RNF144B stimulates the proliferation and inhibits the apoptosis of human spermatogonial stem cells via the FCER2/NOTCH2/HES1 pathway and its abnormality is associated with azoospermia.

Studies on gene regulation and signaling transduction pathways of human spermatogonial stem cells (SSCs) are of the utmost significance for unveiling molecular mechanisms underlying human spermatogenesis and gene therapy of male infertility. We have demonstrated, for the first time, that RNF144B stimulated cell proliferation and inhibited the apoptosis of human SSCs. The target of RNF144B was identified as FCER2 by RNA sequencing. We revealed that RNF144B interacted with FCER2 by immunoprecipitation. Consistently, overexpression of FCER2 reversed the phenotype of proliferation and apoptosis of human SSCs caused by RNF144B knockdown. Interestingly, FCER2 pulled down N2ICD (NOTCH2 intracellular domain), while N2ICD could bind to FCER2 in human SSCs. The levels of NOTCH2, FCER2, HES1, and HEY1 were reduced by RNF144B siRNA in human SSCs. Significantly, RNF144B was expressed at a lower level in nonobstructive azoospermia (NOA) patients than in the obstructive azoospermia (OA) patients with normal spermatogenesis, and 52 patients with heterozygous mutations of RNF144B were detected in 1,000 NOA patients. These results implicate that RNF144B promotes the proliferation of human SSCs and suppresses their apoptosis via the FCER2/NOTCH2/HES1 pathway and that the abnormality of RNF144B is associated with spermatogenesis failure. This study thus provides novel molecular mechanisms regulating the fate determinations of human SSCs, and it offers new biomarkers for the diagnosis and treatment of male infertility.

CD23 is a glycan-binding receptor in some mammalian species.

CD23, the low-affinity IgE receptor found on B lymphocytes and other cells, contains a C-terminal lectin-like domain that resembles C-type carbohydrate-recognition domains (CRDs) found in many glycan-binding receptors. In most mammalian species, the CD23 residues required to form a sugar-binding site are present, although binding of CD23 to IgE does not involve sugars. Solid-phase binding competition assays, glycoprotein blotting experiments, and glycan array analysis employing the lectin-like domains of cow and mouse CD23 demonstrate that they bind to mannose, GlcNAc, glucose, and fucose and to glycoproteins that bear these sugars in nonreducing terminal positions. Crystal structures of the cow CRD in the presence of α-methyl mannoside and GlcNAcß1-2Man reveal that a range of oligosaccharide ligands can be accommodated in an open binding site in which most interactions are with a single terminal sugar residue. Although mouse CD23 shows a pattern of monosaccharide and glycoprotein binding similar to cow CD23, the binding is weaker. In contrast, no sugar binding was observed in similar experiments with human CD23. The absence of sugar-binding activity correlates with accumulation of mutations in the gene for CD23 in the primate lineage leading to humans, resulting in loss of key sugar-binding residues. These results are consistent with a role for CD23 in many species as a receptor for potentially pathogenic microorganisms as well as IgE. However, the ability of CD23 to bind several different ligands varies between species, suggesting that it has distinct functions in different organisms.

FCER2 T2206C variant associated with FENO levels in asthmatic children using inhaled corticosteroids: The PACMAN study.

