Tagging methyl-CpG-binding domain proteins reveals different spatiotemporal expression and supports distinct functions

Using i-GONAD for Cell-Type-Specific and Systematic Analysis of Developmental Transcription Factors In Vivo

Transcription factors (TFs) regulate gene expression via direct DNA binding together with cofactors and in chromatin remodeling complexes. Their function is thus regulated in a spatiotemporal and cell-type-specific manner. To analyze the functions of TFs in a cell-type-specific context, genome-wide DNA binding, as well as the identification of interacting proteins, is required. We used i-GONAD (improved genome editing via oviductal nucleic acids delivery) in mice to genetically modify TFs by adding fluorescent reporter and affinity tags that can be exploited for the imaging and enrichment of target cells as well as chromatin immunoprecipitation and pull-down assays. As proof-of-principle, we showed the functional genetic modification of the closely related developmental TFs, Bcl11a and Bcl11b, in defined cell types of newborn mice. i-GONAD is a highly efficient procedure for modifying TF-encoding genes via the integration of small insertions, such as reporter and affinity tags. The novel Bcl11a and Bcl11b mouse lines, described in this study, will be used to improve our understanding of the Bcl11 family's function in neurodevelopment and associated disease.

Methyl-CpG binding domain 2 (Mbd2) is an epigenetic regulator of autism-risk genes and cognition

The Methyl-CpG-Binding Domain Protein family has been implicated in neurodevelopmental disorders. The Methyl-CpG-binding domain 2 (Mbd2) binds methylated DNA and was shown to play an important role in cancer and immunity. Some evidence linked this protein to neurodevelopment. However, its exact role in neurodevelopment and brain function is mostly unknown. Here we show that Mbd2-deficiency in mice (Mbd2-/-) results in deficits in cognitive, social and emotional functions. Mbd2 binds regulatory DNA regions of neuronal genes in the hippocampus and loss of Mbd2 alters the expression of hundreds of genes with a robust down-regulation of neuronal gene pathways. Further, a genome-wide DNA methylation analysis found an altered DNA methylation pattern in regulatory DNA regions of neuronal genes in Mbd2-/- mice. Differentially expressed genes significantly overlap with gene-expression changes observed in brains of Autism Spectrum Disorder (ASD) individuals. Notably, downregulated genes are significantly enriched for human ortholog ASD risk genes. Observed hippocampal morphological abnormalities were similar to those found in individuals with ASD and ASD rodent models. Hippocampal Mbd2 knockdown partially recapitulates the behavioral phenotypes observed in Mbd2-/- mice. These findings suggest that Mbd2 is a novel epigenetic regulator of genes that are associated with ASD in humans. Mbd2 loss causes behavioral alterations that resemble those found in ASD individuals.

MBD2 mediates Th17 cell differentiation by regulating MINK1 in Th17-dominant asthma

Objectives: .Asthma is a highly heterogeneous disease, and T-helper cell type 17 (Th17) cells play a pathogenic role in the development of non-T2 severe asthma. Misshapen like kinase 1 (MINK1) is involved in the regulation of Th17 cell differentiation, but its effect on severe asthma remains unclear. Our previous studies showed that methyl-CpG binding domain protein 2 (MBD2) expression was significantly increased in patients with Th17 severe asthma and could regulate Th17 cell differentiation. The aim of this study was to investigate how MBD2 interacts with MINK1 to regulate Th17 cell differentiation in Th17-dominant asthma.

Materials and methods: Female C57BL/6 mice and bronchial epithelial cells (BECs) were used to establish mouse and cell models of Th17-dominant asthma, respectively. Flow cytometry was used to detect Th17 cell differentiation, and the level of IL-17 was detected by enzyme-linked immunosorbent assay (ELISA). Western blot and quantitative real-time PCR (qRT-PCR) were used to detect MBD2 and MINK1 expression. To investigate the role of MBD2 and MINK1 in Th17 cell differentiation in Th17-dominant asthma, the MBD2 and MINK1 genes were silenced or overexpressed by small interfering RNA and plasmid transfection.

