Tanshinone IIA induces ER stress and JNK activation to inhibit tumor growth and enhance anti-PD-1 immunotherapy in non-small cell lung cancer

BACKGROUND

Non-small cell lung cancer (NSCLC) remains at the forefront of new cancer cases, and there is an urgent need to find new treatments or improve the efficacy of existing therapies. In addition to the application in the field of cerebrovascular diseases, recent studies have revealed that tanshinone IIA (Tan IIA) has anticancer activity in a variety of cancers.

PURPOSE

To investigate the potential anticancer mechanism of Tan IIA and its impact on immunotherapy in NSCLC.

METHODS

Cytotoxicity and colony formation assays were used to detect the Tan IIA inhibitory effect on NSCLC cells. This research clarified the mechanisms of Tan IIA in anti-tumor and programmed death-ligand 1 (PD-L1) regulation by using flow cytometry, transient transfection, western blotting and immunohistochemistry (IHC) methods. Besides, IHC was also used to analyze the nuclear factor of activated T cells 1 (NFAT2) expression in NSCLC clinical samples. Two animal models including xenograft mouse model and Lewis lung cancer model were used for evaluating tumor suppressive efficacy of Tan IIA. We also tested the efficacy of Tan IIA combined with programmed cell death protein 1 (PD-1) inhibitors in Lewis lung cancer model.

RESULTS

Tan IIA exhibited good NSCLC inhibitory effect which was accompanied by endoplasmic reticulum (ER) stress response and increasing Ca2+ levels. Moreover, Tan IIA could suppress the NFAT2/ Myc proto oncogene protein (c-Myc) signaling, and it also was able to control the Jun Proto-Oncogene(c-Jun)/PD-L1 axis in NSCLC cells through the c-Jun N-terminal kinase (JNK) pathway. High NFAT2 levels were potential factors for poor prognosis in NSCLC patients. Finally, animal experiments data showed a stronger immune activation phenotype, when we performed treatment of Tan IIA combined with PD-1 monoclonal antibody.

CONCLUSION

The findings of our research suggested a novel mechanism for Tan IIA to inhibit NSCLC, which could exert anti-cancer effects through the JNK/NFAT2/c-Myc pathway. Furthermore, Tan IIA could regulate tumor PD-L1 levels and has the potential to improve the efficacy of PD-1 inhibitors.

Fluid shear force and hydrostatic pressure jointly promote osteogenic differentiation of BMSCs by activating YAP1 and NFAT2

Natural bone tissue features a complex mechanical environment, with cells responding to diverse mechanical stimuli, including fluid shear stress (FSS) and hydrostatic pressure (HP). However, current in vitro experiments commonly employ a singular mechanical stimulus to simulate the mechanical environment in vivo. The understanding of the combined effects and mechanisms of multiple mechanical stimuli remains limited. Hence, this study constructed a mechanical stimulation device capable of simultaneously applying FSS and HP to cells. This study investigated the impact of FSS and HP on the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and examined the distinctions and interactions between the two mechanisms. The results demonstrated that both FSS and HP individually enhanced the osteogenic differentiation of BMSCs, with a more pronounced effect observed through their combined application. BMSCs responded to external FSS and HP stimulation through the integrin-cytoskeleton and Piezo1 ion channel respectively. This led to the activation of downstream biochemical signals, resulting in the dephosphorylation and nuclear translocation of the intracellular transcription factors Yes Associated Protein 1 (YAP1) and nuclear factor of activated T cells 2 (NFAT2). Activated YAP1 could bind to NFAT2 to enhance transcriptional activity, thereby promoting osteogenic differentiation of BMSCs more effectively. This study highlights the significance of composite mechanical stimulation in BMSCs' osteogenic differentiation, offering guidance for establishing a complex mechanical environment for in vitro functional bone tissue construction.

Verapamil modulates NFAT2 to inhibit tumor growth and potentiates PD1ab immune checkpoint inhibitor therapy in cervical cancer treatment

PURPOSE

Current evidence suggests a high co-prevalence of hypertension and cervical cancer. Accordingly, blood pressure control is indicated during anti-tumor drug therapy in this patient population. Over the past few years, immunotherapy has made great strides in treating different cancers. However, the role and clinical significance of verapamil as a first-line anti-hypertensive drug during immunotherapy remain poorly understood, emphasizing the need for further studies.

METHODS

Murine cervical cancer models were employed to assess the effect of verapamil monotherapy and combination with PD1ab. Immunohistochemistry was conducted to quantify the abundance of CD8+ T cell and Ki67+ cells. Several in-vitro and in-vivo assays were used to study the effects of verapamil and explore the preliminary mechanism.

