Cyp2e1 protects against OVA-induced allergic rhinitis through the inhibition of Th2 cell activation and differentiation: Mediated by MAFB

Allergic rhinitis (AR) is a common allergic disease. Cytochrome P450, family 2, subfamily e, polypeptide 1 (Cyp2e1) is a member of the cytochrome P450 family of enzymes, while its role in AR is still unveiled. In AR mice, T cell-specific overexpression of Cyp2e1 relieved the AR symptoms. Overexpressed-Cyp2e1 restrained the infiltration of eosinophils and mast cells in the nasal mucosa of mice, and the inflammatory cells in nasal lavage fluid (NALF). Cyp2e1 overexpressed mice exhibited decreased goblet cell hyperplasia and mucus secretion as well as decreased MUC5AC expression in nasal mucosa. The epithelial permeability and integrity of nasal mucosa were improved upon Cyp2e1 overexpression in AR mice, as evidenced by decreased fluorescein isothiocyanate-dextran 4 content in serum, increased expression of IL-25, IL-33, and TSLP in NALF, and increased expression of ZO-1 and occluding in nasal mucosa. Cyp2e1 inhibited Th2 immune response by decreasing the expression and secretion of IL-4, IL-5, and IL-13 as well as the expression of GATA-3 in NALF or nasal mucosa. We proved that Cyp2e1 inhibited the differentiation of naïve CD4+ T cells toward the Th2 subtype, which was regulated by MAFB by binding to Cyp2e1 promoter to activate its transcription. Overall, these results show the potential role of Cyp2e1 in alleviating AR symptoms by restraining CD4+ T cells to Th2 cell differentiation. Our findings provide further insight into the AR mechanism.

MAFB in macrophages regulates cold-induced neuronal density in brown adipose tissue

Transcription factor MAFB regulates various homeostatic functions of macrophages. This study explores the role of MAFB in brown adipose tissue (BAT) thermogenesis using macrophage-specific Mafb-deficient (Mafbf/f::LysM-Cre) mice. We find that Mafb deficiency in macrophages reduces thermogenesis, energy expenditure, and sympathetic neuron (SN) density in BAT under cold conditions. This phenotype features a proinflammatory environment that is characterized by macrophage/granulocyte accumulation, increases in interleukin-6 (IL-6) production, and IL-6 trans-signaling, which lead to decreases in nerve growth factor (NGF) expression and reduction in SN density in BAT. We confirm MAFB regulation of IL-6 expression using luciferase readout driven by IL-6 promoter in RAW-264.7 macrophage cell lines. Immunohistochemistry shows clustered organization of NGF-producing cells in BAT, which are primarily TRPV1+ vascular smooth muscle cells, as additionally shown using single-cell RNA sequencing and RT-qPCR of the stromal vascular fraction. Treating Mafbf/f::LysM-Cre mice with anti-IL-6 receptor antibody rescues SN density, body temperature, and energy expenditure.

The Expression of MAFB Gene in Circulating Monocytes Is Related to Chronic Inflammatory Status in T2DM Patients

Immune cell-mediated chronic inflammation is one of the causes of type 2 diabetes mellitus (T2DM). Therefore, identifying inflammatory markers in circulating immune cells is highly important for predicting insulin resistance (IR) and the occurrence of T2DM. In this study, we discovered that differentially expressed genes (DEGs) in peripheral blood mononuclear cells (PBMCs) from T2DM patients were associated with innate immunity and chronic inflammatory responses through bulk transcriptome sequencing (bulk RNA-seq). Gene integration analysis revealed that nine DEGs were upregulated, and receiver operating characteristic (ROC) curve analysis revealed that V-maf musculoaponeurotic fibrosarcoma oncogene homolog B (MAFB), a candidate biomarker, has a certain predictive value for T2DM. In population-based cohort studies, we found that MAFB expression was significantly upregulated in the PBMCs of T2DM patients and was significantly correlated with homeostasis model assessment of IR (HOMA-IR), tumor necrosis factor-α (TNF-α), adiponectin (Adipoq), etc. We further evaluated the sensitivity and specificity of MAFB and other clinical parameters for predicting and diagnosing T2DM and found that MAFB expression in PBMCs had a positive effect on the prediction and diagnosis of T2DM. Finally, single-cell RNA sequencing (scRNA-seq) analysis revealed that the increase in MAFB expression was mainly in nonclassical monocytes. Our results suggest that increased MAFB expression in circulating monocytes may mediate chronic inflammatory status in patients with T2DM. Therefore, MAFB gene expression in circulating monocytes has certain clinical significance for predicting and assisting in the diagnosis of T2DM.

Macrophage re-programming by JAK inhibitors relies on MAFB

Monocyte-derived macrophages play a key pathogenic role in inflammatory diseases. In the case of rheumatoid arthritis (RA), the presence of specific synovial tissue-infiltrating macrophage subsets is associated with either active disease or inflammation resolution. JAK inhibitors (JAKi) are the first targeted synthetic disease-modifying antirheumatic drugs (tsDMARD) approved for treatment of RA with comparable efficacy to biologics. However, the effects of JAKi on macrophage specification and differentiation are currently unknown. We have analyzed the transcriptional and functional effects of JAKi on human peripheral blood monocyte subsets from RA patients and on the differentiation of monocyte-derived macrophages promoted by granulocyte-macrophage colony-stimulating factor (GM-CSF), a factor that drives the development and pathogenesis of RA. We now report that JAKi Upadacitinib restores the balance of peripheral blood monocyte subsets in RA patients and skewed macrophages towards the acquisition of an anti-inflammatory transcriptional and functional profile in a dose-dependent manner. Upadacitinib-treated macrophages showed a strong positive enrichment of the genes that define synovial macrophages associated to homeostasis/inflammation resolution. Specifically, Upadacitinib-treated macrophages exhibited significantly elevated expression of MAFB and MAFB-regulated genes, elevated inhibitory phosphorylation of GSK3β, and higher phagocytic activity and showed an anti-inflammatory cytokine profile upon activation by pathogenic stimuli. These outcomes were also shared by macrophages exposed to other JAKi (baricitinib, tofacitinib), but not in the presence of the TYK2 inhibitor deucravacitinib. As a whole, our results indicate that JAKi promote macrophage re-programming towards the acquisition of a more anti-inflammatory/pro-resolution profile, an effect that correlates with the ability of JAKi to enhance MAFB expression.

Knockdown of Galectin-9 alleviates rheumatoid arthritis through suppressing TNF-α-induced activation of fibroblast-like synoviocytes

The role of Galectin-9 (Gal-9) in the pathogenesis of rheumatoid arthritis (RA) remains unclear. This study aimed to investigate the mechanism of action and therapeutic potential of Gal-9 in RA. We detected Gal-9 expression in clinical samples, explored the mechanism of function of Gal-9 by knockdown and overexpression in fibroblast-like synoviocytes (FLSs), and further verified it in collagen-induced arthritis (CIA) model. We found that the levels of Gal-9 were considerably elevated in RA synovium than in osteoarthritis (OA) patients. A substantial decrease of Gal-9 was demonstrated after tumor necrosis factor (TNF-α) inhibitor treatment in the plasma of patients with RA. Additionally, transcriptome sequencing revealed that Gal-9 was involved in the regulation of the TNF-α pathway. Gal-9 was considerably upregulated after TNF-α stimulation in FLSs, and knockdown of Gal-9 substantially inhibited TNF-α activated proliferation, migration and inflammatory response. According to cell transcriptome sequencing results, we further confirmed that Gal-9 could achieve these effects by interacting with MAFB and affecting PI3K/AKT/mTOR pathway. Finally, we knocked down Gal-9 on the CIA model and found that it could alleviate the progression of arthritis. In conclusion, our study revealed that the knockdown of Gal-9 could inhibited TNF-α induced activation in RA through MAFB, PI3K/AKT/mTOR.

