An Analysis of T Cell Intrinsic Roles of<i>E2A</i>by Conditional Gene Disruption in the Thymus

Pan, Li‐Hua; Hanrahan, Jenifer; Li, Jie; Hale, Laura P.; Zhuang, Yuan

doi:10.4049/jimmunol.168.8.3923

Cited by 57 publications

(73 citation statements)

References 30 publications

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“…To study the function of LKB1 in T-cell development, mice bearing a LoxP-flanked gene encoding LKB1 (LKB1 fl/fl ) [20] were bred with mice expressing the Cre recombinase under the control of the proximal Lck promoter (LckCre) [26] to generate LckCre + LKB1 fl/fl mice (homozygous mutant, thereafter referred to as LKB1-deficient). The floxed LKB1 alleles were efficiently deleted in thymocytes, but not in the tails of LKB1-deficient mice, as expected ( Figure 1A).…”

Section: T-cell-specific Deletion Of Lkb1 Disrupts Thymocyte Developmentmentioning

confidence: 99%

The serine/threonine kinase LKB1 controls thymocyte survival through regulation of AMPK activation and Bcl-XL expression

Cao

Liu

et al. 2009

Cell Res

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LKB1 is a serine/threonine kinase that directly activates the energy sensor AMP-activated protein kinase (AMPK) in response to bioenergetic stress, and mainly acts as a tumor suppressor that controls cell polarity and proliferation. Although LKB1 is expressed in multiple tissues including the thymus and the spleen, its roles in T-cell development and function remain unknown. Here, we show that T-cell-specific deletion of LKB1 resulted in reduced survival of double-positive (DP) thymocytes and impaired generation of both CD4 and CD8 single-positive thymocytes. Disruption of LKB1 not only prevented the activation of AMPK but also impaired the expression of anti-apoptotic protein Bcl-XL. Importantly, ectopic expression of either Bcl-XL or the constitutively active AMPK mutant significantly rescued DP thymocytes from LKB1 deficiency-induced cell death. Moreover, ectopic expression of the constitutively active AMPK mutant was found to restore the expression of Bcl-XL in LKB1-deficient DP thymocytes. These findings identify LKB1 as a critical factor for the survival of DP thymocytes through regulation of AMPK activation and Bcl-XL expression.

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Section: T-cell-specific Deletion Of Lkb1 Disrupts Thymocyte Developmentmentioning

confidence: 99%

The serine/threonine kinase LKB1 controls thymocyte survival through regulation of AMPK activation and Bcl-XL expression

Cao

Liu

et al. 2009

Cell Res

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“…For gene array studies, pre-B-cell lines were derived from bone marrow of a mouse carrying the loxp-flanked E2A allele (E2A loxp/loxp ) (17). Transformed cells were then transduced with a retrovirus encoding Cre recombinase as well as a puromycin resistance cassette.…”

Section: Pre-b-cell Lines-thementioning

confidence: 99%

“…However, the strong block in B-lymphocyte development, complex thymocyte phenotype, and poor postnatal survival seen in these mice precluded more detailed studies on functions for E2A in lymphocyte differentiation and lymphoid gene regulation. A conditional E2A deletion model was developed in our laboratory to evaluate roles for E2A specifically in developing lymphocytes (17). Mice carrying the loxp-flanked E2A allele (E2A loxp ) enabled lineage-restricted deletion of the E2A gene based upon ectopic expression of the Cre recombinase.…”

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confidence: 99%

Differential Functions for the Transcription Factor E2A in Positive and Negative Gene Regulation in Pre-B Lymphocytes

