Downregulation of lncRNA MIR17HG reduced tumorigenicity and Treg-mediated immune escape of non-small-cell lung cancer cells through targeting the miR-17-5p/RUNX3 axis.

Long noncoding RNA MIR17HG was involved with the progression of non-small-cell lung cancer (NSCLC), but specific mechanisms of MIR17HG-mediated immune escape of NSCLC cells were still unknown. The present study investigated the function of MIR17HG on regulatory T cell (Treg)-mediated immune escape and the underlying mechanisms in NSCLC. Expression of MIR17HG and miR-17-5p in NSCLC tissue samples were detected using quantitative real-time PCR (qRT-PCR). A549 and H1299 cells were transfected with sh-MIR17HG, miR-17-5p inhibitor, or sh-MIR17HG + miR-17-5p inhibitor, followed by cocultured with Tregs. Cell proliferation was measured using 5-ethynyl-20-deoxyuridine (Edu) staining assay and cell counting kit-8 (CCK-8) assay. Flow cytometry was used for determining positive numbers of FOXP3+CD4+/CD25+/CD8+ Tregs. Through subcutaneous injection with transfected A549 cells, a xenograft nude mouse model was established. Weights and volumes of xenograft tumors were evaluated. Additionally, the expressions of immune-related factors including transforming growth factor beta (TGF-ß), vascular endothelial growth factor A (VEGF-A), interleukin-10 (IL-10), IL-4, and interferon-gamma (IFN-γ) in cultured cells, were evaluated by enzyme-linked immunosorbent assay and western blot analysis. Then, miR-17-5p was decreased and MIR17HG was enhanced in both NSCLC tissues and cell lines. MIR17HG knockdown significantly suppressed cell proliferation, tumorigenicity, and immune capacity of Tregs in A549 and H1299 cells, whereas sh-MIR17HG significantly reduced expression levels of VEGF-A, TGF-ß, IL-4, and IL-10 but promoted the IFN-γ level in vitro and in vivo. Moreover, downregulation of miR-17-5p significantly reversed the effects of sh-MIR17HG. Additionally, we identified that runt- related transcription factor 3 (RUNX3) was a target of miR-17-5p, and sh-MIR17HG and miR-17-5p mimics downregulated RUNX3 expression. In conclusion, downregulation of MIR17HG suppresses tumorigenicity and Treg-mediated immune escape in NSCLC through downregulating the miR-17-5p/RUNX3 axis, indicating that this axis contains potential biomarkers for NSCLC.

Runx3 Regulates CD8+ T Cell Local Expansion and CD43 Glycosylation in Mice by H1N1 Influenza A Virus Infection.

We have recently reported that transcription factor Runx3 is required for pulmonary generation of CD8+ cytotoxic T lymphocytes (CTLs) that play a crucial role in the clearance of influenza A virus (IAV). To understand the underlying mechanisms, we determined the effects of Runx3 knockout (KO) on CD8+ T cell local expansion and phenotypes using an inducible general Runx3 KO mouse model. We found that in contrast to the lungs, Runx3 general KO promoted enlargement of lung-draining mediastinal lymph node (mLN) and enhanced CD8+ and CD4+ T cell expansion during H1N1 IAV infection. We further found that Runx3 deficiency greatly inhibited core 2 O-glycosylation of selectin ligand CD43 on activated CD8+ T cells but minimally affected the cell surface expression of CD43, activation markers (CD44 and CD69) and cell adhesion molecules (CD11a and CD54). Runx3 KO had a minor effect on lung effector CD8+ T cell death by IAV infection. Our findings indicate that Runx3 differently regulates CD8+ T cell expansion in mLNs and lungs by H1N1 IAV infection. Runx3 is required for CD43 core 2 O-glycosylation on activated CD8+ T cells, and the involved Runx3 signal pathway may mediate CD8+ T cell phenotype for pulmonary generation of CTLs.

RUNX3 inhibits KSHV lytic replication by binding to the viral genome and repressing transcription.

