Generation of the floxed allele of the SIP1 (Smad-interacting protein 1) gene for Cre-mediated conditional knockout in the mouse

Zeb2 drives the formation of CD11c+ atypical B cells to sustain germinal centers that control persistent infection

CD11c+ atypical B cells (ABCs) are an alternative memory B cell lineage associated with immunization, infection, and autoimmunity. However, the factors that drive the transcriptional program of ABCs have not been identified, and the function of this population remains incompletely understood. Here, we identified candidate transcription factors associated with the ABC population based on a human tonsillar B cell single-cell dataset. We identified CD11c+ B cells in mice with a similar transcriptomic signature to human ABCs, and using an optimized CRISPR-Cas9 knockdown screen, we observed that loss of zinc finger E-box binding homeobox 2 (Zeb2) impaired ABC formation. Furthermore, ZEB2 haplo-insufficient Mowat-Wilson syndrome (MWS) patients have decreased circulating ABCs in the blood. In Cd23Cre/+Zeb2fl/fl mice with impaired ABC formation, ABCs were dispensable for efficient humoral responses after Plasmodium sporozoite immunization but were required to control recrudescent blood-stage malaria. Immune phenotyping revealed that ABCs drive optimal T follicular helper (TFH) cell formation and germinal center (GC) responses and they reside at the red/white pulp border, likely permitting better access to pathogen antigens for presentation. Collectively, our study shows that ABC formation is dependent on Zeb2, and these cells can limit recrudescent infection by sustaining GC reactions.

CD62L expression marks a functionally distinct subset of memory B cells

The memory B cell response consists of phenotypically distinct subsets that differ in their ability to respond upon antigen re-encounter. However, the pathways regulating the development and function of memory B cell subsets are poorly understood. Here, we show that CD62L and CD44 are progressively expressed on mouse memory B cells and identify transcriptionally and functionally distinct memory B cell subsets. Bcl6 is important in regulating memory B cell subset differentiation with overexpression of Bcl6 resulting in impaired CD62L+ memory B cell development. Bcl6 regulates memory B cell subset development through control of a network of genes, including Bcl2 and Zeb2. Overexpression of Zeb2 impairs the development of CD62L+ memory B cells. Importantly, CD62L is also differentially expressed on human memory B cells following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination and identifies phenotypically distinct populations. Together, these data indicate that CD62L expression marks functionally distinct memory B cell subsets.

Zeb2 regulates differentiation of long-lived effector of invariant natural killer T cells

After activation, some invariant natural killer T (iNKT) cells are differentiated into Klrg1+ long-lived effector NKT1 cells. However, the regulation from the effector phase to the memory phase has not been elucidated. Zeb2 is a zinc finger E homeobox-binding transcription factor and is expressed in a variety of immune cells, but its function in iNKT cell differentiation remains also unknown. Here, we show that Zeb2 is dispensable for development of iNKT cells in the thymus and their maintenance in steady state peripheral tissues. After ligand stimulation, Zeb2 plays essential roles in the differentiation to and maintenance of Klrg1+ Cx3cr1+GzmA+ iNKT cell population derived from the NKT1 subset. Our results including single-cell-RNA-seq analysis indicate that Zeb2 regulates Klrg1+ long-lived iNKT cell differentiation by preventing apoptosis. Collectively, this study reveals the crucial transcriptional regulation by Zeb2 in establishment of the memory iNKT phase through driving differentiation of Klrg1+ Cx3cr1+GzmA+ iNKT population.

Stem cell-based modeling and single-cell multiomics reveal gene-regulatory mechanisms underlying human skeletal development

Although the skeleton is essential for locomotion, endocrine functions, and hematopoiesis, the molecular mechanisms of human skeletal development remain to be elucidated. Here, we introduce an integrative method to model human skeletal development by combining in vitro sclerotome induction from human pluripotent stem cells and in vivo endochondral bone formation by implanting the sclerotome beneath the renal capsules of immunodeficient mice. Histological and scRNA-seq analyses reveal that the induced bones recapitulate endochondral ossification and are composed of human skeletal cells and mouse circulatory cells. The skeletal cell types and their trajectories are similar to those of human embryos. Single-cell multiome analysis reveals dynamic changes in chromatin accessibility associated with multiple transcription factors constituting cell-type-specific gene-regulatory networks (GRNs). We further identify ZEB2, which may regulate the GRNs in human osteogenesis. Collectively, these results identify components of GRNs in human skeletal development and provide a valuable model for its investigation.

Zeb2 DNA-Binding Sites in Neuroprogenitor Cells Reveal Autoregulation and Affirm Neurodevelopmental Defects, Including in Mowat-Wilson Syndrome

Functional perturbation and action mechanism studies have shown that the transcription factor Zeb2 controls cell fate decisions, differentiation, and/or maturation in multiple cell lineages in embryos and after birth. In cultured embryonic stem cells (ESCs), Zeb2’s mRNA/protein upregulation is necessary for the exit from primed pluripotency and for entering general and neural differentiation. We edited mouse ESCs to produce Flag-V5 epitope-tagged Zeb2 protein from one endogenous allele. Using chromatin immunoprecipitation coupled with sequencing (ChIP-seq), we mapped 2432 DNA-binding sites for this tagged Zeb2 in ESC-derived neuroprogenitor cells (NPCs). A new, major binding site maps promoter-proximal to Zeb2 itself. The homozygous deletion of this site demonstrates that autoregulation of Zeb2 is necessary to elicit the appropriate Zeb2-dependent effects in ESC-to-NPC differentiation. We have also cross-referenced all the mapped Zeb2 binding sites with previously obtained transcriptome data from Zeb2 perturbations in ESC-derived NPCs, GABAergic interneurons from the ventral forebrain of mouse embryos, and stem/progenitor cells from the post-natal ventricular-subventricular zone (V-SVZ) in mouse forebrain, respectively. Despite the different characteristics of each of these neurogenic systems, we found interesting target gene overlaps. In addition, our study also contributes to explaining developmental disorders, including Mowat-Wilson syndrome caused by ZEB2 deficiency, and also other monogenic syndromes.

ZEB2 controls kidney stromal progenitor differentiation and inhibits abnormal myofibroblast expansion and kidney fibrosis

FOXD1+ cell-derived stromal cells give rise to pericytes and fibroblasts that support the kidney vasculature and interstitium but are also major precursors of myofibroblasts. ZEB2 is a SMAD-interacting transcription factor that is expressed in developing kidney stromal progenitors. Here we show that Zeb2 is essential for normal FOXD1+ stromal progenitor development. Specific conditional knockout of mouse Zeb2 in FOXD1+ stromal progenitors (Zeb2 cKO) leads to abnormal interstitial stromal cell development, differentiation, and kidney fibrosis. Immunofluorescent staining analyses revealed abnormal expression of interstitial stromal cell markers MEIS1/2/3, CDKN1C, and CSPG4 (NG2) in newborn and 3-week-old Zeb2-cKO mouse kidneys. Zeb2-deficient FOXD1+ stromal progenitors also took on a myofibroblast fate that led to kidney fibrosis and kidney failure. Cell marker studies further confirmed that these myofibroblasts expressed pericyte and resident fibroblast markers, including PDGFRβ, CSPG4, desmin, GLI1, and NT5E. Notably, increased interstitial collagen deposition associated with loss of Zeb2 in FOXD1+ stromal progenitors was accompanied by increased expression of activated SMAD1/5/8, SMAD2/3, SMAD4, and AXIN2. Thus, our study identifies a key role of ZEB2 in maintaining the cell fate of FOXD1+ stromal progenitors during kidney development, whereas loss of ZEB2 leads to differentiation of FOXD1+ stromal progenitors into myofibroblasts and kidney fibrosis.

Dendritic cell functions in vivo: a user's guide to current and next generation mutant mouse models

Dendritic cells (DCs) do not just excel in antigen presentation. They orchestrate information transfer from innate to adaptive immunity, by sensing and integrating a variety of danger signals, and translating them to naïve T cells, to mount specifically tailored immune responses. This is accomplished by distinct DC types specialized in different functions and because each DC is functionally plastic, assuming different activation states depending on the input signals received. Mouse models hold the key to untangle this complexity and determine which DC types and activation states contribute to which functions. Here, we aim to provide comprehensive information for selecting the most appropriate mutant mouse strains to address specific research questions on DCs, considering three in vivo experimental approaches: (i) interrogating the roles of DC types through their depletion; (ii) determining the underlying mechanisms by specific genetic manipulations; (iii) deciphering the spatiotemporal dynamics of DC responses. We summarize the advantages, caveats, suggested use and perspectives for a variety of mutant mouse strains, discussing in more detail the most widely used or accurate models. Finally, we discuss innovative strategies to improve targeting specificity, for the next generation mutant mouse models, and briefly address how humanized mouse models can accelerate translation into the clinic. This article is protected by copyright. All rights reserved.

