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John Svaren - One of the best experts on this subject based on the ideXlab platform.
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Bi-allelic mutations in EGR2 cause autosomal recessive demyelinating neuropathy by disrupting the EGR2-NAB complex.
European journal of neurology, 2020Co-Authors: Vincenzo Lupo, John Svaren, Seongsik Won, Marina Frasquet, Megan S Schnitzler, Sneha S. Komath, Samuel I. Pascual-pascual, Carmen Espinós, Teresa SevillaAbstract:BACKGROUND AND PURPOSE Mutations in the early growth response 2 gene (EGR2) cause demyelinating, but also axonal, neuropathies differing in severity and age of onset. Except for one family, all reported cases have autosomal dominant inheritance and mutations are localized within the three zinc finger (ZNF) DNA-binding domain. The aim of this study was to provide a clinical and molecular analysis of a novel recessive mutation in EGR2. METHODS Clinical and electrophysiological assessments of three affected patients, from a consanguineous family, were performed. Genetic analyses of EGR2 were carried out by Sanger sequencing. Functional effects of clinical recessive mutations were assessed using a mammalian two-hybrid assay. RESULTS A novel missense mutation (c.791C>T; p.P264L) in the homozygous state was detected outside the ZNF domains of the EGR2 gene. Three affected siblings presented with distal demyelinating polyneuropathy with severe sensory loss, progressive thoracolumbar scoliosis and trigeminal neuralgia. Respiratory compromise and cranial nerve dysfunction were also found. Our data indicate that the p.P264L mutation prevents interaction of EGR2 transcription factor with NAB corepressors, suggesting that a disruption of the NAB-EGR2 protein interactions can result in dramatic neuropathy. CONCLUSION Mutations in, or next to, the R1 domain of EGR2 should be considered with extreme caution for genetic counseling, since these could cause a severe neuropathy with an autosomal recessive manner of transmission.
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genome wide analysis of EGR2 sox10 binding in myelinating peripheral nerve
Nucleic Acids Research, 2012Co-Authors: Rajini Srinivasan, Sungwook Jang, Erin A. Jones, Guannan Sun, Sunduz Keles, Courtney Krueger, John J. Moran, John SvarenAbstract:Myelin is essential for the rapidity of saltatory nerve conduction, and also provides trophic support for axons to prevent axonal degeneration. Two critical determinants of myelination are SOX10 and EGR2/KROX20. SOX10 is required for specification of Schwann cells from neural crest, and is required at every stage of Schwann cell development. EGR2/Krox20 expression is activated by axonal signals in myelinating Schwann cells, and is required for cell cycle arrest and myelin formation. To elucidate the integrated function of these two transcription factors during peripheral nerve myelination, we performed in vivo ChIP-Seq analysis of myelinating peripheral nerve. Integration of these binding data with loss-of-function array data identified a range of genes regulated by these factors. In addition, although SOX10 itself regulates EGR2/Krox20 expression, leading to coordinate activation of several major myelin genes by the two factors, there is a large subset of genes that are activated independent of EGR2. Finally, the results identify a set of SOX10-dependent genes that are expressed in early Schwann cell development, but become subsequently repressed by EGR2/KROX20.
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Genome-wide analysis of EGR2/SOX10 binding in myelinating peripheral nerve
Nucleic acids research, 2012Co-Authors: Rajini Srinivasan, Sungwook Jang, Erin A. Jones, Guannan Sun, Sunduz Keles, Courtney Krueger, John J. Moran, John SvarenAbstract:Myelin is essential for the rapidity of saltatory nerve conduction, and also provides trophic support for axons to prevent axonal degeneration. Two critical determinants of myelination are SOX10 and EGR2/KROX20. SOX10 is required for specification of Schwann cells from neural crest, and is required at every stage of Schwann cell development. EGR2/Krox20 expression is activated by axonal signals in myelinating Schwann cells, and is required for cell cycle arrest and myelin formation. To elucidate the integrated function of these two transcription factors during peripheral nerve myelination, we performed in vivo ChIP-Seq analysis of myelinating peripheral nerve. Integration of these binding data with loss-of-function array data identified a range of genes regulated by these factors. In addition, although SOX10 itself regulates EGR2/Krox20 expression, leading to coordinate activation of several major myelin genes by the two factors, there is a large subset of genes that are activated independent of EGR2. Finally, the results identify a set of SOX10-dependent genes that are expressed in early Schwann cell development, but become subsequently repressed by EGR2/KROX20.