Kaposi's sarcoma-associated herpesvirus (KSHV) belongs to the gamma herpesvirus family, which can cause human malignancies including Kaposi sarcoma, primary effusion lymphoma, and multicentric Castleman's diseases. KSHV typically maintains a persistent latent infection within the host. However, after exposure to intracellular or extracellular stimuli, KSHV lytic replication can be reactivated. The reactivation process of KSHV triggers the innate immune response to limit viral replication. Here, we found that the transcriptional regulator RUNX3 is transcriptionally upregulated by the NF-κB signaling pathway in KSHV-infected SLK cells and B cells during KSHV reactivation. Notably, knockdown of RUNX3 significantly promotes viral lytic replication as well as the gene transcription of KSHV. Consistent with this finding, overexpression of RUNX3 impairs viral lytic replication. Mechanistically, RUNX3 binds to the KSHV genome and limits viral replication through transcriptional repression, which is related to its DNA- and ATP-binding ability. However, KSHV has also evolved corresponding strategies to antagonize this inhibition by using the viral protein RTA to target RUNX3 for ubiquitination and proteasomal degradation. Altogether, our study suggests that RUNX3, a novel host-restriction factor of KSHV that represses the transcription of viral genes, may serve as a potential target to restrict KSHV transmission and disease development.IMPORTANCEThe reactivation of Kaposi's sarcoma-associated herpesvirus (KSHV) from latent infection to lytic replication is important for persistent viral infection and tumorigenicity. However, reactivation is a complex event, and the regulatory mechanisms of this process are not fully elucidated. Our study revealed that the host RUNX3 is upregulated by the NF-κB signaling pathway during KSHV reactivation, which can repress the transcription of KSHV genes. At the late stage of lytic replication, KSHV utilizes a mechanism involving RTA to degrade RUNX3, thus evading host inhibition. This finding helps elucidate the regulatory mechanism of the KSHV life cycle and may provide new clues for the development of therapeutic strategies for KSHV-associated diseases.

Differential Runx3, Eomes, and T-bet expression subdivides MS-associated CD4+ T cells with brain-homing capacity.

Multiple sclerosis (MS) is a common and devastating chronic inflammatory disease of the CNS. CD4+ T cells are assumed to be the first to cross the blood-central nervous system (CNS) barrier and trigger local inflammation. Here, we explored how pathogenicity-associated effector programs define CD4+ T cell subsets with brain-homing ability in MS. Runx3- and Eomes-, but not T-bet-expressing CD4+ memory cells were diminished in the blood of MS patients. This decline reversed following natalizumab treatment and was supported by a Runx3+ Eomes+ T-bet- enrichment in cerebrospinal fluid samples of treatment-naïve MS patients. This transcription factor profile was associated with high granzyme K (GZMK) and CCR5 levels and was most prominent in Th17.1 cells (CCR6+ CXCR3+ CCR4-/dim ). Previously published CD28- CD4 T cells were characterized by a Runx3+ Eomes- T-bet+ phenotype that coincided with intermediate CCR5 and a higher granzyme B (GZMB) and perforin expression, indicating the presence of two separate subsets. Under steady-state conditions, granzyme Khigh Th17.1 cells spontaneously passed the blood-brain barrier in vitro. This was only found for other subsets including CD28- cells when using inflamed barriers. Altogether, CD4+ T cells contain small fractions with separate pathogenic features, of which Th17.1 seems to breach the blood-brain barrier as a possible early event in MS.

Runx3 Restoration Regresses K-Ras-Activated Mouse Lung Cancers and Inhibits Recurrence.

Oncogenic K-RAS mutations occur in approximately 25% of human lung cancers and are most frequently found in codon 12 (G12C, G12V, and G12D). Mutated K-RAS inhibitors have shown beneficial results in many patients; however, the inhibitors specifically target K-RASG12C and acquired resistance is a common occurrence. Therefore, new treatments targeting all kinds of oncogenic K-RAS mutations with a durable response are needed. RUNX3 acts as a pioneer factor of the restriction (R)-point, which is critical for the life and death of cells. RUNX3 is inactivated in most K-RAS-activated mouse and human lung cancers. Deletion of mouse lung Runx3 induces adenomas (ADs) and facilitates the development of K-Ras-activated adenocarcinomas (ADCs). In this study, conditional restoration of Runx3 in an established K-Ras-activated mouse lung cancer model regressed both ADs and ADCs and suppressed cancer recurrence, markedly increasing mouse survival. Runx3 restoration suppressed K-Ras-activated lung cancer mainly through Arf-p53 pathway-mediated apoptosis and partly through p53-independent inhibition of proliferation. This study provides in vivo evidence supporting RUNX3 as a therapeutic tool for the treatment of K-RAS-activated lung cancers with a durable response.