Results: Mouse and BEC models of Th17-dominant asthma were established successfully. The main manifestations were increased neutrophils in BALF, airway hyperresponsiveness (AHR), activated Th17 cell differentiation, and high IL-17 levels. The expression of MBD2 in lung tissues and BECs from the Th17-dominant asthma group was significantly increased, while the corresponding expression of MINK1 was significantly impaired. Through overexpression or silencing of MBD2 and MINK1 genes, we have concluded that MBD2 and MINK1 regulate Th17 cell differentiation and IL-17 release. Interestingly, MBD2 was also found to negatively regulate the expression of MINK1.

Conclusion: Our findings have revealed new roles for MBD2 and MINK1, and provide new insights into epigenetic regulation of Th17-dominant asthma, which is dominated by neutrophils and Th17 cells. This study could lead to new therapeutic targets for patients with Th17-dominant asthma.

DNA Methylation: Genomewide Distribution, Regulatory Mechanism and Therapy Target

DNA methylation is the most important epigenetic modification involved in the regulation of transcription, imprinting, establishment of X-inactivation, and the formation of a chromatin structure. DNA methylation in the genome is often associated with transcriptional repression and the formation of closed heterochromatin. However, the results of genome-wide studies of the DNA methylation pattern and transcriptional activity of genes have nudged us toward reconsidering this paradigm, since the promoters of many genes remain active despite their methylation. The differences in the DNA methylation distribution in normal and pathological conditions allow us to consider methylation as a diagnostic marker or a therapy target. In this regard, the need to investigate the factors affecting DNA methylation and those involved in its interpretation becomes pressing. Recently, a large number of protein factors have been uncovered, whose ability to bind to DNA depends on their methylation. Many of these proteins act not only as transcriptional activators or repressors, but also affect the level of DNA methylation. These factors are considered potential therapeutic targets for the treatment of diseases resulting from either a change in DNA methylation or a change in the interpretation of its methylation level. In addition to protein factors, a secondary DNA structure can also affect its methylation and can be considered as a therapy target. In this review, the latest research into the DNA methylation landscape in the genome has been summarized to discuss why some DNA regions avoid methylation and what factors can affect its level or interpretation and, therefore, can be considered a therapy target.

Computational discovery of novel inhibitory candidates targeting versatile transcriptional repressor MBD2

Genome methylation is a key epigenetic mechanism in various biological events such as development, cellular differentiation, cancer progression, aging, and iPSC reprogramming. Crosstalk between DNA methylation and gene expression is mediated by MBD2, known as the reader of DNA methylation and suggested as a drug target. Despite its magnitude of significance, a scarcely limited number of small molecules to be used as inhibitors have been detected so far. Therefore, we screened a comprehensive compound library to elicit MBD2 inhibitor candidates. Promising molecules were subjected to computational docking analysis by targeting the methylated DNA-binding domain of human MBD2. We could detect reasonable binding energies and docking residues, presumably located in druggable pockets. Docking results were also validated via MD simulation and per-residue energy decomposition calculation. Drug-likeness of these small molecules was assessed through ADMET prediction to foresee off-target side effects for future studies. All computational approaches notably highlighted two compounds named CID3100583 and 8,8-ethylenebistheophylline. These compounds have become prominent as novel candidates, possibly disrupting MBD2_MBD-DNA interaction. Consequently, these compounds have been considered prospective inhibitors with the usage potential in a wide range of applications from cancer treatment to somatic cell reprogramming protocols.

MBD2 as a Potential Novel Biomarker for Identifying Severe Asthma With Different Endotypes

Background: Studies have shown that methyl-CpG binding domain protein 2 (MBD2) expression is significantly elevated in a neutrophil-dominant severe asthma mouse model. It also regulates Th17 cell differentiation. The objective of this study was to investigate the relationship between serum MBD2 levels in patients with severe asthma with different endotypes.

Methods: Eligible adults with confirmed asthma (n = 63) underwent a clinical assessment, asthma control test and pulmonary function test and were classified as having mild, moderate or severe asthma. Severe asthma endotypes were defined according to the percentage of Th2 and Th17 cells in the peripheral blood and by the type of inflammation. The percentage of Th2 and Th17 cells in the peripheral blood was determined by flow cytometry. Serum MBD2, eosinophilic cationic protein and myeloperoxidase were measured by enzyme-linked immunosorbent assay. Correlations of MBD2 expression with clinical parameters were evaluated using Spearman's rank correlation analysis.