BACKGROUND: The FCER2 gene, via encoding of the CD23 receptor, plays an important role in the regulation of IgE responses. A genetic variant of the FCER2 gene (T2206C) was previously shown to be associated with IgE levels in asthmatic children. IgE sensitization has also been linked to increased levels of fractional exhaled nitric oxide (FENO). OBJECTIVE: To investigate whether the FCER2 T2206C variant influences FENO levels in asthmatic children with a reported use of inhaled corticosteroids (ICS). METHODS: This cross-sectional study involved 593 asthmatic children with a reported use of ICS, availability of FENO measurements and genotyping data on the FCER2 T2206C variant (rs28364072). An additive genetic model was assumed, and the association between the FCER2 T2206C variant and the log-transformed (ln) FENO levels was evaluated using linear regression analysis, adjusted for age, sex, adapted British Thoracic Society (BTS) treatment steps and atopy. RESULTS: The mean age of the population was 9.1 ± 2.2 years, and the median of FENO levels was 13.0 ppb with an interquartile range (IQR) of (8.0-27.5 ppb). The minor allele (G) frequency of rs28364072 was 29.6%, and each extra copy of the G allele was significantly associated with a lower level of the geometric mean of FENO (log scale, ß = -0.12, 95% CI: -0.23, -0.02). CONCLUSION AND CLINICAL RELEVANCE: Our results showed that the FCER2 T2206C variant was significantly associated with lower FENO levels in carriers of the G allele. Nevertheless, this SNP contributed little to the variability in FENO levels in this patient population. Our findings contribute to the present knowledge on FENO in asthmatic children; however, future replication studies are required to establish the role of this gene in relation to FENO.

A role of FCER1A and FCER2 polymorphisms in IgE regulation.

BACKGROUND: Both FCER2 and FCER1A encode subunits of IgE receptors. Variants in FCER1A were previously identified as major determinants of IgE levels in genome-wide association studies. METHODS: Here we investigated in detail whether FCER2 polymorphisms affect IgE levels alone and/or by interaction with FCER1A polymorphisms. To cover the genetic information of FCER2, 21 single-nucleotide polymorphisms (SNPs) were genotyped by Illumina HumanHap300 BeadChip (5 SNPs) and the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS; 14 SNPs) in at least 1303 Caucasian children (651 asthmatics) (ISAAC II/ MAGICS population); genotypes of two SNPs were imputed. RESULTS: SNP rs3760687 showed the most consistent effect on total serum IgE levels (b [SE] = -0.38 [0.16]; P = 0.016), while FCER2 polymorphisms in general were predominantly associated with mildly-to-moderately increased IgE levels (50th and 66th percentiles). Gene-by-gene interaction analysis suggests that FCER2 polymorphism rs3760687 influences IgE levels mainly in individuals not homozygous for the risk allele of FCER1A polymorphism rs2427837, which belongs to the major IgE-determining tagging bin in the population. CONCLUSION: FCER2 polymorphism rs3760687 affects moderately elevated total serum IgE levels, especially in the absence of homozygosity for the risk allele of FCER1A SNP rs2427837.

[The correlation between FCER2 gene polymorphism and the efficacy of inhaled corticosteroids in patients with chronic rhinosinusitis].

Objective:To investigate the correlation between FCER2（2206A>G） gene polymorphism and the efficacy of inhaled corticosteroids（ICS） in patients with chronic rhinosinusitis（CRS）. Methods:A total of 208 CRS patients were routinely treated with functional endonasal sinus surgery and postoperative ICS. DNA extraction, PCR amplification and gene sequencing were performed to observe the FCER2（2206A>G） gene polymorphism and calculate the allele frequency. The visual analog scale（VAS） score, Lund-Kennedy score, and computed tomography（CT） Lund-Mackay score were determined 6 months after surgery among patients with different genotypes. Moreover, the polymorphism frequency was compared among different subgroups（chronic rhinosinusitis with nasal polyps versus chronic rhinosinusitis without nasal polyps, eosinophilic chronic rhinosinusitis versus non-eosinophilic chronic rhinosinusitis）. Results:There were FCER2（2206A>G） gene polymorphism in patients with CRS, and the phenotypes included 3 genotypes, AA, AG and GG, with distribution frequencies of 68（32.7%）, 116（55.8%） and 24（11.5%） cases, respectively. No significant differences were found in age, VAS score, nasal endoscopic Lund-Kennedy score and CT imaging Lund-Mackay score among patients with CRS of each genotype before surgery. In patients with the AA genotype, the changes in VAS score（5.74±1.10）, Lund Kennedy score（5.92 ± 1.14）, and CT imaging Lund-Mackay score（13.26±4.26） were significantly higher than in patients with the AG（4.37±0.86, 5.37±1.24, 10.82±3.77） and GG（4.26±0.80, 5.18±1.56, 10.10±3.53） genotype（P<0.05）. However, there were no marked difference between patients with the AG genotype and those with the GG genotype（P>0.05）. Compared with patients with non-eosinophilic sinusitis, Among them, the differences between the GG genotype and AG /AA genes were more significant in eosinophilic sinusitis compared to non-eosinophilic sinusitis（P<0.01）. Conclusion:The FCER2（2206A>G） gene in patients with CRS has genetic polymorphism and is associated with the recovery of CRS patients after surgery, individual corticosteroid sensitivity, and subgroup variability.