RUNX3 inactivates oncogenic MYC through disruption of MYC/MAX complex and subsequent recruitment of GSK3ß-FBXW7 cascade.

MYC is one of the most commonly dysregulated proto-oncogenes in cancer. MYC promotes cancer initiation and maintenance by regulating multiple biological processes, such as proliferation and stem cell function. Here, we show that developmental regulator RUNX3 targets MYC protein for rapid degradation through the glycogen synthase kinase-3 beta-F-box/WD repeat-containing protein 7 (GSK3ß-FBXW7) proteolytic pathway. The evolutionarily conserved Runt domain of RUNX3 interacts directly with the basic helix-loop-helix leucine zipper of MYC, resulting in the disruption of MYC/MAX and MYC/MIZ-1 interactions, enhanced GSK3ß-mediated phosphorylation of MYC protein at threonine-58 and its subsequent degradation via the ubiquitin-proteasomal pathway. We therefore uncover a previously unknown mode of MYC destabilization by RUNX3 and provide an explanation as to why RUNX3 inhibits early-stage cancer development in gastrointestinal and lung mouse cancer models.

C/ebpα represses the oncogenic Runx3-Myc axis in p53-deficient osteosarcoma development.

Osteosarcoma (OS) is characterized by TP53 mutations in humans. In mice, loss of p53 triggers OS development, and osteoprogenitor-specific p53-deleted mice are widely used to study the process of osteosarcomagenesis. However, the molecular mechanisms underlying the initiation or progression of OS following or parallel to p53 inactivation remain largely unknown. Here, we examined the role of transcription factors involved in adipogenesis (adipo-TFs) in p53-deficient OS and identified a novel tumor suppressive molecular mechanism mediated by C/ebpα. C/ebpα specifically interacts with Runx3, a p53 deficiency-dependent oncogene, and, in the same manner as p53, decreases the activity of the oncogenic axis of OS, Runx3-Myc, by inhibiting Runx3 DNA binding. The identification of a novel molecular role for C/ebpα in p53-deficient osteosarcomagenesis underscores the importance of the Runx-Myc oncogenic axis as a therapeutic target for OS.

RUNX3 regulates the susceptibility against EGFR-targeted non-small cell lung cancer therapy using 47Sc-conjugated cetuximab.

BACKGROUND: Radioimmunotherapy with cetuximab and conjugates with various radioisotopes is a feasible treatment option for different tumor models. Scandium-47 (47Sc), one of several ß--particle-emitting radioisotopes, displays favorable physical and chemical properties for conjugation to monoclonal antibodies. However, the therapeutic efficacy of 47Sc in preclinical and clinical studies is largely unknown. Given that intrinsic alterations in tumors greatly contribute to resistance to anti-epidermal growth factor receptor (EGFR)-targeted therapy, research on overcoming resistance to radioimmunotherapy using cetuximab is required. METHODS: 47Sc was produced by irradiation of a CaCO3 target at the HANARO research reactor in KAERI (Korea Atomic Energy Research Institute) and prepared by chromatographic separation of the irradiated target. Cetuximab was conjugated with 47Sc using the bifunctional chelating agent DTPA. Radiochemical purity was determined using instant thin-layer chromatography. The immunoreactivity of 47Sc-DTPA-cetuximab was evaluated using the Lindmo method and an in vitro cell-binding assay. The inhibitory effects of cetuximab and 47Sc-DTPA-cetuximab were confirmed using cell growth inhibition and BrdU cell proliferation assays. Differences in protein expression levels between cetuximab- and 47Sc-DTPA-cetuximab-treated cells were confirmed using western blotting. Complex formation between RUNX3 and DNA repair components was confirmed using immunoprecipitation and western blotting. RESULTS: Cetuximab induces cell cycle arrest and cell death in EGFR-overexpressing NSCLC cells. Radiolabeling of cetuximab with 47Sc led to increased therapeutic efficacy relative to cetuximab alone. Application of 47Sc-DTPA-cetuximab induced DNA damage responses, and activation of RUNX3 significantly enhanced the therapeutic efficacy of 47Sc-DTPA-cetuximab. RUNX3 mediated susceptibility to EGFR-targeted NSCLC therapy using 47Sc-DTPA-cetuximab via interaction with components of the DNA damage and repair machinery. CONCLUSIONS: 47Sc-DTPA-cetuximab promoted cell death in EGFR-overexpressing NSCLC cells by targeting EGFR and inducing DNA damage as a result of ß irradiation emitted from the conjugated 47Sc. Activation of RUNX3 played a key role in DNA damage and repair processes in response to the ionizing radiation and inhibited cell growth, thus leading to more effective tumor suppression. RUNX3 can potentially moderate susceptibility to 47Sc-conjugated cetuximab by modulating DNA damage and repair process mechanisms.