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yy1 as a molecular link between neuregulin and transcriptional modulation of peripheral myelination
Nature Neuroscience, 2010Co-Authors: Jin Young Kim, John Svaren, Jeffrey L Dupree, Ambika Tewari, Carmen V Melendezvasquez, Patrizia CasacciaAbstract:Fast axonal conduction depends on myelin, which is formed by Schwann cells in the PNS. We found that the transcription factor Yin Yang 1 (YY1) is crucial for peripheral myelination. Conditional ablation of Yy1 in the Schwann cell lineage resulted in severe hypomyelination, which occurred independently of altered Schwann cell proliferation or apoptosis. In Yy1 mutant mice, Schwann cells established a 1:1 relationship with axons but were unable to myelinate them. The Schwann cells expressed low levels of myelin proteins and of EGR2 (also called Krox20), which is an important regulator of peripheral myelination. In vitro, Schwann cells that lacked Yy1 did not upregulate EGR2 in response to neuregulin1 and did not express myelin protein zero. This phenotype was rescued by overexpression of EGR2. In addition, neuregulin-induced phosphorylation of YY1 was required for transcriptional activation of EGR2. Thus, YY1 emerges as an important activator of peripheral myelination that links neuregulin signaling with EGR2 expression.
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locus wide identification of EGR2 krox20 regulatory targets in myelin genes
Journal of Neurochemistry, 2010Co-Authors: Sungwook Jang, Rajini Srinivasan, Erin A. Jones, Li-wei Chang, Rakesh Nagarajan, Guannan Sun, Sunduz Keles, Courtney Krueger, John SvarenAbstract:Myelination of peripheral nerves by Schwann cells depends upon a gene regulatory network controlled by early growth response EGR2/Krox20, which is specifically required for Schwann cells to initiate and maintain myelination. To elucidate the mechanism by which EGR2 regulates gene expression during myelination, we have performed chromatin immunoprecipitation analysis on myelinating rat sciatic nerve in vivo. The resulting samples were applied to a tiled microarray consisting of a broad spectrum of genes that are activated or repressed in EGR2-deficient mice. The results show extensive binding within myelin-associated genes, as well as some genes that become repressed in myelinating Schwann cells. Many of the EGR2 peaks coincide with regions of open chromatin, which is a marker of enhancer regions. In addition, further analysis showed that there is substantial colocalization of EGR2 binding with Sox10, a transcription factor required for Schwann cell specification and other stages of Schwann cell development. Finally, we have found that EGR2 binds to promoters of several lipid biosynthetic genes, which is consistent with their dramatic up-regulation during the formation of lipid-rich myelin. Overall, this analysis provides a locus-wide profile of EGR2 binding patterns in major myelin-associated genes using myelinating peripheral nerve.
Marina L. Kennerson - One of the best experts on this subject based on the ideXlab platform.