Knockout of Zeb2 ameliorates progression of renal tubulointerstitial fibrosis in a mouse model of renal ischemia-reperfusion injury

BACKGROUND

Zeb2, a zinc finger E-box-binding homeobox transcription factor, regulates transforming growth factor (TGF)-β signaling pathway. However, its role in the pathogenesis of acute kidney injury (AKI) and AKI to chronic kidney disease (CKD) transition is unclear.

METHODS

We evaluated Zeb2 function in a bilateral renal ischemia-reperfusion injury (IRI)-induced AKI model using proximal tubule-specific Zeb2 conditional knockout (Zeb2-cKO) and wild-type (WT) mice, and in renal biopsy samples.

RESULTS

In Zeb2-cKO mice, the levels of plasma creatinine and blood urea nitrogen post-IRI were significantly lower than that in WT mice. Immunohistological analysis revealed mild tubular injury, reduced neutrophil infiltration, less fibrotic changes, and reduced expression of fibrotic proteins (collagen type IV, α-smooth muscle actin [α-SMA], fibronectin, and connective tissue growth factor [CTGF]), at 3-14 days post-IRI. Zeb2 expression was upregulated in proximal tubular cells post-IRI in WT mice. Zeb2 siRNA transfection reduced TGF-β stimulated mRNA and protein expression of collagen type IV, α-SMA, fibronectin, and CTGF in cultured renal tubular cells. Patients with AKI to CKD transition exhibited high Zeb2 expression in renal tubules, as revealed by renal biopsy. Hypoxia and CoCl2-treatment upregulated Zeb2 promoter activity and mRNA and protein expression in cultured renal tubular epithelial cells, suggesting a regulatory role for hypoxia.

CONCLUSIONS

Zeb2 was upregulated in renal tissues in both mice and humans with AKI. Zeb2 regulates fibrotic pathways in the pathogenesis of AKI and AKI to CKD transition. Therefore, inhibition of Zeb2 could be a potential therapeutic strategy for AKI.

Interplay between the EMT transcription factors ZEB1 and ZEB2 regulates hematopoietic stem and progenitor cell differentiation and hematopoietic lineage fidelity

The ZEB2 transcription factor has been demonstrated to play important roles in hematopoiesis and leukemic transformation. ZEB1 is a close family member of ZEB2 but has remained more enigmatic concerning its roles in hematopoiesis. Here, we show using conditional loss-of-function approaches and bone marrow (BM) reconstitution experiments that ZEB1 plays a cell-autonomous role in hematopoietic lineage differentiation, particularly as a positive regulator of monocyte development in addition to its previously reported important role in T-cell differentiation. Analysis of existing single-cell (sc) RNA sequencing (RNA-seq) data of early hematopoiesis has revealed distinctive expression differences between Zeb1 and Zeb2 in hematopoietic stem and progenitor cell (HSPC) differentiation, with Zeb2 being more highly and broadly expressed than Zeb1 except at a key transition point (short-term HSC [ST-HSC]➔MPP1), whereby Zeb1 appears to be the dominantly expressed family member. Inducible genetic inactivation of both Zeb1 and Zeb2 using a tamoxifen-inducible Cre-mediated approach leads to acute BM failure at this transition point with increased long-term and short-term hematopoietic stem cell numbers and an accompanying decrease in all hematopoietic lineage differentiation. Bioinformatics analysis of RNA-seq data has revealed that ZEB2 acts predominantly as a transcriptional repressor involved in restraining mature hematopoietic lineage gene expression programs from being expressed too early in HSPCs. ZEB1 appears to fine-tune this repressive role during hematopoiesis to ensure hematopoietic lineage fidelity. Analysis of Rosa26 locus–based transgenic models has revealed that Zeb1 as well as Zeb2 cDNA-based overexpression within the hematopoietic system can drive extramedullary hematopoiesis/splenomegaly and enhance monocyte development. Finally, inactivation of Zeb2 alone or Zeb1/2 together was found to enhance survival in secondary MLL-AF9 acute myeloid leukemia (AML) models attesting to the oncogenic role of ZEB1/2 in AML.

This study shows that the closely related transcription factors ZEB1 and ZEB2 cooperate to restrain myeloid and lymphoid differentiation programs in hematopoietic stem and progenitor cells, ensuring fidelity of differentiation in multiple lineages.

MicroRNA miR-215-5p regulates doxorubicin-induced cardiomyocyte injury by targeting ZEB2

ABSTRACT

Doxorubicin (DOX) is a chemotherapeutic drug for treating various cancers. However, the DOX-induced cardiotoxicity greatly limits its clinical application. MicroRNAs (miRNAs) are emerged as critical mediators of cardiomyocyte injury. This work explored the function of miR-215-5p in the regulation of DOX-induced mouse HL-1 cardiomyocyte injury. An in vitro model of DOX-treated cardiotoxicity was established in HL-1 cells. Gene expression was measured by RT-qPCR. Cell viability was detected using CCK-8. Cell death and apoptosis were tested using TUNEL, flow cytometry, and caspase 3/7 activity assays. Luciferase reporter assay was used to examine the target of miR-215-5p. We found that DOX induced cardiomyocyte injury and upregulated miR-215-5p in HL-1 cells. Inhibition of miR-215-5p attenuated DOX-induced cardiomyocyte death and apoptosis in vitro. Mechanistical experiments indicated that ZEB2 was targeted by miR-215-5p. Additionally, ZEB2 expression was reduced in DOX-treated HL-1 cells. Rescue assays indicated that ZEB2 knockdown reversed the effects of miR-215-5p inhibition. In conclusion, miR-215-5p inhibition protects HL-1 cells against DOX-induced injury by upregulating ZEB2 expression.

Differential usage of transcriptional repressor Zeb2 enhancers distinguishes adult and embryonic hematopoiesis

The transcriptional repressor ZEB2 regulates development of many cell fates among somatic, neural, and hematopoietic lineages, but the basis for its requirement in these diverse lineages is unclear. Here, we identified a 400-basepair (bp) region located 165 kilobases (kb) upstream of the Zeb2 transcriptional start site (TSS) that binds the E proteins at several E-box motifs and was active in hematopoietic lineages. Germline deletion of this 400-bp region (Zeb2Δ-165mice) specifically prevented Zeb2 expression in hematopoietic stem cell (HSC)-derived lineages. Zeb2Δ-165 mice lacked development of plasmacytoid dendritic cells (pDCs), monocytes, and B cells. All macrophages in Zeb2Δ-165 mice were exclusively of embryonic origin. Using single-cell chromatin profiling, we identified a second Zeb2 enhancer located at +164-kb that was selectively active in embryonically derived lineages, but not HSC-derived ones. Thus, Zeb2 expression in adult, but not embryonic, hematopoiesis is selectively controlled by the -165-kb Zeb2 enhancer.

