric BCP-ALL. Using IL-3 dependent BaF3 cells as study model to test the leukemia transformation potential of MEIS1-FOXO1. Results: A novel MEIS1-FOXO1 fusion was identified in one cease of pediatric B-ALL. Panel next generation sequencing (NGS) showed that the leukemia clone had concurrent NRASG12D, TP53R273H, WHSC1E1099K, ABCC1R1166X, PHGR1H37P, HOXA3P219L and DSTP4606L somatic mutation. This patient was enrolled in CCCG-ALL2015 clinical trial (ChiCTR-IPR-14005706) and achieved completed remission and low minimal residual disease (MRD) level (MRD<0.01%) at day 19 from induction therapy. Functional study showed that MEIS1-FOXO1 fusion gene can potentiate BaF3 cells growth independent of IL3 supplement, as compared to those without MEIS1-FOXO1 fusion transduction. In the meanwhile, we have found that MEIS1-FOXO1 fusion gene can drive cells into S-phase with concurrent decreased G0/G1 phase, which might be its oncogenic role in leukemogenesis. Using qPCR methods, we have found that MEIS1-FOXO1 fusion gene altered the cell cycle related genes expression. Conclusions: Integrating the FOXO1-fusion reports, our data have added more evidence to underline the role of FOXO1 deregulation in the pathogenesis of acute lymphoblastic leukemia. Novel fusion of MEIS1-FOXO1 can potentiate B-ALL via cell cycle entry. Detailed mechanisms involved into the MEIS1-FOXO1 should be further investigated. DisclosuresNo relevant conflicts of interest to declare.

P47phox-Dependent Reactive Oxygen Species Stimulate Nuclear Translocation of the FoxO1 Transcription Factor During Metabolic Inhibition in Cardiomyoblasts

Reactive oxygen species (ROS) control forkhead box O (FOXO) transcription factor activity by influencing their nuclear translocation. However, knowledge of the ROS cellular source(s) involved herein remains scarce. Recently, we have shown p47phox-dependent activation of ROS-producing NADPH oxidase (NOX) at the nuclear pore in H9c2 rat cardiomyoblasts in response to ischemia. This localizes NOX perfectly to affect protein nuclear translocation, including that of transcription factors. In the current study, involvement of p47phox-dependent production of ROS in the nuclear translocation of FOXO1 was analyzed in H9c2 cells following 4 h of metabolic inhibition (MI), which mimics the effects of ischemia. Nuclear translocation of FOXO1 was determined by quantitative digital-imaging fluorescence and western blot analysis. Subsequently, the effect of inhibiting p47phox-dependent ROS production by short hairpin RNA (shRNA) transfection on FOXO1 translocation was analyzed by digital-imaging microscopy. MI induced a significant translocation of FOXO1 into the nucleus. Transfection with p47phox-shRNA successfully knocked-down p47phox expression, reduced nuclear nitrotyrosine production, an indirect marker for ROS production, and inhibited the nuclear translocation of FOXO1 following MI. With these results, we show for the first time that nuclear import of FOXO1 induced by MI in H9c2 depends critically on p47phox-mediated ROS production.

FoxK1/K2 Are New, Important Components of IR and IGF1R Signaling and Control of Cell Proliferation and Metabolism