RESULTS

Monotherapy with verapamil or PD1ab immune checkpoint inhibitor significantly suppressed the growth of subcutaneously grafted U14 cells in WT BABL/c mice, respectively, with increased survival time of mice. Consistent results were observed in the melanoma model. Furthermore, we substantiated that verapamil significantly impaired tumor proliferation and migration of SiHa human cervical cancer cells in vitro and in vivo. In silico analysis using TCGA data revealed that NFAT2 expression negatively correlated with patient survival. The CCK8 assay revealed that verapamil abrogated the stimulatory effect of NFAT2 after knockdown of NFAT2.

CONCLUSIONS

Our results suggest that verapamil inhibits tumor growth by modulating NFAT2 expression and enhancing tumor immune responses to PD1ab, which can be harnessed for cervical cancer therapy, especially for patients with comorbid hypertension. Indeed, further clinical trials are warranted to increase the robustness of our findings.

miR-125b-5p alleviates the damage of myocardial infarction by inhibiting the NFAT2 to reduce F2RL2 expression

Aim: To explore the effect of miR-125b-5p/nuclear factor of activated T cells 1 (NFAT2)/F2RL2 on myocardial infarction (MI). Method: After establishment of MI mouse model and oxygen glucose deprivation (OGD)-induced cell model, the effects of NFAT2 on the process of MI were observed, the effects of miR-125b-5p/NFAT2/F2RL2 on the cell viability, apoptosis, and inflammatory factors levels were determined. Result: NFAT2 silencing relieved MI and inhibited the inflammation in MI model mice. In OGD-induced human coronary artery endothelial cells and human cardiac microvascular endothelial cells, miR-125b-5p enhanced cell viability, yet repressed cell apoptosis and inflammatory factors and NFAT2 levels. NFAT2 overexpression reversed the effects of miR-125b-5p, while F2RL2 silencing offset the effects of NFAT2 overexpression. Conclusion: MiR-125b-5p alleviates MI injury by inhibiting NFAT2 level to reduce F2RL2 expression.

Mitochondrial calcium signaling mediated transcriptional regulation of keratin filaments is a critical determinant of melanogenesis

Mitochondria are versatile organelles that regulate several physiological functions. Many mitochondria-controlled processes are driven by mitochondrial Ca2+ signaling. However, role of mitochondrial Ca2+ signaling in melanosome biology remains unknown. Here, we show that pigmentation requires mitochondrial Ca2+ uptake. In vitro gain and loss of function studies demonstrated that Mitochondrial Ca2+ Uniporter (MCU) is crucial for melanogenesis while the MCU rheostats, MCUb and MICU1 negatively control melanogenesis. Zebrafish and mouse models showed that MCU plays a vital role in pigmentation in vivo. Mechanistically, MCU controls activation of transcription factor NFAT2 to induce expression of three keratins (keratin 5, 7 and 8), which we report as positive regulators of melanogenesis. Interestingly, keratin 5 in turn modulates mitochondrial Ca2+ uptake thereby this signaling module acts as a negative feedback loop that fine-tunes both mitochondrial Ca2+ signaling and melanogenesis. Mitoxantrone, an FDA approved drug that inhibits MCU, decreases physiological melanogenesis. Collectively, our data demonstrates a critical role for mitochondrial Ca2+ signaling in vertebrate pigmentation and reveal the therapeutic potential of targeting MCU for clinical management of pigmentary disorders. Given the centrality of mitochondrial Ca2+ signaling and keratin filaments in cellular physiology, this feedback loop may be functional in a variety of other pathophysiological conditions.

HIV-1 Transcriptional Activator Tat Inhibits IL2 Expression by Preventing the Presence of Pol II on the IL2 Promoter

HIV-1 infection leads to a gradual loss of T helper cells, chronic immune activation, and eventual immune system breakdown. HIV-1 causes deregulation of the expression of IL-2, a cytokine important for T helper cell growth and survival, which is downregulated in HIV-1 patients. The present study addresses the regulation of IL2 expression via HIV-1 Tat transcriptional activator. We used J-LAT cells, a T cell line that serves as a latency model for studies of HIV-1 expression in T cells, and as controls a T cell line lacking HIV-1 elements and a T cell line with a stably integrated copy of the HIV-1-LTR promoter. We show that endogenously expressed Tat inhibits IL2 transcription in J-Lat cells via its presence in the ARRE-1/2 elements of the IL2 promoter and that the inhibition of IL2 expression is mediated by Tat inhibiting Pol II activity at the IL2 promoter, which is mediated by preventing the presence of Pol II at the ARRE-1/2 elements. Overall, Tat is present at the IL2 promoter, apart from its cognate HIV-1 LTR target. This supports our current knowledge of how HIV-1 affects the host transcriptional machinery and reflects the potential of Tat to disrupt transcriptional regulation of host genes to manipulate cell responses.