ZEB2, the Mowat-Wilson Syndrome Transcription Factor: Confirmations, Novel Functions, and Continuing Surprises

After its publication in 1999 as a DNA-binding and SMAD-binding transcription factor (TF) that co-determines cell fate in amphibian embryos, ZEB2 was from 2003 studied by embryologists mainly by documenting the consequences of conditional, cell-type specific Zeb2 knockout (cKO) in mice. In between, it was further identified as causal gene causing Mowat-Wilson Syndrome (MOWS) and novel regulator of epithelial–mesenchymal transition (EMT). ZEB2’s functions and action mechanisms in mouse embryos were first addressed in its main sites of expression, with focus on those that helped to explain neurodevelopmental and neural crest defects seen in MOWS patients. By doing so, ZEB2 was identified in the forebrain as the first TF that determined timing of neuro-/gliogenesis, and thereby also the extent of different layers of the cortex, in a cell non-autonomous fashion, i.e., by its cell-intrinsic control within neurons of neuron-to-progenitor paracrine signaling. Transcriptomics-based phenotyping of Zeb2 mutant mouse cells have identified large sets of intact-ZEB2 dependent genes, and the cKO approaches also moved to post-natal brain development and diverse other systems in adult mice, including hematopoiesis and various cell types of the immune system. These new studies start to highlight the important adult roles of ZEB2 in cell–cell communication, including after challenge, e.g., in the infarcted heart and fibrotic liver. Such studies may further evolve towards those documenting the roles of ZEB2 in cell-based repair of injured tissue and organs, downstream of actions of diverse growth factors, which recapitulate developmental signaling principles in the injured sites. Evident questions are about ZEB2’s direct target genes, its various partners, and ZEB2 as a candidate modifier gene, e.g., in other (neuro)developmental disorders, but also the accurate transcriptional and epigenetic regulation of its mRNA expression sites and levels. Other questions start to address ZEB2’s function as a niche-controlling regulatory TF of also other cell types, in part by its modulation of growth factor responses (e.g., TGFβ/BMP, Wnt, Notch). Furthermore, growing numbers of mapped missense as well as protein non-coding mutations in MOWS patients are becoming available and inspire the design of new animal model and pluripotent stem cell-based systems. This review attempts to summarize in detail, albeit without discussing ZEB2’s role in cancer, hematopoiesis, and its emerging roles in the immune system, how intense ZEB2 research has arrived at this exciting intersection.

Adhesion dynamics in the neocortex determine the start of migration and the post-migratory orientation of neurons

The neocortex is stereotypically organized into layers of excitatory neurons arranged in a precise parallel orientation. Here we show that dynamic adhesion both preceding and following radial migration is essential for this organization. Neuronal adhesion is regulated by the Mowat-Wilson syndrome-associated transcription factor Zeb2 (Sip1/Zfhx1b) through direct repression of independent adhesion pathways controlled by Neuropilin-1 (Nrp1) and Cadherin-6 (Cdh6). We reveal that to initiate radial migration, neurons must first suppress adhesion to the extracellular matrix. Zeb2 regulates the multipolar stage by transcriptional repression of Nrp1 and thereby downstream inhibition of integrin signaling. Upon completion of migration, neurons undergo an orientation process that is independent of migration. The parallel organization of neurons within the neocortex is controlled by Cdh6 through atypical regulation of integrin signaling via its RGD motif. Our data shed light on the mechanisms that regulate initiation of radial migration and the postmigratory orientation of neurons during neocortical development.

Neurological Phenotype of Mowat-Wilson Syndrome

Mowat-Wilson Syndrome (MWS) (OMIM # 235730) is a rare disorder due to ZEB2 gene defects (heterozygous mutation or deletion). The ZEB2 gene is a widely expressed regulatory gene, extremely important for the proper prenatal development. MWS is characterized by a specific facial gestalt and multiple musculoskeletal, cardiac, gastrointestinal, and urogenital anomalies. The nervous system involvement is extensive and constitutes one of the main features in MWS, heavily affecting prognosis and life quality of affected individuals. This review aims to comprehensively organize and discuss the neurological and neurodevelopmental phenotype of MWS. First, we will describe the role of ZEB2 in the formation and development of the nervous system by reviewing the preclinical studies in this regard. ZEB2 regulates the neural crest cell differentiation and migration, as well as in the modulation of GABAergic transmission. This leads to different degrees of structural and functional impairment that have been explored and deepened by various authors over the years. Subsequently, the different neurological aspects of MWS (head and brain malformations, epilepsy, sleep disorders, and enteric and peripheral nervous system involvement, as well as developmental, cognitive, and behavioral features) will be faced one at a time and extensively examined from both a clinical and etiopathogenetic point of view, linking them to the ZEB2 related pathways.

Zeb2 Is a Regulator of Astrogliosis and Functional Recovery after CNS Injury

The astrocytic response to injury is characterized on the cellular level, but our understanding of the molecular mechanisms controlling the cellular processes is incomplete. The astrocytic response to injury is similar to wound-healing responses in non-neural tissues that involve epithelial-to-mesenchymal transitions (EMTs) and upregulation in ZEB transcription factors. Here we show that injury-induced astrogliosis increases EMT-related genes expression, including Zeb2, and long non-coding RNAs, including Zeb2os, which facilitates ZEB2 protein translation. In mouse models of either contusive spinal cord injury or transient ischemic stroke, the conditional knockout of Zeb2 in astrocytes attenuates astrogliosis, generates larger lesions, and delays the recovery of motor function. These findings reveal ZEB2 as an important regulator of the astrocytic response to injury and suggest that astrogliosis is an EMT-like process, which provides a conceptual connection for the molecular and cellular similarities between astrogliosis and wound-healing responses in non-neural tissue.

Genetic models of human and mouse dendritic cell development and function

Dendritic cells (DCs) develop in the bone marrow from haematopoietic progenitors that have numerous shared characteristics between mice and humans. Human counterparts of mouse DC progenitors have been identified by their shared transcriptional signatures and developmental potential. New findings continue to revise models of DC ontogeny but it is well accepted that DCs can be divided into two main functional groups. Classical DCs include type 1 and type 2 subsets, which can detect different pathogens, produce specific cytokines and present antigens to polarize mainly naive CD8+ or CD4+ T cells, respectively. By contrast, the function of plasmacytoid DCs is largely innate and restricted to the detection of viral infections and the production of type I interferon. Here, we discuss genetic models of mouse DC development and function that have aided in correlating ontogeny with function, as well as how these findings can be translated to human DCs and their progenitors.

Genetics Underlying the Interactions between Neural Crest Cells and Eye Development

The neural crest is a unique, transient stem cell population that is critical for craniofacial and ocular development. Understanding the genetics underlying the steps of neural crest development is essential for gaining insight into the pathogenesis of congenital eye diseases. The neural crest cells play an under-appreciated key role in patterning the neural epithelial-derived optic cup. These interactions between neural crest cells within the periocular mesenchyme and the optic cup, while not well-studied, are critical for optic cup morphogenesis and ocular fissure closure. As a result, microphthalmia and coloboma are common phenotypes in human disease and animal models in which neural crest cell specification and early migration are disrupted. In addition, neural crest cells directly contribute to numerous ocular structures including the cornea, iris, sclera, ciliary body, trabecular meshwork, and aqueous outflow tracts. Defects in later neural crest cell migration and differentiation cause a constellation of well-recognized ocular anterior segment anomalies such as Axenfeld–Rieger Syndrome and Peters Anomaly. This review will focus on the genetics of the neural crest cells within the context of how these complex processes specifically affect overall ocular development and can lead to congenital eye diseases.

Zeb2 regulates the balance between retinal interneurons and Müller glia by inhibition of BMP-Smad signaling

The interplay between signaling molecules and transcription factors during retinal development is key to controlling the correct number of retinal cell types. Zeb2 (Sip1) is a zinc-finger multidomain transcription factor that plays multiple roles in central and peripheral nervous system development. Haploinsufficiency of ZEB2 causes Mowat-Wilson syndrome, a congenital disease characterized by intellectual disability, epilepsy and Hirschsprung disease. In the developing retina, Zeb2 is required for generation of horizontal cells and the correct number of interneurons; however, its potential function in controlling gliogenic versus neurogenic decisions remains unresolved. Here we present cellular and molecular evidence of the inhibition of Müller glia cell fate by Zeb2 in late stages of retinogenesis. Unbiased transcriptomic profiling of control and Zeb2-deficient early-postnatal retina revealed that Zeb2 functions in inhibiting Id1/2/4 and Hes1 gene expression. These neural progenitor factors normally inhibit neural differentiation and promote Müller glia cell fate. Chromatin immunoprecipitation (ChIP) supported direct regulation of Id1 by Zeb2 in the postnatal retina. Reporter assays and ChIP analyses in differentiating neural progenitors provided further evidence that Zeb2 inhibits Id1 through inhibition of Smad-mediated activation of Id1 transcription. Together, the results suggest that Zeb2 promotes the timely differentiation of retinal interneurons at least in part by repressing BMP-Smad/Notch target genes that inhibit neurogenesis. These findings show that Zeb2 integrates extrinsic cues to regulate the balance between neuronal and glial cell types in the developing murine retina.

