Transcriptional coactivator EDF-1 is required for PPARgamma-stimulated adipogenesis

EDF1 accelerates ganglioside GD3 accumulation to boost CD52-mediated CD8+ T cell dysfunction in neuroblastoma

BACKGROUND

Heterogeneous clinical features and prognosis in neuroblastoma (NB) children are frequently dominated by immune elements. Dysfunction and apoptosis in immune cells result from the exposure to continuous tumor-related antigen stimulation and coinhibitory signals. To date, key factors pointing to the restriction of NB-specific CD8+ T cells remain elusive.

METHODS

We performed bulk-RNA sequencing and lipidomic analyses of children with mediastinal NB. Bioinformatics analysis and biological validation were applied to uncover the underlying mechanism.

RESULTS

Three subtypes were identified using nonnegative matrix factorization (NMF), among which we highlighted an apoptotic status of infiltrated CD8+ T cells, along with the highest CD52 and EDF1 expression in Cluster3 (C3) subtypes. It was verified that high EDF1 expression in NB cells led to Lactosylceramide (LacCer) accumulation, as well as downstream ganglioside-GD3, which subsequently increased the expression of CD52 and immune checkpoint genes, chemotaxis, and apoptosis-related events in activated CD8+T cells. Mechanistically, EDF1 was recruited as a coactivator to form the NF-κB/RelA/EDF1 complex, which further prevented the promoter region methylation of ST8SIA1, to elevate its transcription.

CONCLUSION

These findings characterize abundant GD3 in NB cells, which regulated by the EDF1/RelA/ST8SIA1 axis, is responsible for CD8+ T cell dysfunction. Inhibition of EDF1 may reduce suppressive factors and prevent immune escape of NB cells. Modulating NB-associated GD3 levels through metabolic intervention is beneficial for tuning the depth and duration of responses to current NB therapies. The integration of transcriptomic and lipidomic data offers a more comprehensive understanding of the interaction between LacCer metabolites and the immune status in NB.

Vitamin D Prevents High Glucose-Induced Lipid Droplets Accumulation in Cultured Endothelial Cells: The Role of Thioredoxin Interacting Protein

Vitamin D (VitD) exerts protective effects on the endothelium, which is fundamental for vascular integrity, partly by inhibiting free radical formation. We found that VitD prevents high glucose-induced Thioredoxin Interacting Protein (TXNIP) upregulation. Increased amounts of TXNIP are responsible for the accumulation of reactive oxygen species and, as a consequence, of lipid droplets. This is associated with increased amounts of triglycerides as the result of increased lipogenesis and reduced fatty acid oxidation. Remarkably, VitD rebalances the redox equilibrium, restores normal lipid content, and prevents the accumulation of lipid droplets. Our results highlight TXNIP as one of the targets of VitD in high glucose-cultured endothelial cells and shed some light on the protective effect of VitD on the endothelium.

Magnesium Deficiency Induces Lipid Accumulation in Vascular Endothelial Cells via Oxidative Stress-The Potential Contribution of EDF-1 and PPARγ

Background: Magnesium deficiency contributes to atherogenesis partly by promoting the dysfunction of endothelial cells, which are critical in vascular homeostasis and diseases. Since EDF-1 and PPARγ regulate crucial endothelial activities, we investigated the modulation of these proteins involved in lipogenesis as well the deposition of lipids in human endothelial cells cultured in different concentrations of magnesium. Methods: Human endothelial cells from the umbilical vein were cultured in medium containing from 0.1 to 5 mM magnesium for 24 h. The levels of EDF-1 and PPARγ were visualized by Western blot. Reactive oxygen species (ROS) were measured by DCFDA. Lipids were detected after O Red Oil staining. Results: Magnesium deficiency leads to the accumulation of ROS which upregulate EDF-1. Further, PPARγ is increased after culture in low magnesium, but independently from ROS. Moreover, lipids accumulate in magnesium-deficient cells. Conclusions: Our results suggest that magnesium deficiency leads to the deposition of lipids by inducing EDF-1 and PPARγ. The increase in intracellular lipids might be interpreted as an adaptive response of endothelial cells to magnesium deficiency.

Magnesium Calcium Phosphate Cement Incorporating Citrate for Vascularized Bone Regeneration

The development of bioactive bone cement is still a challenge for vascularized bone regeneration. Citrate participated in multiple biological processes, such as energy metabolism, osteogenesis, and angiogenesis. However, it is difficult to obtain a thorough and comprehensive understanding on osteogenic effects of exogenous citrate from different experimental conditions and treatment methods. In this study, by using a magnesium calcium phosphate cement (MCPC) matrix, we investigated the dual effect of exogenous citrate on osteogenesis and angiogenesis. Our studies show that citrate elevates the osteogenic function of osteoblasts under low doses and the angiogenic function of vascular endothelial cells under a broader dose range. These findings furnish a new strategy for regulating angiogenesis and osteogenic differentiation by administration of citrate in MCPC, driving the development of bioactive bone repair materials.

