Txnip regulates the Oct4-mediated pluripotency circuitry via metabolic changes upon differentiation.

Thioredoxin interacting protein (Txnip) is a stress-responsive factor regulating Trx1 for redox balance and involved in diverse cellular processes including proliferation, differentiation, apoptosis, inflammation, and metabolism. However, the biological role of Txnip function in stem cell pluripotency has yet to be investigated. Here, we reveal the novel functions of mouse Txnip in cellular reprogramming and differentiation onset by involving in glucose-mediated histone acetylation and the regulation of Oct4, which is a fundamental component of the molecular circuitry underlying pluripotency. During reprogramming or PSC differentiation process, cellular metabolic and chromatin remodeling occur in order to change its cellular fate. Txnip knockout promotes induced pluripotency but hinders initial differentiation by activating pluripotency factors and promoting glycolysis. This alteration affects the intracellular levels of acetyl-coA, a final product of enhanced glycolysis, resulting in sustained histone acetylation on active PSC gene regions. Moreover, Txnip directly interacts with Oct4, thereby repressing its activity and consequently deregulating Oct4 target gene transcriptions. Our work suggests that control of Txnip expression is crucial for cell fate transitions by modulating the entry and exit of pluripotency.

SARS-CoV-2 peptides bind to NKG2D and increase NK cell activity.

Immune dysregulation is commonly observed in patients with coronavirus disease 2019 (COVID-19). Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induces severe lung inflammation and innate immune cell dysregulation. However, the precise interaction between SARS-CoV-2 and the innate immune system is currently unknown. To understand the interaction between SARS-CoV-2 and natural killer (NK) cells, several SARS-CoV-2 S protein peptides capable of binding to the NKG2D receptor were screened by in silico analysis. Among them, two peptides, cov1 and cov2, bound to NK cells and NKG2D receptors. These cov peptides increased NK cytotoxicity toward lung cancer cells, stimulated interferon gamma (IFN-γ) production by NK cells, and likely mediated these responses through the phosphorylation of Vav1, a key downstream-signaling molecule of NKG2D and NK activation genes. The direct interaction between SARS-CoV-2 and NK cells is a novel finding, and modulation of this interaction has potential clinical application as a therapeutic target for COVID-19.

TXNIP Regulates Natural Killer Cell-Mediated Innate Immunity by Inhibiting IFN-γ Production during Bacterial Infection.

The function of natural killer (NK) cell-derived interferon-γ (IFN-γ) expands to remove pathogens by increasing the ability of innate immune cells. Here, we identified the critical role of thioredoxin-interacting protein (TXNIP) in the production of IFN-γ in NK cells during bacterial infection. TXNIP inhibited the production of IFN-γ and the activation of transforming growth factor ß-activated kinase 1 (TAK1) activity in primary mouse and human NK cells. TXNIP directly interacted with TAK1 and inhibited TAK1 activity by interfering with the complex formation between TAK1 and TAK1 binding protein 1 (TAB1). Txnip-/- (KO) NK cells enhanced the activation of macrophages by inducing IFN-γ production during Pam3CSK4 stimulation or Staphylococcus aureus (S. aureus) infection and contributed to expedite the bacterial clearance. Our findings suggest that NK cell-derived IFN-γ is critical for host defense and that TXNIP plays an important role as an inhibitor of NK cell-mediated macrophage activation by inhibiting the production of IFN-γ during bacterial infection.

Thioredoxin-interacting protein-derived peptide (TN13) inhibits LPS-induced inflammation by inhibiting p38 MAPK signaling.

Inflammation comprises an innate immune response, and is mainly induced by macrophages to protect the host from pathogens and mechanical injuries. The p38 mitogen-activated protein kinase (MAPK) pathway is a key regulator of inflammatory responses in macrophages. Here, we investigated the anti-inflammatory effects of thioredoxin-interacting protein-derived peptide (TN13) in macrophages in vitro and in vivo. Human immunodeficiency virus (HIV) trans-activator protein (TAT)-conjugated TN13 (TAT-TN13) was found to penetrate RAW 264.7 cells and decrease p38 MAPK activation in a dose-dependent manner. We also showed that TAT-TN13 could significantly inhibit lipopolysaccharide (LPS)-induced expression of macrophage activation-related receptors including CD80, CD86, and MHC II, as well as the transcriptional activation of nuclear factor-kappa B (NF-κB) and activator protein-1 (AP-1) in RAW 264.7 cells and primary mouse splenic macrophages. Furthermore, TAT-TN13 decreased the LPS-induced production of proinflammatory cytokines and mediators such as tumor necrosis factor α (TNF-α), interleukin-1ß (IL-1ß), interleukin-6 (IL-6), nitric oxide (NO), inducible NO synthase (iNOS), and cyclooxygenase 2 (COX-2) in RAW 264.7 cells and mice. These results indicate that TAT-TN13 can inhibit macrophage-derived inflammation by inhibiting p38 MAPK activity and might represent a potential novel drug for the treatment of inflammation-related diseases.