NFAT inhibitor 11R-VIVIT ameliorates mouse renal fibrosis after ischemia-reperfusion-induced acute kidney injury

Acute kidney injury (AKI) with maladaptive tubular repair leads to renal fibrosis and progresses to chronic kidney disease (CKD). At present, there is no curative drug to interrupt AKI-to-CKD progression. The nuclear factor of the activated T cell (NFAT) family was initially identified as a transcription factor expressed in most immune cells and involved in the transcription of cytokine genes and other genes critical for the immune response. NFAT2 is also expressed in renal tubular epithelial cells (RTECs) and podocytes and plays an important regulatory role in the kidney. In this study, we investigated the renoprotective effect of 11R-VIVIT, a peptide inhibitor of NFAT, on renal fibrosis in the AKI-to-CKD transition and the underlying mechanisms. We first examined human renal biopsy tissues and found that the expression of NFAT2 was significantly increased in RTECs in patients with severe renal fibrosis. We then established a mouse model of AKI-to-CKD transition using bilateral ischemia-reperfusion injury (Bi-IRI). The mice were treated with 11R-VIVIT (5 mg/kg, i.p.) on Days 1, 3, 10, 17 and 24 after Bi-IRI. We showed that the expression of NFAT2 was markedly increased in RTECs in the AKI-to-CKD transition. 11R-VIVIT administration significantly inhibited the nuclear translocation of NFAT2 in RTECs, decreased the levels of serum creatinine and blood urea nitrogen, and attenuated renal tubulointerstitial fibrosis but had no toxic side effects on the heart and liver. In addition, we showed that 11R-VIVIT administration alleviated RTEC apoptosis after Bi-IRI. Consistently, preapplication of 11R-VIVIT (100 nM) and transfection with NFAT2-targeted siRNA markedly suppressed TGFβ-induced HK-2 cell apoptosis in vitro. In conclusion, 11R-VIVIT administration inhibits IRI-induced NFAT2 activation and prevents AKI-to-CKD progression. Inhibiting NFAT2 may be a promising new therapeutic strategy for preventing renal fibrosis after IR-AKI.

Transient receptor potential ankyrin 1 mediates cisplatin-induced apoptosis in renal tubular cells via calcium-dependent signaling pathway

BACKGROUND

Cisplatin has been a vital drug used for tumor treatment because of its excellent effect on numerous malignant solid cancers. Nonetheless, its nephrotoxicity is non-negligible in clinical practice. This study aims to provide a new understanding of the molecular mechanism of transient receptor potential ankyrin 1 (TRPA1) in cisplatin-induced renal apoptosis.

METHODS

We evaluated the effect on apoptosis, TRPA1 expression, and intracellular calcium concentration of human kidney 2 (HK-2) cells induced by diamminedichloroplatinum (DDP). Additionally, we also assessed DDP-induced apoptosis, the expression of Bax, caspase3, cleaved-cas3, p53, Bcl-2 and intracellular calcium concentration combined with HC-030031 and/or pifithrin-α. The effect of FK506 on apoptosis of HK-2 cells induced by DDP and the expression of the nuclear factor of activated T cells (NFAT) protein treated with HC-030031, pifithrin-α, and/or FK506 were also explored.

RESULTS

The results showed that apoptosis, TRPA1 expression, and intracellular calcium concentration of HK-2 cell induced by DDP were enhanced in a dose-dependent manner. HC-030031 and pifithrin-α relieved apoptosis, and intracellular calcium concentration and the expression of NFAT and phospho-NFAT (p-NFAT) were induced by DDP. HC-030031 combined with pifithrin-α further aggravated the above-mentioned tendency, including relieved apoptosis, intracellular calcium concentration, and NFAT and p-NFAT expression. HC-030031 and FK506 decelerated the apoptosis, and NFAT and p-NFAT expression of HK-2 cells was induced by DDP, while simultaneous treatment with HC-030031 and FK506 further decreased apoptosis and protein expression. However, the expression of Bcl-2 increased when HC-030031, pifithrin-α, or FK506 was used alone, and HC-030031 combined with pifithrin-α or FK506 further improved the expression of Bcl-2.

