Folic Acid Supports Pluripotency and Reprogramming by Regulating LIF/STAT3 and MAPK/ERK Signaling

Folic acid mitigates the developmental and neurotoxic effects of bisphenol A in zebrafish by inhibiting the oxidative stress/JNK signaling pathway

Bisphenol A (BPA) is a widespread environmental endocrine disruptor (EED) that can cause various environmental and health issues by inducing oxidative stress. The c-Jun N-terminal kinase (JNK) signaling pathway plays a crucial role in oxidative stress-mediated cellular damage. Although folic acid (FA) has demonstrated antioxidant properties, its potential protective effects against BPA-induced developmental and neurotoxicity, as well as the mechanisms involved in the JNK signaling pathway, are still not completely understood. Zebrafish embryos were exposed to different concentrations of BPA ranging from 20 to 40 µM, with or without treatment of 50 µM FA, starting at 6 hours post-fertilization (hpf). Various parameters such as hatchability, survival rate, body length, and heart rate were measured and analyzed. Transcriptome sequencing was conducted to study the changes in gene expression. Oxidative stress markers, including reactive oxygen species (ROS), lipid peroxidation (LPO), hydrogen peroxide (H2O2), and catalase (CAT) activity, were assessed. The expression of proteins related to the mitogen-activated protein kinase (MAPK)/JNK pathway was analyzed using western blot. Neurodevelopmental and apoptotic outcomes were evaluated through behavioral tests, immunofluorescence and RT-qPCR examinations. The study found that exposure to BPA led to a decrease in hatchability, survival, body length, heart rate, total antioxidant capacity and promoted apoptosis in zebrafish larvae. However, supplementation with FA was able to alleviate these negative effects. BPA exposure increased levels of ROS, LPO, and H2O2, while decreasing CAT activity in zebrafish larvae. Treatment with FA effectively reduced BPA-induced oxidative stress and restored antioxidant defense systems. Moreover, KEGG pathway enrichment analysis revealed that the MAPK signaling pathway was the most enriched signaling pathway. Further studies revealed that BPA activated the JNK signaling pathway, while FA suppressed this activation. Additionally, FA significantly improved BPA-induced neurobehavioral deficits and protected against neurocytological alterations. Our findings demonstrate that FA effectively protects against BPA-induced developmental and neurotoxic effects in zebrafish by suppressing oxidative stress and inhibiting the JNK signaling pathway. This study provides new strategies and insights for preventing BPA-induced developmental and neurotoxicity in aquatic organisms.

Maternal Folic Acid Supplementation Improves the Intestinal Health of Offspring Porcine by Promoting the Proliferation and Differentiation of Intestinal Stem Cells

Maternal folic acid intake has important effects on offspring growth and development. The mechanism involved in the renewal of intestinal epithelial cells remains unclear. Thus, this study aimed to investigate the potential effect of maternal folic acid supplementation during gestation and lactation on the structural and functional development of the small intestine in piglet offspring. Twenty-four Duroc sows were assigned to a control group (CON) and a folic-acid-supplemented group (CON + FA, supplemented with 15 mg/kg of folic acid). The results showed that maternal folic acid supplementation throughout gestation and lactation significantly increased the body weight, serum folate level, and intestinal folate metabolism in piglets. It also improved the villus length, villus height-to-crypt depth ratio, and transcript levels of nutrient transporters (GLUT4, SNAT2, FABP2, and SLC7A5) in piglets' duodenum and jejunum. In addition, maternal folic acid supplementation increased Ki67-positive cells and the expression of proliferation-related marker genes (C-Myc, CyclinD1, and PCNA) in piglets' intestinal stem cells. It also boosted the expression of genes associated with mature secreted cells (ChrA, Muc2, Lyz, Vil1), indicating enhanced proliferation and differentiation of intestinal stem cells. These findings demonstrate that maternal folic acid supplementation enhances growth performance and gut health in piglet offspring by promoting epithelial cell renewal equilibrium.

The roles of JAK2/STAT3 signaling in fusion of the secondary palate

Cleft palate has a multifactorial etiology. In palatal fusion, the contacting medial edge epithelium (MEE) forms the epithelial seam, which is subsequently removed with the reduction of p63. Failure in this process results in a cleft palate. We herein report the involvement of janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling in palatal fusion and that folic acid rescues the fusing defect by reactivating JAK2/STAT3. In closure of bilateral palatal shelves, STAT3 phosphorylation was activated at the fusing MEE and mesenchyme underlying the MEE. JAK2 inhibition by AG490 inhibited STAT3 phosphorylation and resulted in palatal fusion failure without removal of the epithelial seam, in which p63 and keratin 17 (K17) periderm markers were retained. Folic acid application restored STAT3 phosphorylation in AG490-treated palatal explants and rescued the fusion defect, in which the p63- and K17-positive epithelial seam were removed. The AG490-induced palatal defect was also rescued in p63 haploinsufficient explants. These findings suggest that JAK2/STAT3 signaling is involved in palatal fusion by suppressing p63 expression in MEE and that folate restores the fusion defect by reactivating JAK2/STAT3.