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A de novo EGR2 variant, c.1232A > G p.Asp411Gly, causes severe early-onset Charcot-Marie-Tooth Neuropathy Type 3 (Dejerine-Sottas Neuropathy)
Scientific reports, 2019Co-Authors: Bianca R. Grosz, Natasha Golovchenko, Melina Ellis, Kishore R. Kumar, Garth A. Nicholson, Anthony Antonellis, Marina L. KennersonAbstract:EGR2 (early growth response 2) is a crucial transcription factor for the myelination of the peripheral nervous system. Mutations in EGR2 are reported to cause a heterogenous spectrum of peripheral neuropathy with wide variation in both severity and age of onset, including demyelinating and axonal forms of Charcot-Marie Tooth (CMT) neuropathy, Dejerine-Sottas neuropathy (DSN/CMT3), and congenital hypomyelinating neuropathy (CHN/CMT4E). Here we report a sporadic de novo EGR2 variant, c.1232A > G (NM_000399.5), causing a missense p.Asp411Gly substitution and discovered through whole-exome sequencing (WES) of the proband. The resultant phenotype is severe demyelinating DSN with onset at two years of age, confirmed through nerve biopsy and electrophysiological examination. In silico analyses showed that the Asp411 residue is evolutionarily conserved, and the p.Asp411Gly variant was predicted to be deleterious by multiple in silico analyses. A luciferase-based reporter assay confirmed the reduced ability of p.Asp411Gly EGR2 to activate a PMP22 (peripheral myelin protein 22) enhancer element compared to wild-type EGR2. This study adds further support to the heterogeneity of EGR2-related peripheral neuropathies and provides strong functional evidence for the pathogenicity of the p.Asp411Gly EGR2 variant.
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a de novo EGR2 variant c 1232a g p asp411gly causes severe early onset charcot marie tooth neuropathy type 3 dejerine sottas neuropathy
Scientific Reports, 2019Co-Authors: Bianca R. Grosz, Natasha Golovchenko, Melina Ellis, Kishore R. Kumar, Garth A. Nicholson, Anthony Antonellis, Marina L. KennersonAbstract:EGR2 (early growth response 2) is a crucial transcription factor for the myelination of the peripheral nervous system. Mutations in EGR2 are reported to cause a heterogenous spectrum of peripheral neuropathy with wide variation in both severity and age of onset, including demyelinating and axonal forms of Charcot-Marie Tooth (CMT) neuropathy, Dejerine-Sottas neuropathy (DSN/CMT3), and congenital hypomyelinating neuropathy (CHN/CMT4E). Here we report a sporadic de novo EGR2 variant, c.1232A > G (NM_000399.5), causing a missense p.Asp411Gly substitution and discovered through whole-exome sequencing (WES) of the proband. The resultant phenotype is severe demyelinating DSN with onset at two years of age, confirmed through nerve biopsy and electrophysiological examination. In silico analyses showed that the Asp411 residue is evolutionarily conserved, and the p.Asp411Gly variant was predicted to be deleterious by multiple in silico analyses. A luciferase-based reporter assay confirmed the reduced ability of p.Asp411Gly EGR2 to activate a PMP22 (peripheral myelin protein 22) enhancer element compared to wild-type EGR2. This study adds further support to the heterogeneity of EGR2-related peripheral neuropathies and provides strong functional evidence for the pathogenicity of the p.Asp411Gly EGR2 variant.
Jeffrey Milbrandt - One of the best experts on this subject based on the ideXlab platform.
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EGR2 mutations in inherited neuropathies dominant negatively inhibit myelin gene expression
Neuron, 2001Co-Authors: Rakesh Nagarajan, John Svaren, Nam Le, Toshiyuki Araki, Mark A Watson, Jeffrey MilbrandtAbstract:Abstract The identification of EGR2 mutations in patients with neuropathies and the phenotype EGR2/Krox20 −/− have demonstrated that the EGR2 transcription factor is critical for peripheral nerve myelination. However, the mechanism by which these mutations cause disease remains unclear, as most patients present with disease in the heterozygous state, whereas EGR2 +/− mice are phenotypically normal. To understand the effect of aberrant EGR2 activity on Schwann cell gene expression, we performed microarray expression profiling to identify genes regulated by EGR2 in Schwann cells. These include genes encoding myelin proteins and enzymes required for synthesis of normal myelin lipids. Using these newly identified targets, we have shown that neuropathy-associated EGR2 mutants dominant-negatively inhibit wild-type EGR2-mediated expression of essential myelin genes to levels sufficiently low to result in the abnormal myelination observed in these patients.