Clinical significance of determining the hypermethylation of the RUNX3 gene promoter and its cohypermethylation with the BRCA1 gene for patients with breast cancer.

PURPOSE: The aim of this study was to assess the clinical significance of RUNX3 gene hypermethylation in the pathogenetic mechanisms of breast cancer in women, taking into account its cohypermethylation with the BRCA1 gene. METHODS: This study included 74 women with newly diagnosed breast cancer (samples from female primary breast carcinomas and paired peripheral blood samples) and 62 women without oncological pathology-control group (peripheral blood samples). Epigenetic testing for hypermethylation status studying was performed in all samples on freshly collected material with the addition of a preservative before the storage and DNA isolation. RESULTS: Hypermethylation of the RUNX3 gene promoter region was detected in 71.6% samples of breast cancer tissue and in 35.13% samples of blood. The RUNX3 gene promoter region hypermethylation was significantly higher among breast cancer patients compared to the control group. The frequency of cohypermethylation in RUNX3 and BRCA1 genes was significantly increased in breast cancer tissues compared to the blood of patients. CONCLUSION: A significantly increased frequency of the hypermethylation of the RUNX3 gene promoter region and its cohypermethylation with the BRCA1 gene promoter region was found in tumor tissue and blood samples from patients with breast cancer, in contrast to the control group. The identified differences indicate the importance of further investigations of suppressor genes cohypermethylation in patients with breast cancer. Further large-scale studies are needed to find out whether the detected hypermethylation and cohypermethylation of the RUNX3 gene promoter region will have an impact on the treatment strategy in patients.

The RUNX Family of Proteins, DNA Repair, and Cancer.

The RUNX family of transcription factors, including RUNX1, RUNX2, and RUNX3, are key regulators of development and can function as either tumor suppressors or oncogenes in cancer. Emerging evidence suggests that the dysregulation of RUNX genes can promote genomic instability in both leukemia and solid cancers by impairing DNA repair mechanisms. RUNX proteins control the cellular response to DNA damage by regulating the p53, Fanconi anemia, and oxidative stress repair pathways through transcriptional or non-transcriptional mechanisms. This review highlights the importance of RUNX-dependent DNA repair regulation in human cancers.

p53 Deficiency-Dependent Oncogenicity of Runx3.

The RUNX transcription factors are frequently dysregulated in human cancers, suggesting their potential as attractive targets for drug treatment. However, all three transcription factors have been described as both tumor suppressors and oncogenes, indicating the need to determine their molecular mechanisms of action. Although RUNX3 has long been considered a tumor suppressor in human cancers, several recent studies have shown that RUNX3 is upregulated during the development or progression of various malignant tumors, suggesting it may act as a "conditional" oncogene. Resolving this paradox and understanding how a single gene can exhibit both oncogenic and tumor-suppressive properties is essential for successful drug targeting of RUNX. This review describes the evidence for the activities of RUNX3 in human cancer and proposes an explanation for the duality of RUNX3 involving the status of p53. In this model, p53 deficiency causes RUNX3 to become oncogenic, leading to aberrant upregulation of MYC.

Prox2 and Runx3 vagal sensory neurons regulate esophageal motility.

