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Pankow A, Sun XH. The divergence between T cell and innate lymphoid cell fates controlled by E and Id proteins. Front Immunol 2022; 13:960444. [PMID: 36032069 PMCID: PMC9399370 DOI: 10.3389/fimmu.2022.960444] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 07/13/2022] [Indexed: 11/18/2022] Open
Abstract
T cells develop in the thymus from lymphoid primed multipotent progenitors or common lymphoid progenitors into αβ and γδ subsets. The basic helix-loop-helix transcription factors, E proteins, play pivotal roles at multiple stages from T cell commitment to maturation. Inhibitors of E proteins, Id2 and Id3, also regulate T cell development while promoting ILC differentiation. Recent findings suggest that the thymus can also produce innate lymphoid cells (ILCs). In this review, we present current findings that suggest the balance between E and Id proteins is likely to be critical for controlling the bifurcation of T cell and ILC fates at early stages of T cell development.
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Affiliation(s)
- Aneta Pankow
- Program in Arthritis and Clinical Immunology, Oklahoma Medical Research Foundation, Oklahoma City, OK, United States
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Xiao-Hong Sun
- Program in Arthritis and Clinical Immunology, Oklahoma Medical Research Foundation, Oklahoma City, OK, United States
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
- *Correspondence: Xiao-Hong Sun,
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ILC Differentiation in the Thymus. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1365:25-39. [DOI: 10.1007/978-981-16-8387-9_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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3
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Inhibitor of Differentiation-3 and Estrogenic Endocrine Disruptors: Implications for Susceptibility to Obesity and Metabolic Disorders. BIOMED RESEARCH INTERNATIONAL 2018; 2018:6821601. [PMID: 29507860 PMCID: PMC5817379 DOI: 10.1155/2018/6821601] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 11/07/2017] [Accepted: 11/23/2017] [Indexed: 12/28/2022]
Abstract
The rising global incidence of obesity cannot be fully explained within the context of traditional risk factors such as an unhealthy diet, physical inactivity, aging, or genetics. Adipose tissue is an endocrine as well as a metabolic organ that may be susceptible to disruption by environmental estrogenic chemicals. Since some of the endocrine disruptors are lipophilic chemicals with long half-lives, they tend to bioaccumulate in the adipose tissue of exposed populations. Elevated exposure to these chemicals may predispose susceptible individuals to weight gain by increasing the number and size of fat cells. Genetic studies have demonstrated that the transcriptional regulator inhibitor of differentiation-3 (ID3) promotes high fat diet-induced obesity in vivo. We have shown previously that PCB153 and natural estrogen 17β-estradiol increase ID3 expression. Based on our findings, we postulate that ID3 is a molecular target of estrogenic endocrine disruptors (EEDs) in the adipose tissue and a better understanding of this relationship may help to explain how EEDs can lead to the transcriptional programming of deviant fat cells. This review will discuss the current understanding of ID3 in excess fat accumulation and the potential for EEDs to influence susceptibility to obesity or metabolic disorders via ID3 signaling.
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Zhao Y, Ling F, Griffin TM, He T, Towner R, Ruan H, Sun XH. Up-regulation of the Sirtuin 1 (Sirt1) and peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) genes in white adipose tissue of Id1 protein-deficient mice: implications in the protection against diet and age-induced glucose intolerance. J Biol Chem 2014; 289:29112-22. [PMID: 25190816 DOI: 10.1074/jbc.m114.571679] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Id1, a helix-loop-helix (HLH) protein that inhibits the function of basic HLH E protein transcription factors in lymphoid cells, has been implicated in diet- and age-induced obesity by unknown mechanisms. Here we show that Id1-deficient mice are resistant to a high fat diet- and age-induced obesity, as revealed by reduced weight gain and body fat, increased lipid oxidation, attenuated hepatosteatosis, lower levels of lipid droplets in brown adipose tissue, and smaller white adipocytes after a high fat diet feeding or in aged animals. Id1 deficiency improves glucose tolerance, lowers serum insulin levels, and reduces TNFα gene expression in white adipose tissue. Id1 deficiency also increased expression of Sirtuin 1 and peroxisome proliferator-activated receptor γ coactivator 1α, regulators of mitochondrial biogenesis and energy expenditure, in the white adipose tissue. This effect was accompanied by the elevation of several genes encoding proteins involved in oxidative phosphorylation and fatty acid oxidation, such as cytochrome c, medium-chain acyl-CoA dehydrogenase, and adipocyte protein 2. Moreover, the phenotype for Id1 deficiency was similar to that of mice expressing an E protein dominant-positive construct, ET2, suggesting that the balance between Id and E proteins plays a role in regulating lipid metabolism and insulin sensitivity.