Evaluation of colorectal cancer liver metastases based on liquid biopsy combined with folate receptor- Positive circulating tumor cells and HSP90

OBJECTIVE

Liver metastasis of colorectal cancer (LMCRC) is a major cause of cancer-related deaths worldwide. We can reduce the mortality rate by discerning the risk of liver metastases in patients with colorectal cancer at an early stage. Hence, we combined the use of folate receptor (FR)-labeled circulating tumor cells (FR+CTCs) and the metastasis-related marker, heat shock protein 90 (HSP90), to screen patients with colorectal cancer and explore the prognostic factors of patients with high expression of FR+CTC and HSP90.

PATIENTS AND METHODS

A retrospective study of 356 patients with measurable colorectal cancer was performed. Negative enrichment and FR-targeted fluorescence quantitative PCR was utilized to detect FR+CTC. An ELISA kit was used to detect HSP90 expression. A timely follow-up study of patients with colorectal cancer was made.

RESULTS

Colorectal patients with liver metastases showed high expression of FR+CTCs and HSP90. The diagnostic ability of the combined receiver operating characteristic curve of FR+CTC and HSP90 (area under the curve [AUC]=0.79, sensitivity 70.55%, specificity 92.66%) was significantly greater than that of a single index. The results of timely follow-up of patients showed that the high expression of FR+CTC significantly shortened the median disease-free survival (mDFS) of 36.5 months (95% confidence interval [CI]: 14.13-58.87, Logrank p < 0.0001) compared with the low expression cohort. The mDFS of the HSP90 high-expression cohort was significantly higher than that of the low-expression cohort (Logrank p = 0.0002), mDFS=58.47 months (95% CI: 37.12-79.81, Logrank p < 0.0001). We performed univariate and multivariate analyses to show that FR+CTC and HSP90 were risk factors for the progression of metastatic colorectal cancer (MCRC) disease. We then constructed a high- and low-risk score model of risk factors to evaluate MCRC. The diagnostic sensitivity of the risk model for MCRC was significantly improved (AUC=0.89, sensitivity 85.29%, specificity 81.33%), and the mDFS of patients in a high-risk group increased to 33.28 months (95% CI: 27.24-39.31, Logrank p < 0.0001). The establishment of the model improves the early screening of patients with MCRC.

CONCLUSION

Patients with colorectal cancer and high expression of FR+CTC and HSP90 are at risk of liver metastasis and this suggests a poor prognosis. Combining the two markers can improve the early screening and diagnosis of LMCRC patients. In addition, combining a multivariate risk model can further assist patients in appropriate stratification and the design of tailored treatment regimens. However, further validation these markers is needed before their routine clinical application.

Emerging roles for folate receptor FOLR1 in signaling and cancer

Folates are B vitamins that function in one-carbon metabolism. Folate receptors are one of three major types of folate transporters. The folate receptors FOLR1 and FOLR2 are overexpressed in multiple cancers. The overexpression of FOLR1 is often associated with increased cancer progression and poor patient prognosis. There is emerging evidence that FOLR1 is involved in signaling pathways that are independent of one-carbon metabolism. Recent publications implicate a direct role of FOLR1 in three signaling pathways: JAK-STAT3, ERK1/2, and as a transcription factor. Six other signaling pathways have been proposed to include FOLR1, but these currently lack sufficient data to infer a direct signaling role for FOLR1. We discuss the data that support noncanonical roles for FOLR1, and its limitations.