Insulin and IGF-1 are regulators of cell growth and metabolism. Despite considerable progress in understanding the molecular mechanisms underlying these effects, except for members of the FoxO family, many regulators of the transcriptional effects of these hormones remain poorly understood. To identify new components of IR/IGF1R signaling, we created brown preadipocyte lines in which both endogenous IR and IGF1R genes had been deleted and then reconstituted these cells with normal IR, IGF1R or chimeric receptors containing the extracellular domain of IR fused to intracellular domain of IGF1R and vice versa. Mass spectroscopic proteomic analysis revealed a number of proteins co-precipitated with each receptor construct, in both ligand stimulation-dependent and -independent manners. Among the proteins that associated with both receptors and chimeric receptors in a ligand-dependent manner was FoxK1. In contrast to FoxO1, the transcription factor FoxK1 was translocated from the cytoplasm to the nucleus after insulin stimulation, a pattern that is reciprocal to that of FoxO1 after insulin stimulation. We show that FoxK1 and FoxK2 are phosphorylated in two major domains and that translocation to the nucleus is dependent on the Akt-mTOR mediated phosphorylation, while their localization to the cytoplasm in the basal state is dependent on GSK3 phosphorylation. Knockdown of FoxK1 and FoxK2 in a mouse hepatocyte cell line causes marked alteration of the transcription of genes associated with apoptotic pathway and down-regulation of genes involved in control of cell cycle and metabolism. This resulted in decreased cell proliferation and altered mitochondrial fatty acid metabolism in these cells. Thus, insulin stimulates the reciprocal translocation of FoxKs and FoxO1 between the cytoplasm and nucleus turning off FoxO1-regulated genes and turning on FoxK-regulated genes resulting in an elaborate balance in insulin regulation of metabolism, growth and cell survival. Disclosure M. Sakaguchi: None. W. Cai: None. C. Wang: None. T.M. Batista: None. E. Araki: Speaker's Bureau; Self; Astellas Pharma US, Inc., MSD K.K., Kowa Pharmaceuticals America, Inc., Sanofi, Novo Nordisk Inc.. Research Support; Self; Astellas Pharma US, Inc., MSD K.K., Ono Pharmaceutical Co., Ltd., Shionogi &amp; Co., Ltd., Takeda Pharmaceuticals U.S.A., Inc., Daiichi Sankyo Company, Limited, Nippon Boehringer Ingelheim Co. Ltd., Novartis Pharma K.K., Novo Nordisk Inc., Sanofi, Mitsubishi Tanabe Pharma Corporation, Sumitomo Dainippon Pharma Co., Ltd., Taisho Toyama Pharmaceutical Co. C. Kahn: Advisory Panel; Self; CohBar, ERX Therapeutics, AntriaBio, Inc.. Board Member; Self; Kaleio Biosciences.

Pharmacologic Inhibition of FOXO1 Improves Cardiac Function by Enhancing Glucose Metabolism and Attenuating Apoptosis in Type‐1 Diabetic Rats

IntroductionDiabetic cardiomyopathy, which comprises structural and functional abnormalities of the myocardium, is a major etiological factor for death in diabetic patients. Altered cardiac energy metabolism and increased cardiac apoptosis may underlie the pathology of diabetic cardiomyopathy. Forkhead transcriptional factor (FOXO1) is preferably activated in the myocardium of Type2 diabetic mice and mediates excessive lipid metabolism, resulting in diabetic cardiomyopahty. However, the effect of FOXO1 in cardiac glucose oxidation and apoptosis and its contribution to cardiac function in Type 1 diabetes‐induced cardiomyopathy are largely unknown. Thus, the present study aimed to investigate whether or not pharmacological inhibition of FOXO1 by its selective inhibitor AS1842856 can attenuate diabetic cardiomyopathy in Type 1 diabetic rats and the underlying mechanisms.MethodsControl or streptozotocin (STZ, 65 mg/kg)‐induced diabetic Sprague Dawley rats (n=7 per group) received vehicle or AS1842856 (50 mg/kg) by gavage twice daily for one week starting four weeks after STZ injection. On the day of harvest, the left ventricular (LV) functions of the rats were assessed by Pressure‐volume (PV) loop analysis and the heart tissue were collected for immunofluorescence, qPCR, Western blotting, etc. The translocation of FOXO1 from cytoplasm to nucleus was performed by immunofluorescence. The mRNA expression of pyruvate dehydrogenase kinase 4 (PDK4) was measured by qPCR. The protein levels of FOXO1, phosphorylated‐FOXO1(S256), PDK4, phosphorylated pyruvate dehydrogenase (pSer293‐PDH), B‐cell lymphoma 2 (BCl2), Bcl‐2‐like protein 4 (Bax), total and cleaved‐caspase3 were detected by Western blotting analysis. TUNEL assay was performed for detection of apoptosis in the cardiac tissue.ResultsPV loop analysis indicated that heart rate (HR, bpm) was significantly reduced, and time constant of LV pressure decay (TAU, ms), slope of the end‐diastolic pressure‐volume relationship (EdPVR, mmHg/μl) were all significantly increased in Type‐1 diabeticrats as compared to non‐diabetic control rats (all P &lt;0.05), suggesting that Type‐1 diabetic rats indicated cardiac diastolic dysfunction. These changes were associated with remarkably increased FOXO1 activity (decreased P‐FOXO1/FOXO1 ratio, increased FOXO1 nuclear translocation), reduced cardiac glucose oxidation (increased mRNA and protein expression of PDK4 and reduced expression of P‐PDH) and enhanced cardiac apoptosis (reduced Bcl2/Bax ratio, increased cleaved‐caspase3/total caspase 3 ratio and TUNEL positive cells) in Type‐1 diabetic rats (all P &lt;0.05, vs. Control rats). However, administration of FOXO1 inhibitor AS1842856 significantly inhibited FOXO1 activity (increased P‐FOXO1/FOXO1 ratio, decreased FOXO1 nuclear translocation), increased HR, decreased TAU and EDSPVR, and reverted all the above‐mentioned diabetes‐induced biochemical changes, suggesting that pharmacological inhibition of FOXO1 may attenuate cardiomyopathy in Type‐1 diabetic rats via enhanced glucose oxidation and reduced cardiac apoptosis.ConclusionFoxO1 in mediating PDK4 expression and subsequent PDH inactivation in the heart and also activation of cardiac apoptosis may represent major mechanisms whereby inhibition of FOXO1 improves cardiac function in early stage of diabetic cardiomyopathy in Type 1 diabetic rats and may provide a promising therapeutic target to treat the disease.Support or Funding InformationThe authors' work was supported by the General Research Fund (17124614M, Research Grants Council of Hong Kong).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Tenascin-C Modulates Cell Cycle Progression to Enhance Tumour Cell Proliferation through AKT/FOXO1 Signalling in Pancreatic Cancer.

