Dusp5 negatively regulates IL-33-mediated eosinophil survival and function

Advancing toward a unified eosinophil signature from transcriptional profiling

Eosinophils are granulocytes that can accumulate in increased numbers in tissues and/or peripheral blood in disease. Phenotyping of eosinophils in health and disease has the potential to improve the precision of diagnosis and choice of therapies for eosinophilic-associated diseases. Transcriptional profiling of eosinophils has been plagued by cell fragility and difficulty isolating high-quality RNA. With several technological advances, single-cell RNA sequencing has become possible with eosinophils, at least from mice, while bulk RNA sequencing and microarrays have been performed in both murine and human samples. Anticipating more eosinophil transcriptional profiles in the coming years, we provide a summary of prior studies conducted on mouse and human eosinophils in blood and tissue, with a discussion of the advantages and potential pitfalls of various approaches. Common technical standards in studying eosinophil biology would help advance the field and make cross-study comparisons possible. Knowledge gaps and opportunities include identifying a minimal set of genes that define the eosinophil lineage, comparative studies between active disease and remission vs. homeostasis or development, especially in humans, and a comprehensive comparison between murine and human eosinophils at the transcriptional level. Characterizing such transcriptional patterns will be important to understanding the complex and diverse roles of eosinophils in both health and disease.

BAP1-mediated MAFF deubiquitylation regulates tumor growth and is associated with adverse outcomes in colorectal cancer

BACKGROUND

Despite improvements in colorectal cancer (CRC) treatment, the prognosis for advanced CRC patients remains poor. Disruption of protein stability is one of the important factors in cancer development and progression. In this study, we aim to identify and analyze novel dysregulated proteins in CRC, assessing their significance and the mechanisms.

METHODS

Using quantitative proteomics, expression pattern analysis, and gain-of-function/loss-of-function experiments, we identify novel functional protein dysregulated by ubiquitin-proteasome axis in CRC. Prognostic significance was evaluated in a training cohort of 546 patients and externally validated in 794 patients. Mechanistic insights are gained through molecular biology experiments, deubiquitinating enzymes (DUBs) expression library screening, and RNA sequencing.

RESULTS

MAFF protein emerged as the top novel candidate substrate regulated by ubiquitin-proteasome in CRC. MAFF protein was preferentially downregulated in CRC compared to adjacent normal tissues. More importantly, multicenter cohort study identified reduced MAFF protein expression as an independent predictor of overall and disease-free survival in CRC patients. The in vitro and vivo assays showed that MAFF overexpression inhibited CRC growth, while its knockdown had the opposite effect. Intriguingly, we found the abnormal expression of MAFF protein was predominantly regulated via ubiquitination of MAFF, with K48-ubiquitin being dominant. BAP1 as a nuclear deubiquitinating enzyme (DUB), bound to and deubiquitinated MAFF, thereby stabilizing it. Such stabilization upregulated DUSP5 expression, resulting in the inhibition of ERK phosphorylation.

CONCLUSIONS

This study describes a novel BAP1-MAFF signaling axis which is crucial for CRC growth, potentially serving as a therapeutic target and a promising prognostic biomarker for CRC.

Integrated analyses reveal CST7 and DUSP5 regulate Th2 cells differentiation to promote chronic HBV infection

Chronicity of HBV infection is a complex process influenced by both viral and host factors. Understanding the complex interplay between HBV and cellular immunity is critical. In this study, we used bulk expression datasets for CHB liver tissue from GSE83148 and GSE84044, and scRNA-seq data of CHB liver samples from GSE182159 to find critical genes and immune cells accounted for CHB. We first identified DEGs closely associated with CHB by WGCNA and these genes were intricately linked to differentiation of Th2 cells, which were significantly higher in CHB and positively associated with ALT, AST, HBV-DNA, Scheuer grade and Scheuer stage. Among these DEGs, CST7 and DUSP5 highly expressed in CHB and positively associated with ALT, AST, HBV-DNA, Scheuer grade and Scheuer stage. Moreover, through scRNA-seq, we also found that CST7 and DUSP5 upregulated in Th2 cells and regulated differentiation of naive CD4+ T cells to Th2 cells. Finally, in-vitro studies also showed that HBV infection could significantly up-regulate DUSP5 and CST7 expression. This research strongly revealed that HBV could up-regulate CST7 and DUSP5 to drive differentiation of naive CD4+ T cells into Th2 cells and contribute to CHB, which may pave the way for immunotherapeutic interventions.

Epithelial cells derived exosomal miR-203a-3p facilitates stromal inflammation of type IIIA chronic prostatitis/chronic pelvic pain syndrome by targeting DUSP5 and increasing MCP-1 generation

Increased proinflammatory cytokines and infiltration of inflammatory cells in the stroma are important pathological features of type IIIA chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS-A), and the interaction between stromal cells and other cells in the inflammatory microenvironment is closely related to the inflammatory process of CP/CPPS-A. However, the interaction between stromal and epithelial cells remains unclear. In this study, inflammatory prostate epithelial cells (PECs) released miR-203a-3p-rich exosomes and facilitated prostate stromal cells (PSCs) inflammation by upregulating MCP-1 expression. Mechanistically, DUSP5 was identified as a novel target gene of miR-203a-3p and regulated PSCs inflammation through the ERK1/2/MCP-1 signaling pathway. Meanwhile, the effect of exosomes derived from prostatic fluids of CP/CPPS-A patients was consistent with that of exosomes derived from inflammatory PECs. Importantly, we demonstrated that miR-203a-3p antagomirs-loaded exosomes derived from PECs targeted the prostate and alleviated prostatitis by inhibiting the DUSP5-ERK1/2 pathway. Collectively, our findings provide new insights into underlying the interaction between PECs and PSCs in CP/CPPS-A, providing a promising therapeutic strategy for CP/CPPS-A.

Epigenetic signatures in cardiac fibrosis: Focusing on noncoding RNA regulators as the gatekeepers of cardiac fibroblast identity

Cardiac fibroblasts play a pivotal role in cardiac fibrosis by transformation of fibroblasts into myofibroblasts, which synthesis and secrete a large number of extracellular matrix proteins. Ultimately, this will lead to cardiac wall stiffness and impaired cardiac performance. The epigenetic regulation and fate reprogramming of cardiac fibroblasts has been advanced considerably in recent decades. Non coding RNAs (microRNAs, lncRNAs, circRNAs) regulate the functions and behaviors of cardiac fibroblasts, including proliferation, migration, phenotypic transformation, inflammation, pyroptosis, apoptosis, autophagy, which can provide the basis for novel targeted therapeutic treatments that abrogate activation and inflammation of cardiac fibroblasts, induce different death pathways in cardiac fibroblasts, or make it sensitive to established pathogenic cells targeted cytotoxic agents and biotherapy. This review summarizes our current knowledge in this field of ncRNAs function in epigenetic regulation and fate determination of cardiac fibroblasts as well as the details of signaling pathways contribute to cardiac fibrosis. Moreover, we will comment on the emerging landscape of lncRNAs and circRNAs function in regulating signal transduction pathways, gene translation processes and post-translational regulation of gene expression in cardiac fibroblast. In the end, the prospect of cardiac fibroblasts targeted therapy for cardiac fibrosis based on ncRNAs is discussed.

Strategies targeting IL-33/ST2 axis in the treatment of allergic diseases

Interleukin-33 (IL-33) and its receptor Serum Stimulation-2 (ST2, also called Il1rl1) are members of the IL-1 superfamily that plays a crucial role in allergic diseases. The interaction of IL-33 and ST2 mainly activates NF-κB signaling and MAPK signaling via the MyD88/IRAK/TRAF6 module, resulting in the production and secretion of pro-inflammatory cytokines. The IL-33/ST2 axis participates in the pathogenesis of allergic diseases, and therefore serves as a promising strategy for allergy treatment. In recent years, strategies blocking IL-33/ST2 through targeting regulation of IL-33 and ST2 or targeting the molecules involved in the signal transduction have been extensively studied mostly in animal models. These studies provide various potential therapeutic agents other than antibodies, such as small molecules, nucleic acids and traditional Chinese medicines. Herein, we reviewed potential targets and agents targeting IL-33/ST2 axis in the treatment of allergic diseases, providing directions for further investigations on treatments for IL-33 induced allergic diseases.