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Affiliation(s)
- Ying Zhao
- From the Program in Immunobiology and Cancer Research
| | - Flora Ling
- From the Program in Immunobiology and Cancer Research, Department of Cell Biology and
| | - Timothy M Griffin
- Program in Free Radical Biology and Aging, and Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, and
| | - Ting He
- Advanced Magnetic Resonance Center, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104
| | - Rheal Towner
- Advanced Magnetic Resonance Center, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104
| | - Hong Ruan
- Department of Physiology and Biophysics, Rutgers University, Piscataway, New Jersey 08854
| | - Xiao-Hong Sun
- From the Program in Immunobiology and Cancer Research, Department of Cell Biology and
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Liu C, Wang HC, Yu S, Jin R, Tang H, Liu YF, Ge Q, Sun XH, Zhang Y. Id1 expression promotes T regulatory cell differentiation by facilitating TCR costimulation. THE JOURNAL OF IMMUNOLOGY 2014; 193:663-672. [PMID: 24920844 DOI: 10.4049/jimmunol.1302554] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
T regulatory (Treg) cells play crucial roles in the regulation of cellular immunity. The development of Treg cells depends on signals from TCRs and IL-2Rs and is influenced by a variety of transcription factors. The basic helix-loop-helix proteins are known to influence TCR signaling thresholds. Whether this property impacts Treg differentiation is not understood. In this study, we interrogated the role of basic helix-loop-helix proteins in the production of Treg cells using the CD4 promoter-driven Id1 transgene. We found that Treg cells continued to accumulate as Id1 transgenic mice aged, resulting in a significant increase in Treg cell counts in the thymus as well as in the periphery compared with wild-type controls. Data from mixed bone marrow assays suggest that Id1 acts intrinsically on developing Treg cells. We made a connection between Id1 expression and CD28 costimulatory signaling because Id1 transgene expression facilitated the formation of Treg precursors in CD28(-/-) mice and the in vitro differentiation of Treg cells on thymic dendritic cells despite the blockade of costimulation by anti-CD80/CD86. Id1 expression also allowed in vitro Treg differentiation without anti-CD28 costimulation, which was at least in part due to enhanced production of IL-2. Notably, with full strength of costimulatory signals, however, Id1 expression caused modest but significant suppression of Treg induction. Finally, we demonstrate that Id1 transgenic mice were less susceptible to the induction of experimental autoimmune encephalomyelitis, thus illustrating the impact of Id1-mediated augmentation of Treg cell levels on cellular immunity.
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Affiliation(s)
- Chen Liu
- Department of Immunology, Peking University Health Science Center, Beijing, China
| | | | - Sen Yu
- Department of Immunology, Peking University Health Science Center, Beijing, China
| | - Rong Jin
- Department of Immunology, Peking University Health Science Center, Beijing, China
| | - Hui Tang
- Department of Immunology, Peking University Health Science Center, Beijing, China
| | - Yuan-Feng Liu
- Department of Immunology, Peking University Health Science Center, Beijing, China
| | - Qing Ge
- Department of Immunology, Peking University Health Science Center, Beijing, China
| | - Xiao-Hong Sun
- Oklahoma Medical Research Foundation, Oklahoma City, OK
| | - Yu Zhang
- Department of Immunology, Peking University Health Science Center, Beijing, China
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Zhang P, Zhao Y, Sun XH. Notch-regulated periphery B cell differentiation involves suppression of E protein function. THE JOURNAL OF IMMUNOLOGY 2013; 191:726-36. [PMID: 23752615 DOI: 10.4049/jimmunol.1202134] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Notch signaling pathway plays important roles in promoting the generation of marginal zone (MZ) B cells at the expense of follicular (FO) B cells during periphery B cell maturation, but the underlying molecular mechanisms are not well understood. We hypothesize that Notch favors the generation of MZ B cells by downregulating E protein activity. In this study, we demonstrated that expression of Id2 and ankyrin-repeat SOCS box-containing protein 2 was elevated in MZ B cells and by Notch signaling. Id2 inhibits the DNA binding activity of E proteins, whereas ankyrin-repeat SOCS box-containing protein 2 facilitates E protein ubiquitination. Next, we examined the phenotypes of splenic B cells in mice expressing constitutively active Notch1 and/or two gain-of-function mutants of E proteins that counteract Id2-mediated inhibition or Notch-induced degradation. We found that upregulation of E proteins promoted the formation of FO B cells, whereas it suppressed the maturation of MZ B cells. In contrast, excessive amounts of Notch1 stimulated the differentiation of MZ B cells and inhibited the production of FO B cells. More interestingly, the effects of Notch1 were reversed by gain of E protein function. Furthermore, high levels of Bcl-6 expression in FO B cells was shown to be diminished by Notch signaling and restored by E proteins. In addition, E proteins facilitated and Notch hindered the differentiation of transitional B cells. Taken together, it appears that Notch regulates peripheral B cell differentiation, at least in part, through opposing E protein function.