Treatment of a young child with multicentric carpotarsal osteolysis exhibiting joint inflammation and dysfunctional bone formation

Multicentric carpotarsal osteolysis (MCTO) is a rare skeletal dysplasia characterized by osteolysis of the carpal and tarsal bones. Antiresorptive agents have proven ineffective and the pathogenesis of MCTO remains poorly understood. We report a young child with a novel variant in MAFB who demonstrated clinical improvement of joint symptoms following anti-rheumatic therapies. Also, radiographs from a young age suggest that dysfunctional bone formation may play a role in the skeletal phenotype of MCTO.

Exploring Large MAF Transcription Factors: Functions, Pathology, and Mouse Models with Point Mutations

Large musculoaponeurotic fibrosarcoma (MAF) transcription factors contain acidic, basic, and leucine zipper regions. Four types of MAF have been elucidated in mice and humans, namely c-MAF, MAFA, MAFB, and NRL. This review aimed to elaborate on the functions of MAF transcription factors that have been studied in vivo so far, as well as describe the pathology of human patients and corresponding mouse models with c-MAF, MAFA, and MAFB point mutations. To identify the functions of MAF transcription factors in vivo, we generated genetically modified mice lacking c-MAF, MAFA, and MAFB and analyzed their phenotypes. Further, in recent years, c-MAF, MAFA, and MAFB have been identified as causative genes underpinning many rare diseases. Careful observation of human patients and animal models is important to examine the pathophysiological mechanisms underlying these conditions for targeted therapies. Murine models exhibit phenotypes similar to those of human patients with c-MAF, MAFA, and MAFB mutations. Therefore, generating these animal models emphasizes their usefulness for research uncovering the pathophysiology of point mutations in MAF transcription factors and the development of etiology-based therapies.

A report of 5 Indian families with multicentric carpotarsal osteolysis syndrome

Multicentric carpotarsal osteolysis syndrome (MCTO) is a rare autosomal dominant skeletal dysplasia characterised by swelling and restriction of movement in the wrist and ankle joints, as well as osteolysis of the carpal and tarsal bones, that can be misdiagnosed as juvenile idiopathic arthritis. We describe five Indian families with heterozygous nonrecurrent missense pathogenic variants in exon 1 of MAF bZIP transcription factor B (MAFB).

Misexpression of LINC01410, FOSL1, and MAFB in peripheral blood mononuclear cells associated with diabetic nephropathy

AIMS

Currently, diabetic nephropathy (DN) is considered the leading cause of the end-stage renal disease (ESRD). However, its specific molecular mechanism is still unclear, and there is still a lack of effective diagnostic and therapeutic methods.

METHOD

A pathway was assumed after bioinformatics analysis of GEO datasets related to individuals with various levels of DN, LINC01410, MAFB, and FOSL1. Then, 46 patients with type 2 diabetes (T2DM) and different levels of albuminuria, and 12 individuals without diabetes, were selected. qPCR was performed to evaluate gene expression. One-way ANOVA followed by Tukey's -and linear trend tests were performed to analyze gene expression in different stages of the disease. Moreover, receiver operating characteristic (ROC) curves and the correlation between LINC01410, FOSL1, and MAFB were analyzed.

RESULTS

LINC01410, MAFB, and FOSL1 were selected based on bioinformatics analyses. The qPCR results showed that the expression of LINC01410 decreased, and FOSL1 and MAFB increased in micro-and macroalbuminuria groups compared to normoalbuminuria groups (P < 0.05). ROC curves demonstrated a significant diagnostic accuracy of LINC01410, MAFB, and FOSL1 between DN and participants with normoalbuminuria (P < 0.05). Pearson's correlation analysis revealed a positive association between the expressions of FOSL1 and MAFB (p = 0.01, r = 0.39). However, there was no correlation between LINC01410 with MAFB and FOSL1 (p = 0.23 and p = 0.21, respectively).

CONCLUSION

Dysregulation of LINC01410, MAFB, and FOSL1 is related to DN. These results may provide new insights into the role of LINC01410, MAFB, and FOSL1 as potential biomarkers in DN.

Transcriptomic atlas and interaction networks of brain cells in mouse CNS demyelination and remyelination

Demyelination is a hallmark of multiple sclerosis, leukoencephalopathies, cerebral vasculopathies, and several neurodegenerative diseases. The cuprizone mouse model is widely used to simulate demyelination and remyelination occurring in these diseases. Here, we present a high-resolution single-nucleus RNA sequencing (snRNA-seq) analysis of gene expression changes across all brain cells in this model. We define demyelination-associated oligodendrocytes (DOLs) and remyelination-associated MAFBhi microglia, as well as astrocytes and vascular cells with signatures of altered metabolism, oxidative stress, and interferon response. Furthermore, snRNA-seq provides insights into how brain cell types connect and interact, defining complex circuitries that impact demyelination and remyelination. As an explicative example, perturbation of microglia caused by TREM2 deficiency indirectly impairs the induction of DOLs. Altogether, this study provides a rich resource for future studies investigating mechanisms underlying demyelinating diseases.

Single nucleus multiomics identifies ZEB1 and MAFB as candidate regulators of Alzheimer's disease-specific cis-regulatory elements

Cell type-specific transcriptional differences between brain tissues from donors with Alzheimer's disease (AD) and unaffected controls have been well documented, but few studies have rigorously interrogated the regulatory mechanisms responsible for these alterations. We performed single nucleus multiomics (snRNA-seq plus snATAC-seq) on 105,332 nuclei isolated from cortical tissues from 7 AD and 8 unaffected donors to identify candidate cis-regulatory elements (CREs) involved in AD-associated transcriptional changes. We detected 319,861 significant correlations, or links, between gene expression and cell type-specific transposase accessible regions enriched for active CREs. Among these, 40,831 were unique to AD tissues. Validation experiments confirmed the activity of many regions, including several candidate regulators of APP expression. We identified ZEB1 and MAFB as candidate transcription factors playing important roles in AD-specific gene regulation in neurons and microglia, respectively. Microglia links were globally enriched for heritability of AD risk and previously identified active regulatory regions.

[Retracted] MicroRNA‑152 inhibits cell proliferation, migration and invasion by directly targeting MAFB in nasopharyngeal carcinoma

Following the publication of this paper, it was drawn to the Editor's attention by a concerned reader that certain of the cell migration and invasion assay data shown in Fig. 3A and B were strikingly similar to data appearing in different form in other articles by different authors at different research institutes, some of which have been retracted; moreover, there appeared to be some overlapping data examining the western blots featured in Figs. 5B and 6A. Owing to the fact that the contentious data in the above article had already been published, or were already under consideration for publication, prior to its submission to Molecular Medicine Reports, the Editor has decided that this paper should be retracted from the Journal. After having been in contact with the authors, they agreed with the decision to retract the paper. The Editor apologizes to the readership for any inconvenience caused. [Molecular Medicine Reports 15: 948‑956, 2017; DOI: 10.3892/mmr.2016.6059].

