1,720,979 research outputs found
A CURIous Case of Molecular Kidnapping
No full textIn this issue of Molecular Cell, Albert et al. (2016) demonstrate how the production of rRNA and ribosomal proteins is coordinated through a two-step response to stress that requires cross-talk between a dedicated transcription factor and a ribosome assembly factor. (c) 2016 Elsevier Inc.111sciescopu
Emerging Functions of Regulatory T Cells in Tissue Homeostasis
Full text linkCD4+Foxp3+ regulatory T-cells (Tregs) are a unique subset of helper T-cells, which regulate immune response and establish peripheral tolerance. Tregs not only maintain the tone and tenor of an immune response by dominant tolerance but, in recent years, have also been identified as key players in resolving tissue inflammation and as mediators of tissue healing. Apart from being diverse in their origin (thymic and peripheral) and location (lymphoid and tissue resident), Tregs are also phenotypically heterogeneous as per the orientation of ongoing immune response. In this review, we discuss the recent advances in the field of Treg biology in general, and non-lymphoid and tissue-resident Tregs in particular. We elaborate upon well-known visceral adipose tissue, colon, skin, and tumor-infiltrating Tregs and newly identified tissue Treg populations as in lungs, skeletal muscle, placenta, and other tissues. Our attempt is to differentiate Tregs based on distinctive properties of their location, origin, ligand specificity, chemotaxis, and specific suppressive mechanisms. Despite ever expanding roles in maintaining systemic homeostasis, Tregs are employed by large varieties of tumors to dampen antitumor immunity. Thus, a comprehensive understanding of Treg biology in the context of inflammation can be instrumental in effectively managing tissue transplantation, autoimmunity, and antitumor immune responses. © 2018 Sharma and Rudra1
Regulatory T cells as therapeutic targets and mediators
Full text linkWith the advent of the concept of dominant tolerance and the subsequent discovery of
CD4þ regulatory T cells expressing the transcription factor FOXP3 (Tregs), almost all productive
as well as nonproductive immune responses can be compartmentalized to a binary of
immune effector T cells and immune regulatory Treg populations. A beneficial immune
response warrants the timely regulation by Tregs, whereas a nonproductive immune
response indicates insufficient effector functions or an outright failure of tolerance. There
are ample reports supporting role of Tregs in suppressing spontaneous auto-immune diseases
as well as promoting immune evasion by cancers. To top up their importance, several
non-immune functions like tissue homeostasis and regeneration are also being attributed to
Tregs. Hence, after being in the center stage of basic and translational immunological
research, Tregs are making the next jump towards clinical studies. Therefore, newer small
molecules, biologics as well as adoptive cell therapy (ACT) approaches are being tested to
augment or undermine Treg responses in the context of autoimmunity and cancer. In this
brief review, we present the strategies to modulate Tregs towards a favorable clinical
outcome. c. 2019 Taylor & Francis Group, LLC11sciescopu
Inflammation-induced Id2 promotes plasticity in regulatory T cells
Full text linkTH17 cells originating from regulatory T (Treg) cells upon loss of the Treg-specific transcription factor Foxp3 accumulate in sites of inflammation and aggravate autoimmune diseases. Whether an active mechanism drives the generation of these pathogenic ��ex-Foxp3 TH17�� cells, remains unclear. Here we show that pro-inflammatory cytokines enhance the expression of transcription regulator Id2, which mediates cellular plasticity of Treg into ex-Foxp3 TH17 cells. Expression of Id2 in in vitro differentiated iTreg cells reduces the expression of Foxp3 by sequestration of the transcription activator E2A, leading to the induction of TH17-related cytokines. Treg-specific ectopic expression of Id2 in mice significantly reduces the Treg compartment and causes immune dysregulation. Cellular fate-mapping experiments reveal enhanced Treg plasticity compared to wild-type, resulting in exacerbated experimental autoimmune encephalomyelitis pathogenesis or enhanced anti-tumor immunity. Our findings suggest that controlling Id2 expression may provide a novel approach for effective Treg cell immunotherapies for both autoimmunity and cancer. (C) 2018, The Author(s