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the transcription factor egr3 modulates sensory axon myotube interactions during muscle spindle morphogenesis
Developmental Biology, 2001Co-Authors: Warren G Tourtellotte, Cynthia Kellerpeck, Jeffrey Milbrandt, Jan KuceraAbstract:Abstract The Egr family of zinc-finger transcription factors, consisting of Egr1, EGR2, Egr3, and Egr4, are involved in cellular growth and differentiation. Adult Egr3-deficient mice are ataxic and lack muscle spindle proprioceptors that normally develop at the sites of Ia afferent-myotube contacts during embryogenesis. To resolve whether spindles form and then degenerate, or whether they never form in the absence of Egr3, we examined the spatiotemporal expression of Egr3 relative to spindle development. In wild type mice, Egr3 was expressed in developing myotubes shortly after they were innervated by Ia afferents and its expression was controlled by innervation because it dissipated following nerve transection. In Egr3-deficient mice, myotubes received Ia afferent innervation and assembled normally into spindles during embryogenesis. However, newborn Egr3-deficient spindles had few internal myonuclei in intrafusal fibers and thin capsules. Moreover, slow-developmental myosin heavy chain was not induced in embryonic Egr3-deficient spindles suggesting that impairments in differentiation were present before they could be detected morphologically. After birth, sensory and motor innervation withdrew from the Egr3-deficient spindles, and the spindles disassembled. In spite of the spindle disassembly and retraction of afferents from muscles, the cell bodies of proprioceptive neurons within dorsal root ganglia were retained. We conclude that Egr3 has an essential role in regulating genes required for the transformation of undifferentiated myotubes into intrafusal fibers, and hence for the phenotypic differentiation of spindles.
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Functional Consequences of Mutations in the Early Growth Response 2 Gene (EGR2) Correlate with Severity of Human Myelinopathies
Human molecular genetics, 1999Co-Authors: Laura E. Warner, John Svaren, Jeffrey Milbrandt, James R. LupskiAbstract:The early growth response 2 gene (EGR2 )i s a Cys2His2 zinc finger transcription factor which is thought to play a role in the regulation of peripheral nervous system myelination. This idea is based partly on the phenotype of homozygous Krox20 (EGR2) knockout mice, which display hypomyelination of the PNS and a block of Schwann cells at an early stage of differentiation. Mutations in the human EGR2 gene have recently been associated with the inherited peripheral neuropathies Charcot‐Marie‐ Tooth type 1, Dejerine‐Sottas syndrome and congenital hypomyelinating neuropathy. Three of the four EGR2 mutations are dominant and occur within the zinc finger DNA-binding domain. The fourth mutation is recessive and affects the inhibitory domain (R1) that binds the NAB transcriptional co-repressors. A combination of DNA-binding assays and transcriptional analysis was used to determine the functional consequences of these mutations. The zinc finger mutations affect DNA binding and the amount of residual binding directly correlates with disease severity. The R1 domain mutation prevents interaction of EGR2 with the NAB co-repressors and thereby increases transcriptional activity. These data provide insight into the possible disease mechanisms underlying EGR2 mutations and the reason for varying severity and differences in inheritance patterns.
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Novel mutants of NAB corepressors enhance activation by Egr transactivators
The EMBO Journal, 1998Co-Authors: John Svaren, Bradley R. Sevetson, Thomas Golda, Jeffrey J. Stanton, Alex H. Swirnoff, Jeffrey MilbrandtAbstract:The NGFI-A binding corepressors NAB1 and NAB2 interact with a conserved domain (R1 domain) within the Egr1/NGFI-A and EGR2/Krox20 transactivators, and repress the transcription of Egr target promoters. Using a novel adaptation of the yeast two-hybrid screen, we have identified several point mutations in NAB corepressors that interfere with their ability to bind to the Egr1 R1 domain. Surprisingly, NAB proteins bearing some of these mutations increased Egr1 activity dramatically. The mechanism underlying the unexpected behavior of these mutants was elucidated by the discovery that NAB conserved domain 1 (NCD1) not only binds to Egr proteins but also mediates multimerization of NAB molecules. The activating mutants exert a dominant negative effect on NAB repression by multimerizing with native NAB proteins and preventing binding of endogenous NAB proteins with Egr transactivators. To examine NAB repression of a native Egr target gene, we show that NAB2 represses EGR2/Krox20-mediated activation of the bFGF/FGF-2 promoter, and that repression is reversed by coexpression of dominant negative NAB2. Because of their specific ability to alleviate NAB repression of Egr target genes, the dominant negative NAB mutants will be useful in elucidating the mechanism and function of NAB corepressors.
