Myc-interacting Zinc Finger Protein Research Articles

Low NDRG2, regulated by the MYC/MIZ-1 complex and methylation, predicts poor outcomes in DLBCL patients.

Diffuse large B-cell lymphoma (DLBCL) represents the most common tumor in non-Hodgkin's lymphoma. N-Myc downstream-regulated gene 2 (NDRG2) is a tumor suppressor highly expressed in healthy tissues but downregulated in many cancers. Although cell proliferation-related metabolism rewiring has been well characterized, less is known about the mechanism of metabolic changes with DLBCL. Herein, we investigated the expressions of NDRG2, MYC and Myc-interacting zinc finger protein 1 (MIZ-1) in seven human lymphoma (mostly DLBCLs) cell lines. NDRG2 expression was inversely correlated with the expressions of MYC and MIZ-1. Further, we explored the regulatory mechanism and biological functions underlying the lymphomagenesis involving NDRG2, MYC and MIZ-1. MYC and MIZ-1 promoted DLBCL cell proliferation, while NDRG2 induced apoptosis in LY8 cells. Moreover, NDRG2 methylation was reversed by the 5-Aza-2'-deoxycytidine (5-Aza-CDR) treatment, triggering the downregulation of MYC and inhibiting DLBCL cell survival. MYC interacts with NDRG2 to regulate energy metabolism associated with mTOR. Remarkably, supporting the biological significance, the converse correlation between NDRG2 and MYC was observed in human DLBCL tumor tissues (R = -0.557). Bioinformatics analysis further validated the association among NDRG2, MYC, MIZ-1, mTOR, and related metabolism genes. Additionally, NDRG2 (P = 0.001) and MYC (P < 0.001) were identified as promising prognostic biomarkers in DLBCL patients through survival analysis. Together, our data demonstrate that the MYC/MIZ-1 complex interplays with NDRG2 to influence the proliferation and apoptosis of DLBCL cells and show the characterizations of NDRG2, MYC and MIZ-1 for metabolism features and prediction prognosis in DLBCL.

Meta-analysis and transcriptomic analysis reveal that NKRF and ZBTB17 regulate the NF-κB signaling pathway, contributing to the shared molecular mechanisms of Alzheimer's disease and atherosclerosis.

Alzheimer's disease (AD) and atherosclerosis (AS) are widespread diseases predominantly observed in the elderly population. Despite their prevalence, the underlying molecular interconnections between these two conditions are not well understood. Utilizing meta-analysis, bioinformatics methodologies, and the GEO database, we systematically analyzed transcriptome data to pinpoint key genes concurrently differentially expressed in AD and AS. Our experimental validations in mouse models highlighted the prominence of two genes, NKRF (NF-κB-repressing factor) and ZBTB17 (MYC-interacting zinc-finger protein 1). These genes appear to influence the progression of both AD and AS by modulating the NF-κB signaling pathway, as confirmed through subsequent invitro and invivo studies. This research uncovers a novel shared molecular pathway between AD and AS, underscoring the significant roles of NKRF and ZBTB17 in the pathogenesis of these disorders.

A TNFα/Miz1-positive feedback loop inhibits mitophagy in hepatocytes and propagates non-alcoholic steatohepatitis