Polymorphisms in the FCER2 gene have associations with asthma and chronic obstructive pulmonary disease.

Background: Asthma and chronic obstructive pulmonary disease (COPD) are heterogenetic diseases and exhibit many similarities. Dutch hypothesis proposed that these two diseases may have common genetic origins. This study aims to investigate whether asthma and COPD share a common genetic background in Chinese patients. Methods: In this case-control study, single nucleotide polymorphisms (SNPs) were genotyped using SNaPshot. Haplotype disease analysis and haplotype phenotype analysis were applied to assess the relationship between three polymorphisms of the FCER2 gene and the risk of COPD/asthma. Additionally, associations between polymorphisms of the FCER2 gene and phenotypes were analyzed. Results: We detected ten SNPs of seven genes (FCER1A, FCGR2A, FCGR2B, CHI3L1, ADRB2, STAT6, and FCER2) expressed by airway epithelial cells. We detected genotypes and allele distributions in 251 COPD patients, 597 asthma patients, and 632 healthy controls. A significant difference was found in the FCER2 gene (rs28364072) between COPD patients and controls (P=0.009). Significant differences were observed in the genotype and allele distributions of rs1801274 (FCGR2A), rs12368672 (STAT6), and rs2228137 (FCER2) between asthma patients and controls (P=0.004, 0.007 and 0.010, respectively). Notably, polymorphisms of FCER2 gene were associated with the risk of both COPD (P=0.009 for rs28364072) and asthma (P=0.01 for rs2228137). Haplotype analysis revealed that haplotype T-G-T (alleles of rs28364072, rs2228137, and rs3760687, respectively) was significantly associated with a higher risk of asthma [odds ratios (OR) =2.25, 95% confidence interval (CI): 1.26-4.01, P=0.006]. Further analysis showed that the C-A-C haplotype and C-G-T haplotype were associated with increased blood eosinophils in either COPD or asthma patients (P=0.034, and P<0.001, respectively). Moreover, haplotypes C-A-C, C-G-C, and T-G-C showed significant associations with serum IgE levels in asthma patients (P=0.002, 0.041, and 0.004, respectively). Conclusions: Our data suggest that the FCER2 gene might associate with predisposition to asthma and COPD, while FCER2 haplotypes were associated with pulmonary function measurements and blood eosinophils counts in both diseases. Our findings support the common genetic basis for asthma and COPD, suggesting a potential therapeutic target for the two diseases.

Targeting Nuclear NOTCH2 by Gliotoxin Recovers a Tumor-Suppressor NOTCH3 Activity in CLL.