The Role of Epinephelus coioides DUSP5 in Regulating Singapore Grouper Iridovirus Infection

The dual-specificity phosphatase (DUSP) family plays an important role in response to adverse external factors. In this study, the DUSP5 from Epinephelus coioides, an important marine fish in Southeast Asia and China, was isolated and characterized. As expected, E. coioides DUSP5 contained four conserved domains: a rhodanese homology domain (RHOD); a dual-specificity phosphatase catalytic domain (DSPc); and two regions of low compositional complexity, indicating that E. coioides DUSP5 belongs to the DUSP family. E. coioides DUSP5 mRNA could be detected in all of the examined tissues, and was mainly distributed in the nucleus. Infection with Singapore grouper iridovirus (SGIV), one of the most important pathogens of marine fish, could inhibit the expression of E. coioides DUSP5. The overexpression of DUSP5 could significantly downregulate the expression of the key SGIV genes (MCP, ICP18, VP19, and LITAF), viral titers, the activity of NF-κB and AP-I, and the expression of pro-inflammatory factors (IL-6, IL-8, and TNF-α) of E. coioides, but could upregulate the expressions of caspase3 and p53, as well as SGIV-induced apoptosis. The results demonstrate that E. coioides DUSP5 could inhibit SGIV infection by regulating E. coioides immune-related factors, indicating that DUSP5 might be involved in viral infection.

Rhinovirus infection of the airway epithelium enhances mast cell immune responses via epithelial-derived interferons

BACKGROUND

Mast cells (MCs) within the airway epithelium in asthma are closely related to airway dysfunction, but cross talk between airway epithelial cells (AECs) and MCs in asthma remains incompletely understood. Human rhinovirus (RV) infections are key triggers for asthma progression, and AECs from individuals with asthma may have dysregulated antiviral responses.

OBJECTIVE

We utilized primary AECs in an ex vivo coculture model system to examine cross talk between AECs and MCs after epithelial rhinovirus infection.

METHODS

Primary AECs were obtained from 11 children with asthma and 10 healthy children, differentiated at air-liquid interface, and cultured in the presence of laboratory of allergic diseases 2 (LAD2) MCs. AECs were infected with rhinovirus serogroup A 16 (RV16) for 48 hours. RNA isolated from both AECs and MCs underwent RNA sequencing. Direct effects of epithelial-derived interferons on LAD2 MCs were examined by real-time quantitative PCR.

RESULTS

MCs increased expression of proinflammatory and antiviral genes in AECs. AECs demonstrated a robust antiviral response after RV16 infection that resulted in significant changes in MC gene expression, including upregulation of genes involved in antiviral responses, leukocyte activation, and type 2 inflammation. Subsequent ex vivo modeling demonstrated that IFN-β induces MC type 2 gene expression. The effects of AEC donor phenotype were small relative to the effects of viral infection and the presence of MCs.

CONCLUSIONS

There is significant cross talk between AECs and MCs, which are present in the epithelium in asthma. Epithelial-derived interferons not only play a role in viral suppression but also further alter MC immune responses including specific type 2 genes.

BAF53A drives colorectal cancer development by regulating DUSP5-mediated ERK phosphorylation

BAF53A, an important subunit of the SWI/SNF epigenetic chromatin regulatory complex, has been implicated as the driver of diverse cancers. However, the role of BAF53A in colorectal cancer (CRC) remains poorly understood. Here, we examined the expression of BAF53A in CRC samples and observed that BAF53A was significantly upregulated in CRC tissues compared with paired adjacent normal tissues. In vitro and in vivo studies suggested that ectopic expression of BAF53A promoted colorectal cancer cell proliferation, colony formation, and tumorigenesis, whereas knockdown of BAF53A hindered these cellular functions. DUSP5 (dual-specificity phosphatase 5), an ERK1/2-specific endogenous phosphatase, was expressed at low levels in CRC. We found a negative correlation between BAF53A and DUSP5 expression in a set of CRC samples. Mechanistic studies revealed that P63 was a potential transcription repressor of DUSP5. BAF53A could interact with P63, decreasing the DUSP5 expression level and subsequently promoting ERK1/2 phosphorylation. Thus, our study provides insights into the applicability of the BAF53A-DUSP5-ERK1/2 axis as a potential therapeutic target in CRC.

Effect of Autolyzed Yarrowia lipolytica on the Growth Performance, Antioxidant Capacity, Intestinal Histology, Microbiota, and Transcriptome Profile of Juvenile Largemouth Bass (Micropterus salmoides)

The improper components of formulated feed can cause the intestinal dysbiosis of juvenile largemouth bass and further affect fish health. A 28 day feeding trial was conducted to investigate the effect of partially replacing fish meal (FM) with autolyzed Yarrowia lipolytica (YL) on juvenile largemouth bass (Micropterus salmoides). We considered four diets—control, YL25, YL50, and YL75—in which 0%, 25%, 50%, and 75% of the FM content, respectively, was replaced with YL. According to results, the weight gain rate (WGR) and specific growth rate (SGR) of the fish with the YL25 and YL50 diets were significantly higher than the WGR and SGR with the control diet, while the YL75 diet significantly reduced fish growth and antioxidant enzymes activities, and shortened the villus height in the intestinal mucosa. The 16S rRNA analysis of the intestinal microbiota showed that the relative abundance of Mycoplasma was significantly increased with the YL25 and YL50 diets, while the Enterobacteriacea content was increased with the YL75 diet. Moreover, our transcriptome analysis revealed that certain differentially expressed genes (DEGs) that are associated with growth, metabolism, and immunity were modulated by YL inclusion treatment. Dietary YL25 and YL50 significantly reduced the mRNA level of ERBB receptor feedback inhibitor 1 (errfi1) and dual-specificity phosphatases (dusp), while the expression of the suppressor of cytokine signaling 1 (socs1), the transporter associated with antigen processing 2 subunit type a (tap2a), and the major histocompatibility complex class I-related gene (MHC-I-l) were sharply increased with YL75 treatment. We determined that the optimum dose of dietary YL required for maximum growth without any adverse influence on intestinal health was 189.82 g/kg (with 31.63% of the fishmeal replaced by YL), while an excessive substitution of YL for fishmeal led to suppressed growth and antioxidant capacity, as well as intestinal damage for juvenile largemouth bass.

Suppression of mutant Kirsten-RAS (KRASG12D)-driven pancreatic carcinogenesis by dual-specificity MAP kinase phosphatases 5 and 6

The cytoplasmic phosphatase DUSP6 and its nuclear counterpart DUSP5 are negative regulators of RAS/ERK signalling. Here we use deletion of either Dusp5 or Dusp6 to explore the roles of these phosphatases in a murine model of KRASG12D-driven pancreatic cancer. By 56-days, loss of either DUSP5 or DUSP6 causes a significant increase in KRASG12D-driven pancreatic hyperplasia. This is accompanied by increased pancreatic acinar to ductal metaplasia (ADM) and the development of pre-neoplastic pancreatic intraepithelial neoplasia (PanINs). In contrast, by 100-days, pancreatic hyperplasia is reversed with significant atrophy of pancreatic tissue and weight loss observed in animals lacking either DUSP5 or DUSP6. On further ageing, Dusp6-/- mice display accelerated development of metastatic pancreatic ductal adenocarcinoma (PDAC), while in Dusp5-/- animals, although PDAC development is increased this process is attenuated by atrophy of pancreatic acinar tissue and severe weight loss in some animals before cancer could progress. Our data suggest that despite a common target in the ERK MAP kinase, DUSP5 and DUSP6 play partially non-redundant roles in suppressing oncogenic KRASG12D signalling, thus retarding both tumour initiation and progression. Our data suggest that loss of either DUSP5 or DUSP6, as observed in certain human tumours, including the pancreas, could promote carcinogenesis.