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sensory ataxia and muscle spindle agenesis in mice lacking the transcription factor egr3
Nature Genetics, 1998Co-Authors: Warren G Tourtellotte, Jeffrey MilbrandtAbstract:Muscle spindles are skeletal muscle sensory organs that provide axial and limb position information (proprioception) to the central nervous system. Spindles consist of encapsulated muscle fibers (intrafusal fibers) that are innervated by specialized motor and sensory axons. Although the molecular mechanisms involved in spindle ontogeny are poorly understood, the innervation of a subset of developing myotubes (type I) by peripheral sensory afferents (group Ia) is a critical event for inducing intrafusal fiber differentiation and subsequent spindle formation1,2,3. The Egr family of zinc-finger transcription factors, whose members include Egr1 (NGFI-A), EGR2 (Krox-20), Egr3 and Egr4 (NGFI-C), are thought to regulate critical genetic programs involved in cellular growth and differentiation (refs 4, 5, 6, 7, 8 and W.G.T. et al., manuscript submitted). Mice deficient in Egr3 were generated by gene targeting and had gait ataxia, increased frequency of perinatal mortality, scoliosis, resting tremors and ptosis. Although extrafusal skeletal muscle fibers appeared normal, Egr3-deficient animals lacked muscle spindles, a finding that is consistent with their profound gait ataxia. Egr3 was highly expressed in developing muscle spindles, but not in Ia afferent neurons or their terminals during developmental periods that coincided with the induction of spindle morphogenesis by sensory afferent axons. These results indicate that type I myotubes are dependent upon Egr3-mediated transcription for proper spindle development.
Ping Wang - One of the best experts on this subject based on the ideXlab platform.
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EGR2 regulation in T cells is mediated through IFNγ/STAT1 and IL-6/STAT3 signalling pathway.
Pathology research and practice, 2020Co-Authors: Nima Taefehshokr, Tizong Miao, Alistair L. J. Symonds, Ping WangAbstract:The immune system is a host defence system to protect the body against foreign invaders. T cells are one of the major components of the immune cells and they are essential for immune responses. Early growth response gene (EGR2) in T cells is important for maintaining immune functions of T cells by promoting adaptive immune responses while controlling inflammation and preventing the development of autoimmune diseases. A study by our group demonstrated the function of EGR2 as a checkpoint regulator controlling the proliferation and differentiation of the T cells. In association, EGR2 and 3 play indispensable role in T cell immune response, but the mechanism regulating EGR2 expression in T cells is still unclear. In this study, we analysed the EGR2 expression mechanism in CD4 T cells under antigen stimulation. We found that EGR2 expression is regulated by different cytokines including IL-2 and IL-4, which increased EGR2 induction in activated T cells. However, inflammatory cytokines, including INFγ and IL-6, suppressed EGR2 expression through STAT1 and STAT3 signalling pathway respectively, highlighting a mechanism for tolergenic immune response on T cells.