Results: Serum MBD2 levels were upregulated in patients with severe asthma compared to healthy controls and patients with mild to moderate asthma. MBD2 was also significantly increased in patients with Th17 severe asthma compared to patients with type 2 severe asthma. Furthermore, MBD2 was positively correlated with MPO and Th17 cells but negatively correlated with ECP and Th2 cells in patients with severe asthma.

Conclusions: These findings suggest that serum MBD2 may be a potential new biomarker for identifying severe asthma, Th17 severe asthma and the type of airway inflammation. However, these findings are still preliminary and need to be further investigated.

Silencing of MBD2 and EZH2 inhibits the proliferation of colorectal carcinoma cells by rescuing the expression of SFRP

The secreted frizzled related proteins (SFRPs) are extracellular inhibitors of WNT pathway signaling. Methyl-CpG binding domain protein 2 (MBD2) and enhancer of zeste homolog 2 (EZH2) are core members of the methylated DNA binding domain (MBD) and polycomb group (PcG) protein families for epigenetic regulation, respectively. This study aimed to ascertain the potential role of MBD2 and EZH2 proteins in colorectal cancer (CRC) and its effects on the expression of SFRP. Bioinformatics, real-time quantitative polymerase chain reaction (qPCR) and western blot analysis were used to detect the expression of MBD2, EZH2, and SFRP in CRC cell lines and tissues. The functions of MBD2 and EZH2 in regards to cell proliferation, cell cycle distribution, apoptosis and invasion were examined in CRC cell lines. Methylation-specific PCR (MSP) was used to detect the methylation status of the SFRP promoter. The results revealed that the mRNA expression levels of SFRP were significantly decreased in CRC tissues and cell lines compared to these levels in the adjacent tissues and NCM460, respectively. However, the mRNA levels of EZH2 and MBD2 genes were highly expressed in CRC cell lines. We found that reducing MBD2 and EZH2 expression together remarkably inhibited and decreased the proliferation, migration and invasion abilities of the CRC cell lines compared to reducing one of each. Flow cytometric analysis showed that knockdown of MBD2 and EZH2 together in CRC affected cell apoptosis and the cell cycle progression more effectively than knockdown of one of each. The mRNA expression of SFRP1 was reactivated by silencing of MBD2 but not EZH2 in SW480 and HCT116 cells. SFRP4 and SFRP5 mRNA expression was reactivated by silencing of EZH2 but not MBD2 only in SW480 cells. However, depletion of both MBD2 and EZH2 restored SFRP1, SFRP2, SFRP4, and SFRP5 mRNA expression more effectively in CRC cells. Interestingly, there was no significant change in the methylation status of SFRP1, SFRP2, SFRP4, and SFRP5 gene promoter between before and after interference with MBD2, EZH2, and both. In conclusion, our results suggest that silencing of MBD2 and EZH2 simultaneously was able to rescue the expression of SFRP and inhibit the proliferation of CRC cells more effectively. However, the underlying regulatory mechanism system of MBD2 and EZH2 for SFRP in CRC requires further research.

Footprints of global change in marine life: Inferring past environment based on DNA methylation and gene expression marks

Ocean global warming affects the distribution, life history and physiology of marine life. Extreme events, like marine heatwaves, are increasing in frequency and intensity. During sensitive stages of early fish development, the consequences may be long-lasting and mediated by epigenetic mechanisms. Here, we used European sea bass as a model to study the possible long-lasting effects of a marine heatwave during early development. We measured DNA methylation and gene expression in four tissues (brain, muscle, liver and testis) and detected differentially methylated regions (DMRs). Six genes were differentially expressed and contained DMRs three years after exposure to increased temperature, indicating direct phenotypic consequences and representing persistent changes. Interestingly, nine genes contained DMRs around the same genomic regions across tissues, therefore consisting of common footprints of developmental temperature in environmentally responsive loci. These loci are, to our knowledge, the first metastable epialleles (MEs) described in fish. MEs may serve as biomarkers to infer past life history events linked with persistent consequences. These results highlight the importance of subtle phenotypic changes mediated by epigenetics to extreme weather events during sensitive life stages. Also, to our knowledge, it is the first time the molecular effects of a marine heatwave during the lifetime of individuals are assessed. MEs could be used in surveillance programs aimed at determining the footprints of climate change on marine life. Our study paves the way for the identification of conserved MEs that respond equally to environmental perturbations across species. Conserved MEs would constitute a tool of assessment of global change effects in marine life at a large scale.