NOTCH signaling represents a promising therapeutic target in chronic lymphocytic leukemia (CLL). We compared the anti-neoplastic effects of the nuclear NOTCH2 inhibitor gliotoxin and the pan-NOTCH γ-secretase inhibitor RO4929097 in primary CLL cells with special emphasis on the individual roles of the different NOTCH receptors. Gliotoxin rapidly induced apoptosis in all CLL cases tested, whereas RO4929097 exerted a variable and delayed effect on CLL cell viability. Gliotoxin-induced apoptosis was associated with inhibition of the NOTCH2/FCER2 (CD23) axis together with concomitant upregulation of the NOTCH3/NR4A1 axis. In contrast, RO4929097 downregulated the NOTCH3/NR4A1 axis and counteracted the spontaneous and gliotoxin-induced apoptosis. On the cell surface, NOTCH3 and CD23 expression were mutually exclusive, suggesting that downregulation of NOTCH2 signaling is a prerequisite for NOTCH3 expression in CLL cells. ATAC-seq confirmed that gliotoxin targeted the canonical NOTCH signaling, as indicated by the loss of chromatin accessibility at the potential NOTCH/CSL site containing the gene regulatory elements. This was accompanied by a gain in accessibility at the NR4A1, NFκB, and ATF3 motifs close to the genes involved in B-cell activation, differentiation, and apoptosis. In summary, these data show that gliotoxin recovers a non-canonical tumor-suppressing NOTCH3 activity, indicating that nuclear NOTCH2 inhibitors might be beneficial compared to pan-NOTCH inhibitors in the treatment of CLL.

Study of the correlations between fractional exhaled nitric oxide in exhaled breath and atopic status, blood eosinophils, FCER2 mutation, and asthma control in Vietnamese children.

INTRODUCTION: Fractional exhaled nitric oxide (FENO) is a biomarker of airway inflammation in asthma. The measurement of FENO is utilized to assist in the diagnosis and treatment of children with asthma, especially for those treated with inhaled corticosteroids. OBJECTIVES: The aims of this study were to evaluate the correlations between FENO and atopic status, blood eosinophil levels, FCER2 mutation, and asthma control in Vietnamese children. SUBJECTS AND METHODS: This was a prospective and descriptive study approved by the local Ethical Board. All children with uncontrolled asthma, seen in the National Hospital of Pediatrics (Hanoi, Vietnam), were included. Exhaled breath FENO, blood eosinophils, skin prick test, total IgE, asthma control test (ACT), and FCER2 gene polymorphism were performed at inclusion. They were followed up at 3 months to evaluate clinical status, FENO levels, and ACT. RESULTS: Forty-two children with uncontrolled asthma with a mean age of 10±3 years (6-16 years) were included. The male/female ratio was 2.5/1. The mean FENO levels were 26±25 ppb. FENO was significantly higher in patients with a positive skin prick test for respiratory allergens (P<0.05). FENO was significantly correlated with blood eosinophil levels (r=0.5217; P=0.0004). Five of the 32 subjects (15.6%) had a mutation of FCER2 gene (rs28364072 SNP). In this group, the levels of FENO were highest (37±10 ppb; P<0.05). The levels of FENO were significantly decreased after 3 months of treatment (17±8 ppb vs 26±25 ppb; P<0.05). Significant correlations between inhaled corticosteroid doses and FENO levels occurred at 1 and 3 months (r=0.415, P=0.007; r=0.396, P=0.010; respectively). There were no correlations between FENO levels, ACT, and daily use of salbutamol. After 3 months, asthma remained uncontrolled in 22.2% of children. CONCLUSION: The measurement of FENO levels is a useful and feasible tool to predict clinical, biological, and asthma control in Vietnamese children.

Dock10 regulates CD23 expression and sustains B-cell lymphopoiesis in secondary lymphoid tissue.

Dock10, a guanine nucleotide exchange factor for the Rho GTPases Rac1 and Cdc42, affects cell morphology, membrane protrusive activity, and cell movement. Dock10 is prominently expressed in lymphoid tissue and upregulated by IL-4 in B cells. To investigate the physiological role of Dock10, WT mice and Dock10 KO mice were used. KO mice showed decreased numbers of B cells in spleen, both follicular B cells and marginal zone B cells, and in peripheral blood, but not in bone marrow. The antiapoptotic effect of IL-4 in vitro, the migratory response to CXCL13 or CCL21 in vitro, and the whole genome expression profile were intact in spleen B cells from KO mice. CD23, the low-affinity receptor for immunoglobulin E, was overexpressed on follicular B cells from KO mice, suggesting that Dock10 negatively regulates membrane CD23 expression. Negative regulation of CD23 expression by Dock10 could play a role in B cell maturation and function.