Multicentric Carpotarsal Osteolysis: a Contemporary Perspective on the Unique Skeletal Phenotype

PURPOSE OF REVIEW

Multicentric carpotarsal osteolysis (MCTO) is an ultra-rare disorder characterized by osteolysis of the carpal and tarsal bones, subtle craniofacial deformities, and nephropathy. The molecular pathways underlying the pathophysiology are not well understood.

RECENT FINDINGS

MCTO is caused by heterozygous mutations in MAFB, which encodes the widely expressed transcription factor MafB. All MAFB mutations in patients with MCTO result in replacement of amino acids that cluster in a phosphorylation region of the MafB transactivation domain and account for a presumed gain-of-function for the variant protein. Since 2012, fewer than 60 patients with MCTO have been described with 20 missense mutations in MAFB. The clinical presentations are variable, and a genotype-phenotype correlation is lacking. Osteolysis, via excessive osteoclast activity, has been regarded as the primary mechanism, although anti-resorptive agents demonstrate little therapeutic benefit. This paper appraises current perspectives of MafB protein action, inflammation, and dysfunctional bone formation on the pathogenesis of the skeletal phenotype in MCTO. More research is needed to understand the pathogenesis of MCTO to develop rational therapies.

Case report: Mafb promoter activity may define the alveolar macrophage dichotomy

Cre-LoxP system has been widely used to induce recombination of floxed genes of interest. Currently available macrophage promoter-specific Cre recombinase mice strains have various limitations that warrants the testing of additional Cre strains. V-maf musculoaponeurotic fibrosarcoma oncogene family, protein b -Cre (Mafb-Cre) mice label macrophages in most organs such as spleen, small intestine, lung, bone marrow, and peritoneal cavity. However, whether Mafb-Cre recombinase targets the gene recombination in alveolar macrophage remains untested. Here, we utilized Mafb^Cre/WTR26^mTmG/WT strain that expresses mTOM protein in all the cells of mouse body except for those that express Mafb-Cre-regulated mEGFP. We performed fluorescent microscopy and flow cytometry to analyze mTOM and mEGFP expression in alveolar macrophages from Mafb^Cre/WTR26^mTmG/WT mice. Our analyses revealed that the Mafb-Cre is active in only ~40% of the alveolar macrophages in an age-independent manner. While Mafb- (mTOM+/mEGFP-) and Mafb+ (mEGFP+) alveolar macrophages exhibit comparable expression of CD11b and CD11c surface markers, the surface expression of MHCII is elevated in the Mafb+ (mEGFP+) macrophages. The bone marrow-derived macrophages from Mafb^Cre/WTR26^mTmG/WT mice are highly amenable to Cre-LoxP recombination in vitro. The bone marrow depletion and reconstitution experiment revealed that ~98% of alveolar macrophages from Mafb^Cre/WTR26^mTmG/WT → WT chimera are amenable to the Mafb-Cre-mediated recombination. Finally, the Th2 stimulation and ozone exposure to the Mafb^Cre/WTR26^mTmG/WT mice promote the Mafb-Cre-mediated recombination in alveolar macrophages. In conclusion, while the Mafb-/Mafb+ dichotomy thwarts the use of Mafb-Cre for the induction of floxed alleles in the entire alveolar macrophage population, this strain provides a unique tool to induce gene deletion in alveolar macrophages that encounter Th2 microenvironment in the lung airspaces.

Macrophage-Specific, Mafb-Deficient Mice Showed Delayed Skin Wound Healing

Macrophages play essential roles throughout the wound repair process. Nevertheless, mechanisms regulating the process are poorly understood. MAFB is specifically expressed in the macrophages in hematopoietic tissue and is vital to homeostatic function. Comparison of the skin wound repair rates in macrophage-specific, MAFB-deficient mice (Mafb^f/f::LysM-Cre) and control mice (Mafb^f/f) showed that wound healing was significantly delayed in the former. For wounded GFP knock-in mice with GFP inserts in the Mafb locus, flow cytometry revealed that their GFP-positive cells expressed macrophage markers. Thus, macrophages express Mafb at wound sites. Immunohistochemical (IHC) staining, proteome analysis, and RT-qPCR of the wound tissue showed relative downregulation of Arg1, Ccl12, and Ccl2 in Mafb^f/f::LysM-Cre mice. The aforementioned genes were also downregulated in the bone marrow-derived, M2-type macrophages of Mafb^f/f::LysM-Cre mice. Published single-cell RNA-Seq analyses showed that Arg1, Ccl2, Ccl12, and Il-10 were expressed in distinct populations of MAFB-expressing cells. Hence, the MAFB-expressing macrophage population is heterogeneous. MAFB plays the vital role of regulating multiple genes implicated in wound healing, which suggests that MAFB is a potential therapeutic target in wound healing.

MAFB promotes the malignant phenotypes by IGFBP6 in esophageal squamous cell carcinomas

Esophageal squamous cell carcinoma (ESCC) is one of the most common malignant diseases in the world. Although the somatic alterations have been fully identified, there are still no targeted drugs at present. Our previous studies revealed that loss of grand H3K27me3 domains mediated transcriptional activation of a series of genes in ESCC. Among them, we focus on the investigation of MAFB, as its high expression is associated with a poor prognosis in ESCC. Functional assays show that knockdown of MAFB significantly suppresses cell growth, migration and invasion. Mechanistic investigation demonstrates that MAFB exerts its function by upregulating IGFBP6. Our findings suggest that MAFB may play a tumor-promoting role and may act as a potential therapeutic target for ESCC.

Role of the Transcription Factor MAFA in the Maintenance of Pancreatic β-Cells

Pancreatic β-cells are specialized to properly regulate blood glucose. Maintenance of the mature β-cell phenotype is critical for glucose metabolism, and β-cell failure results in diabetes mellitus. Recent studies provide strong evidence that the mature phenotype of β-cells is maintained by several transcription factors. These factors are also required for β-cell differentiation from endocrine precursors or maturation from immature β-cells during pancreatic development. Because the reduction or loss of these factors leads to β-cell failure and diabetes, inducing the upregulation or inhibiting downregulation of these transcription factors would be beneficial for studies in both diabetes and stem cell biology. Here, we discuss one such factor, i.e., the transcription factor MAFA. MAFA is a basic leucine zipper family transcription factor that can activate the expression of insulin in β-cells with PDX1 and NEUROD1. MAFA is indeed indispensable for the maintenance of not only insulin expression but also function of adult β-cells. With loss of MAFA in type 2 diabetes, β-cells cannot maintain their mature phenotype and are dedifferentiated. In this review, we first briefly summarize the functional roles of MAFA in β-cells and then mainly focus on the molecular mechanism of cell fate conversion regulated by MAFA.