Emerging Functions of IL-33 in Homeostasis and Immunity

Our understanding of the functions of the IL-1 superfamily cytokine and damage-associated molecular pattern IL-33 continues to evolve with our understanding of homeostasis and immunity. The early findings that IL-33 is a potent driver of type 2 immune responses promoting parasite expulsion, but also inflammatory diseases like allergy and asthma, have been further supported. Yet, as the importance of a type 2 response in tissue repair and homeostasis has emerged, so has the fundamental importance of IL-33 to these processes. In this review, we outline an evolving understanding of IL-33 immunobiology, paying particular attention to how IL-33 directs a network of ST2+ regulatory T cells, reparative and regulatory macrophages, and type 2 innate lymphoid cells that are fundamental to tissue development, homeostasis, and repair.

Expected final online publication date for the Annual Review of Immunology, Volume 40 is April 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

IL-33 genetics and epigenetics in immune-related diseases

Interleukin-33 (IL-33) is a 30KDa protein, which belongs to the Interleukin-1 cytokine family. It is a crucial regulator of innate and adaptive immune responses. This interleukin is additionally involved in the inflammatory reaction versus helminthic infections. Interleukin 33 acts on group 2 innate lymphoid cells and mast cells macrophages, dendritic cells and CD4 + Th2 cells eliciting a type 2 immune response. Moreover, the cytokine can activate the ST2 of Tregs, demonstrating its ability to downregulate inflammation. IL-33 has also an intracellular function by regulating transcription. The active IL-33 doesn’t have a signal peptide, so it’s not released across a normal secretory pathway; the interleukin is released when the cells are damages and acts like an “alarmin”. Its influence on immune activation could be slightly adjusted via fine epigenetic interactions involving cascade pathways and immune genes. Due to the diverse data emerged from different experimental research, we decided span literature to clarify, as much as possible, how IL-33 is influenced by and influence gene expression. The authors reported how its balance is influenced, according to the tissue considered. Fundamental for immune-related diseases, IL-33 has a key role in controlling inflammation. The understanding of the cytokine switch will be fundamental in a near future in order to block or activate some immune pathways. In fact, we could control interleukins effects not only by monoclonal antibodies but also by using siRNA or miRNAs for silencing or expressing key genes.

Silencing of AFAP1-AS1 lncRNA impairs cell proliferation and migration by epigenetically promoting DUSP5 expression in pre-eclampsia

As a unique and common obstetric complication of pregnant women, pre-eclampsia (PE) has been the first leading cause of maternal and perinatal morbidity and mortality in the world. Mounting studies have demonstrated that an abnormality of long noncoding RNA (lncRNA) expression was related to the pathological process of PE. Here, we showed that lncRNA AFAP1-AS1 was markedly downregulated in pre-eclamptic placentas. We further investigated the mechanism underlying the regulatory role of AFAP1-AS1 in PE using human trophoblast cells. In vitro functional assays revealed that AFAP1-AS1 knockdown inhibited trophoblast proliferation, migration, and invasion. Moreover, AFAP1-AS1 interacts with EZH2 and inhibits DUSP5 expression through modulating H3K27m3 in the DUSP5 promoter of trophoblast cells, thus being involved in PE pathogenesis. Overall, these findings suggest that AFAP1-AS1 could potentially become a prognostic biomarker as well as a new therapeutic target for PE.

DUSP5 promotes osteogenic differentiation through SCP1/2-dependent phosphorylation of SMAD1

Dual‐specificity phosphatases (DUSPs) are defined by their capability to dephosphorylate both phosphoserine/phosphothreonine (pSer/pThr) and phosphotyrosine (pTyr). DUSP5, a member of DUSPs superfamily, is located in the nucleus and plays crucially regulatory roles in the signaling pathway transduction. In our present study, we discover that DUSP5 significantly promotes osteogenic differentiation of mesenchymal stromal cells (MSCs) by activating SMAD1 signaling pathway. Mechanistically, DUSP5 physically interacts with the phosphatase domain of small C‐terminal phosphatase 1/2 (SCP1/2, SMAD1 phosphatases) by the linker region. In addition, we further confirm that DUSP5 activates SMAD1 signaling through a SCP1/2‐dependent manner. Specifically, DUSP5 attenuates the SCP1/2‐SMAD1 interaction by competitively binding to SCP1/2, which is responsible for the SMAD1 dephosphorylation, and thus results in the activation of SMAD1 signaling. Importantly, DUSP5 expression in mouse bone marrow MSCs is significantly reduced in ovariectomized (OVX) mice in which osteogenesis is highly passive, and overexpression of Dusp5 via tail vein injection reverses the bone loss of OVX mice efficiently. Collectively, this work demonstrates that the linker region of DUSP5 maybe a novel chemically modifiable target for controlling MSCs fate choices and for osteoporosis treatment.

IL-3 is essential for ICOS-L stabilization on mast cells, and sustains the IL-33-induced RORγt+ Treg generation via enhanced IL-6 induction

IL-33 is a member of the IL-1 family. By binding to its receptor ST2 (IL-33R) on mast cells, IL-33 induces the MyD88-dependent activation of the TAK1-IKK2 signalling module resulting in activation of the MAP kinases p38, JNK1/2 and ERK1/2, and of NFκB. Depending on the kinases activated in these pathways, the IL-33-induced signalling is essential for production of IL-6 or IL-2. This was shown to control the dichotomy between RORγt+ and Helios+ Tregs , respectively. SCF, the ligand of c-Kit (CD117), can enhance these effects. Here, we show that IL-3, another growth factor for mast cells, is essential for the expression of ICOS-L on BMMCs, and costimulation with IL-3 potentiated the IL-33-induced IL-6 production similar to SCF. In contrast to the enhanced IL-2 production by SCF-induced modulation of the IL-33 signalling, IL-3 blocked the production of IL-2. Consequently, IL-3 shifted the IL-33-induced Treg dichotomy towards RORγt+ Tregs at the expense of RORγt- Helios+ Tregs . However, ICOS-L expression was downregulated by IL-33. In line with that, ICOS-L did not play any important role in the Treg modulation by IL-3/IL-33-activated mast cells. These findings demonstrate that different from the mast cell growth factor SCF, IL-3 can alter the IL-33-induced and mast cell-dependent regulation of Treg subpopulations by modulating mast cell-derived cytokine profiles.

SARS-CoV-2 Switches 'on' MAPK and NFκB Signaling via the Reduction of Nuclear DUSP1 and DUSP5 Expression

Mitogen-activated protein kinases (MAPK) and NF-kappaB (NF-κB) pathway regulate many cellular processes and are essential for immune cells function. Their activity is controlled by dual-specificity phosphatases (DUSPs). A comprehensive analysis of publicly available gene expression data sets of human airway epithelial cells (AECs) infected with SARS-CoV-2 identified DUSP1 and DUSP5 among the lowest induced transcripts within these pathways. These proteins are known to downregulate MAPK and NF-κB pathways; and their lower expression was associated with increased activity of MAPK and NF-κB signaling and enhanced expression of proinflammatory cytokines such as TNF-α. Infection with other coronaviruses did not have a similar effect on these genes. Interestingly, treatment with chloroquine and/or non-steroidal anti-inflammatory drugs counteracted the SARS-CoV-2 induced reduction of DUSP1 and DUSP5 genes expression. Therapeutically, impeding this evasion mechanism of SARS-CoV-2 may help control the exaggerated activation of these immune regulatory pathways during a COVID-19 infection.

Initiation and Pathogenesis of Severe Asthma with Fungal Sensitization

Fungi represent one of the most diverse and abundant eukaryotes on earth, and their ubiquity and small proteolytically active products make them pervasive allergens that affect humans and other mammals. The immunologic parameters surrounding fungal allergies are still not fully elucidated despite their importance given that a large proportion of severe asthmatics are sensitized to fungal allergens. Herein, we explore fungal allergic asthma with emphasis on mouse models that recapitulate the characteristics of human disease, and the main leukocyte players in the pathogenesis of fungal allergies. The endogenous mycobiome may also contribute to fungal asthma, a phenomenon that we discuss only superficially, as much remains to be discovered.