Greenbaum¹,

Lazorchak²,

Zhuang

2004

Journal of Biological Chemistry

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The transcription factors encoded by the E2A gene have been shown to play essential roles in the initiation and progression of lymphocyte development. However, there is still a lack of comprehensive understanding of E2A downstream genes in B-cell development. We previously developed a gene tagging-based chromatin immunoprecipitation (ChIP) system to directly evaluate E2A target genes in B-cell development. Here, we have improved this ChIP strategy and used it in conjunction with microarray analysis on E2A-deficient pre-B-cell lines to determine E2A target genes in lymphocyte development. Both microarray data and ChIP studies confirmed that E2A directly controls IgH gene expression. The microarray assay also revealed genes that were significantly up-regulated after E2A disruption. ChIP analysis showed that E2A was most likely to be directly involved in repression of some of these target genes such as Nfil3 and FGFR2. An inducible E2A reconstitution system further demonstrated that E2A-mediated repression of Nfil3 and FGFR2 was reversible. Collectively, these findings indicate that E2A is a positive regulator for one set of genes and a negative regulator for another set of genes in developing B lymphocytes.Lymphocytes develop from multipotent hematopoietic stem cells to provide cell-mediated and humoral immunological protection against foreign antigens. Hematopoietic stem cells give rise to mature B-and T-lymphocytes through a series of well defined and highly ordered differentiation stages in the bone marrow and thymus, respectively (1). These stages are functionally defined by the progressive assembly and expression of the lymphocyte antigen receptors. These antigen receptors are generated through tightly regulated genomic recombination events at the B-and T-lymphocyte antigen receptor loci to establish a diverse pool of receptor specificities (2).Antigen receptor gene recombination and thus lymphocyte differentiation requires the activity of numerous broadly expressed and lineage-specific transcription factors. The basic helix-loop-helix transcription factors encoded by the E2A gene have been identified as essential regulators of gene expression during lymphocyte development (3). The E2A proteins were initially characterized as immunoglobulin heavy (IgH) 1 and light chain enhancer-binding factors and have since been shown to bind consensus E-box motifs (CANNTG) in the promoters and enhancers of numerous lymphoid lineage-specific genes (4, 5). E2A proteins are highly expressed in lymphoid progenitor populations (6) and are required for the initiation of B-lymphocyte development in the bone marrow. Mice deficient for E2A show a complete and persistent block at the earliest stage of B-cell development prior to the initiation of immunoglobulin heavy chain rearrangements (7,8).E2A has been implicated in regulating the expression of multiple BCR complex components, including the surrogate light chain 5, the BCR signaling molecule mb-1, and the immunoglobulin heavy chain (IgH) and k light chain genes (9 -15). Whereas ...

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“…E2A f/f Mx-Cre tg mice were created by crossing mice carrying the type I IFN-inducible Cre transgene (Mx-Cre) (22) with E2A conditional mice (23). Mx-Cre expression was induced by i.p.…”

Section: Mice and Cell Linesmentioning

confidence: 99%

“…The conditional E2A and HEB alleles were created by flanking the exons that encode the E47 and E12 bHLH domains of E2A and the bHLH domain of HEB with loxP recombination sites (Ref. 23; J. Wojciehowski and Y. Zhuang, unpublished data). Whole bone marrow from an adult E2A f/f HEB f/f mouse was transformed with AbMuLV and the resulting stable pre-B cell line was infected with a retrovirus expressing Cre recombinase to simultaneously delete E2A and HEB (Fig.…”

Section: The Loss Of E2a and Heb Perturbs But Does Not Abolish B Linementioning

confidence: 99%

E2A Promotes the Survival of Precursor and Mature B Lymphocytes

Lazorchak

Wojciechowski

Dai

et al. 2006

The Journal of Immunology

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The basic helix-loop-helix transcription factor E2A is an essential regulator of B lymphocyte lineage commitment and is required to activate the expression of numerous B lineage-specific genes. Studies involving ectopic expression of Id proteins, which inhibit E2A as well as other basic helix-loop-helix proteins such as HEB, suggest additional roles of E2A at later stages of B cell development. We use E2A-deficient and E2A and HEB double-deficient pre-B cell lines to directly assess the function of E2A and HEB in B cell development after lineage commitment. We show that, in contrast to the established role of E2A in lineage commitment, elimination of E2A and HEB in pre-B cell lines has only a modest negative impact on B lineage gene expression. However, E2A single and E2A and HEB double-deficient but not HEB single-deficient cell lines show dramatically enhanced apoptosis upon growth arrest. To address the possible role of E2A in the regulation of B cell survival in vivo, we crossed IFN-inducible Cre-transgenic mice to E2A conditional mice. Cre-mediated E2A deletion resulted in a block in bone marrow B cell development and a significant reduction in the proportion and total number of splenic B cells in these mice. We show that Cre-mediated deletion of E2A in adoptively transferred mature B cells results in the rapid depletion of the transferred population within 24 h of Cre induction. These results reveal that E2A is not required to maintain B cell fate but is essential in promoting pre-B and B cell survival.

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An Analysis of T Cell Intrinsic Roles ofE2Aby Conditional Gene Disruption in the Thymus

Cited by 57 publications

References 30 publications

The serine/threonine kinase LKB1 controls thymocyte survival through regulation of AMPK activation and Bcl-XL expression

The serine/threonine kinase LKB1 controls thymocyte survival through regulation of AMPK activation and Bcl-XL expression

Differential Functions for the Transcription Factor E2A in Positive and Negative Gene Regulation in Pre-B Lymphocytes

E2A Promotes the Survival of Precursor and Mature B Lymphocytes

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