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Affiliation(s)
- Ping Zhang
- Immunobiology and Cancer Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
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7
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Liu C, Jin R, Wang HC, Tang H, Liu YF, Qian XP, Sun XY, Ge Q, Sun XH, Zhang Y. Id1 expression promotes peripheral CD4+ T cell proliferation and survival upon TCR activation without co-stimulation. Biochem Biophys Res Commun 2013; 436:47-52. [PMID: 23707719 DOI: 10.1016/j.bbrc.2013.05.054] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Accepted: 05/05/2013] [Indexed: 01/10/2023]
Abstract
Although the role of E proteins in the thymocyte development is well documented, much less is known about their function in peripheral T cells. Here we demonstrated that CD4 promoter-driven transgenic expression of Id1, a naturally occurring dominant-negative inhibitor of E proteins, can substitute for the co-stimulatory signal delivered by CD28 to facilitate the proliferation and survival of naïve CD4+ cells upon anti-CD3 stimulation. We next discovered that IL-2 production and NF-κB activity after anti-CD3 stimulation were significantly elevated in Id1-expressing cells, which may be, at least in part, responsible for the augmentation of their proliferation and survival. Taken together, results from this study suggest an important role of E and Id proteins in peripheral T cell activation. The ability of Id proteins to by-pass co-stimulatory signals to enable T cell activation has significant implications in regulating T cell immunity.
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Affiliation(s)
- Chen Liu
- Department of Immunology, Peking University Health Science Center, Beijing, China
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8
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Yang W, Itoh F, Ohya H, Kishimoto F, Tanaka A, Nakano N, Itoh S, Kato M. Interference of E2-2-mediated effect in endothelial cells by FAM96B through its limited expression of E2-2. Cancer Sci 2011; 102:1808-14. [DOI: 10.1111/j.1349-7006.2011.02022.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
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9
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Li X, von Boehmer H. Notch Signaling in T-Cell Development and T-ALL. ISRN HEMATOLOGY 2011; 2011:921706. [PMID: 22111016 PMCID: PMC3200084 DOI: 10.5402/2011/921706] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Accepted: 12/15/2010] [Indexed: 11/23/2022]
Abstract
The Notch signaling pathway is an evolutionarily conserved cell signaling system present in most multicellular organisms, as it controls cell fate specification by regulating cell proliferation, differentiation, apoptosis, and survival. Regulation of the Notch signaling pathway can be achieved at multiple levels. Notch proteins are involved in lineage fate decisions in a variety of tissues in various species. Notch is essential for T lineage cell differentiation including T versus B and αβ versus γδ lineage specification. In this paper, we discuss Notch signaling in normal T-cell maturation and differentiation as well as in T-cell acute lymphoblastic lymphoma/leukemia.