Local anesthetic levobupivacaine inhibits stemness of osteosarcoma cells by epigenetically repressing MAFB though reducing KAT5 expression

Osteosarcoma is the most prevalent bone cancer and accounts for over half of sarcomas. In this study, we identified that the treatment of levobupivacaine suppressed proliferation of osteosarcoma cells in vitro. The tumor xenograft analysis showed that levobupivacaine significantly repressed the osteosarcoma cell growth in the nude mice. The treatment of levobupivacaine improved the apoptosis rate and attenuated invasion and migration abilities of osteosarcoma cells. The sphere formation capabilities of osteosarcoma cells were repressed by levobupivacaine. The protein levels of Sox-2, Oct3/4, and Nanog were inhibited by the treatment of levobupivacaine in osteosarcoma cells. Regarding mechanism, we identified that levobupivacaine inhibited MAFB and KAT5 expression in osteosarcoma cells. We observed that lysine acetyltransferase 5 could enriched in the promoter region of MAF BZIP transcription factor B, while levobupivacaine treatment could repressed the enrichment. The suppression of KAT5 by siRNA repressed the enrichment of histone H3 acetylation at lysine 27 and RNA polymerase II on promoter of MAFB. The expression of MAFB was decreased by KAT5 knockdown in osteosarcoma cells. The expression of MAFB was repressed by levobupivacaine, while the overexpression of KAT5 could reverse the repression of MAFB. KAT5 contributes to the cell proliferation and stemness of osteosarcoma cells. The overexpression of KAT5 or MAFB could reverse levobupivacaine-attenuated cell proliferation and stemness of osteosarcoma cells. Therefore, we concluded that local anesthetic levobupivacaine inhibited stemness of osteosarcoma cells by epigenetically repressing MAFB though reducing KAT5 expression. Levobupivacaine may act as a potential therapeutic candidate for osteosarcoma by targeting cancer stem cells.

Multicentric Carpotarsal Osteolysis Syndrome in a Mother and Daughter with a MAFB Missense Variant and Natural History of the Disease

Multicentric carpotarsal osteolysis syndrome (MCTO; MIM #166300) is a rare skeletal disorder characterized by osteolysis affecting particularly the carpal, metacarpal, and tarsal bones, although other bones might be involved. MCTO is an autosomal dominant disease caused by heterozygous variants in the MAFB gene, frequently misdiagnosed as juvenile rheumatoid arthritis due to similar clinical manifestations. This study reports the first Brazilian family diagnosed with MCTO with progressive osteolysis of the carpal and tarsal bones, presenting a c.161C>T (p.Ser54Leu) heterozygous variant in the MAFB gene, describing the clinical, radiological, and molecular findings, compared with literature data, and discussing the different clinical and molecular diagnosis, as well as the natural history of the disease. Since MCTO is a disorder with progressive symptoms, an early diagnosis is important to avoid unnecessary investigations and treatments and to provide the proper follow-up.

What's happening where when SARS-CoV-2 infects: are TLR7 and MAFB sufficient to explain patient vulnerability?

The present COVID-19 pandemic has revealed that several characteristics render patients especially prone to developing severe COVID-19 disease, i.e., the male sex, obesity, and old age. An explanation for the observed pattern of vulnerability has been proposed which is based on the concept of low sensitivity of the TLR7-signaling pathway at the time of infection as a common denominator of vulnerable patient groups.

We will discuss whether the concept of established TLR-tolerance in macrophages and dendritic cells of the obese and elderly prior to infection can explain not only the vulnerability of these two demographic groups towards development of a severe infection with SARS-CoV-2, but also the observed cytokine response in these vulnerable patients, which is skewed towards pro-inflammatory cytokines with a missing interferon signature.

Magnesium favors the capacity of vitamin D3 to induce the monocyte differentiation of U937 cells

The hematopoietic U937 cells are able to differentiate into monocytes, macrophages, or osteoclasts when stimulated, respectively, with vitamin D3 (VD3), phorbol 12-myristate 13-acetate (PMA) or PMA plus VD3. We have previously demonstrated that magnesium (Mg) strongly potentiates the osteoclastic differentiation of U937 cells. In this study, we investigated whether such an effect may be ascribed to a capacity of Mg to modulate the monocyte differentiation of U937 cells and/or to an ability of Mg and VD3 to act directly and independently on the early phases of the osteoclastic differentiation. To address this issue, we subjected U937 cells to an individual and combined treatment with Mg and VD3 and then we analyzed, by flow cytometry and quantitative real-time polymerase chain reaction, the expression of a number of genes related to the early phases of the differentiation pathways under consideration. The results obtained indicated that Mg favors the monocyte differentiation of U937 cells induced by VD3 and at the same time, Mg contrasts the inhibitory effect that VD3 exerts on the osteoclastic differentiation in the absence of PMA. The crucial and articulated role played by Mg in diverse pathways of the osteoclastic differentiation of U973 cells is emphasized.

Cyclosporine A Treatment of Proteinuria in a New Case of MAFB-Associated Glomerulopathy without Extrarenal Involvement: A Case Report

The MAFB gene encodes an important basic leucine zipper transcription factor that functions in glomerular podocytes, macrophages, and osteoclasts. Recently, MAFB was identified as the gene that was responsible for causing nephropathy with focal segmental glomerulosclerosis (FSGS) with multicentric carpotarsal osteolysis (MCTO) or Duane retraction syndrome (DRS). Here, we describe a patient with nephropathy associated with FSGS who exhibited a novel stop-gain variant in the MAFB gene (NM_005461:c.590C>A (p.Ser197Ter)). The patient's father exhibited proteinuria with FSGS with possible DRS, whereas the patient exhibited nephropathy with FSGS and nearly normal eye movement and hearing function, as well as intact bone structure in the extremities. Conventional oral steroids or immunosuppressive drugs have not demonstrated effectiveness for patients with nephropathy who exhibit pathogenic variants in MAFB, except for a patient with nephropathy with FSGS and MCTO who experienced attenuated proteinuria within the subnephrotic range in response to cyclosporine A (CyA) treatment for at least 4 years. Thus, we attempted administration of CyA in our patient. Unexpectedly, the patient demonstrated good and rapid responses to CyA, including a partial reduction in proteinuria from approximately 2.0 g/g Cr to proteinuria within the subnephrotic range (0.27 g/g Cr) after 13 months of observation. Our findings suggest that CyA may be a suitable treatment option for patients with nephropathy with FSGS who exhibit pathogenic MAFB variants.

Zebrafish mafbb Mutants Display Osteoclast Over-Activation and Bone Deformity Resembling Osteolysis in MCTO Patients

Multicentric carpotarsal osteolysis (MCTO) is a rare skeletal dysplasia with osteolysis at the carpal and tarsal bones. Heterozygous missense mutations in the transcription factor MAFB are found in patients with MCTO. MAFB is reported to negatively regulate osteoclastogenesis in vitro. However, the in vivo function of MAFB and its relation to MCTO remains unknown. In this study, we generated zebrafish MAFB homolog mafbb mutant utilizing CRISPR/Cas9 technology. Mafbb deficient zebrafish demonstrated enhanced osteoclast cell differentiation and abnormal cartilage and bone development resembling MCTO patients. It is known that osteoclasts are hematopoietic cells derived from macrophages. Loss of mafbb caused selective expansion of definitive macrophages and myeloid cells, supporting that mafbb restricts myeloid differentiation in vivo. We also demonstrate that MAFB MCTO mutations failed to rescue the defective osteoclastogenesis in mafbb^-/- embryos, but did not affect osteoclast cells in wild type embryos. The mechanism of MCTO mutations is likely haploinsufficiency. Zebrafish mafbb mutant provides a useful model to study the function of MAFB in osteoclastogenesis and the related MCTO disease.