Non-alcoholic steatohepatitis (NASH) is a chronic inflammatory disease that can further progress to cirrhosis and hepatocellular carcinoma. However, the key molecular mechanisms behind this process have not been clarified. We analyzed human NASH and normal liver tissue samples by RNA-sequencing and liquid chromatography-mass spectrometry, identifying hepatocyte cytosolic protein Myc-interacting zinc-finger protein 1 (Miz1) as a potential target in NASH progression. We established a Western diet+fructose-induced NASH model in hepatocyte-specific Miz1 knockout and adeno-associated virus type 8-overexpressing mice. Human NASH liver organoids were used to confirm the mechanism, and immunoprecipitation and mass spectrometry were used to detect proteins that could interact with Miz1. We demonstrate that Miz1 is reduced in hepatocytes in human NASH. Miz1 is shown to bind to peroxiredoxin 6 (PRDX6), retaining it in the cytosol, blocking its interaction with mitochondrial Parkin at Cys431, and inhibiting Parkin-mediated mitophagy. In NASH livers, loss of hepatocyte Miz1 results in PRDX6-mediated inhibition of mitophagy, increased dysfunctional mitochondria in hepatocytes, and production of proinflammatory cytokines, including TNFα, by hepatic macrophages. Crucially, the increased production of TNFα results in a further reduction in hepatocyte Miz1 by E3-ubiquitination. This produces a positive feedback loop of TNFα-mediated hepatocyte Miz1 degradation, resulting in PRDX6-mediated inhibition of hepatocyte mitophagy, with the accumulation of dysfunctional mitochondria in hepatocytes and increased macrophage TNFα production. Our study identified hepatocyte Miz1 as a suppressor of NASH progression via its role in mitophagy; we also identified a positive feedback loop by which TNFα production induces degradation of cytosolic Miz1, which inhibits mitophagy and thus leads to increased macrophage TNFα production. Interruption of this positive feedback loop could be a strategy to inhibit the progression of NASH. Non-alcoholic steatohepatitis (NASH) is a chronic inflammatory disease that can further develop into cirrhosis and hepatocellular carcinoma. However, the key molecular mechanism of this process has not been fully clarified. Herein, we identified a positive feedback loop of macrophage TNFα-mediated hepatocyte Miz1 degradation, resulting in PRDX6-mediated inhibition of hepatocyte mitophagy, aggravation of mitochondrial damage and increased macrophage TNFα production. Our findings not only provide mechanistic insight into NASH progression but also provide potential therapeutic targets for patients with NASH. Our human NASH liver organoid culture is therefore a useful platform for exploring treatment strategies for NASH development.

RNA polymerase I inhibition induces terminal differentiation, growth arrest, and vulnerability to senolytics in colorectal cancer cells.

Ribosomal biogenesis and protein synthesis are deregulated in most cancers, suggesting that interfering with translation machinery may hold significant therapeutic potential. Here, we show that loss of the tumor suppressor adenomatous polyposis coli (APC), which constitutes the initiating event in the adenoma carcinoma sequence for colorectal cancer (CRC), induces the expression of RNA polymerase I (RNAPOL1) transcription machinery, and subsequently upregulates ribosomal DNA (rDNA) transcription. Targeting RNAPOL1 with a specific inhibitor, CX5461, disrupts nucleolar integrity, and induces a disbalance of ribosomal proteins. Surprisingly, CX5461‐induced growth arrest is irreversible and exhibits features of senescence and terminal differentiation. Mechanistically, CX5461 promotes differentiation in an MYC‐interacting zinc‐finger protein 1 (MIZ1)‐ and retinoblastoma protein (Rb)‐dependent manner. In addition, the inhibition of RNAPOL1 renders CRC cells vulnerable towards senolytic agents. We validated this therapeutic effect of CX5461 in murine‐ and patient‐derived organoids, and in a xenograft mouse model. These results show that targeting ribosomal biogenesis together with targeting the consecutive, senescent phenotype using approved drugs is a new therapeutic approach, which can rapidly be transferred from bench to bedside.

Myc-Interacting Zinc Finger Protein 1 (Miz-1) Is Essential to Maintain Homeostasis and Immunocompetence of the B Cell Lineage.