Identification of DNA (de)methylation-related genes and their transcriptional response to environmental challenges in an invasive model ascidian

Marine invasive species are constantly challenged by acute or recurring environmental stresses during their range expansions. DNA methylation-mediated stress memory has been proposed to effectively affect species' response and enhance their overall performance in recurring environmental challenges. In order to further test this proposal in marine invasive species, we identified genes in the DNA methylation and demethylation processes in the highly invasive model species, Ciona robusta, and subsequently investigated the expression patterns of these genes under recurring salinity stresses. After a genome-wide comprehensive survey, we found a total of six genes, including two genes of DNA methyltransferase 3a (DNMT3a1 and DNMT3a2), and one gene of DNA methyltransferase 1 (DNMT1), methyl-CpG-binding domain protein 2 (MBD2), methyl-CpG-binding domain protein 4 (MBD4) and ten-eleven-translocation protein 1 (TET1). Phylogenetic reconstruction and domain arrangement analyses showed that the deduced proteins of the identified genes were evolutionarily conserved and functionally similar with their orthologs. All genes were constitutively expressed in all four tested tissues. Interestingly, we found time-dependent and stress-specific gene expression patterns under high and low salinity stresses. Under the recurring high salinity stresses, DNMT3a1 and TET1 conformed to the definition of memory genes, while under the recurring low salinity stresses, two DNMT3a paralogues were identified as the memory genes. Altogether, our results clearly showed that the transcriptional patterns of (de)methylation-related genes were significantly influenced by environmental stresses, and the transcriptional memory of some (de)methylation-related genes should play crucial roles in DNA methylation-mediated stress memory during the process of biological invasions.

Regulation of stem/progenitor cell maintenance by BMP5 in prostate homeostasis and cancer initiation

Tissue homeostasis relies on the fine regulation between stem and progenitor cell maintenance and lineage commitment. In the adult prostate, stem cells have been identified in both basal and luminal cell compartments. However, basal stem/progenitor cell homeostasis is still poorly understood. We show that basal stem/progenitor cell maintenance is regulated by a balance between BMP5 self-renewal signal and GATA3 dampening activity. Deleting Gata3 enhances adult prostate stem/progenitor cells self-renewal capacity in both organoid and allograft assays. This phenotype results from a local increase in BMP5 activity in basal cells as shown by the impaired self-renewal capacity of Bmp5-deficient stem/progenitor cells. Strikingly, Bmp5 gene inactivation or BMP signaling inhibition with a small molecule inhibitor are also sufficient to delay prostate and skin cancer initiation of Pten-deficient mice. Together, these results establish BMP5 as a key regulator of basal prostate stem cell homeostasis and identifies a potential therapeutic approach against Pten-deficient cancers.

DNA looping by two 5-methylcytosine-binding proteins quantified using nanofluidic devices

Background

MeCP2 and MBD2 are members of a family of proteins that possess a domain that selectively binds 5-methylcytosine in a CpG context. Members of the family interact with other proteins to modulate DNA packing. Stretching of DNA–protein complexes in nanofluidic channels with a cross-section of a few persistence lengths allows us to probe the degree of compaction by proteins.

Results

We demonstrate DNA compaction by MeCP2 while MBD2 does not affect DNA configuration. By using atomic force microscopy (AFM), we determined that the mechanism for compaction by MeCP2 is the formation of bridges between distant DNA stretches and the formation of loops.