MAFB and MAF Transcription Factors as Macrophage Checkpoints for COVID-19 Severity

Defective IFN production and exacerbated inflammatory and pro-fibrotic responses are hallmarks of SARS-CoV-2 infection in severe COVID-19. Based on these hallmarks, and considering the pivotal role of macrophages in COVID-19 pathogenesis, we hypothesize that the transcription factors MAFB and MAF critically contribute to COVID-19 progression by shaping the response of macrophages to SARS-CoV-2. Our proposal stems from the recent identification of pathogenic lung macrophage subsets in severe COVID-19, and takes into consideration the previously reported ability of MAFB to dampen IFN type I production, as well as the critical role of MAFB and MAF in the acquisition and maintenance of the transcriptional signature of M-CSF-conditioned human macrophages. Solid evidences are presented that link overexpression of MAFB and silencing of MAF expression with clinical and biological features of severe COVID-19. As a whole, we propose that a high MAFB/MAF expression ratio in lung macrophages could serve as an accurate diagnostic tool for COVID-19 progression. Indeed, reversing the macrophage MAFB/MAF expression ratio might impair the exacerbated inflammatory and profibrotic responses, and restore the defective IFN type I production, thus becoming a potential strategy to limit severity of COVID-19.

Association between MAFB rs17820943 and rs6072081 polymorphism and risk of nonsyndromic cleft lip with or without cleft palate: a meta-analysis

While there have been previous studies examining the relation between the rs17820943 and rs6072081 polymorphisms in the v-maf musculoaponeurotic fibrosarcoma oncogene homolog B (MAFB) gene and rates of nonsyndromic cleft lip with or without cleft palate (NSCL/P), at present the results of these studies have been inconsistent. This meta-analysis therefore aimed to conduct a more robust assessment of the association between the MAFB rs17820943 and rs6072081 polymorphisms and NSCL/P risk. The Embase, Web of Science, PubMed, the China National Knowledge Internet (CNKI), and Wanfang databases were systematically searched to identify relevant studies. In total, five studies incorporating 2769 patients and 2885 controls were identified assessing the rs17820943 polymorphism and three studies incorporating 1242 patients and 1310 controls assessing the rs6072081 polymorphism were identified. This analysis revealed the MAFB rs17820943 and rs6072081 polymorphisms to be linked to a significantly reduced NSCL/P risk (rs17820943: C vs T: OR=0.76, 95% CI=0.70-0.82; CC vs CT: OR=0.75, 95% CI=0.67-0.85; CC vs TT: OR=0.58, 95% CI=0.49-0.67; CC+CT vs TT: OR=0.67, 95% CI=0.59-0.77; CT+TT vs CC: OR=1.43, 95% CI=1.28-1.60; rs6072081: A vs G: OR=0.77, 95%CI=0.68-0.86; AA vs AG: OR=0.76, 95%CI=0.64-0.90; AA vs GG: OR=0.58, 95%CI=0.45-0.74; AA+AG vs GG: OR=0.68, 95%CI=0.54-0.84; AG+GG vs AA: OR=1.40, 95% CI=1.19-1.65). The results of the present meta-analysis indicate that in an East Asian population, for both rs17820943 and rs6072081 were associated with NSCL/P.

RECQL4, Negatively Regulated by miR-10a-5p, Facilitates Cell Proliferation and Invasion via MAFB in Ovarian Cancer

The high frequency of somatic copy number alterations, as opposed to point mutations, is considered a unique feature of ovarian cancer. Amplification-dependent overexpression of RecQ protein-like 4 (RECQL4), which participates in DNA replication and repair, mediates the development of various cancers, but its pathobiological and clinical roles are poorly understood. Here, using bioinformatics analysis, RECQL4 amplification was found to occur in 27% of ovarian cancer samples in the TCGA cohort. RECQL4 was found to be upregulated and associated with a poor prognosis based on the immunohistochemistry staining of ovarian cancer. Functionally, RECQL4 overexpression increased proliferation and invasion of ovarian cancer cells. RECQL4 silencing had the opposite effects. In addition, RECQL4 knockdown enhanced the sensitivity of ovarian cancer cells to cisplatin and PARP inhibitor (PARPi). Further mechanistic investigations revealed that MAFB was a downstream target of RECQL4. The oncogenic effect of RECQL4 was attenuated after MAFB knockdown. Moreover, RECQL4 overexpression was negatively regulated by the tumor suppressor miR-10a-5p. Collectively, these findings indicate that genomic amplification and low expression of miR-10a-5p contribute to RECQL4 overexpression in ovarian cancer. This is the first study to reveal the oncogenic functions and clinical significance of RECQL4 in ovarian cancer.

An Inducible Diabetes Mellitus Murine Model Based on MafB Conditional Knockout under MafA-Deficient Condition

Diabetes mellitus is an increasingly severe chronic metabolic disease that is occurring at an alarming rate worldwide. Various diabetic models, including non-obese diabetic mice and chemically induced diabetic models, are used to characterize and explore the mechanism of the disease’s pathophysiology, in hopes of detecting and identifying novel potential therapeutic targets. However, this is accompanied by disadvantages, such as specific conditions for maintaining the incidence, nonstable hyperglycemia induction, and potential toxicity to other organs. Murine MAFA and MAFB, two closely-linked islet-enriched transcription factors, play fundamental roles in glucose sensing and insulin secretion, and maintenance of pancreatic β-cell, respectively, which are highly homologous to human protein orthologs. Herein, to induce the diabetes mellitus model at a specific time point, we generated Pdx1-dependent Mafb-deletion mice under Mafa knockout condition (A0B^Δpanc), via tamoxifen-inducible Cre-loxP system. After 16 weeks, metabolic phenotypes were characterized by intraperitoneal glucose tolerance test (IPGTT), urine glucose test, and metabolic parameters analysis. The results indicated that male A0B^Δpanc mice had obvious impaired glucose tolerance, and high urine glucose level. Furthermore, obvious renal lesions, impaired islet structure and decreased proportion of insulin positive cells were observed. Collectively, our results indicate that A0B^Δpanc mice can be an efficient inducible model for diabetes research.

MAFB modulates the maturation of lymphatic vascular networks in mice

BACKGROUND

Lymphatic vessels play key roles in tissue fluid homeostasis, immune cell trafficking and in diverse disease settings. Lymphangiogenesis requires lymphatic endothelial cell (LEC) differentiation, proliferation, migration, and co-ordinated network formation, yet the transcriptional regulators underpinning these processes remain to be fully understood. The transcription factor MAFB was recently identified as essential for lymphangiogenesis in zebrafish and in cultured human LECs. MAFB is activated in response to VEGFC-VEGFR3 signaling and acts as a downstream effector. However, it remains unclear if the role of MAFB in lymphatic development is conserved in the mammalian embryo.

RESULTS

We generated a Mafb loss-of-function mouse using CRISPR/Cas9 gene editing. Mafb mutant mice presented with perinatal lethality associated with cyanosis. We identify a role for MAFB in modifying lymphatic network morphogenesis in the developing dermis, as well as developing and postnatal diaphragm. Furthermore, mutant vessels displayed excessive smooth muscle cell coverage, suggestive of a defect in the maturation of lymphatic networks.