DUSP5 suppresses interleukin-1β-induced chondrocyte inflammation and ameliorates osteoarthritis in rats

Osteoarthritis (OA) is a chronic degenerative joint disease characterized by deterioration of articular cartilage. Dual specificity phosphatase 5 (DUSP5), a member of the DUSP subfamily, is known to regulate cellular inflammation. Here, we studied the relationship between DUSP5 and OA by knockdown and overexpression DUSP5, respectively. Results from in vitro experiments demonstrated that the knockdown of DUSP5 increased interleukin-1β (IL-1β)-induced expression of inflammatory genes, such as inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX2), and matrix metalloproteinases (MMPs) in chondrocytes, whereas it decreased the expression of anti-inflammatory genes, such as tissue inhibitor of metalloproteinase 3 (TIMP3) and IL-10. Conversely, the overexpression of DUSP5 suppressed the IL-1β-induced expression of iNOS, COX-2, and MMPs, and upregulated the expression of TIMP3 and IL-10. Moreover, knockdown of DUSP5 enhanced the IL-1β-induced activation of NF-κB and ERK pathways, whereas its overexpression inhibited these pathways. DUSP5 overexpression prevented cartilage degeneration in a rat OA model, while its knockdown reversed that effect. Our findings reveal that DUSP5 suppresses IL-1β-induced chondrocyte inflammation by inhibiting the NF-κB and ERK signaling pathways and ameliorates OA.

The Intestinal Epithelium at the Forefront of Host-Helminth Interactions

Gastrointestinal helminth infection still constitutes a major public health issue, particularly in the developing world. As these parasites can undergo a large part of their lifecycle within the intestinal tract the host has developed various structural and cellular specializations at the epithelial barrier to contend with infection. Detailed characterization of these cells will provide important insights about their contributions to the protective responses mediated against helminths. Here, we discuss how key components of the intestinal epithelium may function to limit the initial establishment of helminths, and how these cells are altered during an active response to infection.

microRNA-95 knockdown inhibits epithelial-mesenchymal transition and cancer stem cell phenotype in gastric cancer cells through MAPK pathway by upregulating DUSP5

This study investigated the role of microRNA-95 (miR-95) in gastric cancer (GC) and to elucidate the underlying mechanism. Initially, bioinformatic prediction was used to predict the differentially expressed genes and related miRNAs in GC. miR-95 and DUSP5 expression was altered in GC cell line (MGC803) to evaluate their respective effects on the epithelial-mesenchymal transition (EMT) process, cellular processes (cell proliferation, migration, invasion, cell cycle, and apoptosis), cancer stem cell (CSC) phenotype, as well as tumor growth ability. It was further predicted in bioinformatic prediction and verified in GC tissue and cell line experiments that miR-95 was highly expressed in GC. miR-95 negatively regulated DUSP5, which resulted in the MAPK pathway activation. Inhibited miR-95 or overexpressed DUSP5 was observed to inhibit the levels of CSC markers (CD133, CD44, ALDH1, and Lgr5), highlighting the inhibitory role in the CSC phenotype. More important, evidence was obtained demonstrating that miR-95 knockdown or DUSP5 upregulation exerted an inhibitory effect on the EMT process, cellular processes, and tumor growth. Together these results, miR-95 knockdown inhibited GC development via DUSP5-dependent MAPK pathway.

Influence of dual-specificity protein phosphatase 5 on mechanical properties of rat cerebral and renal arterioles

We recently reported that KO of Dual-specificity protein phosphatase 5 (Dusp5) enhances myogenic reactivity and blood flow autoregulation in the cerebral and renal circulations in association with increased levels of pPKC and pERK1/2 in the cerebral and renal arteries and arterioles. In the kidney, hypertension-related renal damage was significantly attenuated in Dusp5 KO rats. Elevations in pPKC and pERK1/2 promote calcium influx in VSMC and facilitate vasoconstriction. However, whether DUSP5 plays a role in altering the passive mechanical properties of cerebral and renal arterioles has never been investigated. In this study, we found that KO of Dusp5 did not alter body weights, kidney and brain weights, plasma glucose, and HbA1C levels. The expression of pERK is higher in the nucleus of primary VSMC isolated from Dusp5 KO rats. Dusp5 KO rats exhibited eutrophic vascular hypotrophy with smaller intracerebral parenchymal arterioles and renal interlobular arterioles without changing the wall-to-lumen ratios. These arterioles from Dusp5 KO rats displayed higher myogenic tones, better distensibility, greater compliance, and less stiffness compared with arterioles from WT control rats. VSMC of Dusp5 KO rats exhibited a stronger contractile capability. These results demonstrate, for the first time, that DUSP5 contributes to the regulation of the passive mechanical properties of cerebral and renal arterioles and provide new insights into the role of DUSP5 in vascular function, cancer, stroke, and other cardiovascular diseases.

A Dual Role for Macrophages in Modulating Lung Tissue Damage/Repair during L2 Toxocara canis Infection

Macrophages that are classically activated (M1) through the IFN-γ/STAT1 signaling pathway have a major role in mediating inflammation during microbial and parasitic infections. In some cases, unregulated inflammation induces tissue damage. In helminth infections, alternatively activated macrophages (M2), whose activation occurs mainly via the IL-4/STAT6 pathway, have a major role in mediating protection against excessive inflammation, and has been associated with both tissue repair and parasite clearance. During the lung migratory stage of Toxocara canis, the roles of M1 and M2 macrophages in tissue repair remain unknown. To assess this, we orally infected wild-type (WT) and STAT1 and STAT6-deficient mice (STAT1^-/- and STAT6^-/-) with L2 T. canis, and evaluated the role of M1 or M2 macrophages in lung pathology. The absence of STAT1 favored an M2 activation pattern with Arg1, FIZZ1, and Ym1 expression, which resulted in parasite resistance and lung tissue repair. In contrast, the absence of STAT6 induced M1 activation and iNOS expression, which helped control parasitic infection but generated increased inflammation and lung pathology. Next, macrophages were depleted by intratracheally inoculating mice with clodronate-loaded liposomes. We found a significant reduction in alveolar macrophages that was associated with higher lung pathology in both WT and STAT1^-/- mice; in contrast, STAT6^-/- mice receiving clodronate-liposomes displayed less tissue damage, indicating critical roles of both macrophage phenotypes in lung pathology and tissue repair. Therefore, a proper balance between inflammatory and anti-inflammatory responses during T. canis infection is necessary to limit lung pathology and favor lung healing.

Knockout of Dual-Specificity Protein Phosphatase 5 Protects Against Hypertension-Induced Renal Injury

Dual-specificity protein phosphatase 5 (DUSP5) is a member of the tyrosine-threonine phosphatase family with the ability to dephosphorylate and inactivate extracellular signal-related kinase (ERK). The present study investigates whether knockout (KO) of Dusp5 improves renal hemodynamics and protects against hypertension-induced renal injury. The renal expression of DUSP5 was reduced, and the levels of phosphorylated (p) ERK1/2 and p-protein kinase C (PKC) α were elevated in the KO rats. KO of Dusp5 enhanced the myogenic tone of the renal afferent arteriole and interlobular artery in vitro with or without induction of deoxycorticosterone acetate-salt hypertension. Inhibition of ERK1/2 and PKC diminished the myogenic response to a greater extent in Dusp5 KO rats. Autoregulation of renal blood flow was significantly impaired in hypertensive wild-type (WT) rats but remained intact in Dusp5 KO animals. Proteinuria was markedly decreased in hypertensive KO versus WT rats. The degree of glomerular injury was reduced, and the expression of nephrin in the glomerulus was higher in hypertensive Dusp5 KO rats. Renal fibrosis and medullary protein cast formation were attenuated in hypertensive Dusp5 KO rats in association with decreased expression of monocyte chemoattractant protein 1, transforming growth factor-β1, matrix metalloproteinase (MMP) 2, and MMP9. These results indicate that KO of Dusp5 protects against hypertension-induced renal injury, at least in part, by maintaining the myogenic tone of the renal vasculature and extending the range of renal blood flow autoregulation to higher pressures, which diminish glomerular injury, protein cast formation, macrophage infiltration, and epithelial-mesenchymal transformation in the kidney. SIGNIFICANCE STATEMENT: Dual-specificity protein phosphatase 5 (DUSP5) is a tyrosine-threonine phosphatase that inactivates extracellular signal-related kinase (ERK). We previously reported that knockout (KO) of Dusp5 enhanced the myogenic response and autoregulation in the cerebral circulation. The present study investigates whether KO of DUSP5 improves renal hemodynamics and protects against hypertension-induced renal injury. Downregulation of DUSP5 enhanced the myogenic tone of renal arteriole and artery and autoregulation of renal blood flow in association with reduced proteinuria, glomerular injury, and interstitial fibrosis after the induction of hypertension. Inhibition of ERK1/2 and protein kinase C diminished the myogenic response to a greater extent in Dusp5 KO rats. These results suggest that DUSP5 might be a viable drug target for the treatment of hypertension nephropathy.