Vagal sensory neurons monitor mechanical and chemical stimuli in the gastrointestinal tract. Major efforts are underway to assign physiological functions to the many distinct subtypes of vagal sensory neurons. Here, we use genetically guided anatomical tracing, optogenetics, and electrophysiology to identify and characterize vagal sensory neuron subtypes expressing Prox2 and Runx3 in mice. We show that three of these neuronal subtypes innervate the esophagus and stomach in regionalized patterns, where they form intraganglionic laminar endings. Electrophysiological analysis revealed that they are low-threshold mechanoreceptors but possess different adaptation properties. Lastly, genetic ablation of Prox2 and Runx3 neurons demonstrated their essential roles for esophageal peristalsis in freely behaving mice. Our work defines the identity and function of the vagal neurons that provide mechanosensory feedback from the esophagus to the brain and could lead to better understanding and treatment of esophageal motility disorders.

MicroRNA-17 Family Targets RUNX3 to Increase Proliferation and Migration of Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is one common cancer in the world. Previous studies have shown that miR-17 family members are elevated in most tumors and promote tumor progression. However, there is no comprehensive analysis of the expression and functional mechanism of the microRNA-17 (miR-17) family in HCC. The aim of this study is to comprehensively analyze the function of the miR-17 family in HCC and the molecular mechanism of its role. Bioinfoimatics analysis of the miR-17 family expression profile and its relationship to clinical significance using The Cancer Genome Atlas (TCGA) database, and this result was confirmed using quantitative real-time polymerase chain reaction. miR-17 family members were tested for functional effects through transfection of miRNA precursors and inhibitors, and monitoring cell viability and migration by cell count and wound healing assays. In addition, we using dual-luciferase assay and Western blot demonstrated the targeting relationship between the miRNA-17 family and RUNX3. These members of miR-17 family were highly expressed in HCC tissues, and the overexpression of the miR-17 family promoted the proliferation and migration of SMMC-7721 cells, whereas treatment with anti-miR17 inhibitors caused the opposite effects. Notably, we also found that inhibitors anti-each member of miR-17 can suppress the expression of the entire family member. In addition, they can bind to the 3' untranslated region of RUNX3 to regulate its expression at the translational level. Our results proved that miR-17 family has oncogenic characteristics, overexpression every member of the family contributed to HCC cell proliferation and migration by reducing the translation of RUNX3.

Role of RUNX3 in Restriction Point Regulation.

A cell cycle is a series of events that takes place in a cell as it grows and divides. At the G1 phase of cell cycle, cells monitor their cumulative exposure to specific signals and make the critical decision to pass through the restriction (R)-point. The R-point decision-making machinery is fundamental to normal differentiation, apoptosis, and G1-S transition. Deregulation of this machinery is markedly associated with tumorigenesis. Therefore, identification of the molecular mechanisms that govern the R-point decision is one of the fundamental issues in tumor biology. RUNX3 is one of the genes frequently inactivated in tumors by epigenetic alterations. In particular, RUNX3 is downregulated in most K-RAS-activated human and mouse lung adenocarcinomas (ADCs). Targeted inactivation of Runx3 in the mouse lung induces adenomas (ADs), and markedly shortens the latency of ADC formation induced by oncogenic K-Ras. RUNX3 participates in the transient formation of R-point-associated activator (RPA-RX3-AC) complexes, which measure the duration of RAS signals and thereby protect cells against oncogenic RAS. This review focuses on the molecular mechanism by which the R-point participates in oncogenic surveillance.

RUNX3 Meets the Ubiquitin-Proteasome System in Cancer.

RUNX3 is a transcription factor with regulatory roles in cell proliferation and development. While largely characterized as a tumor suppressor, RUNX3 can also be oncogenic in certain cancers. Many factors account for the tumor suppressor function of RUNX3, which is reflected by its ability to suppress cancer cell proliferation after expression-restoration, and its inactivation in cancer cells. Ubiquitination and proteasomal degradation represent a major mechanism for the inactivation of RUNX3 and the suppression of cancer cell proliferation. On the one hand, RUNX3 has been shown to facilitate the ubiquitination and proteasomal degradation of oncogenic proteins. On the other hand, RUNX3 can be inactivated through the ubiquitin-proteasome system. This review encapsulates two facets of RUNX3 in cancer: how RUNX3 suppresses cell proliferation by facilitating the ubiquitination and proteasomal degradation of oncogenic proteins, and how RUNX3 is degraded itself through interacting RNA-, protein-, and pathogen-mediated ubiquitination and proteasomal degradation.