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Affiliation(s)
- Xiaoyu Li
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Harvard Medical School, 44 Binney Street, Boston, MA 02115, USA
| | - Harald von Boehmer
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Harvard Medical School, 44 Binney Street, Boston, MA 02115, USA
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Cochrane SW, Zhao Y, Perry SS, Urbaniak T, Sun XH. Id1 has a physiological role in regulating early B lymphopoiesis. Cell Mol Immunol 2010; 8:41-9. [PMID: 21200383 DOI: 10.1038/cmi.2010.58] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Basic helix-loop-helix E proteins play critical roles in B-cell development by stimulating B cell-specific gene expression and immunoglobulin gene rearrangement. The function of E proteins can be effectively suppressed by their naturally occurring inhibitors, Id1 to 4. Ectopic expression of Id1 has been shown to block B-cell development at the early pro-B cell stage. However, whether Id1 plays a physiological role in controlling B lymphopoiesis was not known. Although Id1-deficient mice do not exhibit significant abnormalities in steady-state B lymphopoiesis, we detected more robust B-cell engraftment in transplant recipients of Id1-deficient bone marrow compared to those of wild-type donor cells. In culture, Id1 ablation dramatically enhances B-lineage cell production without any marked effects on myeloid differentiation. Consistently, Id1 expression was found in pro-B but not pre-B cells as measured by enhanced green fluorescent protein (EGFP) fluorescence and by quantitative reverse transcription-PCR. Although loss of Id1 did not alter the number of B-cell colonies generated from whole bone marrow or the proliferation rate of developing B cells, B-cell colonies were detectable at a much earlier time point and the size of the colonies were larger. Therefore, we infer that Id1-deficient progenitors possess higher potential to differentiate to the pre-B cell stage when a proliferative burst occurs. Taken together, we present evidence to suggest that Id1 plays a physiological role in restraining the developmental progression, which may be important for proper B-cell differentiation in the bone marrow.
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Affiliation(s)
- Shawn W Cochrane
- Immunobiology and Cancer Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
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11
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Inhibition of endothelial cell activation by bHLH protein E2-2 and its impairment of angiogenesis. Blood 2010; 115:4138-47. [PMID: 20231428 DOI: 10.1182/blood-2009-05-223057] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
E2-2 belongs to the basic helix-loop-helix (bHLH) family of transcription factors. E2-2 associates with inhibitor of DNA binding (Id) 1, which is involved in angiogenesis. In this paper, we demonstrate that E2-2 interacts with Id1 and provide evidence that this interaction potentiates angiogenesis. Mutational analysis revealed that the HLH domain of E2-2 is required for the interaction with Id1 and vice versa. In addition, Id1 interfered with E2-2-mediated effects on luciferase reporter activities. Interestingly, injection of E2-2-expressing adenoviruses into Matrigel plugs implanted under the skin blocked in vivo angiogenesis. In contrast, the injection of Id1-expressing adenoviruses rescued E2-2-mediated inhibition of in vivo angiogenic reaction. Consistent with the results of the Matrigel plug assay, E2-2 could inhibit endothelial cell (EC) migration, network formation, and proliferation. On the other hand, knockdown of E2-2 in ECs increased EC migration. The blockade of EC migration by E2-2 was relieved by exogenous expression of Id1. We also demonstrated that E2-2 can perturb VEGFR2 expression via inhibition of VEGFR2 promoter activity. This study suggests that E2-2 can maintain EC quiescence and that Id1 can counter this effect.
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12
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Id1 attenuates Notch signaling and impairs T-cell commitment by elevating Deltex1 expression. Mol Cell Biol 2009; 29:4640-52. [PMID: 19564409 DOI: 10.1128/mcb.00119-09] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Complete inhibition of E protein transcription factors by Id1 blocks the developmental transition of CD4/CD8 double-negative 1 (DN1; CD44(+) CD25(-)) thymocytes to the DN2 (CD44(+) CD25(+)) stage. To understand the underlying mechanisms, we observed that mRNA levels of Deltex1, as well as Deltex4, were dramatically elevated in Id1-expressing thymocytes, which could result in developmental arrest by attenuating Notch function. In support of this hypothesis, we found that Deltex1 ablation enabled Id1-expressing progenitors to differentiate to the DN3 (CD44(-) CD25(+)) stage, which was accompanied by enhanced Notch1 expression in T-cell progenitors. Consistently, constitutive activation of Notch1 drove the differentiation of Id1-expressing progenitors to the DN3 stage. Furthermore, we showed that Gfi1b levels decreased, whereas GATA3 levels increased in Id1 transgenic thymocytes. When overexpressed, GATA3 was able to upregulate Deltex1 transcription. Thus, T-cell commitment may be controlled by the interplay among E proteins, Gfi1b, and GATA3 transcription regulators, which influence Notch function through the expression of Deltex1.