Heterogeneity and clonal relationships of adaptive immune cells in ulcerative colitis revealed by single-cell analyses

Inflammatory bowel disease (IBD) encompasses a spectrum of gastrointestinal disorders driven by dysregulated immune responses against gut microbiota. We integrated single-cell RNA and antigen receptor sequencing to elucidate key components, cellular states, and clonal relationships of the peripheral and gastrointestinal mucosal immune systems in health and ulcerative colitis (UC). UC was associated with an increase in IgG1⁺ plasma cells in colonic tissue, increased colonic regulatory T cells characterized by elevated expression of the transcription factor ZEB2, and an enrichment of a γδ T cell subset in the peripheral blood. Moreover, we observed heterogeneity in CD8⁺ tissue-resident memory T (T_RM) cells in colonic tissue, with four transcriptionally distinct states of differentiation observed across health and disease. In the setting of UC, there was a marked shift of clonally related CD8⁺ T_RM cells toward an inflammatory state, mediated, in part, by increased expression of the T-box transcription factor Eomesodermin. Together, these results provide a detailed atlas of transcriptional changes occurring in adaptive immune cells in the context of UC and suggest a role for CD8⁺ T_RM cells in IBD.

Interleukin-10 restores glutamate receptor-mediated Ca2+-signaling in brain circuits under loss of Sip1 transcription factor

OBJECTIVE

This study aimed to investigate the connection between the mutation of the Sip1 transcription factor and impaired Ca²⁺-signaling, which reflects changes in neurotransmission in the cerebral cortex in vitro.

METHODS

We used mixed neuroglial cortical cell cultures derived from Sip1 mutant mice. The cells were loaded with a fluorescent ratiometric calcium-sensitive probe Fura-2 AM and epileptiform activity was modeled by excluding magnesium ions from the external media or adding a GABA(A) receptor antagonist, bicuculline. Intracellular calcium dynamics were recorded using fluorescence microscopy. To identify the level of gene expression, the Real-Time PCR method was used.

RESULTS

It was found that cortical neurons isolated from homozygous (Sip1^fl/fl) mice with the Sip1 mutation demonstrate suppressed Ca²⁺ signals in models of epileptiform activity in vitro. Wild-type cortical neurons are characterized by synchronous high-frequency and high-amplitude Ca²⁺ oscillations occurring in all neurons of the network in response to Mg²⁺-free medium and bicuculline. But cortical Sip1^fl/fl neurons only single Ca²⁺ pulses or attenuated Ca²⁺ oscillations are recorded and only in single neurons, while most of the cell network does not respond to these stimuli. This signal deficiency of Sip1^fl/fl neurons correlates with a suppressed expression level of the genes encoding the subunits of NMDA, AMPA, and KA receptors; protein kinases PKA, JNK, CaMKII; and also the transcription factor Hif1α. These negative effects were partially abolished when Sip1^fl/fl neurons are grown in media with anti-inflammatory cytokine IL-10. IL-10 increases the expression of the above-mentioned genes but not to the level of expression in wild-type. At the same time, the amplitudes of Ca²⁺ signals increase in response to the selective agonists of NMDA, AMPA and KA receptors, and the proportion of neurons responding with Ca²⁺ oscillations to a Mg²⁺-free medium and bicuculline increases.

CONCLUSION

IL-10 restores neurotransmission in neuronal networks with the Sip1 mutation by regulating the expression of genes encoding signaling proteins.

The EMT Transcription Factor ZEB2 Promotes Proliferation of Primary and Metastatic Melanoma While Suppressing an Invasive, Mesenchymal-Like Phenotype

Epithelial-to-mesenchymal transition (EMT)-inducing transcription factors (TF) are well known for their ability to induce mesenchymal states associated with increased migratory and invasive properties. Unexpectedly, nuclear expression of the EMT-TF ZEB2 in human primary melanoma has been shown to correlate with reduced invasion. We report here that ZEB2 is required for outgrowth for primary melanomas and metastases at secondary sites. Ablation of Zeb2 hampered outgrowth of primary melanomas in vivo, whereas ectopic expression enhanced proliferation and growth at both primary and secondary sites. Gain of Zeb2 expression in pulmonary-residing melanoma cells promoted the development of macroscopic lesions. In vivo fate mapping made clear that melanoma cells undergo a conversion in state where ZEB2 expression is replaced by ZEB1 expression associated with gain of an invasive phenotype. These findings suggest that reversible switching of the ZEB2/ZEB1 ratio enhances melanoma metastatic dissemination. SIGNIFICANCE: ZEB2 function exerts opposing behaviors in melanoma by promoting proliferation and expansion and conversely inhibiting invasiveness, which could be of future clinical relevance. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/14/2983/F1.large.jpg.

Multifaceted actions of Zeb2 in postnatal neurogenesis from the ventricular-subventricular zone to the olfactory bulb

The transcription factor Zeb2 controls fate specification and subsequent differentiation and maturation of multiple cell types in various embryonic tissues. It binds many protein partners, including activated Smad proteins and the NuRD co-repressor complex. How Zeb2 subdomains support cell differentiation in various contexts has remained elusive. Here, we studied the role of Zeb2 and its domains in neurogenesis and neural differentiation in the young postnatal ventricular-subventricular zone (V-SVZ), in which neural stem cells generate olfactory bulb-destined interneurons. Conditional Zeb2 knockouts and separate acute loss- and gain-of-function approaches indicated that Zeb2 is essential for controlling apoptosis and neuronal differentiation of V-SVZ progenitors before and after birth, and we identified Sox6 as a potential downstream target gene of Zeb2. Zeb2 genetic inactivation impaired the differentiation potential of the V-SVZ niche in a cell-autonomous fashion. We also provide evidence that its normal function in the V-SVZ also involves non-autonomous mechanisms. Additionally, we demonstrate distinct roles for Zeb2 protein-binding domains, suggesting that Zeb2 partners co-determine neuronal output from the mouse V-SVZ in both quantitative and qualitative ways in early postnatal life.

Zeb2 Regulates Myogenic Differentiation in Pluripotent Stem Cells

Skeletal muscle differentiation is triggered by a unique family of myogenic basic helix-loop-helix transcription factors, including MyoD, MRF-4, Myf-5, and Myogenin. These transcription factors bind promoters and distant regulatory regions, including E-box elements, of genes whose expression is restricted to muscle cells. Other E-box binding zinc finger proteins target the same DNA response elements, however, their function in muscle development and regeneration is still unknown. Here, we show that the transcription factor zinc finger E-box-binding homeobox 2 (Zeb2, Sip-1, Zfhx1b) is present in skeletal muscle tissues. We investigate the role of Zeb2 in skeletal muscle differentiation using genetic tools and transgenic mouse embryonic stem cells, together with single-cell RNA-sequencing and in vivo muscle engraftment capability. We show that Zeb2 over-expression has a positive impact on skeletal muscle differentiation in pluripotent stem cells and adult myogenic progenitors. We therefore propose that Zeb2 is a novel myogenic regulator and a possible target for improving skeletal muscle regeneration. The non-neural roles of Zeb2 are poorly understood.

Functional characterization of the ZEB2 regulatory landscape

Zinc finger E-box–binding homeobox 2 (ZEB2) is a key developmental regulator of the central nervous system (CNS). Although the transcriptional regulation of ZEB2 is essential for CNS development, the elements that regulate ZEB2 expression have yet to be identified. Here, we identified a proximal regulatory region of ZEB2 and characterized transcriptional enhancers during neuronal development. Using chromatin immunoprecipitation sequencing for active (H3K27ac) and repressed (H3K27me3) chromatin regions in human neuronal progenitors, combined with an in vivo zebrafish enhancer assay, we functionally characterized 18 candidate enhancers in the ZEB2 locus. Eight enhancers drove expression patterns that were specific to distinct mid/hindbrain regions (ZEB2#e3 and 5), trigeminal-like ganglia (ZEB2#e6 and 7), notochord (ZEB2#e2, 4 and 12) and whole brain (ZEB2#e14). We further dissected the minimal sequences that drive enhancer-specific activity in the mid/hindbrain and notochord. Using a reporter assay in human cells, we showed an increased activity of the minimal notochord enhancer ZEB2#e2 in response to AP-1 and DLX1/2 expressions, while repressed activity of this enhancer was seen in response to ZEB2 and TFAP2 expressions. We showed that Dlx1 but not Zeb2 and Tfap2 occupies Zeb2#e2 enhancer sequence in the mouse notochord at embryonic day 11.5. Using CRISPR/Cas9 genome editing, we deleted the ZEB2#e2 region, leading to reduction of ZEB2 expression in human cells. We thus characterized distal transcriptional enhancers and trans-acting elements that govern regulation of ZEB2 expression during neuronal development. These findings pave the path toward future analysis of the role of ZEB2 regulatory elements in neurodevelopmental disorders, such as Mowat–Wilson syndrome.

