Molecular Mechanism of Allergy-Related Gene Regulation and Hematopoietic Cell Development by Transcription Factors

Altered Transcription Factor Expression Responses to Exercise in Insulin Resistance

PURPOSE

Insulin resistant muscle is resistant to gene expression changes induced by acute exercise. This study was undertaken to identify transcription factors that differentially respond to exercise in insulin resistance. Candidate transcription factors were identified from analysis of 5'-untranslated regions (5'-UTRs) of exercise responsive genes and from analysis of the 5'-UTRs of genes coding for proteins that differ in abundance in insulin resistance.

RESEARCH DESIGN AND METHODS

Twenty participants took part in this study. Insulin sensitivity was assessed by an euglycemic clamp. Participants were matched for aerobic capacity and performed a single 48 min bout of exercise with sets at 70 and 90% of maximum heart rate. Muscle biopsies were obtained at resting conditions, 30 min and 24 h after exercise. Global proteomics analysis identified differentially abundant proteins in muscle. The 5'-UTRs of genes coding for significant proteins were subjected to transcription factor enrichment analysis to identify candidate transcription factors. Q-rt-PCR to determine expression of candidate transcription factors was performed on RNA from resting and post-exercise muscle biopsies; immunoblots quantified protein abundance.

RESULTS

Proteins involved in mitochondrial function, protein targeting and translation, and metabolism were among those significantly different between lean and obese groups. Transcription factor enrichment analysis of genes coding for these proteins revealed new candidate transcription factors to be evaluated along the previously identified factors. Q-rt-PCR analysis of RNA and immunoblot analysis from pre- and post-exercise muscle biopsies revealed several transcription and growth factors that had altered responses to exercise in insulin resistant participants. A significant increase (EGR3 and CTGF) and decrease (RELA and ATF2) in the mRNA expression of transcription and growth factors was found after exercise in the lean group, but not in the obese participants.

CONCLUSIONS

These results confirm findings of an association between insulin sensitivity and transcription factor mRNA response to exercise and show that obesity also may be a sufficient prerequisite for exercise resistance. Analysis of the muscle proteome together with determination of effects of exercise on expression of transcription factors suggests that abnormal responses of transcription factors to exercise may be responsible for differences in protein abundances in insulin resistant muscle.

Rehmannia Glutinosa Pharmacopuncture Solution Regulates Functional Activation, FcεRI Expression, and Signaling Events in Mast Cells

Objectives:

Rehmannia glutinosa pharmacopuncture solution (RGPS) was investigated to determine both its anti-allergic inflammatory effects on mast cells and its detailed mechanism of actions.

Methods:

We investigated whether RGPS suppress cytokines, enzymes, FcεRI expression and FcεRImediated signaling in RBL-2H3 cells stimulated with anti-DNP IgE/DNP-HSA. The suppressive effects of RGPS on the levels of cytokines such as IL-1β, IL-6 and GM-CSF were measured using emzyme-linked immunospecific assay (ELISA). The mRNA expression levels of cytokines, enzymes (HDC2, COX-1, COX-2 and 5LO) and FcεRI αβγsubunits were measured using reverse transcription polymerase chain reaction (RTPCR) method. The activation of FcεRI-mediated signaling was examined using Western blot analyses.

Results:

RGPS suppressed production of proinflamm-atory cytokines (IL-1β, IL-6, and GM-CSF) in stimulated RBL-2H3 cells significantly (p< 0.05). RGPS also suppressed mRNA expression of inflammatory enzymes (HDC2, COX-1, COX-2, 5LO). In addition, mRNA expression levels of FcεRIα, FcεRIβand FcεRIγ were lowered by treatment with RGPS. Finally, RGPS prevented phosphrylation of Lyn, Syk, LAT, Gab2, PLC γ1/2, PI3K, Akt, cPLA₂ and IκBα

Conclusions:

RGPS effectively suppresses mast cell activations such as degranulation and inflammatory response via down-regulation of the FcεRI-mediated signaling pathways in IgE/Ag-stimulated mast cells.

Human FcR polymorphism and disease

Fc receptors play a central role in maintaining the homeostatic balance in the immune system. Our knowledge of the structure and function of these receptors and their naturally occurring polymorphisms, including single nucleotide polymorphisms and/or copy number variations, continues to expand. Through studies of their impact on human biology and clinical phenotype, the contributions of these variants to the pathogenesis, progression, and/or treatment outcome of many diseases that involve immunoglobulin have become evident. They affect susceptibility to bacterial and viral pathogens, constitute as risk factors for IgG or IgE mediated inflammatory diseases, and impact the development of many autoimmune conditions. In this chapter, we will provide an overview of these genetic variations in classical FcγRs, FcRLs, and other Fc receptors, as well as challenges in achieving an accurate and comprehensive understanding of the FcR polymorphisms and genomic architecture.

Milk: an exosomal microRNA transmitter promoting thymic regulatory T cell maturation preventing the development of atopy?

Epidemiological evidence confirmed that raw cow's milk consumption in the first year of life protects against the development of atopic diseases and increases the number of regulatory T-cells (Tregs). However, milk's atopy-protective mode of action remains elusive.This review supported by translational research proposes that milk-derived microRNAs (miRs) may represent the missing candidates that promote long-term lineage commitment of Tregs downregulating IL-4/Th2-mediated atopic sensitization and effector immune responses. Milk transfers exosomal miRs including the ancient miR-155, which is important for the development of the immune system and controls pivotal target genes involved in the regulation of FoxP3 expression, IL-4 signaling, immunoglobulin class switching to IgE and FcϵRI expression. Boiling of milk abolishes milk's exosomal miR-mediated bioactivity. Infant formula in comparison to human breast- or cow's milk is deficient in bioactive exosomal miRs that may impair FoxP3 expression. The boost of milk-mediated miR may induce pivotal immunoregulatory and epigenetic modifications required for long-term thymic Treg lineage commitment explaining the atopy-protective effect of raw cow's milk consumption.The presented concept offers a new option for the prevention of atopic diseases by the addition of physiological amounts of miR-155-enriched exosomes to infant formula for mothers incapable of breastfeeding.