CONCLUSIONS

This work confirms a conserved role for MAFB in murine lymphatics that is subtle and modulatory and may suggest redundancy in MAF family transcription factors during lymphangiogenesis.

miR-217/Mafb Axis Involve in High Glucose-Induced β-TC-tet Cell Damage Via Regulating NF-κB Signaling Pathway

We attempt to explore the role of miR-217 during the process of type 2 diabetes mellitus (T2DM). Mouse β-TC-tet was dealt with 16.7 mM glucose (HG) to imitate the cells in T2DM. Cell proliferation and apoptosis were determined by cell counting kit-8 and flow cytometry. The correlation between miR-217 and Mafb was predicted with biological software and confirmed by dual lucifierase assay. Western blot was applied to detect protein expression. The data from GEO database exhibited that miR-217 was upregulated in T2DM patients. HG treatment upregulated the expression of miR-217, inhibited the proliferation, and promoted the apoptosis and inflammation of β-TC-tet cell. Depletion of miR-217 alleviated the damage of β-TC-tet cell caused by HG. Mafb was affirmed as a target of miR-217 and was negatively modulated by miR-217. Knockdown of Mafb attenuated the alleviation of miR-217 inhibitor on β-TC-tet cell damage. The expression of key proteins in NF-κB signaling pathway was upregulated by HG, and this upregulation tendency was inhibited by miR-217 inhibitor. Moreover, silencing Mafb could alleviate the inhibition of miR-217 inhibitor on these proteins. Our findings insinuated that inhibition of miR-217 could relieve β-TC-tet damage induced by HG through regulating Mafb and NF-κB signaling.

A reciprocal regulation of spermidine and autophagy in podocytes maintains the filtration barrier

Podocyte maintenance and stress resistance are exquisitely based on high basal rates of autophagy making these cells a unique model to unravel mechanisms of autophagy regulation. Polyamines have key cellular functions such as proliferation, nucleic acid biosynthesis and autophagy. Here we test whether endogenous spermidine signaling is a driver of basal and dynamic autophagy in podocytes by using genetic and pharmacologic approaches to interfere with different steps of polyamine metabolism. Translational studies revealed altered spermidine signaling in focal segmental glomerulosclerosis in vivo and in vitro. Exogenous spermidine supplementation emerged as new treatment strategy by successfully activating autophagy in vivo via inhibition of EP300, a protein with an essential role in controlling cell growth, cell division and prompting cells to differentiate to take on specialized functions. Surprisingly, gas chromatography-mass spectroscopy based untargeted metabolomics of wild type and autophagy deficient primary podocytes revealed a positive feedback mechanism whereby autophagy itself maintains polyamine metabolism and spermidine synthesis. The transcription factor MAFB acted as an upstream regulator of polyamine metabolism. Thus, our data highlight a novel positive feedback loop of autophagy and spermidine signaling allowing maintenance of high basal levels of autophagy as a key mechanism to sustain the filtration barrier. Hence, spermidine supplementation may emerge as a new therapeutic to restore autophagy in glomerular disease.

In Vitro Control of Genes Critical for Parathyroid Embryogenesis by Extracellular Calcium

Background

The expression of the parathyroid transcription factors, encoded by the genes GATA3, GCM2, and MAFB, persists after parathyroid morphogenesis. This suggests a role of these genes in the regulatory program that governs parathyroid function in the adult. Indeed, these 3 genes form a transcriptional cascade able to activate PTH gene expression.

Materials and Methods

Adult adenoma parathyroid tissues were put in primary cell culture to evaluate the messenger ribonucleic acid (mRNA) expression of the PTH gene, of the genes involved in the calcium regulatory signaling pathway (CaSR, GNA11, and AP2S1), and of the 3 genes (GATA3, GCM2, and MAFB) involved in the parathyroid morphogenesis in the presence of different extracellular calcium concentrations from 0.1 mM to 3.0 mM.

Aim

The aim of the study was to investigate whether different extracellular calcium conditions could control the expression of transcription factors critical for parathyroid embryogenesis.

Results

The results of the experiments showed that the mRNA expression of GATA3, GCM2, and MAFB genes follows the same response as the PTH gene to extracellular calcium concentrations, with the highest expression at low calcium (0.1 mM) and the lowest at high calcium (3.0 mM). Conversely, the genes involved in the calcium signaling in the parathyroid cells showed a variable response to the extracellular calcium concentrations, with the CaSR and GNA11 genes exhibiting a sensitivity to low calcium concentrations.

Conclusions

These findings indicate that transcription factors recognized for their role in parathyroid embryogenesis show a response to extracellular calcium later in adulthood that parallels the behavior of the PTH gene.

Identification of a novel mutation in the MAFB gene in a pediatric patient with multicentric carpotarsal osteolysis syndrome using next-generation sequencing

Multicentric carpotarsal osteolysis syndrome (MCTO) is a rare form of skeletal dysplasia characterized by progressive bone resorption, in the carpal and tarsal bones. Patients may develop chronic kidney disease, which eventually advances to end-stage renal disease (ESRD). Both sporadic and familial cases of autosomal-dominant inheritance are reported in literature. Here, we report a case of a 10.5-year-old boy who presented with CKD stage V, and who suffered from bone deformities and difficulty in walking at a younger age. He was diagnosed with MCTO and subjected to genetic analysis. We identified a novel mutation (NM_005461.5:c.173C > G) in the exon 1 of MAFB using next-generation sequencing. However, the mutation was not detected in his asymptomatic parents or siblings. This novel heterozygous mutation has not been reported previously. Our results show that the new mutation broadens the spectrum of disease phenotypes. This mutation may be helpful to confirm the potential cases of MCTO, which although can be identified through radiographic findings, stand a high chance of being misdiagnosed as rheumatological disease or as a metabolic bone disease secondary to CKD.

Association between 20q12 rs13041247 polymorphism and risk of nonsyndromic cleft lip with or without cleft palate: a meta-analysis

BACKGROUND

Previous genome-wide association studies have identified a link between the rs13041247 single nucleotide polymorphisms (SNPs) in the chromosome 20q12 locus and the development of the congenital malformation known as nonsyndromic cleft lip with or without cleft palate (NSCL/P). The present meta-analysis was therefore designed to formally assess the relationship between rs13041247 and NSCL/P.

METHODS

We searched Embase, Web of Science, PubMed, the China National Knowledge Internet (CNKI), and the China Wanfang database in order to identify relevant published through 25 June 2019. This allowed us to identify 13 studies incorporating 4914 patients and 5981 controls for whom rs13041247 genotyping had been conducted, with STATA 12.0 then being used to conduct a meta-analysis of these pooled results. The I² statistic was used to compare heterogeneity among studies.