Upregulation of Ets1 expression by NFATc2 and NFKB1/RELA promotes breast cancer cell invasiveness
Full text linkBreast cancer is highly aggressive and is the leading cause of cancer-related mortality in women in developed countries. The ETS proto-oncogene 1 (Ets1) has versatile roles during the cellular processes of cancer development. It is often highly expressed in breast cancers and mediates migration and invasion of human breast cancer cells. However, underlying mechanisms of Ets1 gene expression is still ambiguous. Here, we identified a core-regulatory element (CRE) located in the Ets1 promoter region (−540/−80 bp from TSS) that contains elements responsible for associating with NFATs and NF-κBs. Compared with the less metastatic breast cancer cells, metastatic breast cancer cells (MDA-MB-231) show open chromatin configurations in the CRE, which facilitates direct binding of NFATc2 and/or NFKB1/RELA complex to trans-activate Ets1 transcription. Moreover, enhanced level of Nfatc2 and Nfkb1 positively correlated with Ets1 expression in the human breast cancer specimens. Deletion of the CRE region by CRISPR/Cas9 system resulted in significant reduction in Ets1 expression, which led to alterations of Ets1-mediated transcription programs including tumor invasiveness-related genes. Proper regulation of Ets1 gene expression by targeting the NFATc2 and NFKB1/RELA interaction could be a potential therapeutic target for Ets1-mediated metastatic breast cancer.11sciescopu
Bcl11b prevents catastrophic autoimmunity by controlling multiple aspects of a regulatory T cell gene expression program
Full text linkFoxp3 and its protein partners establish a regulatory T (Treg) cell transcription profile and promote immunological tolerance. However, molecular features contributing to a Treg-specific gene expression program are still incompletely understood. We find that the transcription factor Bcl11b is a prominent Foxp3 cofactor with multifaceted functions in Treg biology. Optimal genomic recruitment of Foxp3 and Bcl11b is critically interdependent. Genome-wide occupancy studies coupled with gene expression profiling reveal that Bcl11b, in association with Foxp3, is primarily responsible in establishing a Treg-specific gene activation program. Furthermore, Bcl11b restricts misdirected recruitment of Foxp3 to sites, which would otherwise result in an altered Treg transcriptome profile. Consequently, Treg-specific ablation of Bcl11b results in marked breakdown of immune tolerance, leading to aggressive systemic autoimmunity. Our study provides previously underappreciated mechanistic insights into molecular events contributing to basic aspects of Treg function. Furthermore, it establishes a therapeutic target with potential implications in autoimmunity and cancer. Copyright © 2019 The Author
KLK5 induces shedding of DPP4 from circulatory Th17 cells in type 2 diabetes
Full text linkObjective: Increasing plasma levels and activity of dipeptidyl peptidase-4 (DPP4 or CD26) are associated with rapid progression of metabolic syndrome to overt type 2 diabetes mellitus (T2DM). While DPP4 inhibitors are increasingly used as anti-hyperglycemic agents, the reason for the increase in plasma DPP4 activity in T2DM patients remains elusive.
Methods: We looked into the source of plasma DPP4 activity in a cohort of 135 treatment naive nonobese (BMI < 30) T2DM patients. A wide array of ex vivo, in vitro, and in silico methods were employed to study enzyme activity, gene expression, subcellular localization, protease identification, surface expression, and protein–protein interactions.
Results: We show that circulating immune cells, particularly CD4+ T cells, served as an important source for the increase in plasma DPP4 activity in T2DM. Moreover, we found kallikrein-related peptidase 5 (KLK5) as the enzyme responsible for cleaving DPP4 from the cell surface by directly interacting with the extracellular loop. Expression and secretion of KLK5 is induced in CD4+ T cells of T2DM patients. In addition, KLK5 shed DPP4 from circulating CD4+ T helper (Th)17 cells and shed it into the plasma of T2DM patients. Similar cleavage and shedding activities were not seen in controls.
