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Results for “Receptor, Notch1”

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At least 343 records · Page 19Linked to original sources
PubMed2000

Fringe differentially modulates Jagged1 and Delta1 signalling through Notch1 and Notch2.

Proteins encoded by the fringe family of genes are required to modulate Notch signalling in a wide range of developmental contexts. Using a cell co-culture assay, we find that mammalian Lunatic fringe (Lfng) inhibits Jagged1-mediated signalling and potentiates Delta1-mediated signalling through Notch1. Lfng localizes to the Golgi, and Lfng-dependent modulation of Notch signalling requires both expression of Lfng in the Notch-responsive cell and the Notch extracellular domain. Lfng does not prevent binding of soluble Jagged1 or Delta1 to Notch1-expressing cells. Lfng potentiates both Jagged1- and Delta1-mediated signalling via Notch2, in contrast to its actions with Notch1. Our data suggest that Fringe-dependent differential modulation of the interaction of Delta/Serrate/Lag2 (DSL) ligands with their Notch receptors is likely to have a significant role in the combinatorial repertoire of Notch signalling in mammals.

Alkaline Phosphatase↗
PubMed2003

Regulation of Notch1 and Dll4 by vascular endothelial growth factor in arterial endothelial cells: implications for modulating arteriogenesis and angiogenesis.

Notch and its ligands play critical roles in cell fate determination. Expression of Notch and ligand in vascular endothelium and defects in vascular phenotypes of targeted mutants in the Notch pathway have suggested a critical role for Notch signaling in vasculogenesis and angiogenesis. However, the angiogenic signaling that controls Notch and ligand gene expression is unknown. We show here that vascular endothelial growth factor (VEGF) but not basic fibroblast growth factor can induce gene expression of Notch1 and its ligand, Delta-like 4 (Dll4), in human arterial endothelial cells. The VEGF-induced specific signaling is mediated through VEGF receptors 1 and 2 and is transmitted via the phosphatidylinositol 3-kinase/Akt pathway but is independent of mitogen-activated protein kinase and Src tyrosine kinase. Constitutive activation of Notch signaling stabilizes network formation of endothelial cells on Matrigel and enhances formation of vessel-like structures in a three-dimensional angiogenesis model, whereas blocking Notch signaling can partially inhibit network formation. This study provides the first evidence for regulation of Notch/Delta gene expression by an angiogenic growth factor and insight into the critical role of Notch signaling in arteriogenesis and angiogenesis.

Arteries↗
PubMed2004

p53 regulates thymic Notch1 activation.

Notch is crucial for multiple stages of T cell development, including the CD4+CD8+ double positive (DP)/CD8+ single positive (SP) transition, but regulation of Notchactivation is not well understood. p53 regulates Presenilin1 (PS1) expression, and PS1 cleaves Notch, releasing its intracellular domain (NIC), leading to the expression of downstream targets, e.g. the HES1 gene. We hypothesize that p53 regulates Notch activity during T cell development. We found that Notch1 expression and activation were negatively regulated by p53in several thymoma lines. Additionally, NIC was elevated in Trp53(-/-) thymocytes as compared to Trp53(+/+) thymocytes. To determine if elevated Notch1 activation in Trp53(-/-) thymocytes had an effect on T cell development, CD4 and CD8 expression were analyzed. The CD4+ SP/CD8+ SP T cell ratio was decreased in Trp53(-/-) splenocytes and thymocytes. This alteration in T cell development correlated with the increased Notch1 activation observed in the absence of p53. These data indicate that p53 negatively regulates Notch1 activation during T cell development. Skewing of T cell development toward CD8+SP T cells in Trp53(-/-) mice is reminiscent of the phenotype of NIC-overexpressing mice. Thus, we suggest that p53 plays a role in T cell development, in part by regulating Notch1 activation.

Animals↗
PubMed2007

Notch2, but not Notch1, is required for proximal fate acquisition in the mammalian nephron.

The Notch pathway regulates cell fate determination in numerous developmental processes. Here we report that Notch2 acts non-redundantly to control the processes of nephron segmentation through an Rbp-J-dependent process. Notch1 and Notch2 are detected in the early renal vesicle. Genetic analysis reveals that only Notch2 is required for the differentiation of proximal nephron structures (podocytes and proximal convoluted tubules) despite the presence of activated Notch1 in the nuclei of putative proximal progenitors. The inability of endogenous Notch1 to compensate for Notch2 deficiency may reflect sub-threshold Notch1 levels in the nucleus. In line with this view, forced expression of a gamma-secretase-independent form of Notch1 intracellular domain drives the specification of proximal fates where all endogenous, ligand-dependent Notch signaling is blocked by a gamma-secretase inhibitor. These results establish distinct (non-redundant), instructive roles for Notch receptors in nephron segmentation.

Animals↗
PubMed2004

Kick it up a Notch: NOTCH1 activation in T-ALL.

While the human NOTCH1 gene initially was cloned as part of a translocation breakpoint in T cell acute lymphoblastic leukemia (T-ALL) tumors, this translocation is present in only a small percentage of T-ALL patients. A recent paper by Weng et al. (2004) demonstrates that novel types of activating mutations in the NOTCH1 gene occur in more than half of all T-ALL cases, implicating NOTCH1 as a major player in the etiology of T-ALL.

Gene Expression Regulation, Neoplastic↗
PubMed2001

Separation of Notch1 promoted lineage commitment and expansion/transformation in developing T cells.