RESULTS

In total this analysis incorporated 13 case-control studies. No association between the rs13041247 polymorphism and NSCL/P risk was detected in individuals of Asian ethnicity (C vs T: OR = 0.847, 95% CI = 0.702-1.021; CC vs TT: OR = 0.725, 95% CI = 0.494-1.063; CC vs CT: OR = 0.837, 95% CI = 0.657-1.067; CT + TT vs CC: OR = 1.265, 95% CI = 0.951-1.684; CC + CT vs TT: OR = 0.805, 95% CI = 0.630-1.029) or Caucasian ethnicity (C vs T: OR = 0.936, 95% CI = 0.786-1.114; CC vs TT: OR = 0.988, 95% CI = 0.674-1.446; CC vs CT: OR = 1.197, 95% CI = 0.816-1.757; CT + TT vs CC: OR = 0.918, 95% CI = 0.639-1.318; CC + CT vs TT: OR = 0.855, 95% CI = 0.677-1.081). However, an overall analysis of all participants in these studies revealed the rs13041247 C allele, the CT genotype, and the CC + CT model to be linked to a reduced NSCL/P risk (C vs T: OR = 0.897, 95% CI: 0.723-1.114, P = 0.048; CT vs TT: OR = 0.839, 95% CI: 0.734-0.959, P = 0.01; CC + CT vs TT: OR = 0.824, 95% CI: 0.701-0.968, P = 0.019).

CONCLUSION

These results suggest that the rs13041247 SNP located at the 20q12 chromosomal locus is associated with NSCL/P risk in an overall pooled study population, although this association was not significant in East Asian or Caucasian populations.

Uncovering the role of MAFB in glucagon production and secretion in pancreatic α-cells using a new α-cell-specific Mafb conditional knockout mouse model

Cre/loxP is a site-specific recombination system extensively used to enable the conditional deletion or activation of target genes in a spatial- and/or temporal-specific manner. A number of pancreatic-specific Cre driver mouse lines have been broadly established for studying the development, function and pathology of pancreatic cells. However, only a few models are currently available for glucagon-producing α-cells. Disagreement exists over the role of the MAFB transcription factor in glucagon expression during postnatal life, which might be due to the lack of α-cell-specific Cre driver mice. In the present study, we established a novel Gcg-Cre knock-in mouse line with the Cre transgene expressed under the control of the preproglucagon (Gcg) promoter without disrupting the endogenous Gcg gene expression. Then, we applied this newly developed Gcg-Cre mouse line to generate a new α-cell-specific Mafb conditional knockout mouse model (Mafb^ΔGcg). Not only α-cell number but also glucagon production were significantly decreased in Mafb^ΔGcg mice compared to control littermates, suggesting an indispensable role of MAFB in both α-cell development and function. Taken together, our newly developed Gcg-Cre mouse line, which was successfully utilized to uncover the role of MAFB in α-cells, is a useful tool for genetic manipulation in pancreatic α-cells, providing a new platform for future studies in this field.

Polymorphic Variants of V-Maf Musculoaponeurotic Fibrosarcoma Oncogene Homolog B (rs13041247 and rs11696257) and Risk of Non-Syndromic Cleft Lip/Palate: Systematic Review and Meta-Analysis

Background: Non-syndromic cleft lip/palate (NSCL/P) has an etiology, including both genetic and environmental factors. Herein, we evaluated the association of rs13041247 and rs11696257 v-maf musculoaponeurotic fibrosarcoma oncogene homolog B (MAFB) polymorphisms with the risk of NSCL/P in a meta-analysis. Methods: The PubMed/Medline, Scopus, Cochrane Library, Web of Science, and HuGE Navigator databases were systematically searched to retrieve relevant articles published up to January 2019. The Newcastle–Ottawa scale was applied for quality evaluation of retrieved articles. The 95% confidence interval (CI) and crude odds ratio (OR) were calculated for each study using the Review Manager 5.3 software to show the association between MAFB polymorphisms and risk of NSCL/P. The comprehensive meta-analysis 2.0 software was used to calculate the publication bias. In addition, sensitivity analysis was carried out to show the stability of results. Results: Of 102 articles retrieved from the databases, 10 articles were analyzed in this meta-analysis. Ten articles, including eleven studies reporting rs13041247 MAFB polymorphism, included 3082 NSCL/P patients and 4104 controls. Three studies that reported rs11696257 MAFB polymorphism involved 845 NSCL/P patients and 927 controls. The rs11696257 MAFB polymorphism was not associated with the risk of NSCL/P, but the CC and TC genotypes of rs13041247 polymorphism were associated with the risk of NSCL/P. Nevertheless, the C allele and CC and TC genotypes were associated with a significant decline in the risk of NSCL/P in population-based studies. Conclusions: The results of this meta-analysis demonstrated that the risk of NSCL/P was related to rs13041247 polymorphism, not rs11696257 MAFB polymorphism. Well-designed studies are required to assess the interaction of MAFB and other genes with environmental factors in different ethnic groups.

Family-based study of association between MAFB gene polymorphisms and NSCL/P among Western Han Chinese population

BACKGROUND

Non-syndromic cleft lip with or without cleft palate (NSCL/P) are the most common human congenital birth defects with a complex etiology. MAFB has been reported as a candidate gene involved in the pathogenesis of NSCL/P from genome-wide association study (GWAS) findings, and no replication studies have been performed in Western Han Chinese.

OBJECTIVES

The aim of this study was to investigate the associations of MAFB among NSCL/P trios in Western Han Chinese.

MATERIAL AND METHODS

We selected 6 single nucleotide polymorphisms (SNPs) (rs6072081, rs6065259, rs17820943, rs13041247, rs11698025 and rs6102085) near MAFB based on previous GWAS findings and recruited 298 case-parents trios with NSCL/P from Western Han Chinese population, while genotypes were done by SNPscan technology.

RESULTS

Strong evidence of an association was found at rs17820943 (p = 0.0023; odds ratio - ORtranmission = 0.7 and 95% confidence interval [CI]: 0.55-0.88) and rs13041247 (p = 0.0023; ORtranmission = 0.7 and 95% CI: 0.55-0.88) among NSCL/P; genotypic transmission-disequilibrium test (TDT) analysis further confirmed this. C/C homozygote at rs17820943 (z = 3.44 and p = 0.00058) and T/T homozygote at rs13041247 (z = 3.14 and p = 0.0017) was over-transmitted among NSCL/P, which indicated they could increase the risk of having an affected baby. Sliding window haplotype analysis showed that haplotypes consisting of C allele at rs17820943 and T allele at rs13041247 were still over-transmitted among NSCL/P (lowest p = 0.0021).

CONCLUSIONS

This study further confirmed that the targeted SNPs at MAFB were associated with NSCL/P trios from Western Han Chinese population, which provides more scientific evidence for the future research and genetic counseling.

Involvement of MAFB and MAFF in Retinoid-Mediated Suppression of Hepatocellular Carcinoma Invasion

Retinoids exert antitumor effects through the retinoic acid receptor α (RARα). In the present study, we sought to identify the factors involved in the RARα-mediated transcriptional regulation of the tumor suppressor gene and the tissue factor pathway inhibitor 2 (TFPI2) in hepatocellular carcinoma (HCC). All-trans-retinoic acid (ATRA) was used in the in vitro experiments. Cell invasiveness was measured using trans-well invasion assay. ATRA significantly increased TFPI2 expression through RARα in a human HCC cell line known as HuH7. TFPI2 was vital in the ATRA-mediated suppression of HuH7 cell invasion. The musculo-aponeurotic fibrosarcoma oncogene homolog B (MAFB) significantly enhanced the activation of the TFPI2 promoter via RARα while MAFF inhibited it. The knockdown of RARα or MAFB counteracted the ATRA-mediated suppression of HuH7 cell invasion while the knockdown of MAFF inhibited the invasion. TFPI2 expression in HCC tissues was significantly downregulated possibly due to the decreased expression of RARβ and MAFB. Patients with HCC expressing low MAFB and high MAFF levels showed the shortest disease-free survival time. These results suggest that MAFB and MAFF play critical roles in the antitumor effects of retinoids by regulating the expression of retinoid target genes such as TFPI2 and can be promising for developing therapies to combat HCC invasion.