TLR4/NF-κB axis induces fludarabine resistance by suppressing TXNIP expression in acute myeloid leukemia cells.

Overcoming drug resistance is one of key issues in treating refractory acute myeloid leukemia (AML). The Toll-like receptor 4 (TLR4) signaling pathway is involved in many aspects of biological functions of AML cells, including the regulation of pro-inflammatory cytokine products, myeloid differentiation, and survival of AML cells. Thus, targeting TLR4 of AML patients for therapeutic purposes should be carefully addressed. In this regard, we investigated the possible role of TLR4 as a regulatory factor against fludarabine (FA) cytotoxicity activity. Here, we identified the differential expression of TLR4 and CD14 receptors in AML cell lines and examined their relationship to FA sensitivity. We found that the stimulation of TLR4 with lipopolysaccharide (LPS) in a TLR4-expressing cell line, THP-1, increased cell viability under FA treatment condition and showed that TLR4 stimulation overcame FA sensitivity through the activation of NF-κB, which subsequently upregulated several anti-apoptotic genes. The inhibition of TLR4/NF-κB signaling could partially or completely reverse LPS-induced cell survival under FA treatment conditions. Interestingly, we found that the expression of thioredoxin-interacting protein (TXNIP), a well-known tumor suppressor, was induced by FA treatment; however, it was suppressed by LPS treatment. Furthermore, the expression level of TXNIP was critical for FA-induced cytotoxicity or LPS-induced FA resistance of THP-1 cells. Our data suggest that TXNIP plays an important role in FA-induced cytotoxicity and TLR4/NF-κB-mediated FA resistance of AML cells. Therefore, TXNIP may be a potential therapeutic target for AML treatment.

The infusion of ex vivo, interleukin-15 and -21-activated donor NK cells after haploidentical HCT in high-risk AML and MDS patients-a randomized trial.

Clinical effect of donor-derived natural killer cell infusion (DNKI) after HLA-haploidentical hematopoietic cell transplantation (HCT) was evaluated in high-risk myeloid malignancy in phase 2, randomized trial. Seventy-six evaluable patients (aged 21-70 years) were randomized to receive DNKI (N = 40) or not (N = 36) after haploidentical HCT. For the HCT conditioning, busulfan, fludarabine, and anti-thymocyte globulin were administered. DNKI was given twice 13 and 20 days after HCT. Four patients in the DNKI group failed to receive DNKI. In the remaining 36 patients, median DNKI doses were 1.0 × 108/kg and 1.4 × 108/kg on days 13 and 20, respectively. Intention-to-treat analysis showed a lower disease progression for the DNKI group (30-month cumulative incidence, 35% vs 61%, P = 0.040; subdistribution hazard ratio, 0.50). Furthermore, at 3 months after HCT, the DNKI patients showed a 1.8- and 2.6-fold higher median absolute blood count of NK and T cells, respectively. scRNA-sequencing analysis in seven study patients showed that there was a marked increase in memory-like NK cells in DNKI patients which, in turn, expanded the CD8+ effector-memory T cells. In high-risk myeloid malignancy, DNKI after haploidentical HCT reduced disease progression. This enhanced graft-vs-leukemia effect may be related to the DNKI-induced, post-HCT expansion of NK and T cells. Clinical trial number: NCT02477787.

Synaptotagmin 11 scaffolds MKK7-JNK signaling process to promote stem-like molecular subtype gastric cancer oncogenesis.