Simple SummaryThe immune system of mice and humans acts against pathogenic threats and intrinsic risks such as cancer. B cells, as antibody-producing cells, provide the ability to specifically target these risks. However, aging leads to a progressive loss of this ability and molecular causes of the gradual loss of immunocompetence remain unknown. Using genetically modified mice, we unravel the transcription factor Miz-1 as a key player of B cell aging during bone marrow lymphopoiesis and peripheral maturation. This enables the investigation of B cell-specific aging mechanisms and how to counteract them for therapeutic approaches to improve immunocompetence in the elderly.Aging of the immune system is described as a progressive loss of the ability to respond to immunologic stimuli and is commonly referred to as immunosenescence. B cell immunosenescence is characterized by a decreased differentiation rate in the bone marrow and accumulation of antigen-experienced and age-associated B cells in secondary lymphoid organs (SLOs). A specific deletion of the POZ-domain of the transcription factor Miz-1 in pro-B cells, which is known to be involved in bone marrow hematopoiesis, leads to premature aging of the B cell lineage. In mice, this causes a severe reduction in bone marrow-derived B cells with a drastic decrease from the pre-B cell stage on. Further, mature, naïve cells in SLOs are reduced at an early age, while post-activation-associated subpopulations increase prematurely. We propose that Miz-1 interferes at several key regulatory checkpoints, critical during B cell aging, and counteracts a premature loss of immunocompetence. This enables the use of our mouse model to gain further insights into mechanisms of B cell aging and it can significantly contribute to understand molecular causes of impaired adaptive immune responses to counteract loss of immunocompetence and restore a functional immune response in the elderly.

Identification of an atypical interaction site in the BTB domain of the MYC-interacting zinc-finger protein 1

The repurposing of structurally conserved protein domains in different functional contexts is thought to be a driving force in the evolution of complex protein interaction networks. The BTB/POZ domain is such a versatile binding module that occurs over 200 times in the human proteome with diverse protein-specific adaptations. In BTB-zinc-finger transcription factors, the BTB domain drives homo- and heterodimerization as well as interactions with non-BTB-domain-containing proteins. Which mechanisms encode specificity in these interactions at a structural level is incompletely understood. Here, we uncover an atypical peptide-binding site in the BTB domain of the MYC-interacting zinc-finger protein 1 (MIZ1) that arises from local flexibility of the core BTB fold and may provide a target site for MIZ1-directed therapeutic approaches. Intriguingly, the identified binding mode requires the BTB domain to be in a homodimeric state, thus holding opportunities for functional discrimination between homo- and heterodimers of MIZ1 in the cell.

Myc-Miz1 signaling promotes self-renewal of leukemia stem cells by repressing Cebpα and Cebpδ

Abstractc-Myc (Myc hereafter) is found to be deregulated and/or amplified in most acute myeloid leukemias (AMLs). Almost all AML cells are dependent upon Myc for their proliferation and survival. Thus, Myc has been proposed as a critical anti-AML target. Myc has Max-mediated transactivational and Myc-interacting zinc finger protein 1 (Miz1)-mediated transrepressional activities. The role of Myc-Max–mediated transactivation in the pathogenesis of AML has been well studied; however, the role of Myc-Miz1–mediated transrepression in AML is still somewhat obscure. Myc protein harboring a V394D mutation (MycV394D) is a mutant form of Myc that lacks transrepressional activity due to a defect in its ability to interact with Miz1. We found that, compared with Myc, the oncogenic function of MycV394D is significantly impaired. The AML/myeloproliferative disorder that develops in mice receiving MycV394D-transduced hematopoietic stem/progenitor cells (HSPCs) is significantly delayed compared with mice receiving Myc-transduced HSPCs. Using a murine MLL-AF9 AML model, we found that AML cells expressing MycV394D (intrinsic Myc deleted) are partially differentiated and show reductions in both colony-forming ability in vitro and leukemogenic capacity in vivo. The reduced frequency of leukemia stem cells (LSCs) among MycV394D-AML cells and their reduced leukemogenic capacity during serial transplantation suggest that Myc-Miz1 interaction is required for the self-renewal of LSCs. In addition, we found that MycV394D-AML cells are more sensitive to chemotherapy than are Myc-AML cells. Mechanistically, we found that Myc represses Miz1-mediated expression of CCAAT/enhancer-binding protein α (Cebpα) and Cebpδ, thus playing an important role in the pathogenesis of AML by maintaining the undifferentiated state and self-renewal capacity of LSCs.

Restriction of memory B cell differentiation at the germinal center B cell positive selection stage.