Conclusions: Our study provides mechanistic insights into the molecular interaction between KLK5 and DPP4 as well as CD4+ T cell derived KLK5 mediated enzymatic cleavage of DPP4 from cell surface. Thus, our study uncovers a hitherto unknown cellular source and mechanism behind enhanced plasma DPP4 activity in T2DM
The transcription factor Foxp1 preserves integrity of an active Foxp3 locus in extrathymic Treg cells
Full text linkRegulatory T (Treg) cells, which are broadly classified as thymically derived (tTreg) or extrathymically induced (iTreg), suppress immune responses and display stringent dependence to the transcription factor Foxp3. However precise understanding of molecular events that promote and preserve Foxp3 expression in Treg cells is still evolving. Here we show that Foxpl, a forkhead transcription factor and a sibling family member of Foxp3, is essential for sustaining optimal expression of Foxp3 specifically in iTreg cells. Deletion of Foxp1 renders iTreg cells to gradually lose Foxp3, resulting in dramatically reduced Nrp1(-)Helios(-) iTreg compartment as well as augmented intestinal inflammation in aged mice. Our finding underscores a mechanistic module in which evolutionarily related transcription factors establish a molecular program to ensure efficient immune homeostasis. Furthermore, it provides a novel target that can be potentially modulated to exclusively reinforce iTreg stability keeping their thymic counterpart unperturbed.11sciescopu
The Transcription Factor Ets1 Suppresses T Follicular Helper Type 2 Cell Differentiation to Halt the Onset of Systemic Lupus Erythematosus
No full textSingle-nucleotide polymorphisms in ETS1 are associated with systemic lupus erythematosus (SLE). Ets1?/? mice develop SLE-like symptoms, suggesting that dysregulation of this transcription factor is important to the onset or progression of SLE. We used conditional deletion approaches to examine the impact of Ets1 expression in different immune cell types. Ets1 deletion on CD4+ T cells, but not B cells or dendritic cells, resulted in the SLE autoimmunity, and this was associated with the spontaneous expansion of T follicular helper type 2 (Tfh2) cells. Ets1?/? Tfh2 cells exhibited increased expression of GATA-3 and interleukin-4 (IL-4), which induced IgE isotype switching in B cells. Neutralization of IL-4 reduced Tfh2 cell frequencies and ameliorated disease parameters. Mechanistically, Ets1 suppressed signature Tfh and Th2 cell genes, including Cxcr5, Bcl6, and Il4ra, thus curbing the terminal Tfh2 cell differentiation process. Tfh2 cell frequencies in SLE patients correlated with disease parameters, providing evidence for the relevance of these findings to human disease. Single-nucleotide polymorphisms in ETS1 are associated with systemic lupus erythematosus (SLE). Kim et al. show that Ets1 deletion in T cells, but not B cells or DCs, result in SLE-like humoral autoimmunity, which was due to the expansion of GATA-3+Bcl6+ Tfh2 cells and could be alleviated by neutralizing IL-4. Tfh2 frequencies in SLE patients correlate with disease parameters, suggesting therapeutic relevance for IL-4 blockade. ? 2018 Elsevier In
Ets1 suppresses atopic dermatitis by suppressing pathogenic T cell responses
No full textAtopic dermatitis (AD) is a complex inflammatory skin disease mediated by immune cells of both adaptive and innate types. Among them, CD4(+) Th cells are one of major players of AD pathogenesis. Although the pathogenic role of Th2 cells has been well characterized, Th17/Th22 cells are also implicated in the pathogenesis of AD. However, the molecular mechanisms underlying pathogenic immune responses in AD remain unclear. We sought to investigate how the defect in the AD susceptibility gene, Ets1, is involved in AD pathogenesis in human and mice and its clinical relevance in disease severity by identifying Ets1 target genes and binding partners. Consistent with the decrease in ETS1 levels in severe AD patients and the experimental AD-like skin inflammation model, T cell-specific Ets1-deficient mice (Ets1(Delta dLck)) developed severe AD-like symptoms with increased pathogenic Th cell responses. A T cell-intrinsic increase of gp130 expression upon Ets1 deficiency promotes the gp130-mediated IL-6 signaling pathway, thereby leading to the development of severe AD-like symptoms. Functional blocking of gp130 by selective inhibitor SC144 ameliorated the disease pathogenesis by reducing pathogenic Th cell responses. Our results reveal a protective role of Ets1 in restricting pathogenic Th cell responses and suggest a potential therapeutic target for AD treatment.11Ysciescopu
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