Folic acid pretreatment and its sustained delivery for chondrogenic differentiation of MSCs

Dietary uptake of folic acid (FA) improves cartilage regeneration. In this work, we discovered that three days of FA treatment is highly effective for promoting chondrogenic differentiation of tonsil-derived mesenchymal stem cells (TMSCs). In a three-dimensional pellet culture, the levels of typical chondrogenic biomarkers, sulfated glycosaminoglycan, proteoglycan, type II collagen (COL II), SRY box transcription factor 9 (SOX 9), cartilage oligomeric matrix protein (COMP), and aggrecan (ACAN) increased significantly in proportion to FA concentration up to 30 μM. At the mRNA expression level, COL II, SOX 9, COMP, and ACAN increased 3.6-6.0-fold with FA treatment at 30 μM compared with the control system that did not receive FA treatment, and the levels with FA treatment were 1.6-2.5 times greater than those in the kartogenin-treated positive control system. FA treatment did not increase type I collagen α1 (COL I α1), an osteogenic biomarker which is a concern with most chondrogenic promoters. At the high FA concentration of 100 μM, significant decreases in chondrogenic biomarkers were observed, which might be related to DNA methylation. A thermogel system incorporating TMSCs and FA provided sustained release of FA over several days, similar to the FA treatment. The thermogel system confirmed the efficacy of FA in promoting chondrogenic promotion of TMSCs. The increased nuclear translocation of core-binding factor β subunit (CBFβ) and the runt-related transcription factor 1 (RUNX1) expression after FA treatment, together with molecular docking studies, suggest that the chondrogenic enhancement mechanism of FA is mediated by CBFβ and RUNX1.

Peptide-coating 2D and small chemical molecules prolong the passage of porcine spermatogonia stem cells

Porcine spermatogonia stem cells (pSSCs) are the only type of somatic stem cell that can pass genetic information to the successive generations. Little is known about pSSCs vitality in vitro, and due to their increasing importance in stem cell research, here, we optimized a protocol to culture pSSCs and explored their potential fate in vitro. Utilizing a feeder-free culture system with a 2D peptide-coating and small chemical molecules (including CHIR99021, Repsox, Vatamin C, Folic Acid, and CD Lipid Concentrate), we were able to prolong the culture time of pSSCs by at least three months compared to previous methods. Moreover, we found that pSSCs could proliferate and self-renew in the seminiferous tubules of infertile mice. However, they could not perform meiosis. Our study shows that this feeder-free culture system optimizes cell culture and may facilitate advanced research on SSC biology and genetic manipulation of germ cells.

Differential responses to folic acid in an established keloid fibroblast cell line are mediated by JAK1/2 and STAT3

Keloids are a type of disordered scar formation which not only show heterogeneity between individuals and within the scar itself, but also share common features of hyperproliferation, abnormal extra-cellular matrix deposition and degradation, as well as altered expression of the molecular markers of wound healing. Numerous reports have established that cells from keloid scars display Warburg metabolism—a form of JAK2/STAT3-induced metabolic adaptation typical of rapidly dividing cells in which glycolysis becomes the predominant source of ATP over oxidative phosphorylation (OxPhos). Using the JAK1/2 inhibitor ruxolitinib, along with cells from patients with STAT3 loss of function (STA3 LOF; autosomal dominant hyper IgE syndrome) we examined the role of JAK/STAT signaling in the hyperproliferation and metabolic dysregulation seen in keloid fibroblasts. Although ruxolitinib inhibited hyperactivity in the scratch assay in keloid fibroblasts, it paradoxically exacerbated the hyper-glycolytic state, possibly by further limiting OxPhos via alterations in mitochondrial phosphorylated STAT3 (pSTAT3^Ser727). In healthy volunteer fibroblasts, folic acid exposure recapitulated the exaggerated closure and hyper-glycolytic state of keloid fibroblasts through JAK1/2- and STAT3-dependent pathways. Although additional studies are needed before extrapolating from a representative cell line to keloids writ large, our results provide novel insights into the metabolic consequences of STAT3 dysfunction, suggest a possible role for folate metabolism in the pathogenesis of keloid scars, and offer in vitro pre-clinical data supporting considerations of clinical trials for ruxolitinib in keloid disorder.

Folic acid promotes proliferation and differentiation of porcine pancreatic stem cells into insulin-secreting cells through canonical Wnt and ERK signaling pathway

Porcine pancreatic stem cells (pPSCs) can be induced to differentiate into insulin-producing cells in vitro and thus serve as a major cells source for β-cell regeneration. However, this application is limited by the weak cell proliferation ability and low insulin induction efficiency. In this study, we explored the role of folic acid in the proliferation of pPSCs and the formation of insulin-secreting cells. We found that FA-treated pPSCs cells had a high EDU positive rate, and the proliferation marker molecules PCNA, CyclinD1 and c-Myc were up-regulated, while the expression of folate receptor α (FOLRα) was up-regulated. In further research, interference FOLRα or adding canonical Wnt signaling pathway or ERK signaling pathway inhibitors could significantly inhibit the effect of FA on pPSCs proliferation. Meanwhile, during the differentiation of pPSCs into insulin-secreting cells, we found that the maturation marker genes Insulin, NKX6.1, MafA, and NeuroD1 was upregulated in insulin-secreting cell masses differentiationed from pPSCs after FA treatment, and the functional molecules Insulin and C-peptide were increased, the ability to secrete insulin in response to high glucose was also increased. With the addition of Wnt and ERK signaling pathway inhibitors, the pro-differentiation effect of FA was weakened. In conclusion, FA promotes the proliferation of pPSCs by binding to folate receptor α (FOLRα) and increase the efficiency of directed differentiation of pPSCs into insulin-producing cells by regulating canonical Wnt and ERK signaling pathway. This study lays theoretical foundation for solving the bottleneck in the treatment of diabetes with stem cell transplantation in future.