CONCLUSIONS

TRPA1 mediates cisplatin-induced apoptosis in renal tubular cells via the calcineurin-nuclear factor of activated T-cells-p53 signaling pathway.

The role of NFAT2/miR-20a-5p signaling pathway in the regulation of CD8+ naïve T cells activation and differentiation

T cell dysfunction is a common characteristic in leukemia patients that significantly impacts clinical treatment and prognosis. However, the mechanism underlying T cell dysfunction and its reversal remains unclear. In this study, in accordance with our previous findings, we found that the expression of NFAT2 and pri-miR-17 ~ 92 are lower in peripheral blood CD3⁺ T cells from chronic myelogenous leukemia (CML) patients by gene expression analysis. We further demonstrate that the NFAT2-induced activation, differentiation, and expression of cytokines in human umbilical cord blood CD8⁺ naïve T cells are miR-20a-5p dependent. We also preliminarily explored the relationship between NFAT2 and miR-20a-5p in naive T cells. These results suggest that NFAT2 and miR-20a are crucial for regulating functional CD8⁺ T cells. Additionally, their alteration may be related to CD8⁺ T cell dysfunction in CML patients; thus, NFAT2 and miR-20a-5p may be considered potential targets for revising T cell function in leukemia immunotherapy.

NFAT2-HDAC1 signaling contributes to the malignant phenotype of glioblastoma

BACKGROUND

Deregulation of the nuclear factor of activated T cell (NFAT) pathway has been reported in several human cancers. Particularly, NFAT2 is involved in the malignant transformation of tumor cells and is identified as an oncogene. However, the role of NFAT2 in glioblastoma (GBM) is largely unknown.

METHODS

The expression and prognostic value of NFAT2 were examined in the databases of the Repository of Molecular Brain Neoplasia Data and The Cancer Genome Atlas (TCGA) and clinical samples. The functional effects of silencing or overexpression of NFAT2 were evaluated in glioma stem cell (GSC) viability, invasion, and self-renewal in vitro and in tumorigenicity in vivo. The downstream target of NFAT2 was investigated.

RESULTS

High NFAT2 expression was significantly associated with mesenchymal (MES) subtype and recurrent GBM and predicted poor survival. NFAT2 silencing inhibited the invasion and clonogenicity of MES GSC-enriched spheres in vitro and in vivo. NFAT2 overexpression promoted tumor growth and MES differentiation of GSCs. A TCGA database search showed that histone deacetylase 1 (HDAC1) expression was significantly correlated with that of NFAT2. NFAT2 regulates the transcriptional activity of HDAC1. Rescue of HDAC1 in NFAT2-knockdown GSCs partially restored tumor growth and MES phenotype. Loss of NFAT2 and HDAC1 expression resulted in hyperacetylation of nuclear factor-kappaB (NF-κB), which inhibits NF-κB-dependent transcriptional activity.

CONCLUSION

Our findings suggest that the NFAT2-HDAC1 pathway might play an important role in the maintenance of the malignant phenotype and promote MES transition in GSCs, which provide potential molecular targets for the treatment of GBMs.

NFAT2 overexpression suppresses the malignancy of hepatocellular carcinoma through inducing Egr2 expression

Background

Nuclear factor of activated T cells 2 (NFAT2) has been reported to regulate the development and malignancy of few tumors. In this study, we aimed to explore the effect of NFAT2 expression on cell fate of HepG2 cell and its potential mechanisms.

Methods

Firstly, the pcDNA3.1-NFAT2 plasmid was transfected into HepG2 cells to construct NFAT2 overexpressed HepG2 cells. Then, the chemical count kit-8 cell viability assay, Annexin V-FITC apoptosis detection, EdU labeling proliferation detection, transwell and wound healing experiments were performed. The expression of Egr2 and FasL, and the phosphorylation of AKT and ERK, after ionomycin and PMA co-stimulation, was detected, while the Ca²⁺ mobilization stimulated by K⁺ solution was determined. At last, the mRNA and protein expression of NFAT2, Egr2, FasL, COX-2 and c-myc in carcinoma and adjacent tissues was investigated.

Results

The NFAT2 overexpression suppressed the cell viability, invasion and migration capabilities, and promoted apoptosis of HepG2 cells. NFAT2 overexpression induced the expression of Egr2 and FasL and suppressed the phosphorylation of AKT and ERK. The sensitivity and Ca²⁺ mobilization of HepG2 cells was also inhibited by NFAT2 overexpression. Compared with adjacent tissues, the carcinoma tissues expressed less NFAT2, Egr2, FasL and more COX-2 and c-myc.