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14
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Interleukin-6 aborts lymphopoiesis and elevates production of myeloid cells in systemic lupus erythematosus-prone B6.Sle1.Yaa animals. Blood 2009; 113:4534-40. [PMID: 19224760 DOI: 10.1182/blood-2008-12-192559] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We previously reported the inhibitory action of interleukin-6 (IL-6) on B lymphopoiesis with SHIP(-/-) mice and showed that IL-6 biases lineage commitment toward myeloid cell fates in vitro and in vivo. Because elevated IL-6 is a feature of chronic inflammatory diseases, we applied an animal model of systemic lupus erythematosus (SLE) to determine whether IL-6 has similar effects on hematopoiesis. We found that IL-6 levels were elevated in the B6.Sle1.Yaa mice, and the increase was accompanied by losses of CD19(+) B cells and more primitive B-lymphoid progenitors in bone marrow. Both the CD19(+) B-cell population and their progenitors recovered in an IL-6(-/-) background. The uncommitted progenitors, containing precursors for both lymphoid and myeloid fates, expressed IL-6 receptor-alpha chain and responded to IL-6 by phosphorylation of STAT3. IL-6 stimulation caused uncommitted progenitors to express the Id1 transcription factor, which is known to inhibit lymphopoiesis and elevate myelopoiesis, and its expression was MAPK dependent. We conclude that chronic inflammatory conditions accompanied by increased IL-6 production bias uncommitted progenitors to a myeloid fate by inducing Id1 expression.
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E2A proteins maintain the hematopoietic stem cell pool and promote the maturation of myelolymphoid and myeloerythroid progenitors. Proc Natl Acad Sci U S A 2009; 106:1930-5. [PMID: 19181846 DOI: 10.1073/pnas.0808866106] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Hematopoiesis is a tightly controlled process maintained by a small pool of hematopoietic stem cells (HSCs). Here, we demonstrate that the LT-HSC, MPP, premegakaryocytic/erythroid, Pre CFU-E, Pre GM, MkP, and granulocyte-macrophage compartments were all significantly reduced in E2A-deficient bone marrow. Despite a severe depletion of erythroid progenitors, the erythrocyte and megakaryocyte compartments were equivalent in E2A-deficient bone marrow as compared with wild-type mice. E2A-deficient HSCs also failed to efficiently maintain the HSC pool on serial transplantation, and we demonstrate that the E2A proteins regulate cell cycle progression of HSCs by regulating the expression of p21(Cip1), p27(Kip1), and the thrombopoietin receptor, known regulators of HSC self-renewal activity. Based on these observations, we propose that the E2A proteins promote the developmental progression of the entire spectrum of early hematopoietic progenitors and to suppress an erythroid specific program of gene expression in alternative cell lineages. Last, the data mechanistically link E2A, cell cycle regulators, and the maintenance of the HSC pool in a common pathway.
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Abstract
Hematopoiesis consists of a series of lineage decisions controlled by specific gene expression that is regulated by transcription factors and intracellular signaling events in response to environmental cues. Here, we demonstrate that the balance between E-protein transcription factors and their inhibitors, Id proteins, is important for the myeloid-versus-lymphoid fate choice. Using Id1-GFP knockin mice, we show that transcription of the Id1 gene begins to be up-regulated at the granulocyte-macrophage progenitor stage and continues throughout myelopoiesis. Id1 expression is also stimulated by cytokines favoring myeloid differentiation. Forced expression of Id1 in multipotent progenitors promotes myeloid development and suppresses B-cell formation. Conversely, enhancing E-protein activity by expressing a variant of E47 resistant to Id-mediated inhibition prevents the myeloid cell fate while driving B-cell differentiation from lymphoid-primed multipotent progenitors. Together, these results suggest a crucial function for E proteins in the myeloid-versus-lymphoid lineage decision.