Memory B cells (MBCs) are key for protection from reinfection. However, it is mechanistically unclear how germinal center (GC) B cells differentiate into MBCs. MYC is transiently induced in cells fated for GC expansion and plasma cell (PC) formation, so-called positively selected GC B cells. We found that these cells coexpressed MYC and MIZ1 (MYC-interacting zinc-finger protein 1 [ZBTB17]). MYC and MIZ1 are transcriptional activators; however, they form a transcriptional repressor complex that represses MIZ1 target genes. Mice lacking MYC-MIZ1 complexes displayed impaired cell cycle entry of positively selected GC B cells and reduced GC B cell expansion and PC formation. Notably, absence of MYC-MIZ1 complexes in positively selected GC B cells led to a gene expression profile alike that of MBCs and increased MBC differentiation. Thus, at the GC positive selection stage, MYC-MIZ1 complexes are required for effective GC expansion and PC formation and to restrict MBC differentiation. We propose that MYC and MIZ1 form a module that regulates GC B cell fate.

Schwann cell Myc-interacting zinc-finger protein 1 without pox virus and zinc finger: epigenetic implications in a peripheral neuropathy.

Functionality of adult peripheral nerves essentially relies on differentiation of Schwann cells during postnatal development, as well as fine-tuned re- and transdifferentiation in response to peripheral nerve injury. Epigenetic histone modifications play a major role during the differentiation of embryonic stem cells and diverse organ specific progenitor cells, yet only little is known about the epigenetic regulation of Schwann cells. Just recently, Fuhrmann et al. reported how the transcription factor Myc-interacting zinc-finger protein 1 (Miz1) might contribute to Schwann cell differentiation through repression of the histone demethylase Kdm8. Here, we discuss the potential novel role of Miz1 in Schwann cell differentiation and give a short overview about previously reported histone modifications underlying peripheral nerve development and response to injury.

Miz1 Controls Schwann Cell Proliferation via H3K36me2 Demethylase Kdm8 to Prevent Peripheral Nerve Demyelination.

Schwann cell differentiation and myelination depends on chromatin remodeling, histone acetylation, and methylation, which all affect Schwann cell proliferation. We previously reported that the deletion of the POZ (POxvirus and Zinc finger) domain of the transcription factor Miz1 (Myc-interacting zinc finger protein; encoded by Zbtb17) in mouse Schwann cells (Miz1ΔPOZ) causes a neuropathy at 90 d after birth [postnatal day (P) 90], with a subsequent spontaneous regeneration. Here we show that RNA sequencing from Miz1ΔPOZ and control animals at P30 revealed a set of upregulated genes with a strong correlation to cell-cycle regulation. Consistently, a subset of Schwann cells did not exit the cell cycle as observed in control animals and the growth fraction increased over time. From the RNAseq gene list, two direct Miz1 target genes were identified, one of which encodes the histone H3K36me2 demethylase Kdm8. We show that the expression of Kdm8 is repressed by Miz1 and that its release in Miz1ΔPOZ cells induces a decrease of H3K36me2, especially in deregulated cell-cycle-related genes. The linkage between elevated Kdm8 expression, hypomethylation of H3K36 at cell-cycle-relevant genes, and the subsequent re-entering of adult Schwann cells into the cell cycle suggests that the release of Kdm8 repression in the absence of a functional Miz1 is a central issue in the development of the Miz1ΔPOZ phenotype.SIGNIFICANCE STATEMENT The deletion of the Miz1 (Myc-interacting zinc finger protein 1) POZ (POxvirus and Zinc finger) domain in Schwann cells causes a neuropathy. Here we report sustained Schwann cell proliferation caused by an increased expression of the direct Miz1 target gene Kdm8, encoding a H3K36me2 demethylase. Hence, the demethylation of H3K36 is linked to the pathogenesis of a neuropathy.

Increased expression of Myc-interacting zinc finger protein 1 in APP/PS1 mice.