Pancreatic ductal adenocarcinoma (PDAC) is a disease with an extremely poor prognosis that is characterized by a rich extracellular matrix (ECM). Tenascin-C (TNC) is a component of the ECM and plays a role in tumour progression. In this study, we reported that TNC is overexpressed in PDAC tissues and is correlated with tumour stage and cyclin D1 expression. Cyclin D1 is key regulator of the cell cycle G1/S transition. Further experiments revealed that TNC promotes G1/S transition through AKT signalling. TNC/AKT increases the expression of cyclin D1 by enhancing the transcriptional activity of β-catenin, whereas the translocation of FOXO1 from the nucleus results in the downregulation of p27Kip1. Cyclin D1 and p27Kip1 regulate the activity of cyclin D1-CDK4 complexes and retinoblastoma (Rb), and then they stimulate the progression of G1/S transition and tumour cell proliferation. In conclusion, TNC exerts its activating effect on the proliferation of pancreatic cancer cells in vitro and in vivo through its functional target AKT/FOXO1/β-catenin. The molecular mechanisms that drive PDAC progression will be useful for the development of molecular markers and the evaluation of patient prognosis.

Xihuang Pill Induces Apoptosis of Human Glioblastoma U-87 MG Cells via Targeting ROS-Mediated Akt/mTOR/FOXO1 Pathway.

Xihuang pill (XHP), a traditional Chinese herbal formula, has long been used as an effective agent against multiple tumors. The aim of this study is to evaluate the effects of XHP on the growth inhibition and apoptosis in glioblastoma U-87 MG cells. Gas chromatography-mass spectrometry (GC-MS) was performed for constituent analysis of XHP. Cell viability, cell cycle arrest, generation of reactive oxygen species (ROS), and apoptosis were measured by CCK-8 assay, PI/RNase staining, DCFH-DA assay, TUNEL assay, Annexin V-FITC/PI double staining, and JC-1 assay, respectively. The role of XHP in the regulation of Akt/mTOR/FOXO1 interaction was clarified by using Western Blotting (WB), immunofluorescence (IF), pharmacological inhibitor or antioxidant, and siRNA silencing. The results suggested that XHP could inhibit U-87 MG cells growth and arrest cells in S-phase cell cycle significantly and that the generation of ROS, collapse of mitochondrial membrane potential, enhancement of Bax/Bcl-xL ratio, and reduction of the precursor forms of caspase-9 and caspase-3 caused by XHP prompted that a ROS-mediated mitochondria-dependent apoptosis was possibly involved. Furthermore, XHP affected the Akt/mTOR/FOXO1 pathway via inhibiting the phosphorylation of Akt, mTOR, and FOXO1 and increasing both prototype and nuclear translocation of FOXO1. Inhibition of Akt, mTOR, and FOXO1 by specific inhibitors or siRNA could interpose the apoptotic induction. In conclusion, we demonstrate for the first time that XHP may regulate glioblastoma U-87 MG cell apoptosis via ROS-mediated Akt/mTOR/FOXO1 pathway.