LncPrep + 96kb 2.2 kb Inhibits Estradiol Secretion From Granulosa Cells by Inducing EDF1 Translocation

LncPrep + 96kb is a novel long non-coding RNA expressed in murine granulosa cells with two transcripts that are 2.2 and 2.8 kb in length. However, the potential roles of lncPrep + 96kb in granulosa cells remain poorly understood. In this study, we investigated the effect of the lncPrep + 96kb 2.2 kb transcript on granulosa cells through the overexpression and knockdown of lncPrep + 96kb 2.2 kb. We found that lncPrep + 96kb 2.2 kb inhibited aromatase expression and estradiol production. Endothelial differentiation-related factor 1 (EDF1) is an evolutionarily conserved transcriptional coactivator. We found that EDF1 knockdown inhibited aromatase expression and estradiol production. The RNA immunoprecipitation results also showed that lncPrep + 96kb 2.2 kb can bind to EDF1 and that overexpression of lncPrep + 96kb 2.2 kb induced the translocation of EDF1 from the nucleus to the cytoplasm. The CatRAPID signature revealed that the 1,979–2,077 and 603–690 nucleotide positions in lncPrep + 96kb 2.2 kb were potential binding sites for EDF1. We found that mutating the 1,979–2,077 site rescued the effects of lncPrep + 96kb 2.2 kb on aromatase expression and estradiol production. In conclusion, we are the first to report that specific expression of lncPrep + 96kb 2.2 kb in granulosa cells inhibits the production of estradiol by influencing the localization of EDF1 in granulosa cells. The 1,979–2,077 site of lncPrep + 96kb 2.2 kb contributes to the ability to bind to EDF1.

Citrate reduced oxidative damage in stem cells by regulating cellular redox signaling pathways and represent a potential treatment for oxidative stress-induced diseases

Chemical substances containing citrate such as calcium citrate, citrate esters and citric acid exhibit anti-oxidant and anti-inflammatory properties in different cells and tissues. However, data on the anti-oxidant and anti-inflammatory properties and mechanisms of action of citrate are insufficient. In this study, we systematically evaluated the anti-oxidant capacity of citrate using chemical, cellular and animal assays. Citrate showed a stable molecular structure and did not directly react with oxides. Citrate exerted protective and anti-apoptotic effects on BMSCs and also showed significant inhibitory effects on the oxidative stress and inflammatory reactions in the rat air pouch model. By using proteomics, we found that PPARγ contributed to the upregulation of various free radical scavenging proteins and the downregulation of diverse components of the inflammatory responses. Citrate-regulated global PPARγ expression was evidenced by the significant increase expression of PPARγ in PC12 cell line. Our results provide novel insights into the role of citrate in regulating cellular redox signaling and the function of PPARγ signaling in this process and also provide basic molecular cell biology information to improve the applications of biomaterials or stem cells as treatments for oxidative stress-induced degenerative diseases and inflammatory diseases.

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Citrate exerts anti-oxidant and anti-inflammatory properties in BMSCs and tissues.

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Citrate can upregulate and downregulate anti-oxidant and anti-inflammatory proteins in BMSCs.

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Citrate can regulate anti-oxidant and anti-inflammatory proteins via PPARγ dependent and independent pathways.

The Contribution of EDF1 to PPARγ Transcriptional Activation in VEGF-Treated Human Endothelial Cells

Vascular endothelial growth factor (VEGF) is important for maintaining healthy endothelium, which is crucial for vascular integrity. In this paper, we show that VEGF stimulates the nuclear translocation of endothelial differentiation-related factor 1 (EDF1), a highly conserved intracellular protein implicated in molecular events that are pivotal to endothelial function. In the nucleus, EDF1 serves as a transcriptional coactivator of peroxisome proliferator-activated receptor gamma (PPARγ), which has a protective role in the vasculature. Indeed, silencing EDF1 prevents VEGF induction of PPARγ activity as detected by gene reporter assay. Accordingly, silencing EDF1 markedly inhibits the stimulatory effect of VEGF on the expression of FABP4, a PPARγ-inducible gene. As nitric oxide is a marker of endothelial function, it is noteworthy that we report a link between EDF1 silencing, decreased levels of FABP4, and nitric oxide production. We conclude that EDF1 is required for VEGF-induced activation of the transcriptional activity of PPARγ.