Myc-interacting zinc-finger protein 1 (Miz1) is a member of the poxvirus and zinc-finger domain/zinc finger transcription factor family. Its transcription activation and repression functions in the nucleus are well elucidated; however its cytoplasmic inflammation function is poorly understood and may be associated with the pathogenesis of Alzheimer's disease (AD). The aim of the present study was to investigate the association between AD and Miz1 expression. In the present study, the expression and distribution of Miz1 in wild-type (WT) and amyloid precursor protein/presenelin-1 (AD) mice was studied using reverse transcription-quantitative polymerase chain reaction, western blot analysis, and immunohistochemical and immunofluorescence staining. The results indicated that Miz1 was significantly upregulated in the cortex of AD mice (P<0.05). Double immunofluorescence labeling revealed that Miz1 protein was predominantly expressed in neurons and astrocytes, as evidenced by co-localization with the dendritic markers microtubule associated protein 2 and glial fibrillary acidic protein, respectively. The results of the present study suggest that the expression of Miz1 in the brain tissue of AD mice may serve an important role in AD pathogenesis.

The proto-oncoprotein KR-POK represses transcriptional activation of CDKN1A by MIZ-1 through competitive binding.

This corrects the article DOI: 10.1038/onc.2011.331.

Miz-1 promotes the proliferation of esophageal cancer cells via suppression of p21 and release of p21-arrested cyclinD1.

Tumorigenesis results from various types of dysregulation of oncogenes and tumor suppressors that influence cellular proliferation, differentiation, apoptosis and senescence. The transcription factor Myc-interacting zinc finger protein1 (Miz-1) can either activate or repress gene expression in concert with binding partners including the Myc oncoprotein in several types of tumors. Known target genes of these complexes encode the cyclin‑dependent kinase inhibitors such as cdkn2b (p15) and cdkn1a (p21). In the present study, we showed that the silencing of Miz-1 expression, through shRNA in a lentiviral vector, influenced various biological processes in two types of esophageal carcinoma cell lines. Silencing of the expression of Miz-1 inhibited cell proliferation and promoted apoptosis invitro. Loss of Miz-1 reduced the migration ability in esophageal carcinoma cells. High expression of p21 and downregulation of cyclinD1 accompanied the knockdown of Miz-1. Our data demonstrated that esophageal cancer has a cell cycle arrest pathway via Miz-1, p21 and cyclinD1.

Decreased MIZ1 Expression in Severe Experimental Acute Pancreatitis: A Rat Study.

We tested our hypothesis that Myc-interacting zinc finger protein 1 (MIZ1), a cell cycle regulator, suppressed inflammation, and therefore, represented a useful prognostic marker in patients with acute necrotizing pancreatitis (ANP) complicated by acute lung injury. Sprague-Dawley rats were randomly divided into control and ANP groups at different time points. The MIZ1 protein expression was measured by Western blot and ELISA, and confirmed using immunohistochemistry. The severity of pancreatic and lung injury was evaluated by the injury score and wet/dry weight ratio. The severity of disease was evaluated by serum C-reactive protein (CRP). The MPO activity of lung tissue amylase levels and the degree of inflammation were evaluated by serum tumor necrosis factor (TNF)-α and interleukin (IL)-6 expression. The risk due to multiple factors was investigated by relationship analysis. The serum levels of CRP, amylase, TNF-α, and IL-6 were gradually increased at 6, 24, and 48 h in ANP when compared with the control rats. The MIZ1 expressions were greatly decreased in ANP rats, especially at 24 h. Statistical analysis showed that there were time-dependent differences in ANP rats when compared with control rats (6 vs. 24 or 48 h, P < 0.01). MIZ1 showed close negative correlation with the degree of pancreatic and lung injury, serum amylase, CRP, TNF-α, and IL-6 (P < 0.01, respectively). The decreasing MIZ1 expression was closely correlated with inflammatory response, and development of ANP. Decreasing MIZ1 levels indicate a risk for ANP.