Folic Acid Deficiency Enhances the Tyr705 and Ser727 Phosphorylation of Mitochondrial STAT3 in In Vivo and In Vitro Models of Ischemic Stroke

Ischemic stroke remains one of the most common causes of death and disability worldwide. The stroke patients with an inadequate intake of folic acid tend to have increased brain injury and poorer prognosis. However, the precise mechanisms underlying the harmful effects of folic acid deficiency (FD) in ischemic stroke is still elusive. Here, we aimed to test the hypothesis that mitochondrial localized STAT3 (mitoSTAT3) expression may be involved in the process of neuronal damage induced by FD in in vivo and in vitro models of ischemic stroke. Our results exhibited that FD increased infarct size and aggravated the damage of mitochondrial ultrastructure in ischemic brains. Meanwhile, FD upregulated the phosphorylation levels of mitoSTAT3 at Tyr705 (Y705) and Ser727 (S727) sites in the rat middle cerebral artery occlusion/reperfusion (MCAO/R) model and oxygen-glucose deprivation followed by reperfusion (OGD/R) N2a cells. Furthermore, the inhibition of JAK2 by AG490 led to a significant decrease in FD-induced phosphorylation of Y705, while S727 phosphorylation was unaffected. Conversely, U0126 and LY294002, which respectively inhibited phosphorylation of ERK1/2 and Akt, partially prevented S727 phosphorylation, but had limited effects on the level of pY705, suggesting that phosphorylation of Y705 and S727 is regulated via independent mechanisms in FD-treated brains.

Metabolic-Epigenetic Axis in Pluripotent State Transitions

Cell state transition (CST) occurs during embryo development and in adult life in response to different stimuli and is associated with extensive epigenetic remodeling. Beyond growth factors and signaling pathways, increasing evidence point to a crucial role of metabolic signals in this process. Indeed, since several epigenetic enzymes are sensitive to availability of specific metabolites, fluctuations in their levels may induce the epigenetic changes associated with CST. Here we analyze how fluctuations in metabolites availability influence DNA/chromatin modifications associated with pluripotent stem cell (PSC) transitions. We discuss current studies and focus on the effects of metabolites in the context of naïve to primed transition, PSC differentiation and reprogramming of somatic cells to induced pluripotent stem cells (iPSCs), analyzing their mechanism of action and the causal correlation between metabolites availability and epigenetic alteration.

Anterior cleft palate due to Cbfb deficiency and its rescue by folic acid

Core binding factor β (Cbfb) is a cofactor of the Runx family of transcription factors. Among these transcription factors, Runx1 is a prerequisite for anterior-specific palatal fusion. It was previously unclear, however, whether Cbfb served as a modulator or as an obligatory factor in the Runx signaling process that regulates palatogenesis. Here, we report that Cbfb is essential and indispensable in mouse anterior palatogenesis. Palatal fusion in Cbfb mutants is disrupted owing to failed disintegration of the fusing epithelium specifically at the anterior portion, as observed in Runx1 mutants. In these mutants, expression of TGFB3 is disrupted in the area of failed palatal fusion, in which phosphorylation of Stat3 is also affected. TGFB3 protein has been shown to rescue palatal fusion in vitro. TGFB3 also activated Stat3 phosphorylation. Strikingly, the anterior cleft palate in Cbfb mutants is further rescued by pharmaceutical application of folic acid, which activates suppressed Stat3 phosphorylation and Tgfb3 expression in vitro. With these findings, we provide the first evidence that Cbfb is a prerequisite for anterior palatogenesis and acts as an obligatory cofactor in the Runx1/Cbfb-Stat3-Tgfb3 signaling axis. Furthermore, the rescue of the mutant cleft palate using folic acid might highlight potential therapeutic targets aimed at Stat3 modification for the prevention and pharmaceutical intervention of cleft palate.

Summary: Epithelial deletion of Cbfb results in an anterior cleft palate with impaired fusion of the palatal process; folic acid application rescues the mutant phenotype with Stat3 activation in vitro.