KLF11 mediates PPARγ cerebrovascular protection in ischaemic stroke

Peroxisome proliferator-activated receptor gamma (PPARγ) is emerging as a major regulator in neurological diseases. However, the role of (PPARγ) and its co-regulators in cerebrovascular endothelial dysfunction after stroke is unclear. Here, we have demonstrated that (PPARγ) activation by pioglitazone significantly inhibited both oxygen-glucose deprivation-induced cerebral vascular endothelial cell death and middle cerebral artery occlusion-triggered cerebrovascular damage. Consistent with this finding, selective (PPARγ) genetic deletion in vascular endothelial cells resulted in increased cerebrovascular permeability and brain infarction in mice after focal ischaemia. Moreover, we screened for (PPARγ) co-regulators using a genome-wide and high-throughput co-activation system and revealed KLF11 as a novel (PPARγ) co-regulator, which interacted with (PPARγ) and regulated its function in mouse cerebral vascular endothelial cell cultures. Interestingly, KLF11 was also found as a direct transcriptional target of (PPARγ). Furthermore, KLF11 genetic deficiency effectively abolished pioglitazone cytoprotection in mouse cerebral vascular endothelial cell cultures after oxygen-glucose deprivation, as well as pioglitazone-mediated cerebrovascular protection in a mouse middle cerebral artery occlusion model. Mechanistically, we demonstrated that KLF11 enhanced (PPARγ) transcriptional suppression of the pro-apoptotic microRNA-15a (miR-15a) gene, resulting in endothelial protection in cerebral vascular endothelial cell cultures and cerebral microvasculature after ischaemic stimuli. Taken together, our data demonstrate that recruitment of KLF11 as a novel (PPARγ) co-regulator plays a critical role in the cerebrovascular protection after ischaemic insults. It is anticipated that elucidating the coordinated actions of KLF11 and (PPARγ) will provide new insights into understanding the molecular mechanisms underlying (PPARγ) function in the cerebral vasculature and help to develop a novel therapeutic strategy for the treatment of stroke.

EDF-1 downregulates the CaM/Cn/NFAT signaling pathway during adipogenesis

The endothelial differentiation factor-1 (EDF-1) is a calmodulin binding protein that regulates calmodulin-dependent enzymes. In endothelial cells, this factor can form a protein complex with calmodulin. We analyzed the relationship between this factor and the members of calmodulin/calcineurin/nuclear factor of activated T-cells (NFAT) signaling pathway during adipogenesis of 3T3-F442A cells. We found that the expression of edf1 is upregulated during early adipogenesis, whereas that of calcineurin gene is lowered, suggesting that this pathway should be downregulated to allow for adipogenesis to occur. We also found that EDF-1 associates with calmodulin and calcineurin, most likely inactivating calcineurin. Our results showed that EDF-1 inactivates the calmodulin/calcineurin/NFAT pathway via sequestration of calmodulin, during early adipogenesis, and we propose a mechanism that negatively regulates the activation of calcineurin through a complex formation between EDF-1 and calmodulin. This finding raises the possibility that modulating this pathway might offer some alternatives to regulate adipose biology.

The effects of silencing EDF-1 in human endothelial cells

OBJECTIVE

EDF-1, a 16 kDa highly conserved intracellular protein, serves as a calmodulin binding protein and, upon nuclear translocation, functions as a coactivator of several transcription factors. To understand whether EDF-1 is implicated in regulating endothelial function, we silenced EDF-1 expression using small hairpin (sh) RNA.

METHODS

Human umbilical vein endothelial cells (HUVEC) were utilized and EDF-1 levels were detected by western blot. Cell proliferation, cell organization in fibrin gel and nitric oxide release were evaluated in cells silencing EDF-1 after transfection with shRNA.

RESULTS

EDF-1 was downregulated in quiescent and senescent HUVEC, whereas it was upregulated in proliferating cells. Knocking down EDF-1 promoted the acquisition of a spindle phenotype, inhibited cell proliferation, accelerated the organization into capillary-like networks on fibrin gels and induced the production of nitric oxide (NO). While the total amounts and the degree of phosphorylation of endothelial NO synthase are not altered in cells silencing EDF-1, we found an increased interaction between calmodulin and endothelial NO synthase. Accordingly, the calmodulin inhibitor calmidazolium significantly decreased NO release in cells silencing EDF-1. These results suggest that knocking down EDF-1 might increase free calmodulin which ultimately activates endothelial NO synthase.

CONCLUSIONS

Since EDF-1 (i) is involved in the control of endothelial proliferation and organization, events which are crucial to repair damages to the vessel wall, and (ii) increases NO, which exerts anti-atherogenic and anti-thrombotic effects, we conclude that EDF-1 is implicated in molecular events that are pivotal to endothelial function and, therefore, to vascular integrity.