Dual-Specificity Phosphatases in Immunity and Infection: An Update

Kinase activation and phosphorylation cascades are key to initiate immune cell activation in response to recognition of antigen and sensing of microbial danger. However, for balanced and controlled immune responses, the intensity and duration of phospho-signaling has to be regulated. The dual-specificity phosphatase (DUSP) gene family has many members that are differentially expressed in resting and activated immune cells. Here, we review the progress made in the field of DUSP gene function in regulation of the immune system during the last decade. Studies in knockout mice have confirmed the essential functions of several DUSP-MAPK phosphatases (DUSP-MKP) in controlling inflammatory and anti-microbial immune responses and support the concept that individual DUSP-MKP shape and determine the outcome of innate immune responses due to context-dependent expression and selective inhibition of different mitogen-activated protein kinases (MAPK). In addition to the canonical DUSP-MKP, several small-size atypical DUSP proteins regulate immune cells and are therefore also reviewed here. Unexpected and complex findings in DUSP knockout mice pose new questions regarding cell type-specific and redundant functions. Another emerging question concerns the interaction of DUSP-MKP with non-MAPK binding partners and substrate proteins. Finally, the pharmacological targeting of DUSPs is desirable to modulate immune and inflammatory responses.

Mechanisms by which sialylated milk oligosaccharides impact bone biology in a gnotobiotic mouse model of infant undernutrition

Identifying components of breast milk that influence postnatal development though their effects on the gut microbiota and immune system could provide new therapeutic approaches for childhood undernutrition, including heretofore treatment-refractory linear growth faltering (stunting). Plasma biomarkers of osteoclast-mediated bone resorption and osteoblast-driven bone formation in stunted Bangladeshi children provided evidence for elevated osteoclastic activity. Gnotobiotic mice, colonized with a stunted infant’s gut microbiota, exhibited decreased bone resorption when consuming diets supplemented with a purified bovine oligosaccharide mixture dominated by sialylated structures found in human breast milk. Supplementation decreased osteoclastogenesis while sparing osteoblast activity; the microbiota, intestinal cell populations, and immune mediators contribute to these responses. The influence of milk oligosaccharides on the gut microbiota–bone axis has diagnostic and therapeutic implications.

Undernutrition in children is a pressing global health problem, manifested in part by impaired linear growth (stunting). Current nutritional interventions have been largely ineffective in overcoming stunting, emphasizing the need to obtain better understanding of its underlying causes. Treating Bangladeshi children with severe acute malnutrition with therapeutic foods reduced plasma levels of a biomarker of osteoclastic activity without affecting biomarkers of osteoblastic activity or improving their severe stunting. To characterize interactions among the gut microbiota, human milk oligosaccharides (HMOs), and osteoclast and osteoblast biology, young germ-free mice were colonized with cultured bacterial strains from a 6-mo-old stunted infant and fed a diet mimicking that consumed by the donor population. Adding purified bovine sialylated milk oligosaccharides (S-BMO) with structures similar to those in human milk to this diet increased femoral trabecular bone volume and cortical thickness, reduced osteoclasts and their bone marrow progenitors, and altered regulators of osteoclastogenesis and mediators of Th2 responses. Comparisons of germ-free and colonized mice revealed S-BMO-dependent and microbiota-dependent increases in cecal levels of succinate, increased numbers of small intestinal tuft cells, and evidence for activation of a succinate-induced tuft cell signaling pathway linked to Th2 immune responses. A prominent fucosylated HMO, 2′-fucosyllactose, failed to elicit these changes in bone biology, highlighting the structural specificity of the S-BMO effects. These results underscore the need to further characterize the balance between, and determinants of, osteoclastic and osteoblastic activity in stunted infants/children, and suggest that certain milk oligosaccharides may have therapeutic utility in this setting.

Discovery and Characterization of Halogenated Xanthene Inhibitors of DUSP5 as Potential Photodynamic Therapeutics

Dual specific phosphatases (DUSPs) are an important class of mitogen-activated protein kinase (MAPK) regulators, and are drug targets for treating vascular diseases. Previously we had shown that DUSP5 plays a role in embryonic vertebrate vascular patterning. Herein, we screened a library of FDA-approved drugs and related compounds, using a para-nitrophenylphosphate substrate (pNPP)-based assay. This assay identified merbromin (also known as mercurochrome) as targeting DUSP5; and, we subsequently identified xanthene-ring based merbromin analogs eosin Y, erythrosin B, and rose bengal, all of which inhibit DUSP5 in vitro. Inhibition was time-dependent for merbromin, eosin Y, 2',7'-dibromofluorescein, and 2',7'-dichlorofluorescein, with enzyme inhibition increasing over time. Reaction progress curve data fit best to a slow-binding model of irreversible enzyme inactivation. Potency of the time-dependent compounds, except for 2',7'-dichlorofluorescein, was diminished when dithiothreitol (DTT) was present, suggesting thiol reactivity. Two additional merbromin analogs, erythrosin B and rose bengal also inhibit DUSP5, but have the therapeutic advantage of being less sensitive to DTT and exhibiting little time dependence for inhibition. Inhibition potency is correlated with the xanthene dye's LUMO energy, which affects ability to form light-activated radical anions, a likely active inhibitor form. Consistent with this hypothesis, rose bengal inhibition is light-dependent and demonstrates the expected red shifted spectrum upon binding to DUSP5, with a Kd of 690 nM. These studies provide a mechanistic foundation for further development of xanthene dyes for treating vascular diseases that respond to DUSP5 inhibition, with the following relative potencies: rose bengal > merbromin > erythrosin B > eosin Y.

Dual-specificity phosphatase 5 suppresses ovarian cancer progression by inhibiting IL-33 signaling

Ovarian cancer (OC) is the leading cause of death from gynecological malignancy. Dual-specificity phosphatases (DUSPs) are proteins that are reported involved in carcinogenesis, but their roles in OC have not be extensively studied. Here, we found that DUSP5 is markedly down-regulated in OC tissues. We reanalyzed DUSP5 expression in OC using published microarray data from the Gene Expression Omnibus (GEO) database and found that patients with low DUSP5 expression have significantly shorter overall survival than those with high expression (P < 0.001). Down-regulation of DUSP5 in OC tissues was immunohistochemically confirmed in tissue microarrays containing 15 normal ovary tissue samples and 60 OC specimens. Functional studies suggest that DUSP5 silence facilitates cell proliferation, migration, and invasion of OC cells in vitro. DUSP5 over-expression inhibits cell proliferation but has no effect on OC cell migration or invasion. Mechanistically, silencing DUSP5 transcriptionally activates interleukin 33 (IL-33) expression and secretion. Blockage of IL-33 with a neutralizing anti-IL33 antibody attenuates the effect of DUSP5 silencing to promote cell proliferation, migration, and invasion. Moreover, recombinant IL-33 protein treatment dramatically promotes OC cell proliferation, migration, and invasion with DUSP5 over-expression. Our study provides proof of principle that DUSP5 down-regulation promotes proliferation, migration, and invasion of OC cells via activation of IL-33 signaling.