BACKGROUND: Identifying biomarkers related to the diagnosis and treatment of gastric cancer (GC) has not made significant progress due to the heterogeneity of tumors. Genes involved in histological classification and genetic correlation studies are essential to develop an appropriate treatment for GC. METHODS: In vitro and in vivo lentiviral shRNA library screening was performed. The expression of Synaptotagmin (SYT11) in the tumor tissues of patients with GC was confirmed by performing Immunohistochemistry, and the correlation between the expression level and the patient's survival rate was analyzed. Phospho-kinase array was performed to detect Jun N-terminal kinase (JNK) phosphorylation. SYT11, JNK, and MKK7 complex formation was confirmed by western blot and immunoprecipitation assays. We studied the effects of SYT11 on GC proliferation and metastasis, real-time cell image analysis, adhesion assay, invasion assay, spheroid formation, mouse xenograft assay, and liver metastasis. RESULTS: SYT11 is highly expressed in the stem-like molecular subtype of GC in transcriptome analysis of 527 patients with GC. Moreover, SYT11 is a potential prognostic biomarker for histologically classified diffuse-type GC. SYT11 functions as a scaffold protein, binding both MKK7 and JNK1 signaling molecules that play a role in JNK1 phosphorylation. In turn, JNK activation leads to a signaling cascade resulting in cJun activation and expression of downstream genes angiopoietin-like 2 (ANGPTL2), thrombospondin 4 (THBS4), Vimentin, and junctional adhesion molecule 3 (JAM3), which play a role in epithelial-mesenchymal transition (EMT). SNU484 cells infected with SYT11 shRNA (shSYT11) exhibited reduced spheroid formation, mouse tumor formation, and liver metastasis, suggesting a pro-oncogenic role of SYT11. Furthermore, SYT11-antisense oligonucleotide (ASO) displayed antitumor activity in our mouse xenograft model and was conferred an anti-proliferative effect in SNU484 and MKN1 cells. CONCLUSION: SYT11 could be a potential therapeutic target as well as a prognostic biomarker in patients with diffuse-type GC, and SYT11-ASO could be used in therapeutic agent development for stem-like molecular subtype diffuse GC.

Root Extract of a Micropropagated Prunus africana Medicinal Plant Induced Apoptosis in Human Prostate Cancer Cells (PC-3) via Caspase-3 Activation.

Prostate cancer is one of the major causes of cancer-related deaths among men globally. Medicinal plants have been explored as alternative treatment options. Herein, we assessed the in vitro cytotoxic effects of 70% ethanolic root extracts of six-month-old micropropagated Prunus africana (PIR) on PC-3 prostate cancer cells as an alternative to the traditionally used P. africana stem-bark extract (PWS) treatment. In vitro assays on PC-3 cells included annexin-V and propidium iodide staining, DAPI staining, and caspase-3 activity analysis through western blotting. PC-3 cells were exposed to PWS and PIR at different concentrations, and dose-dependent antiprostate cancer effects were observed. PC-3 cell viability was determined using CCK-8 assay, which yielded IC50 values of 52.30 and 82.40 µg/mL for PWS and PIR, respectively. Annexin-V and PI staining showed dose-dependent apoptosis of PC-3 cells. Significant (p < 0.001) percent of DAPI-stained apoptotic PC-3 cells were observed in PWS, PIR, and doxorubicin treatment compared with the negative control. PWS treatment substantially elevated cleaved caspase-3 levels in PC-3 cells compared with the PIR treatment. These results provide evidence for the antiprostate cancer potential of PIR and sets a basis for further research to enhance future utilization of roots of young micropropagated P. africana for prostate cancer treatment as an alternative to stem bark. Moreover, micropropagation approach may help provide the required raw materials and hence reduce the demand for P. africana from endangered wild population.

Inhibition of Osteoclastogenesis by Thioredoxin-Interacting Protein-Derived Peptide (TN13).

Overactivated osteoclasts lead to many bone diseases, including osteoporosis and rheumatoid arthritis. The p38 MAPK (p38) is an essential regulator of the receptor activator of nuclear factor-κB ligand (RANKL)-mediated osteoclastogenesis and bone loss. We previously reported TAT conjugated thioredoxin-interacting protein-derived peptide (TAT-TN13) as an inhibitor of p38 in hematopoietic stem cells (HSCs). Here, we examined the role of TAT-TN13 in the differentiation and function of osteoclasts. TAT-TN13 significantly suppressed RANKL-mediated differentiation of RAW 264.7 cells and bone marrow macrophages (BMMs) into osteoclasts. TAT-TN13 also inhibited the RANKL-induced activation of NF-κB and nuclear factor of activated T-cells cytoplasmic 1 (NFATc1), leading to the decreased expression of osteoclast-specific genes, including tartrate-resistant acid phosphatase (TRAP) and Cathepsin K. Additionally, TAT-TN13 treatment protected bone loss in ovariectomized (OVX) mice. Taken together, these results suggest that TAT-TN13 inhibits osteoclast differentiation by regulating the p38 and NF-κB signaling pathway; thus, it may be a useful agent for preventing or treating osteoporosis.

TXNIP regulates AKT-mediated cellular senescence by direct interaction under glucose-mediated metabolic stress.