PROP1-Dependent Retinoic Acid Signaling Regulates Developmental Pituitary Morphogenesis and Hormone Expression

Dietary vitamin A is metabolized into bioactive retinoic acid (RA) in vivo and regulates the development of many embryonic tissues. RA signaling is active in the oral ectoderm-derived tissues of the neuroendocrine system, but its role there has not yet been fully explored. We show here that RA signaling is active during pituitary organogenesis and dependent on the pituitary transcription factor Prop1. Prop1-mutant mice show reduced expression of the aldehyde dehydrogenase gene Aldh1a2, which metabolizes the vitamin A-intermediate retinaldehyde into RA. To elucidate the specific function of RA signaling during neuroendocrine development, we studied a conditional deletion of Aldh1a2 and a dominant-negative mouse model of inhibited RA signaling during pituitary organogenesis. These models partially phenocopy Prop1-mutant mice by exhibiting embryonic pituitary dysmorphology and reduced hormone expression, especially thyrotropin. These findings establish the role of RA in embryonic pituitary stem cell progression to differentiated hormone cells and raise the question of gene-by-environment interactions as contributors to pituitary development and disease.

Shared Transcriptional Control of Innate Lymphoid Cell and Dendritic Cell Development

Innate immunity and adaptive immunity consist of highly specialized immune lineages that depend on transcription factors for both function and development. In this review, we dissect the similarities between two innate lineages, innate lymphoid cells (ILCs) and dendritic cells (DCs), and an adaptive immune lineage, T cells. ILCs, DCs, and T cells make up four functional immune modules and interact in concert to produce a specified immune response. These three immune lineages also share transcriptional networks governing the development of each lineage, and we discuss the similarities between ILCs and DCs in this review.

An Nfil3-Zeb2-Id2 pathway imposes Irf8 enhancer switching during cDC1 development

Classical type 1 dendritic cells (cDC1s) are required for antiviral and antitumor immunity, which necessitates an understanding of their development. Development of the cDC1 progenitor requires an E-protein-dependent enhancer located 41 kilobases downstream of the transcription start site of the transcription factor Irf8 (+41-kb Irf8 enhancer), but its maturation instead requires the Batf3-dependent +32-kb Irf8 enhancer. To understand this switch, we performed single-cell RNA sequencing of the common dendritic cell progenitor (CDP) and identified a cluster of cells that expressed transcription factors that influence cDC1 development, such as Nfil3, Id2 and Zeb2. Genetic epistasis among these factors revealed that Nfil3 expression is required for the transition from Zeb2hi and Id2lo CDPs to Zeb2lo and Id2hi CDPs, which represent the earliest committed cDC1 progenitors. This genetic circuit blocks E-protein activity to exclude plasmacytoid dendritic cell potential and explains the switch in Irf8 enhancer usage during cDC1 development.

Development, Diversity, and Function of Dendritic Cells in Mouse and Human

The study of murine dendritic cell (DC) development has been integral to the identification of specialized DC subsets that have unique requirements for their form and function. Advances in the field have also provided a framework for the identification of human DC counterparts, which appear to have conserved mechanisms of development and function. Multiple transcription factors are expressed in unique combinations that direct the development of classical DCs (cDCs), which include two major subsets known as cDC1s and cDC2s, and plasmacytoid DCs (pDCs). pDCs are potent producers of type I interferons and thus these cells are implicated in immune responses that depend on this cytokine. Mouse models deficient in the cDC1 lineage have revealed their importance in directing immune responses to intracellular bacteria, viruses, and cancer through the cross-presentation of cell-associated antigen. Models of transcription factor deficiency have been used to identify subsets of cDC2 that are required for T helper (Th)2 and Th17 responses to certain pathogens; however, no single factor is known to be absolutely required for the development of the complete cDC2 lineage. In this review, we will discuss the current state of knowledge of mouse and human DC development and function and highlight areas in the field that remain unresolved.

Role of Zeb2/Sip1 in neuronal development

Zeb2 (Sip1, Zfhx1b) is a transcription factor that plays essential role in neuronal development. Sip1 mutation in humans was shown to cause Mowat-Wilson syndrome, a syndromic form of Hirschprung's disease. Affected individuals exhibit multiple severe neurodevelopmental defects. Zeb2 can act as both transcriptional repressor and activator. It controls expression of a wide number of genes that regulate various aspects of neuronal development. This review addresses the molecular pathways acting downstream of Zeb2 that cause brain development disorders.

The Transcription Factor ZEB2 Is Required to Maintain the Tissue-Specific Identities of Macrophages

Heterogeneity between different macrophage populations has become a defining feature of this lineage. However, the conserved factors defining macrophages remain largely unknown. The transcription factor ZEB2 is best described for its role in epithelial to mesenchymal transition; however, its role within the immune system is only now being elucidated. We show here that Zeb2 expression is a conserved feature of macrophages. Using Clec4f-cre, Itgax-cre, and Fcgr1-cre mice to target five different macrophage populations, we found that loss of ZEB2 resulted in macrophage disappearance from the tissues, coupled with their subsequent replenishment from bone-marrow precursors in open niches. Mechanistically, we found that ZEB2 functioned to maintain the tissue-specific identities of macrophages. In Kupffer cells, ZEB2 achieved this by regulating expression of the transcription factor LXRα, removal of which recapitulated the loss of Kupffer cell identity and disappearance. Thus, ZEB2 expression is required in macrophages to preserve their tissue-specific identities.

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ZEB2 is highly expressed across the macrophage lineage

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ZEB2 preserves the tissue-specific identities of macrophages across tissues

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ZEB2 deficient macrophages are outcompeted by WT counterparts

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LXRα is crucial for Kupffer cell identity and is maintained by ZEB2

Mutation in the Sip1 transcription factor leads to a disturbance of the preconditioning of AMPA receptors by episodes of hypoxia in neurons of the cerebral cortex due to changes in their activity and subunit composition. The protective effects of interleukin-10

The Sip1 mutation plays the main role in pathogenesis of the Mowat-Wilson syndrome, which is characterized by the pronounced epileptic symptoms. Cortical neurons of homozygous mice with Sip1 mutation are resistant to AMPA receptor activators. Disturbances of the excitatory signaling components are also observed on such a phenomenon of neuroplasticity as hypoxic preconditioning. In this work, the mechanisms of loss of the AMPA receptor's ability to precondition by episodes of short-term hypoxia were investigated on cortical neurons derived from the Sip1 homozygous mice. The preconditioning effect was estimated by the level of suppression of the AMPA receptors activity with hypoxia episodes. Using fluorescence microscopy, we have shown that cortical neurons from the Sip1^fl/fl mice are characterized by the absence of hypoxic preconditioning effect, whereas the amplitude of Ca²⁺-responses to the application of the AMPA receptor agonist, 5-Fluorowillardiine, in neurons from the Sip1 mice brainstem is suppressed by brief episodes of hypoxia. The mechanism responsible for this process is hypoxia-induced desensitization of the AMPA receptors, which is absent in the cortex neurons possessing the Sip1 mutation. However, the appearance of preconditioning in these neurons can be induced by phosphoinositide-3-kinase activation with a selective activator or an anti-inflammatory cytokine interleukin-10.

A Zeb2-miR-200c loop controls midbrain dopaminergic neuron neurogenesis and migration

Zeb2 is a homeodomain transcription factor that plays pleiotropic functions during embryogenesis, but its role for midbrain dopaminergic (mDA) neuron development is unknown. Here we report that Zeb2 is highly expressed in progenitor cells in the ventricular zone of the midbrain floor plate and downregulated in postmitotic neuroblasts. Functional experiments show that Zeb2 expression in the embryonic ventral midbrain is dynamically regulated by a negative feedback loop that involves miR-200c. We also find that Zeb2 overexpression reduces the levels of CXCR4, NR4A2, and PITX3 in the developing ventral midbrain in vivo, resulting in migration and mDA differentiation defects. This phenotype was recapitulated by miR-200c knockdown, suggesting that the Zeb2-miR-200c loop prevents the premature differentiation of mDA progenitors into postmitotic cells and their migration. Together, our study establishes Zeb2 and miR-200c as critical regulators that maintain the balance between mDA progenitor proliferation and neurogenesis.