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EGR2 regulation in t cells is mediated through ifnγ stat1 and il 6 stat3 signalling pathway
Pathology Research and Practice, 2020Co-Authors: Nima Taefehshokr, Tizong Miao, Alistair L. J. Symonds, Ping WangAbstract:The immune system is a host defence system to protect the body against foreign invaders. T cells are one of the major components of the immune cells and they are essential for immune responses. Early growth response gene (EGR2) in T cells is important for maintaining immune functions of T cells by promoting adaptive immune responses while controlling inflammation and preventing the development of autoimmune diseases. A study by our group demonstrated the function of EGR2 as a checkpoint regulator controlling the proliferation and differentiation of the T cells. In association, EGR2 and 3 play indispensable role in T cell immune response, but the mechanism regulating EGR2 expression in T cells is still unclear. In this study, we analysed the EGR2 expression mechanism in CD4 T cells under antigen stimulation. We found that EGR2 expression is regulated by different cytokines including IL-2 and IL-4, which increased EGR2 induction in activated T cells. However, inflammatory cytokines, including INFγ and IL-6, suppressed EGR2 expression through STAT1 and STAT3 signalling pathway respectively, highlighting a mechanism for tolergenic immune response on T cells.
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EGR2 and 3 control inflammation, but maintain homeostasis, of PD-1high memory phenotype CD4 T cells.
Life science alliance, 2020Co-Authors: Alistair L. J. Symonds, Tizong Miao, Wei Zheng, Haiyu Wang, Tieshang Wang, Ruth Kiome, Xiujuan Hou, Ping WangAbstract:The transcription factors EGR2 and 3 are essential for controlling inflammatory autoimmune responses of memory phenotype (MP) CD4 T cells. However, the mechanism is still unclear. We have now found that the EGR2+ subset (PD-1high MP) of MP CD4 T cells expresses high levels of checkpoint molecules (PD-1 and Lag3) and also markers of effector T cells (CXCR3 and ICAM-1). EGR2/3 are not required for PD-1high MP CD4 cell development but mediate a unique transcriptional programme that effectively controls their inflammatory responses, while promoting homeostatic proliferation and adaptive responses. EGR2 negative PD-1high MP CD4 T cells are impaired in homeostatic proliferation and adaptive responses against viral infection but display inflammatory responses to innate stimulation such as IL-12. PD-1high MP CD4 T cells have recently been implicated in rheumatoid arthritis pathogenesis, and we have now found that EGR2 expression is reduced in PD-1high MP CD4 T cells from patients with active rheumatoid arthritis compared with healthy controls. These findings demonstrate that EGR2/3 control the inflammatory responses of PD-1high MP CD4 T cells and maintain their adaptive immune fitness.
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EGR2 and 3 inhibit t bet mediated ifn γ production in t cells
Journal of Immunology, 2017Co-Authors: Tizong Miao, Alistair L. J. Symonds, Randeep Singh, Becky Omodho, Ping WangAbstract:T-bet is important for differentiation of cytotoxic CD8 and Th1 CD4 T cells. We have discovered that EGR2 and 3 are potent inhibitors of T-bet function in CD4 and CD8 effector T cells. EGR2 and 3 were essential to suppress Th1 differentiation in Th2 and Th17 conditions in vitro and also to control IFN-γ-producing CD4 and CD8 T cells in response to virus infection. Together with EGR2 and 3, T-bet is induced in naive T cells by Ag stimulation, but EGR2 and 3 expression was inhibited by Th1-inducing cytokines. We found that EGR2 and 3 physically interact with the T-box domain of T-bet, blocking T-bet DNA binding and inhibiting T-bet-mediated production of IFN-γ. Thus, EGR2 and 3 are antagonists of T-bet function in effector T cells and are important for the control of inflammatory responses of T cells.
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EGR2 and 3 control adaptive immune responses by temporally uncoupling expansion from T cell differentiation.
The Journal of experimental medicine, 2017Co-Authors: Tizong Miao, Alistair L. J. Symonds, Randeep Singh, Janine D. Symonds, Ane Ogbe, Becky Omodho, Bo Zhu, Ping WangAbstract:EGR2 and 3 are important for maintaining immune homeostasis. Here we define a fundamental function of EGR2 and 3 operating as a checkpoint that controls the transition between clonal expansion and differentiation of effector T cells. EGR2 and 3 deficiency resulted in defective clonal expansion but hyperactivation and excessive differentiation of T cells in response to viral infection. Conversely, sustained EGR2 expression enhanced expansion but severely impaired effector differentiation. EGR2 bound to and controlled the expression of genes regulating proliferation (Myc and Myb) and differentiation repressors (Bcl6, Id3), while repressing transcription factors required for effector function (Zeb2, RORa, RORc, and Bhlhe40). EGR2 and 3 expression in T cells was regulated reciprocally by antigen and IFNγ, providing a mechanism for adjusting proliferation and differentiation of individual T cells. Thus, EGR2 and 3 are upstream regulators of effector CD4 and CD8 T cells that are essential for optimal responses with limited immunopathology.