Abstract B08: Loss of functional Miz-1 impairs c-Myc-dependent B cell lymphomagenesis

Abstract Objective: The Myc-interacting zinc finger protein 1 (Miz-1) is a ubiquitous BTB/POZ domain and zinc finger protein that acts as both a transcriptional repressor and activator. The POZ domain of Miz-1 enables protein-protein interactions and facilitates a stable association with chromatin. Miz-1 binds to the proto-oncogen c-Myc and modulates c-Myc target gene expression. Overexpression of c-Myc is an important feature of Burkitt-type B cell lymphomas (BL) caused by c-Myc gene rearrangements. The aim of this project is to determine if Miz-1 is a crucial collaborator of c-Myc in transcriptional regulation of B cells and in the development of c-Myc-dependent B-cell lymphomas. Methods: We are using the Eµ-Myc mouse model to generate Burkitt type c-Myc dependent lymphomas to study the implication of Miz-1 in a c-Myc driven process of malignant transformation. Mice carrying the Eµ-Myc transgene (c-Myc gene placed under the control of Eµ enhancer of the IgH locus) overexpress c-Myc in lymphoid cells and develop a disease similar to Burkitt's lymphoma. Mice that express a conditional non-functional Miz-1 allele lacking the part coding for the POZ domain in B cells (Mb1-Cre-Miz-1fl/fl mice, hereafter called ΔPOZ mice) were crossed with Eµ-Myc transgenic mice. We monitored Eµ-Myc animals expressing wild type or ΔPOZ Miz-1 protein over a period of 500 days. Incidence and latency periods of the development of tumors in both cohorts was compared. Pre-cancerous mice of all genotypes were also investigated to evaluate the influence of Miz-1 during the development of the c-Myc dependant lymphomas. To identify underlying molecular mechanisms, global mRNA expression profiles of pre-neoplastic and tumor cells derived from Eµ-Myc and ΔPOZ/Eµ-Myc mice were performed using high throughput sequencing (RNA-seq). To address the role of Miz-1 in the deregulation of chromatin associated with c-Myc overexpression, chromatin immunoprecipitation coupled to high throughput sequencing (ChIP-seq) was performed on B-lymphoma and pre-tumoral B-cells and compared to normal B-cells. Binding to chromatin of Miz-1 and c-Myc was assessed. Results: ΔPOZ/Eµ-Myc mice develop lymphomas with a significant longer latency and lower incidence than Eµ-Myc mice expressing functional Miz-1 proteins. Additionally, blood analysis of sick animals reveal a lower amount of Large Unstained Cells (LUC) when Miz-1 is mutated. Accordingly, in 40 day old pre-tumoral ΔPOZ/Eµ-Myc animals compared to Eµ-Myc mice, less pre-B and/or pro-B cells were observed in lymphoid organs and little or no LUC were present in the blood. This suggests that Myc driven lymphoma and leukemia is impaired when a ΔPOZ Miz-1 protein is expressed. Our RNA-seq analyses of pre-neoplastic and tumor cells revealed that the expression of ΔPOZ Miz-1 induces deregulation of several genes belonging to different GO (Gene Ontology) functions like “small GTPase-mediated signal transduction”. Interestingly, comparision of RNA-seq and Miz-1 ChIP-seq analyses indicates that some Miz-1 bound genes are deregulated in cells from ΔPOZ/Eµ-Myc mice (e.g: Aurora kinase A (Aurka)). Conclusion: Our data indicate that Miz-1 is required for the efficient development of aggressive c-Myc-driven lymphomas. Miz-1 is probably cooperating with c-Myc in the abnormal transcriptional program that is occuring in lymphoma cells. Therefore, targeting Miz-1 in B-lymphomas could lead to the development of new therapeutic approaches. Citation Format: Julie Ross, René Winkler, Charles Vadnais, Marissa Rashkovan, Christian Kosan, Tarik Möröy. Loss of functional Miz-1 impairs c-Myc-dependent B cell lymphomagenesis. [abstract]. In: Proceedings of the AACR Special Conference on Myc: From Biology to Therapy; Jan 7-10, 2015; La Jolla, CA. Philadelphia (PA): AACR; Mol Cancer Res 2015;13(10 Suppl):Abstract nr B08.