Links between allergy and cardiovascular or hemostatic system

In addition to a well-known immunologic background of atherosclerosis and influences of inflammation on arterial and venous thrombosis, there is growing evidence for the presence of links between allergy and vascular or thrombotic disorders. In this interpretative review, five pretty well-documented areas of such overlap are described and discussed, including: (1) links between atherosclerosis and immunoglobulin E or atopy, (2) mutual effects of blood lipids and allergy, (3) influence of atopy and related disorders on venous thromboembolism, (4) the role of platelets in allergic diseases, and (5) the functions of protein C system in atopic disorders.

Notch1-mediated signaling induces MHC class II expression through activation of class II transactivator promoter III in mast cells

Mast cells constitutively express Notch1 and Notch2 on the cell surface. Notch ligand Dll1 (Delta-like 1) stimulation induces MHC class II expression in mast cells and renders them as antigen-presenting cells. However, nothing is known about the mechanism by which Notch signaling induces MHC class II expression in mast cells. MHC class II genes are regulated by the class II transactivator (CIITA). In mice, transcription of the CIITA gene is controlled by three cell type-specific promoters (pI, pIII, and pIV). Here, we show that CIITA expression induced by Dll1 stimulation in mouse bone marrow-derived mast cells (BMMCs) depends critically on the signal mediated by Notch1 and that the most dominant promoter in Notch signaling-mediated CIITA expression in BMMCs is pIII, which is a lymphoid lineage-specific promoter. ChIP assays indicated that Notch signaling increased the binding of the transcription factor PU.1 to CIITA pIII in BMMCs. The knockdown of PU.1 expression using a specific siRNA suppressed Notch signaling-mediated CIITA expression, suggesting that PU.1 contributes to the expression of MHC class II induced by Notch signaling in mast cells. Furthermore, we show that a portion of freshly isolated splenic mast cells express MHC class II and that the most dominant promoter of CIITA in mast cells is pIII. These findings indicate that activation of CIITA pIII plays an important role in MHC class II expression in mast cells.

Genetic variability of the high-affinity IgE receptor alpha-subunit (FcepsilonRIalpha)

Our knowledge on the variability of FCER1A gene encoding for alpha-subunit of the high-affinity immunoglobulin E receptor (FcepsilonRI) that plays a central role in the pathogenesis of allergy and related disorders, has been recently much extended. Last findings from FCER1A mutational screening and genetic association studies, followed by functional analyses of the polymorphisms, are briefly summarized in this mini-review. The association between FCER1A gene variants and total serum IgE levels seems especially interesting and, supported by functional analyses of polymorphisms, may provide a rationale for pharmacogenetic studies on anti-IgE therapy that indirectly suppresses FcepsilonRI expression.

Identification of a novel transcriptional repressor (HEPIS) that interacts with nsp-10 of SARS coronavirus

A novel gene was previously isolated from a cDNA library of human embryo lung tissue by its encoded protein, which interacts with non-structural protein 10 (nsp-10) of the severe acute respiratory syndrome coronavirus (SARS-CoV). The protein was named human embryo lung cellular protein interacting with SARS-CoV nsp-10 (HEPIS), and it is composed of 147 amino acids with several CK II phosphorylation sites. In the present study, we demonstrated that HEPIS was capable of suppressing chloramphenicol acetyltransferase (CAT) gene expression controlled by different enhancerelements in a transcription assay. HEPIS interacted specifically with the HSP70 TATA sequence, and not with various other enhancer elements in a binding test. Furthermore, we co-immunoprecipitated HEPIS with BTF3, a component of the RNA pol II initiation complex, and observed reduced proliferation of HeLa cells transfected with the HEPIS gene. Taken together, our results suggest that HEPIS may function as a potential transcriptional repressor.

Genetic variability of the high-affinity IgE receptor alpha subunit (Fc epsilon RI alpha) is related to total serum IgE levels in allergic subjects

Known susceptibility genes to atopy and asthma have been identified by linkage or associations with clinical phenotypes, including total serum IgE levels. IgE-mediated sensitivity reactions require a high-affinity IgE receptor (FcepsilonRI), which immobilizes the immunoglobulin on the surface of the effector cells, mostly mast cells and basophils. In this mini-review, recent findings are presented on genetic variation of this receptor, as related to atopy. Transcription of FCER1A gene encoding the receptor alpha subunit can be initiated from two separate promoters, the proximal one and the distal one, which results in a transcript containing two novel untranslated exons (1A, 2A). Our knowledge on the role of this mechanism in allergic diseases is still at an infancy stage. Within regulatory elements of FCER1A some common single nucleotide polymorphisms have functional associations, which were recently reported and replicated in different ethnical groups. Interestingly, these associations do not confer susceptibility to allergic diseases, but rather modulate serum concentrations of IgE. Similarly to the previously investigated beta subunit of the receptor, FCER1A is a good candidate for a quantitative trait locus (QTL) in allergic diseases, and appears to participate in the systemic regulation of IgE levels.