Conclusions

Despite sharing a similar specific DNA-binding domain, the impact of full-length 5-methylcytosine-binding proteins can vary drastically between strong compaction of DNA and no discernable large-scale impact of protein binding. We demonstrate that ATTO 565-labeled MBD2 is a good candidate as a staining agent for epigenetic mapping.

The Molecular Basis of MeCP2 Function in the Brain

MeCP2 is a reader of the DNA methylome that occupies a large proportion of the genome due to its high abundance and the frequency of its target sites. It has been the subject of extensive study because of its link with 'MECP2-related disorders', of which Rett syndrome is the most prevalent. This review integrates evidence from patient mutation data with results of experimental studies using mouse models, cell lines and in vitro systems to critically evaluate our understanding of MeCP2 protein function. Recent evidence challenges the idea that MeCP2 is a multifunctional hub that integrates diverse processes to underpin neuronal function, suggesting instead that its primary role is to recruit the NCoR1/2 co-repressor complex to methylated sites in the genome, leading to dampening of gene expression.

DNA Modification Readers and Writers and Their Interplay

Genomic DNA is modified in a postreplicative manner and several modifications, the enzymes responsible for their deposition as well as proteins that read these modifications, have been described. Here, we focus on the impact of DNA modifications on the DNA helix and review the writers and readers of cytosine modifications and how they interplay to shape genome composition, stability, and function.

DNA Methylation-Governed Gene Expression in Autoimmune Arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease hallmarked by progressive and irreversible joint destruction. RA pathogenesis is a T cell-regulated and B cell-mediated process in which activated lymphocyte-produced chemokines and cytokines promote leukocyte infiltration that ultimately leads to destruction of the joints. There is an obvious need to discover new drugs for RA treatment that have different biological targets or modes of action than the currently employed therapeutics. Environmental factors such as cigarette smoke, certain diet components, and oral pathogens can significantly affect gene regulation via epigenetic factors. Epigenetics opened a new field for pharmacology, and DNA methylation and histone modification-implicated factors are feasible targets for RA therapy. Exploring RA pathogenesis involved epigenetic factors and mechanisms is crucial for developing more efficient RA therapies. Here we review epigenetic alterations associated with RA pathogenesis including DNA methylation and interacting factors. Additionally, we will summarize the literature revealing the involved molecular structures and interactions. Finally, potential epigenetic factor-based therapies will be discussed that may help in better management of RA in the future.

The Methyl-CpG-Binding Domain 2 and 3 Proteins and Formation of the Nucleosome Remodeling and Deacetylase Complex

The Nucleosome Remodeling and Deacetylase (NuRD) complex uniquely combines both deacetylase and remodeling enzymatic activities in a single macromolecular complex. The methyl-CpG-binding domain 2 and 3 (MBD2 and MBD3) proteins provide a critical structural link between the deacetylase and remodeling components, while MBD2 endows the complex with the ability to selectively recognize methylated DNA. Hence, NuRD combines three major arms of epigenetic gene regulation. Research over the past few decades has revealed much of the structural basis driving formation of this complex and started to uncover the functional roles of NuRD in epigenetic gene regulation. However, we have yet to fully understand the molecular and biophysical basis for methylation-dependent chromatin remodeling and transcription regulation by NuRD. In this review, we discuss the structural information currently available for the complex, the role MBD2 and MBD3 play in forming and recruiting the complex to methylated DNA, and the biological functions of NuRD.

DNA Methylation Readers and Cancer: Mechanistic and Therapeutic Applications

DNA methylation is a major epigenetic process that regulates chromatin structure which causes transcriptional activation or repression of genes in a context-dependent manner. In general, DNA methylation takes place when methyl groups are added to the appropriate bases on the genome by the action of "writer" molecules known as DNA methyltransferases. How these methylation marks are read and interpreted into different functionalities represents one of the main mechanisms through which the genes are switched "ON" or "OFF" and typically involves different types of "reader" proteins that can recognize and bind to the methylated regions. A tightly balanced regulation exists between the "writers" and "readers" in order to mediate normal cellular functions. However, alterations in normal methylation pattern is a typical hallmark of cancer which alters the way methylation marks are written, read and interpreted in different disease states. This unique characteristic of DNA methylation "readers" has identified them as attractive therapeutic targets. In this review, we describe the current state of knowledge on the different classes of DNA methylation "readers" identified thus far along with their normal biological functions, describe how they are dysregulated in cancer, and discuss the various anti-cancer therapies that are currently being developed and evaluated for targeting these proteins.