Abstract 997: Loss of Miz-1 increases latency of T-ALL by preventing induction of autophagy

Abstract The Myc-Interacting Zinc-finger protein-1 (Miz-1) can bind to the proto-oncogene c-Myc and the Miz-1/c-Myc complex can regulate the transcription of specific target genes. Miz-1 contains a BTB/POZ domain and thirteen zinc finger domains that mediate binding to DNA and its interaction with partner proteins. While Miz-1 itself functions as a transcriptional transactivator, it enables c-Myc to act as a transcriptional repressor of genes negatively regulating cell cycle progression. We have previously reported that Miz-1 plays an essential role during early stages of T cell development by regulating the translation of p53 via the ribosomal protein L22. Based on this function of Miz-1 in T cell development, we have decided to investigate a potential role of Miz-1 in the development of T cell leukemia or lymphoma. We have used several different experimental models to induce T-ALL in mice that are conditionally deficient for Miz-1. We used non-acute transforming retroviruses, such as Moloney Murine Leukemia Virus (MMLV), which induces T-cell leukemia by activating known oncogenes, including Gfi1, Pim1 and c-Myc via proviral insertion. We also used ENU mutagenesis, which induces T-cell leukemia through activation of the Ras pathway. We observed that Miz-1 is required for the development of T cell leukemia regardless of whether it is induced by MMLV or ENU, since Miz-1-deficient mice succumb to the disease with a significantly longer latency period than WT animals. Importantly, during tumorigenesis a strong counter selection occurs against the loss of Miz-1. Interestingly, MycV394D transgenic animals, carrying a c-Myc protein that can no longer interact directly with Miz-1, develop tumors at a rate comparable to WT mice, indicating that a function of Miz-1 is required for T cell tumorigenesis that is independent of its interaction with c-Myc. Transcriptome analyses showed that Miz-1 deficiency correlated with a decrease of expression in autophagy-related genes, consistent with earlier reports that Miz-1 is necessary for the induction of this pathway. ChIP-seq confirmed that Miz-1 binds to the promoters of these autophagy-related genes, indicating that these genes are activated in the presence of Miz-1, also consistent with previous reports. Furthermore, Miz-1-deficient tumors undergo higher levels of apoptosis than WT tumors. Based on these results, we conclude that Miz-1 is essential for the efficient development of T-ALL and that loss of Miz-1 significantly hinders T-ALL development in part through the inability of these cells to induce autophagy. Citation Format: Marissa Rashkovan, Charles Vadnais, Julie Ross, Jennifer Fraszczak, Tarik Moroy. Loss of Miz-1 increases latency of T-ALL by preventing induction of autophagy. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 997. doi:10.1158/1538-7445.AM2015-997

Myc-interacting zinc-finger protein 1 positively regulates Wnt signalling by protecting Dishevelled from Dapper1-mediated degradation.

Wnt signalling regulates embryonic development and tissue homoeostasis by modulating cell proliferation, differentiation and migration. Dapper1 (Dpr1) has been shown to be an important key negative regulator of Wnt signalling by promoting Dishevelled (Dvl) degradation. In the present study, we found that Myc-interacting zinc-finger protein 1 (MIZ1) interacts with Dpr1 and this interaction attenuates the ability of Dpr1 to induce Dvl2 degradation, thus enhancing Wnt signalling. Mechanistically, MIZ1 is translocated from the nucleus to the cytoplasm upon Wnt3a stimulation or overexpression of Dpr1 and Dvl2, disrupting the interaction between Dpr1 and Dvl2. Furthermore, MIZ1 can promote the proliferation of breast cancer MDA-MB-231 and BT-549 cells through Wnt signalling and reverse the anti-proliferative effect of Dpr1 on colorectal cancer Caco-2. Together, our findings establish a novel layer of Wnt signalling regulation via the MIZ1-Dpr1-Dvl axis.

Schwann cell Miz without POZ: degeneration meets regeneration.