DUSP10 constrains innate IL-33-mediated cytokine production in ST2hi memory-type pathogenic Th2 cells

ST2^hi memory-type Th2 cells are identified as a pathogenic subpopulation in eosinophilic airway inflammation. These ST2^hi pathogenic Th2 cells produce large amount of IL-5 upon T cell receptor stimulation, but not in response to IL-33 treatment. By contrast, IL-33 alone induces cytokine production in ST2⁺ group 2 innate lymphoid cells (ILC2). Here we show that a MAPK phosphatase Dusp10 is a key negative regulator of IL-33-induced cytokine production in Th2 cells. In this regard, Dusp10 is expressed by ST2^hi pathogenic Th2 cells but not by ILC2, and Dusp10 expression inhibits IL-33-induced cytokine production. Mechanistically, this inhibition is mediated by DUSP10-mediated dephosphorylation and inactivation of p38 MAPK, resulting in reduced GATA3 activity. The deletion of Dusp10 renders ST2^hi Th2 cells capable of producing IL-5 by IL-33 stimulation. Our data thus suggest that DUSP10 restricts IL-33-induced cytokine production in ST2^hi pathogenic Th2 cells by controlling p38-GATA3 activity.

T helper 2 (Th2) cells and type 2 innate lymphoid cells (ILC2) respond differently to interleukin-33 (IL-33) stimulation. Here the authors show that a phosphatase, Dusp10, is expressed in Th2, but not ILC2, to dephosphorylate p38 kinase, reduce GATA3 transcription factor activity, and suppress the induction of IL-5 in response to IL-33.

Dual-specificity MAP kinase phosphatases in health and disease

It is well established that a family of dual-specificity MAP kinase phosphatases (MKPs) play key roles in the regulated dephosphorylation and inactivation of MAP kinase isoforms in mammalian cells and tissues. MKPs provide a mechanism of spatiotemporal feedback control of these key signalling pathways, but can also mediate crosstalk between distinct MAP kinase cascades and facilitate interactions between MAP kinase pathways and other key signalling modules. As our knowledge of the regulation, substrate specificity and catalytic mechanisms of MKPs has matured, more recent work using genetic models has revealed key physiological functions for MKPs and also uncovered potentially important roles in regulating the pathophysiological outcome of signalling with relevance to human diseases. These include cancer, diabetes, inflammatory and neurodegenerative disorders. It is hoped that this understanding will reveal novel therapeutic targets and biomarkers for disease, thus contributing to more effective diagnosis and treatment for these debilitating and often fatal conditions.

•

A comprehensive review of the dual-specificity MAP kinase Phosphatases (MKPs)

•

Focus is on MKPs in the regulation of MAPK signalling in health and disease.

•

Covers roles of MKPs in inflammation, obesity/diabetes, cancer and neurodegeneration

Review and Meta-Analyses of TAAR1 Expression in the Immune System and Cancers

Since its discovery in 2001, the major focus of TAAR1 research has been on its role in monoaminergic regulation, drug-induced reward and psychiatric conditions. More recently, TAAR1 expression and functionality in immune system regulation and immune cell activation has become a topic of emerging interest. Here, we review the immunologically-relevant TAAR1 literature and incorporate open-source expression and cancer survival data meta-analyses. We provide strong evidence for TAAR1 expression in the immune system and cancers revealed through NCBI GEO datamining and discuss its regulation in a spectrum of immune cell types as well as in numerous cancers. We discuss connections and logical directions for further study of TAAR1 in immunological function, and its potential role as a mediator or modulator of immune dysregulation, immunological effects of psychostimulant drugs of abuse, and cancer progression.

Long Non-Coding RNAs in Multifactorial Diseases: Another Layer of Complexity

Multifactorial diseases such as cancer, cardiovascular conditions and neurological, immunological and metabolic disorders are a group of diseases caused by the combination of genetic and environmental factors. High-throughput RNA sequencing (RNA-seq) technologies have revealed that less than 2% of the genome corresponds to protein-coding genes, although most of the human genome is transcribed. The other transcripts include a large variety of non-coding RNAs (ncRNAs), and the continuous generation of RNA-seq data shows that ncRNAs are strongly deregulated and may be important players in pathological processes. A specific class of ncRNAs, the long non-coding RNAs (lncRNAs), has been intensively studied in human diseases. For clinical purposes, lncRNAs may have advantages mainly because of their specificity and differential expression patterns, as well as their ideal qualities for diagnosis and therapeutics. Multifactorial diseases are the major cause of death worldwide and many aspects of their development are not fully understood. Recent data about lncRNAs has improved our knowledge and helped risk assessment and prognosis of these pathologies. This review summarizes the involvement of some lncRNAs in the most common multifactorial diseases, with a focus on those with published functional data.

Regulation of eosinophil development and survival

PURPOSE OF REVIEW

Eosinophils are a subset of granulocytes generally associated with type 2 immune responses. They can contribute to protection against helminths but also mediate pro-inflammatory functions during allergic immune responses. Only recently, eosinophils were also found to exert many other functions such as regulation of glucose and fat metabolism, thermogenesis, survival of plasma cells, and antitumor activity. The mechanisms that control eosinophil development and survival are only partially understood.

RECENT FINDINGS

Here we review new findings regarding the role of cell-extrinsic and cell-intrinsic factors for eosinophilopoiesis and eosinophil homeostasis. Several reports provide new insights in the regulation of eosinophil development by transcription factors, miRNAs and epigenetic modifications. Danger signals like lipopolysaccharide or alarmins can activate eosinophils but also prolong their lifespan. We further reflect on the observations that eosinophil development is tightly controlled by the unfolded protein stress response and formation of cytoplasmic granules.

SUMMARY

Eosinophils emerge as important regulators of diverse biological processes. Their differentiation and survival is tightly regulated by factors that are still poorly understood. Newly identified pathways involved in eosinophilopoiesis and eosinophil homeostasis may lead to development of new therapeutic options for treatment of eosinophil-associated diseases.

DUSP5 functions as a feedback regulator of TNFα-induced ERK1/2 dephosphorylation and inflammatory gene expression in adipocytes

Adipose tissue inflammation is a central pathological element that regulates obesity-mediated insulin resistance and type II diabetes. Evidence demonstrates that extracellular signal-regulated kinase (ERK 1/2) activation (i.e. phosphorylation) links tumor necrosis factor α (TNFα) to pro-inflammatory gene expression in the nucleus. Dual specificity phosphatases (DUSPs) inactivate ERK 1/2 through dephosphorylation and can thus inhibit inflammatory gene expression. We report that DUSP5, an ERK1/2 phosphatase, was induced in epididymal white adipose tissue (WAT) in response to diet-induced obesity. Moreover, DUSP5 mRNA expression increased during obesity development concomitant to increases in TNFα expression. Consistent with in vivo findings, DUSP5 mRNA expression increased in adipocytes in response to TNFα, parallel with ERK1/2 dephosphorylation. Genetic loss of DUSP5 exacerbated TNFα-mediated ERK 1/2 signaling in 3T3-L1 adipocytes and in adipose tissue of mice. Furthermore, inhibition of ERK 1/2 and c-Jun N terminal kinase (JNK) signaling attenuated TNFα-induced DUSP5 expression. These data suggest that DUSP5 functions in the feedback inhibition of ERK1/2 signaling in response to TNFα, which resulted in increased inflammatory gene expression. Thus, DUSP5 potentially acts as an endogenous regulator of adipose tissue inflammation; although its role in obesity-mediated inflammation and insulin signaling remains unclear.

Dual Specificity Phosphatase 5-Substrate Interaction: A Mechanistic Perspective

The mammalian genome contains approximately 200 phosphatases that are responsible for catalytically removing phosphate groups from proteins. In this review, we discuss dual specificity phosphatase 5 (DUSP5). DUSP5 belongs to the dual specificity phosphatase (DUSP) family, so named after the family members' abilities to remove phosphate groups from serine/threonine and tyrosine residues. We provide a comparison of DUSP5's structure to other DUSPs and, using molecular modeling studies, provide an explanation for DUSP5's mechanistic interaction and specificity toward phospho-extracellular regulated kinase, its only known substrate. We also discuss new insights from molecular modeling studies that will influence our current thinking of mitogen-activated protein kinase signaling. Finally, we discuss the lessons learned from identifying small molecules that target DUSP5, which might benefit targeting efforts for other phosphatases. © 2017 American Physiological Society. Compr Physiol 7:1449-1461, 2017.