RUNX3 improves CAR-T cell phenotype and reduces cytokine release while maintaining CAR-T function.

CAR-T therapy has shown successful in the treatment of certain types of hematological malignancy, while the efficacy of CAR-T cell in treating solid tumors has been limited due to the exhaustion of CAR-T caused by the tumor microenvironment in solid tumors. Therefore, improving the exhaustion of CAR-T cell is one of the inspiring strategies for CAR-T treatment of solid tumors. As an important regulator in T cell immunity, the transcription factor RUNX3 not only negatively regulates the terminal differentiation T-bet gene, reducing the ultimate differentiation of T cells, but also increases the residency of T cells in non-lymphoid tissues and tumors. By overexpressing RUNX3 in CAR-T cells, we found that increasing the expression of RUNX3 maintained the low differentiation of CAR-T cells, further improving the exhaustion of CAR-T cells during antigen stimulation. In vitro, we found that RUNX3 could reduce the release of cytokines while maintaining CAR-T cells function. In re-challenge experiments, CAR-T cells overexpressing RUNX3 (Runx3-OE CAR-T) were safer than conventional CAR-T cells, while RUNX3 could also maintain the anti-tumor efficacy of CAR-T cells in vivo. Collectively, we found that Runx3-OE CAR-T cells can improve CAR-T phenotype and reduce cytokines release while maintaining CAR-T cells function, which may improve the safety of CAR-T therapy in clinical trials.

Runx3-overexpression cooperates with ex vivo AKT inhibition to generate receptor-engineered T cells with better persistence, tumor-residency, and antitumor ability.

BACKGROUND: Solid tumors pose unique roadblocks to treatment with chimeric antigen receptor (CAR) T cells, including limited T-cell persistence, inefficient tumor infiltration, and an immunosuppressive tumor microenvironment. To date, attempts to overcome these roadblocks have been unsatisfactory. Herein, we reported a strategy of combining Runx3 (encoding RUNX family transcription factor 3)-overexpression with ex vivo protein kinase B (AKT) inhibition to generate CAR-T cells with both central memory and tissue-resident memory characteristics to overcome these roadblocks. METHODS: We generated second-generation murine CAR-T cells expressing a CAR against human carbonic anhydrase 9 together with Runx3-overexpression and expanded them in the presence of AKTi-1/2, a selective and reversible inhibitor of AKT1/AKT2. We explored the influence of AKT inhibition (AKTi), Runx3-overexpression, and their combination on CAR-T cell phenotypes using flow cytometry, transcriptome profiling, and mass cytometry. The persistence, tumor-infiltration, and antitumor efficacy of CAR-T cells were evaluated in subcutaneous pancreatic ductal adenocarcinoma (PDAC) tumor models. RESULTS: AKTi generated a CD62L+central memory-like CAR-T cell population with enhanced persistence, but promotable cytotoxic potential. Runx3-overexpression cooperated with AKTi to generate CAR-T cells with both central memory and tissue-resident memory characteristics. Runx3-overexpression enhanced the potential of CD4+CAR T cells and cooperated with AKTi to inhibit the terminal differentiation of CD8+CAR T cells induced by tonic signaling. While AKTi promoted CAR-T cell central memory phenotype with prominently enhanced expansion ability, Runx3-overexpression promoted the CAR-T cell tissue-resident memory phenotype and further enhanced persistence, effector function, and tumor-residency. These novel AKTi-generated Runx3-overexpressing CAR-T cells exhibited robust antitumor activity and responded well to programmed cell death 1 blockade in subcutaneous PDAC tumor models. CONCLUSIONS: Runx3-overexpression cooperated with ex vivo AKTi to generate CAR-T cells with both tissue-resident and central memory characteristics, which equipped CAR-T cells with better persistence, cytotoxic potential, and tumor-residency ability to overcome roadblocks in the treatment of solid tumors.

Runt-related transcription factor 3, mediated by DNA-methyltransferase 1, regulated Schwann cell proliferation and myelination during peripheral nerve regeneration via JAK/STAT signaling pathway.