Requirement of the Mowat-Wilson Syndrome Gene Zeb2 in the Differentiation and Maintenance of Non-photoreceptor Cell Types During Retinal Development

Mutations in the human transcription factor gene ZEB2 cause Mowat-Wilson syndrome, a congenital disorder characterized by multiple and variable anomalies including microcephaly, Hirschsprung disease, intellectual disability, epilepsy, microphthalmia, retinal coloboma, and/or optic nerve hypoplasia. Zeb2 in mice is involved in patterning neural and lens epithelia, neural tube closure, as well as in the specification, differentiation and migration of neural crest cells and cortical neurons. At present, it is still unclear how Zeb2 mutations cause retinal coloboma, whether Zeb2 inactivation results in retinal degeneration, and whether Zeb2 is sufficient to promote the differentiation of different retinal cell types. Here, we show that during mouse retinal development, Zeb2 is expressed transiently in early retinal progenitors and in all non-photoreceptor cell types including bipolar, amacrine, horizontal, ganglion, and Müller glial cells. Its retina-specific ablation causes severe loss of all non-photoreceptor cell types, cell fate switch to photoreceptors by retinal progenitors, and elevated apoptosis, which lead to age-dependent retinal degeneration, optic nerve hypoplasia, synaptic connection defects, and impaired ERG (electroretinogram) responses. Moreover, overexpression of Zeb2 is sufficient to promote the fate of all non-photoreceptor cell types at the expense of photoreceptors. Together, our data not only suggest that Zeb2 is both necessary and sufficient for the differentiation of non-photoreceptor cell types while simultaneously inhibiting the photoreceptor cell fate by repressing transcription factor genes involved in photoreceptor specification and differentiation, but also reveal a necessity of Zeb2 in the long-term maintenance of retinal cell types. This work helps to decipher the etiology of retinal atrophy associated with Mowat-Wilson syndrome and hence will impact on clinical diagnosis and management of the patients suffering from this syndrome.

ZEB Proteins in Leukemia: Friends, Foes, or Friendly Foes?

ZEB1 and ZEB2 play pivotal roles in solid cancer metastasis by allowing cancer cells to invade and disseminate through the transcriptional regulation of epithelial-to-mesenchymal transition. ZEB expression is also associated with the acquisition of cancer stem cell properties and therapy resistance. Consequently, expression levels of ZEB1/2 and of their direct target genes are widely seen as reliable prognostic markers for solid tumor aggressiveness and cancer patient outcome.

Recent loss-of-function mouse models demonstrated that both ZEBs are also essential hematopoietic transcription factors governing blood lineage commitment and fidelity. Interestingly, both gain- and loss-of-function mutations have been reported in multiple hematological malignancies. Combined with emerging functional studies, these data suggest that ZEB1 and ZEB2 can act as tumor suppressors and/or oncogenes in blood borne malignancies, depending on the cellular context. Here, we review these novel insights and discuss how balanced expression of ZEB proteins may be essential to safeguard the functionality of the immune system and prevent leukemia.

ZEB1, ZEB2, and the miR-200 family form a counterregulatory network to regulate CD8+ T cell fates

Guan et al. identify genetic cooperativity between the transcription factor ZEB1 and the miR-200 family in memory CD8⁺ T cell development, which contrasts with that observed in the EMT. This study also shows that ZEB1 and its closely related homologue, ZEB2, play functionally distinct roles in CD8⁺ T cell differentiation.

Long-term immunity depends partly on the establishment of memory CD8⁺ T cells. We identified a counterregulatory network between the homologous transcription factors ZEB1 and ZEB2 and the miR-200 microRNA family, which modulates effector CD8⁺ T cell fates. Unexpectedly, Zeb1 and Zeb2 had reciprocal expression patterns and were functionally uncoupled in CD8⁺ T cells. ZEB2 promoted terminal differentiation, whereas ZEB1 was critical for memory T cell survival and function. Interestingly, the transforming growth factor β (TGF-β) and miR-200 family members, which counterregulate the coordinated expression of Zeb1 and Zeb2 during the epithelial-to-mesenchymal transition, inversely regulated Zeb1 and Zeb2 expression in CD8⁺ T cells. TGF-β induced and sustained Zeb1 expression in maturing memory CD8⁺ T cells. Meanwhile, both TGF-β and miR-200 family members selectively inhibited Zeb2. Additionally, the miR-200 family was necessary for optimal memory CD8⁺ T cell formation. These data outline a previously unknown genetic pathway in CD8⁺ T cells that controls effector and memory cell fate decisions.

The RNA-binding protein, ZC3H14, is required for proper poly(A) tail length control, expression of synaptic proteins, and brain function in mice

A number of mutations in genes that encode ubiquitously expressed RNA-binding proteins cause tissue specific disease. Many of these diseases are neurological in nature revealing critical roles for this class of proteins in the brain. We recently identified mutations in a gene that encodes a ubiquitously expressed polyadenosine RNA-binding protein, ZC3H14 (Zinc finger CysCysCysHis domain-containing protein 14), that cause a nonsyndromic, autosomal recessive form of intellectual disability. This finding reveals the molecular basis for disease and provides evidence that ZC3H14 is essential for proper brain function. To investigate the role of ZC3H14 in the mammalian brain, we generated a mouse in which the first common exon of the ZC3H14 gene, exon 13 is removed (Zc3h14Δex13/Δex13) leading to a truncated ZC3H14 protein. We report here that, as in the patients, Zc3h14 is not essential in mice. Utilizing these Zc3h14Δex13/Δex13mice, we provide the first in vivo functional characterization of ZC3H14 as a regulator of RNA poly(A) tail length. The Zc3h14Δex13/Δex13 mice show enlarged lateral ventricles in the brain as well as impaired working memory. Proteomic analysis comparing the hippocampi of Zc3h14+/+ and Zc3h14Δex13/Δex13 mice reveals dysregulation of several pathways that are important for proper brain function and thus sheds light onto which pathways are most affected by the loss of ZC3H14. Among the proteins increased in the hippocampi of Zc3h14Δex13/Δex13 mice compared to control are key synaptic proteins including CaMK2a. This newly generated mouse serves as a tool to study the function of ZC3H14 in vivo.

Zeb2 is a negative regulator of midbrain dopaminergic axon growth and target innervation

Neural connectivity requires neuronal differentiation, axon growth, and precise target innervation. Midbrain dopaminergic neurons project via the nigrostriatal pathway to the striatum to regulate voluntary movement. While the specification and differentiation of these neurons have been extensively studied, the molecular mechanisms that regulate midbrain dopaminergic axon growth and target innervation are less clear. Here we show that the transcription factor Zeb2 cell-autonomously represses Smad signalling to limit midbrain dopaminergic axon growth and target innervation. Zeb2 levels are downregulated in the embryonic rodent midbrain during the period of dopaminergic axon growth, when BMP pathway components are upregulated. Experimental knockdown of Zeb2 leads to an increase in BMP-Smad-dependent axon growth. Consequently there is dopaminergic hyperinnervation of the striatum, without an increase in the numbers of midbrain dopaminergic neurons, in conditional Zeb2 (Nestin-Cre based) knockout mice. Therefore, these findings reveal a new mechanism for the regulation of midbrain dopaminergic axon growth during central nervous system development.