DNA Methylation and the Potential Role of Methyl-Containing Nutrients in Cardiovascular Diseases

Patients suffering from cardiovascular diseases (CVDs) experience a low quality of life and increase pressure on healthcare systems both nationally and globally. DNA methylation, which refers to the pathway by which DNA methyltransferase facilitates the addition of a methyl group to DNA, is of critical importance in this respect primarily because the epigenetic modification is implicated in a range of serious conditions including atherosclerosis, CVDs, and cancer. Research findings indicate that the number of epigenetic alterations can be elicited (both in utero and in adults) through the administration of certain nutritional supplements, including folic acid and methionine; this is partly attributable to the effect employed by methyl-containing nutrients in DNA methylation. Thus, for the purpose of illuminating viable therapeutic measures and preventive strategies for CVDs, research should continue to explore the intricate associations that exist between epigenetic regulation and CVD pathogenesis. This review centers on an exposition of the mechanism by which DNA methylation takes place, the impact it has on a range of conditions, and the potential clinical value of nutrition, driven mainly by the observation that nutritional supplements such as folic acid can affect DNA methylation.

DNA Methylation and Adult Neurogenesis

The role of DNA methylation in brain development is an intense area of research because the brain has particularly high levels of CpG and mutations in many of the proteins involved in the establishment, maintenance, interpretation, and removal of DNA methylation impact brain development and/or function. These include DNA methyltransferase (DNMT), Ten-Eleven Translocation (TET), and Methyl-CpG binding proteins (MBPs). Recent advances in sequencing breadth and depth as well the detection of different forms of methylation have greatly expanded our understanding of the diversity of DNA methylation in the brain. The contributions of DNA methylation and associated proteins to embryonic and adult neurogenesis will be examined. Particular attention will be given to the impact on adult hippocampal neurogenesis (AHN), which is a key mechanism contributing to brain plasticity, learning, memory and mood regulation. DNA methylation influences multiple aspects of neurogenesis from stem cell maintenance and proliferation, fate specification, neuronal differentiation and maturation, and synaptogenesis. In addition, DNA methylation during neurogenesis has been shown to be responsive to many extrinsic signals, both under normal conditions and during disease and injury. Finally, crosstalk between DNA methylation, Methyl-DNA binding domain (MBD) proteins such as MeCP2 and MBD1 and histone modifying complexes is used as an example to illustrate the extensive interconnection between these epigenetic regulatory systems.

Readers of DNA methylation, the MBD family as potential therapeutic targets

DNA methylation represents a fundamental epigenetic modification that regulates chromatin architecture and gene transcription. Many diseases, including cancer, show aberrant methylation patterns that contribute to the disease phenotype. DNA methylation inhibitors have been used to block methylation dependent gene silencing to treat hematopoietic neoplasms and to restore expression of developmentally silenced genes. However, these inhibitors disrupt methylation globally and show significant off-target toxicities. As an alternative approach, we have been studying readers of DNA methylation, the 5-methylcytosine binding domain family of proteins, as potential therapeutic targets to restore expression of aberrantly and developmentally methylated and silenced genes. In this review, we discuss the role of DNA methylation in gene regulation and cancer development, the structure and function of the 5-methylcytosine binding domain family of proteins, and the possibility of targeting the complexes these proteins form to treat human disease.