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17
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Transcriptional regulation of lymphocyte development. Curr Opin Genet Dev 2008; 18:441-8. [PMID: 18775782 DOI: 10.1016/j.gde.2008.07.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2008] [Accepted: 07/31/2008] [Indexed: 01/01/2023]
Abstract
B lymphocytes and T lymphocytes develop from hematopoietic stem cells through a series of intermediates with progressively decreased lineage differentiation potential. Differentiation is preceded by increased accessibility of the chromatin at genes that are poised for expression in the progeny of a multipotent cell. During the process of differentiation there is increased expression of lineage-associated genes and repression of lineage-inappropriate genes resulting in commitment to differentiation through a specific lineage. These transcriptional events are coordinated by networks of transcription factors and their associated chromatin remodeling factors. The B lymphocyte lineage provides a paradigm for how these events unfold to promote specification and commitment to a single developmental pathway.
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Yang Y, Wang HC, Sun XH. Id1 induces apoptosis through inhibition of RORgammat expression. BMC Immunol 2008; 9:20. [PMID: 18489764 PMCID: PMC2408562 DOI: 10.1186/1471-2172-9-20] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2008] [Accepted: 05/19/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Basic helix-loop-helix E proteins are transcription factors that play crucial roles in T cell development by controlling thymocyte proliferation, differentiation and survival. E protein functions can be repressed by their naturally occurring inhibitors, Id proteins (Id1-4). Transgenic expression of Id1 blocks T cell development and causes massive apoptosis of developing thymocytes. However, the underlying mechanisms are not entirely understood due to relatively little knowledge of the target genes regulated by E proteins. RESULTS We designed a unique strategy to search for genes directly controlled by E proteins and found RORgammat to be a top candidate. Using microarray analyses and reverse-transcriptase PCR assays, we showed that Id1 expression diminished RORgammat mRNA levels in T cell lines and primary thymocytes while induction of E protein activity restored RORgammat expression. E proteins were found to specifically bind to the promoter region of RORgammat, suggesting their role in activating transcription of the gene. Functional significance of E protein-controlled RORgammat expression was established based on the finding that RORgammat rescued apoptosis caused by Id1 overexpression. Furthermore, expression of RORgammat prevented Id1-induced p38 MAP kinase hyper-activation. CONCLUSION These results suggest that E protein-dependent RORgammat gene expression aids the survival of developing thymocytes, which provides a possible explanation for the massive apoptosis found in Id1 transgenic mice.
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Affiliation(s)
- Yuanzheng Yang
- Immunobiology and Cancer Program, Oklahoma Medical Research Foundation, 825 NE 13th St, Oklahoma City, OK 73104, USA.
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Abstract
Many fundamental concepts about immune system development have changed substantially in the past few years, and rapid advances with animal models are presenting prospects for further discovery. However, continued progress requires a clearer understanding of the relationships between haematopoietic stem cells and the progenitors that replenish each type of lymphocyte pool. Blood-cell formation has traditionally been described in terms of discrete developmental branch points, and a single route is given for each major cell type. As we discuss in this Review, recent findings suggest that the process of B-cell formation is much more dynamic.
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Murre C. Regulation and Function of the E2A Proteins in B Cell Development. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2007; 596:1-7. [PMID: 17338171 DOI: 10.1007/0-387-46530-8_1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Cornelis Murre
- University of California, San Diego, 9500 Gilman Drive, 0377, La Jolla, CA 92093, USA
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Dudley DD, Chaudhuri J, Bassing CH, Alt FW. Mechanism and control of V(D)J recombination versus class switch recombination: similarities and differences. Adv Immunol 2006; 86:43-112. [PMID: 15705419 DOI: 10.1016/s0065-2776(04)86002-4] [Citation(s) in RCA: 193] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
V(D)J recombination is the process by which the variable region exons encoding the antigen recognition sites of receptors expressed on B and T lymphocytes are generated during early development via somatic assembly of component gene segments. In response to antigen, somatic hypermutation (SHM) and class switch recombination (CSR) induce further modifications of immunoglobulin genes in B cells. CSR changes the IgH constant region for an alternate set that confers distinct antibody effector functions. SHM introduces mutations, at a high rate, into variable region exons, ultimately allowing affinity maturation. All of these genomic alteration processes require tight regulatory control mechanisms, both to ensure development of a normal immune system and to prevent potentially oncogenic processes, such as translocations, caused by errors in the recombination/mutation processes. In this regard, transcription of substrate sequences plays a significant role in target specificity, and transcription is mechanistically coupled to CSR and SHM. However, there are many mechanistic differences in these reactions. V(D)J recombination proceeds via precise DNA cleavage initiated by the RAG proteins at short conserved signal sequences, whereas CSR and SHM are initiated over large target regions via activation-induced cytidine deaminase (AID)-mediated DNA deamination of transcribed target DNA. Yet, new evidence suggests that AID cofactors may help provide an additional layer of specificity for both SHM and CSR. Whereas repair of RAG-induced double-strand breaks (DSBs) involves the general nonhomologous end-joining DNA repair pathway, and CSR also depends on at least some of these factors, CSR requires induction of certain general DSB response factors, whereas V(D)J recombination does not. In this review, we compare and contrast V(D)J recombination and CSR, with particular emphasis on the role of the initiating enzymes and DNA repair proteins in these processes.