Sungwook Jang - One of the best experts on this subject based on the ideXlab platform.
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genome wide analysis of EGR2 sox10 binding in myelinating peripheral nerve
Nucleic Acids Research, 2012Co-Authors: Rajini Srinivasan, Sungwook Jang, Erin A. Jones, Guannan Sun, Sunduz Keles, Courtney Krueger, John J. Moran, John SvarenAbstract:Myelin is essential for the rapidity of saltatory nerve conduction, and also provides trophic support for axons to prevent axonal degeneration. Two critical determinants of myelination are SOX10 and EGR2/KROX20. SOX10 is required for specification of Schwann cells from neural crest, and is required at every stage of Schwann cell development. EGR2/Krox20 expression is activated by axonal signals in myelinating Schwann cells, and is required for cell cycle arrest and myelin formation. To elucidate the integrated function of these two transcription factors during peripheral nerve myelination, we performed in vivo ChIP-Seq analysis of myelinating peripheral nerve. Integration of these binding data with loss-of-function array data identified a range of genes regulated by these factors. In addition, although SOX10 itself regulates EGR2/Krox20 expression, leading to coordinate activation of several major myelin genes by the two factors, there is a large subset of genes that are activated independent of EGR2. Finally, the results identify a set of SOX10-dependent genes that are expressed in early Schwann cell development, but become subsequently repressed by EGR2/KROX20.
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Genome-wide analysis of EGR2/SOX10 binding in myelinating peripheral nerve
Nucleic acids research, 2012Co-Authors: Rajini Srinivasan, Sungwook Jang, Erin A. Jones, Guannan Sun, Sunduz Keles, Courtney Krueger, John J. Moran, John SvarenAbstract:Myelin is essential for the rapidity of saltatory nerve conduction, and also provides trophic support for axons to prevent axonal degeneration. Two critical determinants of myelination are SOX10 and EGR2/KROX20. SOX10 is required for specification of Schwann cells from neural crest, and is required at every stage of Schwann cell development. EGR2/Krox20 expression is activated by axonal signals in myelinating Schwann cells, and is required for cell cycle arrest and myelin formation. To elucidate the integrated function of these two transcription factors during peripheral nerve myelination, we performed in vivo ChIP-Seq analysis of myelinating peripheral nerve. Integration of these binding data with loss-of-function array data identified a range of genes regulated by these factors. In addition, although SOX10 itself regulates EGR2/Krox20 expression, leading to coordinate activation of several major myelin genes by the two factors, there is a large subset of genes that are activated independent of EGR2. Finally, the results identify a set of SOX10-dependent genes that are expressed in early Schwann cell development, but become subsequently repressed by EGR2/KROX20.
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locus wide identification of EGR2 krox20 regulatory targets in myelin genes
Journal of Neurochemistry, 2010Co-Authors: Sungwook Jang, Rajini Srinivasan, Erin A. Jones, Li-wei Chang, Rakesh Nagarajan, Guannan Sun, Sunduz Keles, Courtney Krueger, John SvarenAbstract:Myelination of peripheral nerves by Schwann cells depends upon a gene regulatory network controlled by early growth response EGR2/Krox20, which is specifically required for Schwann cells to initiate and maintain myelination. To elucidate the mechanism by which EGR2 regulates gene expression during myelination, we have performed chromatin immunoprecipitation analysis on myelinating rat sciatic nerve in vivo. The resulting samples were applied to a tiled microarray consisting of a broad spectrum of genes that are activated or repressed in EGR2-deficient mice. The results show extensive binding within myelin-associated genes, as well as some genes that become repressed in myelinating Schwann cells. Many of the EGR2 peaks coincide with regions of open chromatin, which is a marker of enhancer regions. In addition, further analysis showed that there is substantial colocalization of EGR2 binding with Sox10, a transcription factor required for Schwann cell specification and other stages of Schwann cell development. Finally, we have found that EGR2 binds to promoters of several lipid biosynthetic genes, which is consistent with their dramatic up-regulation during the formation of lipid-rich myelin. Overall, this analysis provides a locus-wide profile of EGR2 binding patterns in major myelin-associated genes using myelinating peripheral nerve.