Conclusion

The current study firstly suggested that NFAT2 suppressed the aggression and malignancy of HepG2 cells through inducing the expression of Egr2. The absence of NFAT2 and Egr2 in carcinoma tissues reminded us that NFAT2 may be a promising therapeutic target for hepatocellular carcinoma treatment.

Transcription factor Ets-2 regulates the expression of key lymphotropic factors

Transcription factor Ets-2 downregulates the expression of cytokine genes and HIV-1 in resting T-cells. Herein, we studied whether Ets-2 regulates the expression of lymphotropic factors (LFs) NFAT2, NF-κΒ/p65, c-Jun, c-Fos, which regulate the activation/differentiation of T-cells, and kinase CDK10, which controls Ets-2 degradation and repression activity. In silico analysis revealed Ets-2 binding sites on the promoters of NFAT2, c-Jun, c-Fos. The T-cell lines Jurkat (models T-cell signaling/activation) and H938 (contains the HIV-1-LTR) were transfected with an Ets-2 overexpressing vector, in the presence/absence of mitogens. mRNA and protein levels were assessed by qPCR and Western immunoblotting, respectively. Ets-2 overexpression in unstimulated Jurkat increased NFAT2 and c-Jun mRNA/protein, c-Fos mRNA and NF-κΒ/p65 protein, and decreased CDK10 protein. In unstimulated H938, Ets-2 upregulated NFAT2, c-Jun and CDK10 mRNA/protein and NF-κΒ/p65 protein. In stimulated Jurkat, Ets-2 increased NFAT2, c-Jun and c-Fos mRNA/protein and decreased CDK10 mRNA/protein. In stimulated H938 Ets-2 increased NFAT2, c-Jun and c-Fos protein and reduced CDK10 protein levels. Furthermore, Ets-2 overexpression modulated the expression of pro- and anti-apoptotic genes in both cell lines. Ets-2 upregulates the expression of key LFs involved in the activation of cytokine genes or HIV-1 in T-cells, either through its physical interaction with gene promoters or through its involvement in signaling pathways that directly impact their expression. The effect of Ets-2 on CDK10 expression in H938 vs Jurkat cells dictates that, additionally to Ets-2 degradation, CDK10 may facilitate Ets-2 repression activity in cells carrying the HIV-1-LTR, contributing thus to the regulation of HIV latency in virus-infected T-cells.

Genetic Loss of LCK Kinase Leads to Acceleration of Chronic Lymphocytic Leukemia

Most patients with chronic lymphocytic leukemia (CLL) exhibit an indolent disease course and unresponsive B cell receptors (BCRs) exemplified by an anergic phenotype of their leukemic cells. In up to 5% of patients, CLL transforms from an indolent subtype to an aggressive form of B cell lymphoma (Richter's syndrome), which is associated with worse disease outcome and severe downregulation of NFAT2. Here we show that ablation of the tyrosine kinase LCK, which has previously been characterized as a main NFAT2 target gene in CLL, leads to loss of the anergic phenotype, thereby restoring BCR signaling, which results in an acceleration of CLL. Our study identifies LCK as a main player in mediating BCR unresponsiveness and its role as a crucial regulator of anergy in CLL.

Palmitate induces human glomerular mesangial cells fibrosis through CD36-mediated transient receptor potential canonical channel 6/nuclear factor of activated T cell 2 activation

BACKGROUND

Our previous study suggested that palmitate (PA) induces human glomerular mesangial cells (HMCs) fibrosis. However, the mechanism is not fully understood. Recent studies suggested that transient receptor potential canonical channel 6 (TRPC6)/nuclear factor of activated T cell 2 (NFAT2) played an important role in renal fibrosis. Moreover, cluster of differentiation 36 (CD36) regulated the synthesis of TPRC6 agonist diglyceride. In the present study, we investigated whether PA induced HMCs fibrosis via TRPC6/NFAT2 mediated by CD36.

METHODS

A type 2 diabetic nephropathy (DN) model was established in Sprague Dawley rats, and HMCs were stimulated with PA. Lipid accumulation and free fatty acid (FFA) uptake were measured. The expression levels of TGF-β1, p-Smad2/3, FN, TRPC6, NFAT2 and CD36 were evaluated. The intracellular calcium concentration ([Ca²⁺]i) was assessed.