Serendipitous discovery of light-induced (In Situ) formation of an Azo-bridged dimeric sulfonated naphthol as a potent PTP1B inhibitor

BACKGROUND

Protein tyrosine phosphatases (PTPs) like dual specificity phosphatase 5 (DUSP5) and protein tyrosine phosphatase 1B (PTP1B) are drug targets for diseases that include cancer, diabetes, and vascular disorders such as hemangiomas. The PTPs are also known to be notoriously difficult targets for designing inihibitors that become viable drug leads. Therefore, the pipeline for approved drugs in this class is minimal. Furthermore, drug screening for targets like PTPs often produce false positive and false negative results.

RESULTS

Studies presented herein provide important insights into: (a) how to detect such artifacts, (b) the importance of compound re-synthesis and verification, and (c) how in situ chemical reactivity of compounds, when diagnosed and characterized, can actually lead to serendipitous discovery of valuable new lead molecules. Initial docking of compounds from the National Cancer Institute (NCI), followed by experimental testing in enzyme inhibition assays, identified an inhibitor of DUSP5. Subsequent control experiments revealed that this compound demonstrated time-dependent inhibition, and also a time-dependent change in color of the inhibitor that correlated with potency of inhibition. In addition, the compound activity varied depending on vendor source. We hypothesized, and then confirmed by synthesis of the compound, that the actual inhibitor of DUSP5 was a dimeric form of the original inhibitor compound, formed upon exposure to light and oxygen. This compound has an IC50 of 36 μM for DUSP5, and is a competitive inhibitor. Testing against PTP1B, for selectivity, demonstrated the dimeric compound was actually a more potent inhibitor of PTP1B, with an IC50 of 2.1 μM. The compound, an azo-bridged dimer of sulfonated naphthol rings, resembles previously reported PTP inhibitors, but with 18-fold selectivity for PTP1B versus DUSP5.

CONCLUSION

We report the identification of a potent PTP1B inhibitor that was initially identified in a screen for DUSP5, implying common mechanism of inhibitory action for these scaffolds.

Understanding Interleukin 33 and Its Roles in Eosinophil Development

Over the last decade, significant interest in the contribution of three “epithelial-derived cytokines,” such as thymic stromal lymphopoietin, interleukin 25, and interleukin 33 (IL-33), has developed. These cytokines have been strongly linked to the early events that occur during allergen exposures and how they contribute to the subsequent type 2 immune response. Of these three cytokines, IL-33 has proven particularly interesting because of the strong associations found between both it and its receptor, ST2, in several genome-wide association studies of allergic diseases. Further work has demonstrated clear mechanisms through which this cytokine might orchestrate allergic inflammation, including activation of several key effector cells that possess high ST2 levels, including mast cells, basophils, innate lymphoid cells, and eosinophils. Despite this, controversies surrounding IL-33 seem to suggest the biology of this cytokine might not be as simple as current dogmas suggest including: the relevant cellular sources of IL-33, with significant evidence for inducible expression in some hematopoietic cells; the mechanistic contributions of nuclear localization vs secretion; secretion and processing mechanisms; and the biological consequences of IL-33 exposure on different cell types. In this review, we will address the evidence for IL-33 and ST2 regulation over eosinophils and how this may contribute to allergic diseases. In particular, we focus on the accumulating evidence for a role of IL-33 in regulating hematopoiesis and how this relates to eosinophils as well as how this may provide new concepts for how the progression of allergy is regulated.

Dual-specificity phosphatase 5 controls the localized inhibition, propagation, and transforming potential of ERK signaling

Deregulated extracellular signal-regulated kinase (ERK) signaling drives cancer growth. Normally, ERK activity is self-limiting by the rapid inactivation of upstream kinases and delayed induction of dual-specificity MAP kinase phosphatases (MKPs/DUSPs). However, interactions between these feedback mechanisms are unclear. Here we show that, although the MKP DUSP5 both inactivates and anchors ERK in the nucleus, it paradoxically increases and prolongs cytoplasmic ERK activity. The latter effect is caused, at least in part, by the relief of ERK-mediated RAF inhibition. The importance of this spatiotemporal interaction between these distinct feedback mechanisms is illustrated by the fact that expression of oncogenic BRAF^V600E, a feedback-insensitive mutant RAF kinase, reprograms DUSP5 into a cell-wide ERK inhibitor that facilitates cell proliferation and transformation. In contrast, DUSP5 deletion causes BRAF^V600E-induced ERK hyperactivation and cellular senescence. Thus, feedback interactions within the ERK pathway can regulate cell proliferation and transformation, and suggest oncogene-specific roles for DUSP5 in controlling ERK signaling and cell fate.

Dual Specificity Phosphatase 5 Is Essential for T Cell Survival

The mitogen-activated protein kinase (MAPK) pathway regulates many key cellular processes such as differentiation, apoptosis, and survival. The final proteins in this pathway, ERK1/2, are regulated by dual specificity phosphatase 5 (DUSP5). DUSP5 is a nuclear, inducible phosphatase with high affinity and fidelity for ERK1/2. By regulating the final step in the MAPK signaling cascade, DUSP5 exerts strong regulatory control over a central cellular pathway. Like other DUSPs, DUSP5 plays an important role in immune function. In this study, we have utilized new knockout mouse reagents to explore its function further. We demonstrate that global loss of DUSP5 does not result in any gross phenotypic changes. However, loss of DUSP5 affects memory/effector CD8⁺ T cell populations in response to acute viral infection. Specifically, Dusp5^-/- mice have decreased proportions of short-lived effector cells (SLECs) and increased proportions of memory precursor effector cells (MPECs) in response to infection. Further, we show that this phenotype is T cell intrinsic; a bone marrow chimera model restricting loss of DUSP5 to the CD8⁺ T cell compartment displays a similar phenotype. Dusp5^-/- T cells also display increased proliferation, increased apoptosis, and altered metabolic profiles, suggesting that DUSP5 is a pro-survival protein in T cells.

IL-33-Induced Cytokine Secretion and Survival of Mouse Eosinophils Is Promoted by Autocrine GM-CSF

Eosinophils are major effector cells during allergic responses and helminth infections. Recent studies further highlight eosinophils as important players in many other biological processes. Therefore it is important to understand how these cells can be modulated in terms of survival and effector function. In the present study we investigated how eosinophils respond to the alarmin IL-33. We show that IL-33 promotes eosinophil survival in a ST2- and MyD88-dependent manner. IL-33-mediated protection from apoptosis was dependent on autocrine GM-CSF release. In addition, GM-CSF increased the IL-33-induced secretion of IL-4 and IL-13 from eosinophils. Unexpectedly, this effect was further enhanced by cross-linking of Siglec-F, a proposed inhibitory and apopotosis-inducing receptor on eosinophils. Co-culture experiments with eosinophils and macrophages revealed that the IL-33-induced release of IL-4 and IL-13 from eosinophils was required for differentiation of alternatively activated macrophages (AAMs). The differentiation of AAMs could be further increased in the presence of GM-CSF. These results indicate that cross-talk between Siglec-F and the receptors for IL-33, LPS and GM-CSF plays an important role for efficient secretion of IL-4 and IL-13. Deciphering the molecular details of this cross-talk could lead to the development of new therapeutic option to treat eosinophil-associated diseases.