MBD2 upregulates miR-301a-5p to induce kidney cell apoptosis during vancomycin-induced AKI

Despite DNA methylation occurred in acute kidney injury (AKI), how it influenced progression of AKI remains unclear. Methyl-CpG-binding domain protein 2 (MBD2), a protein readers of methylation, was used to analyze the impact of DNA methylation on vancomycin (VAN)-induced AKI. Here, in cultured human kidney tubular epithelial cells (HK-2), we show that knockdown of MBD2 by siRNA attenuated VAN-induced apoptosis, caspase activity, and the expression of BAX and cleaved caspase 3. Interestingly, knockdown of MBD2 by siRNA was associated with the suppression of miR-301a-5p. Mechanistic studies confirmed MBD2 binds to these methylated CpG elements of miR-301a-5p promoter, and then activates miR-301a-5p promoter by suppressing methylation. Furthermore, anti-miR-301a-5p significantly blocked VAN-induced apoptosis and caspase activity in HK-2 cells, which was accompanied by downregulation of p53, and upregulation of MITF, HDGF and MDM-4 together. The latter genes were further identified as target genes of miR-301a-5p, and silencing of MDM-4 promoted p53 accumulation. In vivo, mice with MBD2 knockout (MBD2-KO) were counteracted to VAN-induced AKI, indicated by the analysis of renal function, histology, apoptosis and inflammation. MBD2-KO also significantly suppressed the expression of miR-301a-5p, p53, BAX and cleaved caspase 3, and restored the expression of MDM-4, MITF and HDGF. Finally, in vivo inhibition of miR-301a-5p also ameliorated VAN-induced AKI. Together, these results show the novel MBD2/miR-301a-5p/MITF, HDGF and MDM-4/p53 pathway in VAN-induced AKI.

MBD2 Regulates Th17 Cell Differentiation and Experimental Severe Asthma by Affecting IRF4 Expression

Th17 cells and IL-17 participate in airway neutrophil infiltration characteristics in the pathogenesis of severe asthma. Methyl-CpG binding domain protein 2 (MBD2) expression increased in CD4⁺ T cells in peripheral blood samples of asthma patients. However, little is known about that epigenetic regulation of MBD2 in both immunological pathogenesis of experimental severe asthma and CD4⁺ T cell differentiation. Here, we established a neutrophil-predominant severe asthma model, which was characterized by airway hyperresponsiveness (AHR), BALF neutrophil granulocyte (NEU) increase, higher NEU and IL-17 protein levels, and more Th17 cell differentiation. In the model, MBD2 and IRF4 protein expression increased in the lung and spleen cells. Under overexpression or silencing of the MBD2 and IRF4 gene, the differentiation of Th17 cells and IL-17 secretion showed positive changes. IRF4 protein expression showed a positive change with overexpression or silencing of the MBD2 gene, whereas there was no significant difference in the expression of MBD2 under overexpression or silencing of the IRF4 gene. These data provide novel insights into epigenetic regulation of severe asthma.

Emerging Molecular and Biological Functions of MBD2, a Reader of DNA Methylation

DNA methylation is an epigenetic mark that is essential for many biological processes and is linked to diseases such as cancer. Methylation is usually associated with transcriptional silencing, but new research has challenged this model. Both transcriptional activation and repression have recently been found to be associated with DNA methylation in a context-specific manner. How DNA methylation patterns are interpreted into different functional output remains poorly understood. One mechanism involves the protein ‘readers’ of methylation, which includes the methyl-CpG binding domain (MBD) family of proteins. This review examines the molecular and biological functions of MBD2, which binds to CpG methylation and is an integral part of the nucleosome remodeling and histone deacetylation (NuRD) complex. MBD2 has been linked to immune system function and tumorigenesis, yet little is known about its functions in vivo. Recent studies have found the MBD2 protein is ubiquitously expressed, with relatively high levels in the lung, liver, and colon. Mbd2 null mice surprisingly show relatively mild phenotypes compared to mice with loss of function of other MBD proteins. This evidence has previously been interpreted as functional redundancy between the MBD proteins. Here, we examine and contextualize research that suggests MBD2 has unique properties and functions among the MBD proteins. These functions translate to recently described roles in the development and differentiation of multiple cell lineages, including pluripotent stem cells and various cell types of the immune system, as well as in tumorigenesis. We also consider possible models for the dynamic interactions between MBD2 and NuRD in different tissues in vivo. The functions of MBD2 may have direct therapeutic implications for several areas of human disease, including autoimmune conditions and cancer, in addition to providing insights into the actions of NuRD and chromatin regulation.