Peripheral motor and sensory neuropathies are diseases with different etiologies emerging from genetic disorders, diabetes, infection or inflammation, paraneoplastic damage or intoxications including alcohol abuse (Martyn and Hughes, 1997). Hereditary neuropathies, most of which are subsumed under the hypernym Charcot-Marie Tooth (CMT) disease, are clinically heterogeneous: about 50 affected gene loci encoding about 30 genes have been so far identified to be involved in the pathogenesis of different CMTs (Niemann et al., 2006). Depending on structural and electrophysiological features CMTs are divided into axonal and demyelinating forms. Peripheral myelin protein 22 (PMP22), myelin protein zero (MPZ) and connexin 32 (GJB1) are the most frequently affected genes in human demyelinating neuropathies and a variety of animal models have been designed to mimic these human disorders (Bouhy and Timmerman, 2013). These models rely on the deletion, overexpression or mutation of the gene relevant for a human neuropathy and usually clinical symptoms occur early in life and the course of disease is progressive. Recently, Sanz-Moreno et al. (2014) published the partial deletion of the transcription factor Myc interacting zinc finger protein 1 (Miz1) in Schwann cells of mice and observed a late onset demyelinating neuropathy with a spontaneous clinical remission, introducing a unique new model to study peripheral nerve regeneration.

Late Onset Neuropathy with Spontaneous Clinical Remission in Mice Lacking the POZ Domain of the Transcription Factor Myc-interacting Zinc Finger Protein 1 (Miz1) in Schwann Cells

The transcription factor Miz1 (Myc-interacting zinc finger 1) is a known regulator of the cell cycle but also has cell cycle-independent functions. Here we analyzed the role of Miz1 in the peripheral nervous system, using an early embryonic conditional knock-out model in which the Miz1 POZ domain is ablated in Schwann cells. Although the development of myelinated nerve fibers was not impaired, Miz1ΔPOZ mice acquired behavioral signs of a peripheral neuropathy at the age of 3 months. At this time, ultrastructural analysis of the sciatic nerve showed de- and dysmyelination of fibers, with massive outfoldings and a focal infiltration of macrophages. Although the expression of genes encoding structural myelin proteins, such as periaxin, myelin basic protein, and myelin protein zero, was decreased, genes associated with a negative regulation of myelination, including c-Jun, Sox2, and Id2, were up-regulated in Miz1ΔPOZ mice compared with controls. In animals older than 4 months, the motor disabilities vanished, and the ultrastructure of the sciatic nerve exhibited numerous tomacula and remyelinated fibers, as indicated by thinner myelin. No second acute attack was observed up to the age of 1 year. Thus, the deletion of the Miz1 POZ domain in Schwann cells induces an acute neuropathy with a subsequent regeneration in which there is ongoing balancing between de- and remyelination. Miz1ΔPOZ mice are impaired in the maintenance of myelinated fibers and are a promising model for studying remyelination in adult peripheral nerves.

Epstein-Barr virus nuclear antigen 3A protein regulates CDKN2B transcription via interaction with MIZ-1.

The Epstein–Barr virus (EBV) nuclear antigen 3 family of protein is critical for the EBV-induced primary B-cell growth transformation process. Using a yeast two-hybrid screen we identified 22 novel cellular partners of the EBNA3s. Most importantly, among the newly identified partners, five are known to play direct and important roles in transcriptional regulation. Of these, the Myc-interacting zinc finger protein-1 (MIZ-1) is a transcription factor initially characterized as a binding partner of MYC. MIZ-1 activates the transcription of a number of target genes including the cell cycle inhibitor CDKN2B. Focusing on the EBNA3A/MIZ-1 interaction we demonstrate that binding occurs in EBV-infected cells expressing both proteins at endogenous physiological levels and that in the presence of EBNA3A, a significant fraction of MIZ-1 translocates from the cytoplasm to the nucleus. Moreover, we show that a trimeric complex composed of a MIZ-1 recognition DNA element, MIZ-1 and EBNA3A can be formed, and that interaction of MIZ-1 with nucleophosmin (NPM), one of its coactivator, is prevented by EBNA3A. Finally, we show that, in the presence of EBNA3A, expression of the MIZ-1 target gene, CDKN2B, is downregulated and repressive H3K27 marks are established on its promoter region suggesting that EBNA3A directly counteracts the growth inhibitory action of MIZ-1.