Tip110 Deletion Impaired Embryonic and Stem Cell Development Involving Downregulation of Stem Cell Factors Nanog, Oct4, and Sox2

HIV-1 Tat-interacting protein of 110 kDa, Tip110, plays important roles in multiple biological processes. In this study, we aimed to characterize the function of Tip110 in embryonic development. Transgenic mice lacking expression of a functional Tip110 gene (Tip110^-/- ) died post-implantation, and Tip110^-/- embryos exhibited developmental arrest between 8.5 and 9.5 days post coitum. However, in vitro cultures of Tip110^-/- embryos showed that Tip110 loss did not impair embryo growth from the zygote to the blastocyst. Extended in vitro cultures of Tip110^-/- blastocysts showed that Tip110 loss impaired both blastocyst outgrowth and self-renewal and survival of blastocyst-derived embryonic stem cells. Microarray analysis of Tip110^-/- embryonic stem cells revealed that Tip110 loss altered differentiation, pluripotency, and cycling of embryonic stem cells and was associated with downregulation of several major stem cell factors including Nanog, Oct4, and Sox2 through a complex network of signaling pathways. Taken together, these findings document for the first time the lethal effects of complete loss of Tip110 on mammalian embryonic development and suggest that Tip110 is an important regulator of not only embryonic development but also stem cell factors. Stem Cells 2017;35:1674-1686.

Sip-1 mutations cause disturbances in the activity of NMDA- and AMPA-, but not kainate receptors of neurons in the cerebral cortex

Smad-interacting protein-1 (Sip1) [Zinc finger homeobox (Zfhx1b), Zeb2] is a transcription factor implicated in the genesis of Mowat-Wilson syndrome (MWS) in humans. MWS is a rare genetic autosomal dominant disease caused by a mutation in the Sip1 gene (aka Zeb2 or Zfhx1b) mapped to 2q22.3 locus. MWS affects 1 in every 50-100 newborns worldwide. It is characterized by mental retardation, small stature, typical facial abnormalities as well as disturbances in the development of the cardio-vascular and renal systems as well as some other organs. Sip1 mutations cause abnormal neurogenesis in the brain during development as well as susceptibility to epileptic seizures. In the current study we investigated the role of the Sip1 gene in the activity of NMDA-, AMPA- and KA- receptors. We showed that a particular Sip1 mutation in the mouse causes changes in the activity of both NMDA- and AMPA- receptors in the neocortical neurons in vitro. We demonstrate that neocortical neurons that have only one copy of Sip1 (heterozygous, Sip1^fI/wt), are more sensitive to both NMDA- and AMPA- receptors agonists as compared to wild type neurons (Sip1^wt/wt). This is reflected in higher amplitudes of agonist induced Ca²⁺ signals as well as a lower half maximal effective concentration (ЕC50). In contrast, neurons from homozygous Sip1 mice (Sip1^fI/fI), demonstrate higher resistance to these respective receptor agonists. This is reflected in lower amplitudes of Ca²⁺-responses and so a higher concentration of receptor activators is required for activation.

Critical involvement of ZEB2 in collagen fibrillogenesis: the molecular similarity between Mowat-Wilson syndrome and Ehlers-Danlos syndrome

Mowat-Wilson syndrome (MOWS) is a congenital disease caused by de novo heterozygous loss of function mutations or deletions of the ZEB2 gene. MOWS patients show multiple anomalies including intellectual disability, a distinctive facial appearance, microcephaly, congenital heart defects and Hirschsprung disease. However, the skin manifestation(s) of patients with MOWS has not been documented in detail. Here, we recognized that MOWS patients exhibit many Ehlers-Danlos syndrome (EDS)-like symptoms, such as skin hyperextensibility, atrophic scars and joint hypermobility. MOWS patients showed a thinner dermal thickness and electron microscopy revealed miniaturized collagen fibrils. Notably, mice with a mesoderm-specific deletion of the Zeb2 gene (Zeb2-cKO) demonstrated redundant skin, dermal hypoplasia and miniaturized collagen fibrils similar to those of MOWS patients. Dermal fibroblasts derived from Zeb2-cKO mice showed a decreased expression of extracellular matrix (ECM) molecules, such as collagens, whereas molecules involved in degradation of the ECM, such as matrix metalloproteinases (MMPs), were up-regulated. Furthermore, bleomycin-induced skin fibrosis was attenuated in Zeb2-cKO mice. We conclude that MOWS patients exhibit an EDS-like skin phenotype through alterations of collagen fibrillogenesis due to ZEB2 mutations or deletions.

Differentiation of Mouse Enteric Nervous System Progenitor Cells Is Controlled by Endothelin 3 and Requires Regulation of Ednrb by SOX10 and ZEB2

BACKGROUND & AIMS

Maintenance and differentiation of progenitor cells in the developing enteric nervous system are controlled by molecules such as the signaling protein endothelin 3 (EDN3), its receptor (the endothelin receptor type B [EDNRB]), and the transcription factors SRY-box 10 (SOX10) and zinc finger E-box binding homeobox 2 (ZEB2). We used enteric progenitor cell (EPC) cultures and mice to study the roles of these proteins in enteric neurogenesis and their cross regulation.

METHODS

We performed studies in mice with a Zeb2 loss-of-function mutation (Zeb2^Δ) and mice carrying a spontaneous recessive mutation that prevents conversion of EDN3 to its active form (Edn3^ls). EPC cultures issued from embryos that expressed only wild-type Zeb2 (Zeb2^+/+ EPCs) or were heterozygous for the mutation (Zeb2^Δ/+ EPCs) were exposed to EDN3; we analyzed the effects on cell differentiation using immunocytochemistry. In parallel, Edn3^ls mice were crossed with Zeb2^Δ/+mice; intestinal tissues were collected from embryos for immunohistochemical analyses. We investigated regulation of the EDNRB gene in transactivation and chromatin immunoprecipitation assays; results were validated in functional rescue experiments using transgenes expression in EPCs from retroviral vectors.

RESULTS

Zeb2^Δ/+ EPCs had increased neuronal differentiation compared to Zeb2^+/+ cells. When exposed to EDN3, Zeb2^+/+ EPCs continued expression of ZEB2 but did not undergo any neuronal differentiation. Incubation of Zeb2^Δ/+ EPCs with EDN3, on the other hand, resulted in only partial inhibition of neuronal differentiation. This indicated that 2 copies of Zeb2 are required for EDN3 to prevent neuronal differentiation. Mice with combined mutations in Zeb2 and Edn3 (double mutants) had more severe enteric anomalies and increased neuronal differentiation compared to mice with mutations in either gene alone. The transcription factors SOX10 and ZEB2 directly activated the EDNRB promoter. Overexpression of EDNRB in Zeb2^Δ/+ EPCs restored inhibition of neuronal differentiation, similar to incubation of Zeb2^+/+ EPCs with EDN3.

CONCLUSIONS

In studies of cultured EPCs and mice, we found that control of differentiation of mouse enteric nervous system progenitor cells by EDN3 requires regulation of Ednrb expression by SOX10 and ZEB2.

Zeb2: Inhibiting the inhibitors in Schwann cells

Development of Schwann cells is tightly regulated by concerted action of activating and inhibiting factors. Most of the regulatory feedback loops identified to date are transcriptional activators promoting induction of genes coding for integral myelin proteins and lipids. The mechanisms by which inhibitory factors are silenced during Schwann cell maturation are less well understood. We could recently show a pivotal function for the transcription factor zinc finger E-box binding homeobox 2 (Zeb2) during Schwann cell development and myelination as a transcriptional repressor of maturation inhibitors. Zeb2 belongs to a family of highly conserved 2-handed zinc-finger proteins and represses gene transcription by binding to E-box sequences in the regulatory region of target genes. The protein is known to repress E-cadherin during epithelial to mesenchymal transition (EMT) in tumor malignancy and mediates its functions by interacting with multiple co-factors. During nervous system development, Zeb2 is expressed in neural crest cells, the precursors of Schwann cells, the myelinating glial cells of peripheral nerves. Schwann cells lacking Zeb2 fail to fully differentiate and are unable to sort and myelinate peripheral nerve axons. The maturation inhibitors Sox2, Ednrb and Hey2 emerge as targets for Zeb2-mediated transcriptional repression and show persistent aberrant expression in Zeb2-deficient Schwann cells. While dispensible for adult Schwann cells, re-activation of Zeb2 is essential after nerve injury to allow remyelination and functional recovery. In summary, Zeb2 emerges as an "inhibitor of inhibitors," a novel concept in Schwann cell development and nerve repair.