VE-Cadherin-Mediated Epigenetic Regulation of Endothelial Gene Expression.

The mechanistic foundation of vascular maturation is still largely unknown. Several human pathologies are characterized by deregulated angiogenesis and unstable blood vessels. Solid tumors, for instance, get their nourishment from newly formed structurally abnormal vessels which present wide and irregular interendothelial junctions. Expression and clustering of the main endothelial-specific adherens junction protein, VEC (vascular endothelial cadherin), upregulate genes with key roles in endothelial differentiation and stability. We aim at understanding the molecular mechanisms through which VEC triggers the expression of a set of genes involved in endothelial differentiation and vascular stabilization. We compared a VEC-null cell line with the same line reconstituted with VEC wild-type cDNA. VEC expression and clustering upregulated endothelial-specific genes with key roles in vascular stabilization including claudin-5, vascular endothelial-protein tyrosine phosphatase (VE-PTP), and von Willebrand factor (vWf). Mechanistically, VEC exerts this effect by inhibiting polycomb protein activity on the specific gene promoters. This is achieved by preventing nuclear translocation of FoxO1 (Forkhead box protein O1) and β-catenin, which contribute to PRC2 (polycomb repressive complex-2) binding to promoter regions of claudin-5, VE-PTP, and vWf. VEC/β-catenin complex also sequesters a core subunit of PRC2 (Ezh2 [enhancer of zeste homolog 2]) at the cell membrane, preventing its nuclear translocation. Inhibition of Ezh2/VEC association increases Ezh2 recruitment to claudin-5, VE-PTP, and vWf promoters, causing gene downregulation. RNA sequencing comparison of VEC-null and VEC-positive cells suggested a more general role of VEC in activating endothelial genes and triggering a vascular stability-related gene expression program. In pathological angiogenesis of human ovarian carcinomas, reduced VEC expression paralleled decreased levels of claudin-5 and VE-PTP. These data extend the knowledge of polycomb-mediated regulation of gene expression to endothelial cell differentiation and vessel maturation. The identified mechanism opens novel therapeutic opportunities to modulate endothelial gene expression and induce vascular normalization through pharmacological inhibition of the polycomb-mediated repression system.

PRMT1 promotes hyperglycemia in a FoxO1-dependent manner, affecting glucose metabolism, during hypobaric hypoxia exposure, in rat model.

High-altitude (HA) environment causes changes in cellular metabolism among unacclimatized humans. Previous studies have revealed that insulin-dependent activation of protein kinase B (Akt) regulates metabolic processes via discrete transcriptional effectors. Moreover, protein arginine methyltransferase (PRMT)1-dependent arginine modification of forkhead box other (FoxO)1 protein interferes with Akt-dependent phosphorylation. The present study was undertaken to test the involvement of PRMT1 on FoxO1 activation during hypobaric hypoxia (HH) exposure in rat model. Samples were obtained from normoxia control (NC) and HH-exposed (H) rats, subdivided according to the duration of HH exposure. To explore the specific role played by PRMT1 during HH exposure, samples from 1d pair-fed (PF) NC, 1d acute hypoxia-exposed (AH) placebo-treated, and 1d AH TC-E-5003-treated rats were investigated. Quantitative reverse transcriptase polymerase chain reaction (RT-qPCR) was performed to determine expressions of glycolytic, gluconeogenic enzymes, and insulin response regulating genes. Immuno-blot and enzyme linked immunosorbent assay (ELISA) were used for insulin response regulating proteins. Nuclear translocation of FoxO1 was analyzed using deoxyribonucleic acid (DNA)-binding ELISA kit. We observed HH-induced increase in glycolytic enzyme expressions in hepatic tissue unlike hypothalamic tissue. PRMT1 expression increased during HH exposure, causing insulin resistance and resulting increase in FoxO1 nuclear translocation, leading to hyperglycemia. Conversely, PRMT1 inhibitor treatment promoted inhibition of FoxO1 activity and increase in glucose uptake during HH exposure leading to reduction in blood-glucose and hepatic glycogen levels. PRMT1 might have a potential importance as a therapeutic target for the treatment of HH-induced maladies.