Schwann cells (SCs) play a crucial role in peripheral nerve injury and regeneration. Recently, RUNX3 was found to be linked with neurological dysfunction. We examined the RUNX3 expression in sciatic nerve stumps with peripheral nerve injury of rats, cyclic adenosine monophosphate (cAMP)-induced SCs. MTT assay was applied to determine the proliferation of SCs. Cell migration and apoptosis were assessed using wound healing assay and flow cytometry. Subsequently, we detected the methylation level of RUNX3 using Methylation-specific PCR assay and verified its regulation by DNMT1. The RUNX3 expressions were increased in sciatic nerve stumps with peripheral nerve injury and cAMP-induced SCs differentiation, which were related to demethylation of its promoter region regulated by DNMT1. RUNX3 knockdown notably suppressed the proliferation and migration, and induced the cell apoptosis of SCs. Silencing of RUNX3 inhibited the cAMP-induced morphological changes of SCs and the increase of myelin-related proteins induced by cAMP in SCs, while RUNX3 overexpression exerted opposite effects. Besides, the overexpression of RUNX3 promoted the activation of JAK/STAT signaling to regulate SCs proliferation and myelination. Meanwhile, DNMT1 overexpression inhibited the expression of RUNX3, and cell proliferation and myelination. In conclusion, RUNX3 mediated by DNMT1 regulated SC proliferation and myelination via JAK/STAT signaling pathway.

Genetically encoded Runx3 and CD4+ intestinal epithelial lymphocyte deficiencies link SKG mouse and human predisposition to spondyloarthropathy.

Disturbances in immune regulation, intestinal dysbiosis and inflammation characterize ankylosing spondylitis (AS), which is associated with RUNX3 loss-of-function variants. ZAP70W163C mutant (SKG) mice have reduced ZAP70 signaling, spondyloarthritis and ileitis. In small intestine, Foxp3+ regulatory T cells (Treg) and CD4+CD8αα+TCRαß+ intraepithelial lymphocytes (CD4-IEL) control inflammation. TGF-ß and retinoic acid (RA)-producing dendritic cells and MHC-class II+ intestinal epithelial cells (IEC) are required for Treg and CD4-IEL differentiation from CD4+ conventional or Treg precursors, with upregulation of Runx3 and suppression of ThPOK. We show in SKG mouse ileum, that ZAP70W163C or ZAP70 inhibition prevented CD4-IEL but not Treg differentiation, dysregulating Runx3 and ThPOK. TGF-ß/RA-mediated CD4-IEL development, T-cell IFN-γ production, MHC class-II+ IEC, tissue-resident memory T-cell and Runx3-regulated genes were reduced. In AS intestine, CD4-IEL were decreased, while in AS blood CD4+CD8+ T cells were reduced and Treg increased. Thus, genetically-encoded TCR signaling dysfunction links intestinal T-cell immunodeficiency in mouse and human spondyloarthropathy.

Inducible general knockout of Runx3 profoundly reduces pulmonary cytotoxic CD8+ T cells with minimal effect on outcomes in mice following influenza infection.

Respiratory viruses pose a continuing and substantive threat to human health globally. Host innate and adaptive immune responses are the critical antiviral defense mechanisms to control viral replication and spread. The present study is designed to determine the role of transcription factor Runx3 in the host immune response to influenza A virus (IAV) infection. As Runx3 is required for embryonic development, we generated an inducible Runx3 global knockout (KO) mouse model and found that Runx3 KO in adult C57BL/6 mice minimally affected thymic function under normal conditions and survival was at least 250 days post Runx3 deletion. We applied the mouse model to IAV infection and found that Runx3 KO resulted in a huge reduction (>85%) in numbers of total and antigen-specific pulmonary CD8+ cytotoxic T cells during IAV infection, while it had a minor effect on pulmonary generation of CD4+ T cells. To our surprise, this general KO of Runx3 did not significantly alter viral clearance and animal survival following IAV infection. Interestingly, we found that Runx3 KO significantly increased the numbers of pulmonary innate immune cells such as macrophages and neutrophils and the production of pro-inflammatory cytokines during IAV infection. We further found that Runx3 was strongly detected in CCR2+ immune cells in IAV-infected mouse lungs and was induced in activated macrophages and dendritic cells (DCs). As pulmonary CD8+ cytotoxic T cells play a central role in the clearance of IAV, our findings suggest that Runx3 KO may enhance host innate immunity to compensate for the loss of pulmonary CD8+ cytotoxic T cells during IAV infection.