Role of Macrophages in the Repair Process during the Tissue Migrating and Resident Helminth Infections

The Th1/Th2/Th17 balance is a fundamental feature in the regulation of the inflammatory microenvironment during helminth infections, and an imbalance in this paradigm greatly contributes to inflammatory disorders. In some cases of helminthiasis, an initial Th1 response could occur during the early phases of infection (acute), followed by a Th2 response that prevails in chronic infections. During the late phase of infection, alternatively activated macrophages (AAMs) are important to counteract the inflammation caused by the Th1/Th17 response and larval migration, limiting damage and repairing the tissue affected. Macrophages are the archetype of phagocytic cells, with the primary role of pathogen destruction and antigen presentation. Nevertheless, other subtypes of macrophages have been described with important roles in tissue repair and immune regulation. These types of macrophages challenge the classical view of macrophages activated by an inflammatory response. The role of these subtypes of macrophages during helminthiasis is a controversial topic in immunoparasitology. Here, we analyze some of the studies regarding the role of AAMs in tissue repair during the tissue migration of helminths.

Long noncoding RNA H19 controls DUSP5/ERK1/2 axis in cardiac fibroblast proliferation and fibrosis

Down-regulation of DUSP5 has been shown to increase cell proliferation. DUSP5 expression is regulated through epigenetic events involving LncRNA H19 human choriocarcinoma cell line. However, the molecular mechanisms of H19 modulating the DUSP5 expression in cardiac fibrosis remain largely unknown. Here, we identify H19 negatively regulation of DUSP5 gene expression in cardiac fibroblast and fibrosis tissues. In vivo, the expression levels of H19, DUSP5, α-SMA, p-ERK1/2, and ERK1/2 in cardiac fibrosis tissue were estimated by Western blotting, quantitative reverse transcription-polymerase chain reaction and immunohistochemistry. In vitro stimulation of freshly isolated rat cardiac fibroblasts with recombinant marine TGF-β1 was performed, followed by quantitative reverse transcription-polymerase chain reaction and Western blotting to detect changes in H19, DUSP5, p-ERK1/2, and ERK1/2 levels. Cardiac fibroblasts were transfected with pEX-3-H19 overexpressing, H19-RNAi down-regulating, or pEGFP-C1-DUSP5 overexpressing. Finally, cell proliferation was assessed by the MTT assay and cell cycle. H19 endogenous expression is overexpressed in cardiac fibroblast and fibrosis tissues, and an opposite pattern is observed for DUSP5. H19 ectopic overexpression reduces DUSP5 abundance and increases the proliferation of cardiac fibroblast, whereas H19 silencing causes the opposite effects. In a broader perspective, these results demonstrated that LncRNA H19 contributes to cardiac fibroblast proliferation and fibrosis, which act in part through repression of DUSP5/ERK1/2.

A Player and Coordinator: The Versatile Roles of Eosinophils in the Immune System

Eosinophils have traditionally been associated with allergic diseases and parasite infection. Research advances in the recent decades have brought evolutionary changes in our understanding of eosinophil biology and its roles in immunity. It is currently recognized that eosinophils play multiple roles in both innate and adaptive immunity. As effector cells in innate immunity, eosinophils exert a pro-inflammatory and destructive role in the Th2 immune response associated with allergic inflammation or parasite infection. Eosinophils can also be recruited by danger signals released by pathogen infections or tissue injury, inducing host defense against parasitic, fungal, bacterial or viral infection or promoting tissue repair and remodeling. Eosinophils also serve as nonprofessional antigen-presenting cells in response to allergen challenge or helminth infection, and, meanwhile, are known to function as a versatile coordinator that actively regulates or interacts with various immune cells including T lymphocytes and dendritic cells. More roles of eosinophils implicated in immunity have been proposed including in immune homeostasis, allograft rejection, and anti-tumor immunity. Eosinophil interactions with structural cells are also implicated in the mechanisms in allergic inflammation and in Helicobacter pylori gastritis. These multifaceted roles of eosinophils as both players and coordinators in immune system are discussed in this review.

The regulation of oncogenic Ras/ERK signalling by dual-specificity mitogen activated protein kinase phosphatases (MKPs)

Dual-specificity MAP kinase (MAPK) phosphatases (MKPs or DUSPs) are well-established negative regulators of MAPK signalling in mammalian cells and tissues. By virtue of their differential subcellular localisation and ability to specifically recognise, dephosphorylate and inactivate different MAPK isoforms, they are key spatiotemporal regulators of pathway activity. Furthermore, as they are transcriptionally regulated as downstream targets of MAPK signalling they can either act as classical negative feedback regulators or mediate cross talk between distinct MAPK pathways. Because MAPKs and particularly Ras/ERK signalling are implicated in cancer initiation and development, the observation that MKPs are abnormally regulated in human tumours has been interpreted as evidence that these enzymes can either suppress or promote carcinogenesis. However, definitive evidence of such roles has been lacking. Here we review recent work based on the use of mouse models, biochemical studies and clinical data that demonstrate key roles for MKPs in modulating the oncogenic potential of Ras/ERK signalling and also indicate that these enzymes may play a role in the response of tumours to certain anticancer drugs. Overall, this work reinforces the importance of negative regulatory mechanisms in modulating the activity of oncogenic MAPK signalling and indicates that MKPs may provide novel targets for therapeutic intervention in cancer.

The phosphatase DUSP2 controls the activity of the transcription activator STAT3 and regulates TH17 differentiation

Deregulation of the TH17 subset of helper T cells is closely linked with immunological disorders and inflammatory diseases. However, the mechanism by which TH17 cells are regulated remains elusive. Here we found that the phosphatase DUSP2 (PAC1) negatively regulated the development of TH17 cells. DUSP2 was directly associated with the signal transducer and transcription activator STAT3 and attenuated its activity through dephosphorylation of STAT3 at Tyr705 and Ser727. DUSP2-deficient mice exhibited severe susceptibility to experimental colitis, with enhanced differentiation of TH17 cells and secretion of proinflammatory cytokines. In clinical patients with ulcerative colitis, DUSP2 was downregulated by DNA methylation and was not induced during T cell activation. Our data demonstrate that DUSP2 is a true STAT3 phosphatase that modulates the development of TH17 cells in the autoimmune response and inflammation.

Identification of inhibitors that target dual-specificity phosphatase 5 provide new insights into the binding requirements for the two phosphate pockets

BACKGROUND

Dual-specificity phosphatase-5 (DUSP5) plays a central role in vascular development and disease. We present a p-nitrophenol phosphate (pNPP) based enzymatic assay to screen for inhibitors of the phosphatase domain of DUSP5.

METHODS

pNPP is a mimic of the phosphorylated tyrosine on the ERK2 substrate (pERK2) and binds the DUSP5 phosphatase domain with a Km of 7.6 ± 0.4 mM. Docking followed by inhibitor verification using the pNPP assay identified a series of polysulfonated aromatic inhibitors that occupy the DUSP5 active site in the region that is likely occupied by the dual-phosphorylated ERK2 substrate tripeptide (pThr-Glu-pTyr). Secondary assays were performed with full length DUSP5 with ERK2 as substrate.

RESULTS

The most potent inhibitor has a naphthalene trisulfonate (NTS) core. A search for similar compounds in a drug database identified suramin, a dimerized form of NTS. While suramin appears to be a potent and competitive inhibitor (25 ± 5 μM), binding to the DUSP5 phosphatase domain more tightly than the monomeric ligands of which it is comprised, it also aggregates. Further ligand-based screening, based on a pharmacophore derived from the 7 Å separation of sulfonates on inhibitors and on sulfates present in the DUSP5 crystal structure, identified a disulfonated and phenolic naphthalene inhibitor (CSD (3) _2320) with IC₅₀ of 33 μM that is similar to NTS and does not aggregate.

CONCLUSIONS

The new DUSP5 inhibitors we identify in this study typically have sulfonates 7 Å apart, likely positioning them where the two phosphates of the substrate peptide (pThr-Glu-pTyr) bind, with one inhibitor also positioning a phenolic hydroxyl where the water nucleophile may reside. Polysulfonated aromatic compounds do not commonly appear in drugs and have a tendency to aggregate. One FDA-approved polysulfonated drug, suramin, inhibits DUSP5 and also aggregates. Docking and modeling studies presented herein identify polysulfonated aromatic inhibitors that do not aggregate, and provide insights to guide future design of mimics of the dual-phosphate loops of the ERK substrates for DUSPs.