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Locus-wide identification of EGR2/Krox20 regulatory targets in myelin genes
Journal of neurochemistry, 2010Co-Authors: Sungwook Jang, Rajini Srinivasan, Erin A. Jones, Li-wei Chang, Rakesh Nagarajan, Guannan Sun, Sunduz Keles, Courtney Krueger, John SvarenAbstract:Myelination of peripheral nerves by Schwann cells depends upon a gene regulatory network controlled by early growth response EGR2/Krox20, which is specifically required for Schwann cells to initiate and maintain myelination. To elucidate the mechanism by which EGR2 regulates gene expression during myelination, we have performed chromatin immunoprecipitation analysis on myelinating rat sciatic nerve in vivo. The resulting samples were applied to a tiled microarray consisting of a broad spectrum of genes that are activated or repressed in EGR2-deficient mice. The results show extensive binding within myelin-associated genes, as well as some genes that become repressed in myelinating Schwann cells. Many of the EGR2 peaks coincide with regions of open chromatin, which is a marker of enhancer regions. In addition, further analysis showed that there is substantial colocalization of EGR2 binding with Sox10, a transcription factor required for Schwann cell specification and other stages of Schwann cell development. Finally, we have found that EGR2 binds to promoters of several lipid biosynthetic genes, which is consistent with their dramatic up-regulation during the formation of lipid-rich myelin. Overall, this analysis provides a locus-wide profile of EGR2 binding patterns in major myelin-associated genes using myelinating peripheral nerve.
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active gene repression by the EGR2 nab complex during peripheral nerve myelination
Journal of Biological Chemistry, 2008Co-Authors: Gennifer M. Mager, Sungwook Jang, Lawrence Wrabetz, Rajini Srinivasan, Rebecca Ward, John SvarenAbstract:Abstract The EGR2/Krox20 transactivator is required for activation of many myelin-associated genes during peripheral nerve myelination by Schwann cells. However, recent work has indicated that EGR2 not only activates genes required for peripheral nerve myelination but may also be involved in gene repression. The NAB (NGFI-A/Egr-binding) corepressors interact with EGR2 and are required for proper coordination of myelin formation. Therefore, NAB proteins could mediate repression of some EGR2 target genes, although direct repression by EGR2 or NAB proteins during myelination has not been demonstrated. To define the physiological role of NAB corepression in gene repression by EGR2, we tested whether the EGR2·NAB complex directly repressed specific target genes. A screen for NAB-regulated genes identified several (including Id2, Id4, and Rad) that declined during the course of peripheral nerve myelination. In vivo chromatin immunoprecipitation analysis of the myelinating sciatic nerve was used to show developmental association of both EGR2 and NAB2 on the Id2, Id4, and Rad promoters as they were repressed during the myelination process. In addition, NAB2 represses transcription by interaction with the chromodomain helicase DNA-binding protein 4 (CHD4) subunit of the nucleosome remodeling and deacetylase chromatin remodeling complex, and we demonstrate that CHD4 occupies NAB-repressed promoters in a developmentally regulated manner in vivo. These results illustrate a novel aspect of genetic regulation of peripheral nerve myelination by showing that EGR2 directly represses genes during myelination in conjunction with NAB corepressors. Furthermore, repression of Id2 was found to augment activation of Mpz (myelin protein zero) expression.