Transcription factor Zeb2 regulates commitment to plasmacytoid dendritic cell and monocyte fate

Dendritic cells (DCs) and monocytes develop from a series of bone-marrow-resident progenitors in which lineage potential is regulated by distinct transcription factors. Zeb2 is an E-box-binding protein associated with epithelial-mesenchymal transition and is widely expressed among hematopoietic lineages. Previously, we observed that Zeb2 expression is differentially regulated in progenitors committed to classical DC (cDC) subsets in vivo. Using systems for inducible gene deletion, we uncover a requirement for Zeb2 in the development of Ly-6C^hi monocytes but not neutrophils, and we show a corresponding requirement for Zeb2 in expression of the M-CSF receptor in the bone marrow. In addition, we confirm a requirement for Zeb2 in development of plasmacytoid DCs but find that Zeb2 is not required for cDC2 development. Instead, Zeb2 may act to repress cDC1 progenitor specification in the context of inflammatory signals.

Zeb2 Regulates Cell Fate at the Exit from Epiblast State in Mouse Embryonic Stem Cells

In human embryonic stem cells (ESCs) the transcription factor Zeb2 regulates neuroectoderm versus mesendoderm formation, but it is unclear how Zeb2 affects the global transcriptional regulatory network in these cell‐fate decisions. We generated Zeb2 knockout (KO) mouse ESCs, subjected them as embryoid bodies (EBs) to neural and general differentiation and carried out temporal RNA‐sequencing (RNA‐seq) and reduced representation bisulfite sequencing (RRBS) analysis in neural differentiation. This shows that Zeb2 acts preferentially as a transcriptional repressor associated with developmental progression and that Zeb2 KO ESCs can exit from their naïve state. However, most cells in these EBs stall in an early epiblast‐like state and are impaired in both neural and mesendodermal differentiation. Genes involved in pluripotency, epithelial‐to‐mesenchymal transition (EMT), and DNA‐(de)methylation, including Tet1, are deregulated in the absence of Zeb2. The observed elevated Tet1 levels in the mutant cells and the knowledge of previously mapped Tet1‐binding sites correlate with loss‐of‐methylation in neural‐stimulating conditions, however, after the cells initially acquired the correct DNA‐methyl marks. Interestingly, cells from such Zeb2 KO EBs maintain the ability to re‐adapt to 2i + LIF conditions even after prolonged differentiation, while knockdown of Tet1 partially rescues their impaired differentiation. Hence, in addition to its role in EMT, Zeb2 is critical in ESCs for exit from the epiblast state, and links the pluripotency network and DNA‐methylation with irreversible commitment to differentiation. Stem Cells2017;35:611–625

miR-200 family controls late steps of postnatal forebrain neurogenesis via Zeb2 inhibition

During neurogenesis, generation, migration and integration of the correct numbers of each neuron sub-type depends on complex molecular interactions in space and time. MicroRNAs represent a key control level allowing the flexibility and stability needed for this process. Insight into the role of this regulatory pathway in the brain is still limited. We performed a sequential experimental approach using postnatal olfactory bulb neurogenesis in mice, starting from global expression analyses to the investigation of functional interactions between defined microRNAs and their targets. Deep sequencing of small RNAs extracted from defined compartments of the postnatal neurogenic system demonstrated that the miR-200 family is specifically induced during late neuronal differentiation stages. Using in vivo strategies we interfered with the entire miR-200 family in loss- and gain-of-function settings, showing a role of miR-200 in neuronal maturation. This function is mediated by targeting the transcription factor Zeb2. Interestingly, so far functional interaction between miR-200 and Zeb2 has been exclusively reported in cancer or cultured stem cells. Our data demonstrate that this regulatory interaction is also active during normal neurogenesis.

The EMT transcription factor Zeb2 controls adult murine hematopoietic differentiation by regulating cytokine signaling

Epithelial-to-mesenchymal-transition (EMT) is critical for normal embryogenesis and effective postnatal wound healing, but is also associated with cancer metastasis. SNAIL, ZEB, and TWIST families of transcription factors are key modulators of the EMT process, but their precise roles in adult hematopoietic development and homeostasis remain unclear. Here we report that genetic inactivation of Zeb2 results in increased frequency of stem and progenitor subpopulations within the bone marrow (BM) and spleen and that these changes accompany differentiation defects in multiple hematopoietic cell lineages. We found no evidence that Zeb2 is critical for hematopoietic stem cell self-renewal capacity. However, knocking out Zeb2 in the BM promoted a phenotype with several features that resemble human myeloproliferative disorders, such as BM fibrosis, splenomegaly, and extramedullary hematopoiesis. Global gene expression and intracellular signal transduction analysis revealed perturbations in specific cytokine and cytokine receptor-related signaling pathways following Zeb2 loss, especially the JAK-STAT and extracellular signal-regulated kinase pathways. Moreover, we detected some previously unknown mutations within the human Zeb2 gene (ZFX1B locus) from patients with myeloid disease. Collectively, our results demonstrate that Zeb2 controls adult hematopoietic differentiation and lineage fidelity through widespread modulation of dominant signaling pathways that may contribute to blood disorders.

Loss of Zeb2 in mesenchyme-derived nephrons causes primary glomerulocystic disease

Primary glomerulocystic kidney disease is a special form of renal cystic disorder characterized by Bowman's space dilatation in the absence of tubular cysts. ZEB2 is a SMAD-interacting transcription factor involved in Mowat-Wilson syndrome, a congenital disorder with an increased risk for kidney anomalies. Here we show that deletion of Zeb2 in mesenchyme-derived nephrons with either Pax2-cre or Six2-cre causes primary glomerulocystic kidney disease without tubular cysts in mice. Glomerulotubular junction analysis revealed many atubular glomeruli in the kidneys of Zeb2 knockout mice, which explains the presence of glomerular cysts in the absence of tubular dilatation. Gene expression analysis showed decreased expression of early proximal tubular markers in the kidneys of Zeb2 knockout mice preceding glomerular cyst formation, suggesting that defects in proximal tubule development during early nephrogenesis contribute to the formation of congenital atubular glomeruli. At the molecular level, Zeb2 deletion caused aberrant expression of Pkd1, Hnf1β, and Glis3, three genes causing glomerular cysts. Thus, Zeb2 regulates the morphogenesis of mesenchyme-derived nephrons and is required for proximal tubule development and glomerulotubular junction formation. Our findings also suggest that ZEB2 might be a novel disease gene in patients with primary glomerular cystic disease.

Zeb2 is essential for Schwann cell differentiation, myelination and nerve repair

Schwann cell development and peripheral nerve myelination require the serial expression of transcriptional activators, such as Sox10, Oct6 (also called Scip or Pou3f1) and Krox20 (also called Egr2). Here we show that transcriptional repression, mediated by the zinc-finger protein Zeb2 (also known as Sip1), is essential for differentiation and myelination. Mice lacking Zeb2 in Schwann cells develop a severe peripheral neuropathy, caused by failure of axonal sorting and virtual absence of myelin membranes. Zeb2-deficient Schwann cells continuously express repressors of lineage progression. Moreover, genes for negative regulators of maturation such as Sox2 and Ednrb emerge as Zeb2 target genes, supporting its function as an 'inhibitor of inhibitors' in myelination control. When Zeb2 is deleted in adult mice, Schwann cells readily dedifferentiate following peripheral nerve injury and become repair cells. However, nerve regeneration and remyelination are both perturbed, demonstrating that Zeb2, although undetectable in adult Schwann cells, has a latent function throughout life.

Sip1 regulates the generation of the inner nuclear layer retinal cell lineages in mammals

The transcription factor Sip1 (Zeb2) plays multiple roles during CNS development from early acquisition of neural fate to cortical neurogenesis and gliogenesis. In humans, SIP1 (ZEB2) haploinsufficiency leads to Mowat-Wilson syndrome, a complex congenital anomaly including intellectual disability, epilepsy and Hirschsprung disease. Here we uncover the role of Sip1 in retinogenesis. Somatic deletion of Sip1 from mouse retinal progenitors primarily affects the generation of inner nuclear layer cell types, resulting in complete loss of horizontal cells and reduced numbers of amacrine and bipolar cells, while the number of Muller glia is increased. Molecular analysis places Sip1 downstream of the eye field transcription factor Pax6 and upstream of Ptf1a in the gene network required for generating the horizontal and amacrine lineages. Intriguingly, characterization of differentiation dynamics reveals that Sip1 has a role in promoting the timely differentiation of retinal interneurons, assuring generation of the proper number of the diverse neuronal and glial cell subtypes that constitute the functional retina in mammals.