RESULTS

FFA were elevated in type 2 DN rats with kidney fibrosis in addition to NFAT2 and CD36 expression. In vitro, PA induced HMCs fibrosis, [Ca²⁺]_i elevation and NFAT2 activation. SKF96365 or TRPC6-siRNA could attenuate PA-induced HMCs damage. By contrast, the TRPC6 activator showed the opposite effect. Moreover, NFAT2-siRNA also suppressed PA-induced HMCs fibrosis. CD36 knockdown inhibited the PA-induced [Ca²⁺]_i elevation and NFAT2 expression. In addition, long-term treatment with PA decreased TRPC6 expression in HMCs.

CONCLUSION

The results of this study demonstrated that PA could induce the activation of the [Ca²⁺]_i/NFAT2 signaling pathway through TRPC6, which led to HMCs fibrosis. Although activation of TRPC6 attributed to CD36-mediated lipid deposition, long-term stimulation of PA may lead to negative feedback on the expression of TPRC6.

The Role of GSK3β in T Lymphocytes in the Tumor Microenvironment

Immunotherapy options for patients with cancer have emerged following decades of research on immune responses against tumors. Most treatments in this category harness T cells with specificity for tumor associated antigens, neoantigens, and cancer-testis antigens. GSK3β is a serine-threonine kinase with the highest number of substrates and multifaceted roles in cell function including immune cells. Importantly, inhibitors of GSK3β are available for clinical and research use. Here, we review the possible role of GSK3β in the immune tumor microenvironment, with goal to guide future research that tests GSK3β inhibition as an immunotherapy adjunct.

Genetic loss of NFAT2 (NFATc1) impairs B cell development of B1 and B2 B cells

NFAT2 activity was shown to be of critical importance in B cell receptor signaling, development and proliferation; however its role in B cell development in the periphery is still not completely understood. We confirmed that NFAT2 deletion leads to impaired B1 B cell development, supported by our finding of limited B1 progenitors in the bone marrow and spleen of NFAT2 deficient mice. Moreover, we show for the first time that loss of NFAT2 increases immature B cells in particular transitional T2 and T3 as well as mature follicular B cells while marginal zone B cells are decreased. We further demonstrate that NFAT2 regulates the expression of B220, CD23, CD38, IgM/IgD and ZAP70 in murine B cells. In vivo analyses revealed decreased proliferation and increased apoptosis of NFAT2 deficient B cells. In summary, this study provides an extensive analysis of the role of NFAT2 in peripheral B lymphocyte development.

Conditions of limited calcium influx (CLCI) inhibits IL2 induction and favors expression of anergy-related genes in TCR/CD3 and CD28 costimulated primary human T cells

Calcium is a key regulator of the T cell immune response. Depending on the spatial properties (nucleus versus cytoplasm) of the calcium signals generated after CD3xCD28 stimulation, primary human T cells either mount a productive immune response or develop tolerance. Nuclear calcium acts as a genomic decision maker: during T cell activation, it drives expression of genes associated with a productive immune response while in its absence, stimulated T cells acquire an anergy-like gene profile. Selective inhibition of nuclear calcium signaling in stimulated T cells blocks the productive immune response and directs the cells towards an anergy-like state. Here we show that the two transcriptional programs that include, respectively, the 'activation gene', interleukin 2 (IL2) and 'anergy-related genes', EGR2, EGR3, and CREM have different requirements for transmembrane calcium flux. By either lowering extracellular calcium concentrations with EGTA or using low concentrations of the ORAI blockers, BTP2 or RO2959, we reduced transmembrane calcium flux in human primary T cells stimulated with CD3xCD28. These 'conditions of limited calcium influx' (CLCI) blocked CD3xCD28-induced IL2 expression but only moderately affected induction of the anergy-related genes EGR2, EGR3, and CREM. We observed no difference in NFAT2 nuclear translocation after CD3xCD28 stimulation between normal conditions and CLCI. These results indicate that CLCI favors expression of anergy-related genes in activated human T cells. CLCI may be used to develop novel means for pro-tolerance immunosuppressive treatments.