SUMOylated MAFB promotes colorectal cancer tumorigenesis

The transcription factor, v-maf avian musculoaponeurotic fibrosarcoma oncogene homolog B (MAFB), promotes tumorigenesis in some cancers. In this study, we found that MAFB levels were increased in clinical colorectal cancer (CRC) samples, and higher expression correlated with more advanced TNM stage. We identified MAFB amplifications in a majority of tumor types in an assessment of The Cancer Genome Atlas database. Altered MAFB levels due to gene amplification, deletion, mutation, or transcription upregulation occurred in 9% of CRC cases within the database. shRNA knockdown experiments demonstrated that MAFB deficiency blocked CRC cell proliferation by arresting the cell cycle at G0/G1 phase in vitro. We found that MAFB could be SUMOylated by SUMO1 at lysine 32, and this modification was critical for cell cycle regulation by MAFB in CRC cells. SUMOylated MAFB directly regulated cyclin-dependent kinase 6 transcription by binding to its promoter. MAFB knockdown CRC cell xenograft tumors in mice grew more slowly than controls, and wild-type MAFB-overexpressing tumors grew more quickly than tumors overexpressing MAFB mutated at lysine 32. These data suggest that SUMOylated MAFB promotes CRC tumorigenesis through cell cycle regulation. MAFB and its SUMOylation process may serve as novel therapeutic targets for CRC treatment.

Aryl Hydrocarbon Receptor Controls Monocyte Differentiation into Dendritic Cells versus Macrophages

After entering tissues, monocytes differentiate into cells that share functional features with either macrophages or dendritic cells (DCs). How monocyte fate is directed toward monocyte-derived macrophages (mo-Macs) or monocyte-derived DCs (mo-DCs) and which transcription factors control these differentiation pathways remains unknown. Using an in vitro culture model yielding human mo-DCs and mo-Macs closely resembling those found in vivo in ascites, we show that IRF4 and MAFB were critical regulators of monocyte differentiation into mo-DCs and mo-Macs, respectively. Activation of the aryl hydrocarbon receptor (AHR) promoted mo-DC differentiation through the induction of BLIMP-1, while impairing differentiation into mo-Macs. AhR deficiency also impaired the in vivo differentiation of mouse mo-DCs. Finally, AHR activation correlated with mo-DC infiltration in leprosy lesions. These results establish that mo-DCs and mo-Macs are controlled by distinct transcription factors and show that AHR acts as a molecular switch for monocyte fate specification in response to micro-environmental factors.

The multi-faceted role of retinoid X receptor in bone remodeling

Retinoid X receptors (RXRs) form a unique subclass within the nuclear receptor (NR) superfamily of ligand-dependent transcription factors. RXRs are obligatory partners for a number of other NRs, placing RXRs in a coordinating role at the crossroads of multiple signaling pathways. In addition, RXRs can function as self-sufficient homodimers. Recent advances have revealed RXRs as novel regulators of osteoclastogenesis and bone remodeling. This review outlines the versatility of RXR action in the control of transcription of bone-forming osteoblasts and bone-resorbing osteoclasts, both through heterodimerization with other NRs and through RXR homodimerization. RXR signaling is currently a major therapeutic target and, therefore, knowledge of how RXR signaling affects bone remodeling creates enormous potential for the translation of basic research findings into successful clinical therapies to increase bone mass and improve bone quality.

Genetic variants of 20q12 contributed to non-syndromic orofacial clefts susceptibility

OBJECTIVE

Previous genomewide association studies (GWAS) identified a region near MAFB at chr20q12 associated with non-syndromic orofacial clefts (NSOC) susceptibility. However, whether other SNPs in this area could independently contribute to non-syndromic orofacial clefts in Chinese populations remained obscure.

MATERIALS AND METHODS

We selected 24 SNPs based on a haplotype-tagging SNP strategy and evaluated their associations with risk of non-syndromic orofacial clefts in a large-scale two-stage case-control study with 1278 cases and 1295 controls. Genotyping was performed with Sequenom and TaqMan assay. Associations between the SNPs and risk of non-syndromic orofacial clefts were estimated from unconditional logistic regression analyses.

RESULTS

Overall, six SNPs were found to be the susceptible factors of non-syndromic orofacial clefts. The most significant and independent SNP was rs6129653 (additive model of P value = 1.4E-06). In subgroup analysis, its significant associations with cleft lip only (CLO) and cleft lip and palate (CLP) were observed. Furthermore, in silico bioinformatics analysis indicated that rs6129653 was located in the transcriptionally active region and associated with MAFB expression in human brain tissues.

CONCLUSIONS

Rs6129653 was an independent locus of non-syndromic orofacial clefts among Chinese populations possibly due to its potential of distal transcriptional regulation of MAFB expression.

DNMT3A R882 mutation is associated with elevated expression of MAFB and M4/M5 immunophenotype of acute myeloid leukemia blasts

Researchers have recognized that aberrant methylation is an important initiating event in the pathogenesis of hematological malignancies. DNMT3A is a DNA methyltransferase that plays a vital role in de novo methylation of DNA. Somatic mutation of DNMT3A, especially at the Arg882 (R882) site of the DNMT3A coding sequence, has been identified in pre-leukemic stem cell clones as one of the driver mutations of acute myeloid leukemia (AML). Statistical analysis has indicated that patients with AML with DNMT3A mutation tend to have the M4/M5 subtype of AML according to the French-American-British classification. In this study we aimed to investigate the association between the typical immunophenotype of leukemic blasts and mutation of DNMT3A R882. In addition, we further determined the relationship between DNMT3A R882 mutation and the expression of monocytic differentiation genes, and its clinical significance.

Association study of single nucleotide polymorphisms of MAFB with non-syndromic cleft lip with or without cleft palate in a population in Heilongjiang Province, northern China

Non-syndromic cleft lip with or without cleft palate (NSCLP) is a common complex birth defect. MAFB (v-maf musculoaponeurotic fibrosarcoma oncogene homolog B) is a new gene that may be involved in susceptibility to cleft lip with or without cleft palate (CL/P). To further assess its role in NSCLP, we investigated 3 identified single nucleotide polymorphisms in MAFB (rs13041247, rs6065259, and rs11696257) and examined them for association with NSCLP in 344 patients and 324 healthy controls in a northern Chinese Han population with a high incidence of the syndrome. Peripheral blood samples were taken when patients enrolled in the study and DNA samples were extracted from the blood. The 3 single nucleotide polymorphisms were genotyped using a mini-sequencing method (Snapshot(®) Multiplex System for SNP genotyping, Life Technologies Ltd, Paisley, UK). We found that rs6065259 was the most important single nucleotide polymorphism in MAFB (OR6065259-AA=0.45; 95% CI: 0.28 to 0.71; p=0.0027), followed by rs13041247; however, no association was found between rs11696257 and NSCLP. Our study provides further evidence regarding the role of MAFB variations in the development of NSCLP in this northern Chinese Han population.