Aging is associated with an inevitable and universal loss of cell homeostasis and restricts an organism's lifespan by an increased susceptibility to diseases and tissue degeneration. The glucose uptake associated with producing energy for cell survival is one of the major causes of ROS production under physiological conditions. However, the overall mechanisms by which glucose uptake results in cellular senescence remain mysterious. In this study, we found that TXNIP deficiency accelerated the senescent phenotypes of MEF cells under high glucose condition. TXNIP-/- MEF cells showed greater induced glucose uptake and ROS levels than wild-type cells, and N-acetylcysteine (NAC) treatment rescued the cellular senescence of TXNIP-/- MEF cells. Interestingly, TXNIP-/- MEF cells showed continuous activation of AKT during long-term subculture, and AKT signaling inhibition completely blocked the cellular senescence of TXNIP-/- MEF cells. In addition, we found that TXNIP interacted with AKT via the PH domain of AKT, and their interaction was increased by high glucose or H2 O2 treatment. The inhibition of AKT activity by TXNIP was confirmed using western blotting and an in vitro kinase assay. TXNIP deficiency in type 1 diabetes mice (Akita) efficiently decreased the blood glucose levels and finally increased mouse survival. However, in normal mice, TXNIP deficiency induced metabolic aging of mice and cellular senescence of kidney cells by inducing AKT activity and aging-associated gene expression. Altogether, these results suggest that TXNIP regulates cellular senescence by inhibiting AKT pathways via a direct interaction under conditions of glucose-derived metabolic stress.

Suppressor of Cytokine Signaling 2 Negatively Regulates NK Cell Differentiation by Inhibiting JAK2 Activity.

Suppressor of cytokine signaling (SOCS) proteins are negative regulators of cytokine responses. Although recent reports have shown regulatory roles for SOCS proteins in innate and adaptive immunity, their roles in natural killer (NK) cell development are largely unknown. Here, we show that SOCS2 is involved in NK cell development. SOCS2-/- mice showed a high frequency of NK cells in the bone marrow and spleen. Knockdown of SOCS2 was associated with enhanced differentiation of NK cells in vitro, and the transplantation of hematopoietic stem cells (HSCs) into congenic mice resulted in enhanced differentiation in SOCS2-/- HSCs. We found that SOCS2 could inhibit Janus kinase 2 (JAK2) activity and JAK2-STAT5 signaling pathways via direct interaction with JAK2. Furthermore, SOCS2-/- mice showed a reduction in lung metastases and an increase in survival following melanoma challenge. Overall, our findings suggest that SOCS2 negatively regulates the development of NK cells by inhibiting JAK2 activity via direct interaction.

Macrophage migration inhibitory factor interacts with thioredoxin-interacting protein and induces NF-κB activity.

The nuclear factor kappa B (NF-κB) pathway is pivotal in controlling survival and apoptosis of cancer cells. Macrophage migration inhibitory factor (MIF), a cytokine that regulates the immune response and tumorigenesis under inflammatory conditions, is upregulated in various tumors. However, the intracellular functions of MIF are unclear. In this study, we found that MIF directly interacted with thioredoxin-interacting protein (TXNIP), a tumor suppressor and known inhibitor of NF-κB activity, and MIF significantly induced NF-κB activation. MIF competed with TXNIP for NF-κB activation, and the intracellular MIF induced NF-κB target genes, including c-IAP2, Bcl-xL, ICAM-1, MMP2 and uPA, by inhibiting the interactions between TXNIP and HDACs or p65. Furthermore, we identified the interaction motifs between MIF and TXNIP via site-directed mutagenesis of their cysteine (Cys) residues. Cys57 and Cys81 of MIF and Cys36 and Cys120 of TXNIP were responsible for the interaction. MIF reversed the TXNIP-induced suppression of cell proliferation and migration. Overall, we suggest that MIF induces NF-κB activity by counter acting the inhibitory effect of TXNIP on the NF-κB pathway via direct interaction with TXNIP. These findings reveal a novel intracellular function of MIF in the progression of cancer.

Thioredoxin-interacting protein regulates haematopoietic stem cell ageing and rejuvenation by inhibiting p38 kinase activity.

Ageing is a natural process in living organisms throughout their lifetime, and most elderly people suffer from ageing-associated diseases. One suggested way to tackle such diseases is to rejuvenate stem cells, which also undergo ageing. Here we report that the thioredoxin-interacting protein (TXNIP)-p38 mitogen-activated protein kinase (p38) axis regulates the ageing of haematopoietic stem cells (HSCs), by causing a higher frequency of long-term HSCs, lineage skewing, a decrease in engraftment, an increase in reactive oxygen species and loss of Cdc42 polarity. TXNIP inhibits p38 activity via direct interaction in HSCs. Furthermore, cell-penetrating peptide (CPP)-conjugated peptide derived from the TXNIP-p38 interaction motif inhibits p38 activity via this docking interaction. This peptide dramatically rejuvenates aged HSCs in vitro and in vivo. Our findings suggest that the TXNIP-p38 axis acts as a regulatory mechanism in HSC ageing and indicate the potent therapeutic potential of using CPP-conjugated peptide to rejuvenate aged HSCs.