NFAT1 and NFAT2 Differentially Regulate CTL Differentiation Upon Acute Viral Infection

CD8⁺ T cell differentiation orchestrated by transcription regulators is critical for balancing pathogen eradication and long-term immunity by effector and memory CTLs, respectively. The transcription factor Nuclear Factor of Activated T cells (NFAT) family members are known for their roles in T cell development and activation but still largely undetermined in CD8⁺ T cell differentiation in vivo. Here, we interrogated the role of two NFAT family members, NFAT1 and NFAT2, in the effector and memory phase of CD8⁺ T cell differentiation using LCMV^Arm acute infection model. We found that NFAT1 is critical for effector population generation whereas NFAT2 is required for promoting memory CTLs in a cell intrinsic manner. Moreover, we found that mice lacking both NFAT1 and NFAT2 in T cells display a significant increase in KLRG1^hi CD127^hi population and are unable to clear an acute viral infection. NFAT-deficient CTLs showed different degrees of impaired IFN-γ and TNF-α expression with NFAT1 being mainly responsible for IFN-γ production upon ex-vivo stimulation as well as for antigen-specific cytotoxicity. Our results suggest that NFAT1 and NFAT2 have distinct roles in mediating CD8⁺ T cell differentiation and function.

[NFAT2 mediates high glucose-induced apoptosis in glomerular podocytes in vitro]

OBJECTIVE

To determine whether hyperglycemia activates NFAT2 in cultured podocytes to cause podocyte apoptosis and explore the role of NFAT2 in high glucose-induced podocyte apoptosis.

METHODS

Immortalized mouse podocytes were cultured in the presence of normal (5.3 mmol/L) or high glucose (10, 20, 30, and 40 mmol/L) or pretreated with 11R-vivit (100 nmol/L) or cyclosporine A (500 nmol/L) before exposure to 20 mmol/L glucose for different durations (0.5-48 h). The activation of NFAT2 in the podocytes was detected using Western blotting and immunofluorescence assay. The role of NFAT2 in hyperglycemia-induced podocyte apoptosis was explored by observing the inhibition of NFAT2 activation by 11R-vivit using flow cytometry. Intracellular Ca²⁺ was monitored in high glucose-treated podocytes using Fluo-3/AM. The mRNA and protein expressions of the apoptosis gene Bax were detected using real time-qPCR and Western blotting.

RESULTS

Exposure to high glucose in the medium time- and dose-dependently activated NFAT2 in cultured podocytes. Pretreatment with cyclosporine A or 11R- VIVIT completely blocked nuclear accumulation of NFAT2. Treatment with 11R- vivit also inhibited high glucoseinduced apoptosis in cultured podocytes. Exposure to high glucose obviously increased [Ca^{2 +}]I in the podocytes to cause activation of calcineurin and the subsequent increment of nuclear accumulation of NFAT2 and Bax expression.

CONCLUSIONS

High glucose-induced apoptosis in podocytes is mediated by calcineurin/NFAT2/Bax signaling pathway, which may serve as a potential target for therapeutic intervention.

AKAP150 involved in paclitaxel-induced neuropathic pain via inhibiting CN/NFAT2 pathway and downregulating IL-4

Antitubulin chemotherapeutics agents, such as paclitaxel, are effective chemotherapy drugs for cancer treatment. However, painful neuropathy is a major adverse effect limiting the wider application of chemotherapeutics. In this study, we found that A-kinase anchor protein 150 (AKAP150) was significantly upregulated after paclitaxel injection. Inhibition of AKAP150 via siRNA or AKAP150^flox/flox in rodents alleviated the pain behavior induced by paclitaxel, and partly restored the decreased calcineurin (CN) phosphatase activity after paclitaxel treatment. Paclitaxel decreased the expression of anti-inflammatory cytokine interleukin-4 (IL-4), and intrathecal injections of IL-4 effectively alleviated paclitaxel-induced hypersensitivity and the frequency of dorsal root ganglion (DRG) neurons action potential. The decreased CN enzyme activity, resulted in reduced protein expression of nuclear factor of activated T cells 2 (NFAT2) in cell nuclei. Chromatin immunoprecipitation showed that, NFAT2 binds to the IL-4 gene promoter regulating the protein expression of IL-4. Overexpression of NFAT2 by intrathecal injection of the AAV5-NFAT2-GFP virus alleviated the pain behavior induced by paclitaxel via increasing the expression of IL-4. Knocked down AKAP150 by siRNA or AAV5-Cre-GFP partly restored the expression of IL-4 in DRG. Our results indicated that regulation of IL-4 via the CN/NFAT2 pathway mediated by AKAP150 could be a pivotal treatment target for paclitaxel-induced neuropathic pain and or other neuropsychiatric disorders.