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Affiliation(s)
- Darryll D Dudley
- Howard Hughes Medical Institute, The Children's Hospital Boston, CBR Institute for Biomedical Research, and Harvard Medical School, Boston, MA 02115, USA
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Pelayo R, Welner RS, Nagai Y, Kincade PW. Life before the pre-B cell receptor checkpoint: specification and commitment of primitive lymphoid progenitors in adult bone marrow. Semin Immunol 2005; 18:2-11. [PMID: 16310376 DOI: 10.1016/j.smim.2005.10.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The production of B cells is a complex process determined by well-timed combinations of intrinsic factors and environmental cues that guide the differentiation of primitive progenitors in the bone marrow. Expression of several key transcription factors and receptor-stromal cell ligand interactions are landmarks of the earliest events in B lymphopoiesis in adult bone marrow. We describe this as a gradual loss of options for other blood cell lineages coincident with gain of essential properties. Experimental, stress or infection-related deregulation may change B cell fate specification, commitment or population dynamics, and consequently the production rate of mature populations.
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Affiliation(s)
- Rosana Pelayo
- Immunobiology and Cancer Program, Oklahoma Medical Research Foundation, 825 N.E. 13th Street, Oklahoma City, OK 73104, USA
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Abstract
Helix-loop-helix (HLH) proteins are transcriptional regulators that control a wide variety of developmental pathways in both invertebrate and vertebrate organisms. Results obtained in the past decade have shown that HLH proteins also contribute to the development of lymphoid lineages. A subset of HLH proteins, the 'E proteins', seems to be particularly important for proper lymphoid development. Members of the E protein family include E12, E47, E2-2 and HEB. The E proteins contribute to B lineage- and T lineage-specific gene expression programs, regulate lymphocyte survival and cellular proliferation, activate the rearrangement of antigen receptor genes and control progression through critical developmental checkpoints. This review discusses HLH proteins in lymphocyte development and homeostasis.
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Affiliation(s)
- Cornelis Murre
- Division of Biological Sciences, University of California, San Diego, La Jolla, California 92903, USA.
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Lazorchak A, Jones ME, Zhuang Y. New insights into E-protein function in lymphocyte development. Trends Immunol 2005; 26:334-8. [PMID: 15922950 DOI: 10.1016/j.it.2005.03.011] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2004] [Revised: 02/28/2005] [Accepted: 03/24/2005] [Indexed: 11/20/2022]
Abstract
Lymphocyte development has long served as an experimental paradigm, revealing fundamental mechanisms of gene regulation and cellular differentiation in mammals. The study of E-protein-mediated transcriptional regulation in lymphocyte development provides a means to address these mechanistic issues. Both genetic and biochemical studies have defined many important regulatory events during lymphocyte development that are mediated by E-proteins. The E2A gene, one of the three known E-protein genes in mammals, has a particularly important role in B-lymphocyte development. Major progress has been made in recent years towards understanding the physiological targets of E2A during B-lymphocyte development. Most notably, new insights have been gained regarding the role of E2A in controlling lineage commitment and V(D)J recombination. This Review focuses primarily on E2A-mediated gene regulation during B-lymphocyte development.
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Affiliation(s)
- Adam Lazorchak
- Department of Immunology, Duke University Medical Center, Durham, NC 27710, USA
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