NFAT2 Regulates Generation of Innate-Like CD8+ T Lymphocytes and CD8+ T Lymphocytes Responses

Nuclear factor of activated T cells (NFAT) 2 null mutant mice die in utero of cardiac failure, precluding analysis of the role of NFAT2 in lymphocyte responses. Only the NFAT2^-/-/Rag-1^-/- chimeric mice model gave insight into the role of NFAT2 transcription factor in T lymphocyte development, activation, and differentiation. As reports are mainly focused on the role of NFAT2 in CD4⁺ T lymphocytes activation and differentiation, we decided to investigate NFAT2's impact on CD8⁺ T lymphocyte responses. We report that NFAT2 is phosphorylated and inactive in the cytoplasm of naive CD8⁺ T cells, and upon TCR stimulation, it is dephosphorylated and translocated into the nucleus. To study the role of NFAT2 in CD8⁺ T responses, we employed NFAT2^fl/flCD4-Cre mice with NFAT2 deletion specifically in T cells. Interestingly, the absence of NFAT2 in T cells resulted in increased percentage of non-conventional innate-like CD8⁺ T cells. These cells were CD122⁺, rapid producer of interferon gamma (IFN-γ) and had characteristics of conventional memory CD8⁺ T cells. We also observed an expansion of PLZF⁺ expressing CD3⁺ thymocyte population in the absence of NFAT2 and increased IL-4 production. Furthermore, we found that CD8⁺ T lymphocytes deficient in NFAT2 had reduced activation, proliferation, and IFN-γ and IL-2 production at suboptimal TCR strength. NFAT2 absence did not significantly influence differentiation of CD8⁺ T cells into cytotoxic effector cells but reduced their IFN-γ production. This work documents NFAT2 as a negative regulator of innate-like CD8⁺ T cells development. NFAT2 is required for complete CD8⁺ T cell responses at suboptimal TCR stimulation and regulates IFN-γ production by cytotoxic CD8⁺ T cells in vitro.

Suppression of T-cell activation in vitro and in vivo by cordycepin from Cordyceps militaris

BACKGROUND

In addition to achieving a balance between the positive (controlling rejection) and the negative (infection and malignancy) aspects of drug-induced immunodeficiency, new immunosuppressive combinations must address the issue of nonimmune drug toxicity that may be dose limiting. Cordycepin is a type of adenosine analog extracted from Cordyceps militaris. In the present study, we investigated its immunosuppressive effect on T cell both in vitro and in vivo.

METHODS

We evaluated the effects of cordycepin on concanavalin A-induced production of immune mediators in mouse splenocyte by enzyme-linked immunosorbent assay and flow cytometry. Furthermore, using Western blotting, we studied signal transduction mechanisms to determine how cordycepin inhibited T-cell activation in purified mouse T lymphocytes. To confirm the immunosuppressive activity of cordycepin in vivo, we induced the T cell-mediated delayed-type hypersensitivity reaction in a 2,4-dinitro-1-fluorobenzene-induced mouse model.

RESULTS

The in vitro results showed that cordycepin markedly suppressed concanavalin A-induced splenocyte proliferation, Th1 and Th2 cytokine production, and the ratio of CD4(+)-to-CD8(+) T cells. The administration of cordycepin in vivo markedly suppressed the T cell-mediated delayed-type hypersensitivity reaction. The data revealed that cordycepin effectively shocked the nuclear factor kappa B and nuclear factor of activated T cells 2 signal transduction pathways but had no effect on the mitogen activated protein kinase signal transduction pathway.

CONCLUSIONS

These observations indicated that cordycepin has a potential role in downregulating the immune system and could be developed as a useful immunosuppressive agent for treating undesired immune responses.

Downregulation of NFAT2 promotes melanogenesis in B16 melanoma cells

Nuclear factor of activated T-cells (NFAT) proteins are, calcium-regulated transcription factors, key regulator of stimulation-dependent gene activation. In our microarray analysis for the genes expressed in human black and white hairs, NFAT2 was significantly upregulated in the white hair, compared to the black hair. The aim of this study was to investigate functional role of NFAT2 in melanogenesis. Western blot analysis was performed to investigate the expression of NFAT2 protein in B16 melanoma cells. Our data showed that NFAT2 expression was increased in the hypopigmented B16 cells, while tyrosinase and MITF expression was decreased. To investigate the potential role of NFAT2, the recombinant adenovirus expressing microRNA specific for NFAT2 was transduced into the cultured B16 melanoma cells. Consistently, inhibition of NFAT2 enhanced tyrosinase activity and melanin content. Moreover, cyclosporine A, which is known as a calcineurin inhibitor blocking NFAT activation, enhanced tyrosinase activity and melanin content. These data suggest that NFAT2 may play an important role in regulation of melanogenesis in melanocyte.