Notch1 signaling is required for T cell development. We have previously demonstrated that expression of a dominant active Notch1 (ICN1) transgene in hematopoietic stem cells (HSCs) leads to thymic-independent development of CD4(+)CD8(+) double-positive (DP) T cells in the bone marrow (BM). To understand the function of Notch1 in early stages of T cell development, we assessed the ability of ICN1 to induce extrathymic T lineage commitment in BM progenitors from mice that varied in their capacity to form a functional pre-T cell receptor (TCR). Whereas mice repopulated with ICN1 transduced HSCs from either recombinase deficient (Rag-2(-/)-) or Src homology 2 domain--containing leukocyte protein of 76 kD (SLP-76)(-/)- mice failed to develop DP BM cells, recipients of ICN1-transduced Rag-2(-/)- progenitors contained two novel BM cell populations indicative of pre-DP T cell development. These novel BM populations are characterized by their expression of CD3 epsilon and pre-T alpha mRNA and the surface proteins CD44 and CD25. In contrast, complementation of Rag-2(-/)- mice with a TCR beta transgene restored ICN1-induced DP development in the BM within 3 wk after BM transfer (BMT). At later time points, this population selectively and consistently gave rise to T cell leukemia. These findings demonstrate that Notch signaling directs T lineage commitment from multipotent progenitor cells; however, both expansion and leukemic transformation of this population are dependent on T cell-specific signals associated with development of DP thymocytes.

Animals↗
PubMed2000

Activated Notch1 modulates gene expression in B cells similarly to Epstein-Barr viral nuclear antigen 2.

Both Epstein-Barr viral nuclear antigen 2 (EBNA2) and activated Notch transactivate genes by interacting with the transcription factor RBP-Jkappa. The viral protein EBNA2 may hence be regarded as a functional equivalent of an activated Notch receptor. Until now, nothing has been known about the physiological role of Notch signaling in B cells. Here we investigated whether activated Notch can induce the same phenotypic changes as EBNA2 in Burkitt's lymphoma cells. An estrogen receptor fusion protein of the intracellular part of mouse Notch 1 (mNotch1-IC), mimicking in the presence of estrogen a constitutively active Notch receptor, was stably transfected into the Burkitt's lymphoma cell lines BL41-P3HR1 and HH514. Northern blot analysis revealed that the LMP2A gene is induced by Notch-IC in the presence of estrogen, whereas increased expression of LMP1 could be detected only if cycloheximide was simultaneously added. Concerning the cellular genes regulated by EBNA2, Notch-IC was able to upregulate CD21 but not CD23 expression. Immunoglobulin mu (Igmu) expression, which is downregulated by EBNA2, was also negatively regulated by Notch-IC. Similarly to EBNA2, Notch-IC was able to repress c-myc expression, which is under the control of the immunoglobulin heavy-chain locus in Burkitt's lymphoma cells with a t(8;14) translocation. The data show that Notch-IC is able to participate in gene regulation in B cells.

Animals↗
PubMed1997

Alagille syndrome is caused by mutations in human Jagged1, which encodes a ligand for Notch1.

Alagille syndrome is an autosomal dominant disorder characterized by abnormal development of liver, heart, skeleton, eye, face and, less frequently, kidney. Analyses of many patients with cytogenetic deletions or rearrangements have mapped the gene to chromosome 20p12, although deletions are found in a relatively small proportion of patients (< 7%). We have mapped the human Jagged1 gene (JAG1), encoding a ligand for the developmentally important Notch transmembrane receptor, to the Alagille syndrome critical region within 20p12. The Notch intercellular signalling pathway has been shown to mediate cell fate decisions during development in invertebrates and vertebrates. We demonstrate four distinct coding mutations in JAG1 from four Alagille syndrome families, providing evidence that it is the causal gene for Alagille syndrome. All four mutations lie within conserved regions of the gene and cause translational frameshifts, resulting in gross alterations of the protein product Patients with cytogenetically detectable deletions including JAG1 have Alagille syndrome, supporting the hypothesis that haploinsufficiency for this gene is one of the mechanisms causing the Alagille syndrome phenotype.

Alagille Syndrome↗
PubMed2003

Notch-induced E2A ubiquitination and degradation are controlled by MAP kinase activities.

Notch signals are important for lymphocyte development but downstream events that follow Notch signaling are not well understood. Here, we report that signaling through Notch modulates the turnover of E2A proteins including E12 and E47, which are basic helix-loop-helix proteins crucial for B and T lymphocyte development. Notch-induced degradation requires phosphorylation of E47 by p42/p44 MAP kinases. Expression of the intracellular domain of Notch1 (N1-IC) enhances the association of E47 with the SCF(Skp2) E3 ubiquitin ligase and ubiquitination of E47, followed by proteasome-mediated degradation. Furthermore, N1-IC induces E2A degradation in B and T cells in the presence of activated MAP kinases. Activation of endogenous Notch receptors by treatment of splenocytes with anti-IgM or anti-CD3 plus anti-CD28 also leads to E2A degradation, which is blocked by the inhibitors of Notch activation or proteasome function. Notch-induced E2A degradation depends on the function of its downstream effector, RBP-Jkappa, probably to activate target genes involved in the ubiquitination of E2A proteins. Thus we propose that Notch regulates lymphocyte differentiation by controlling E2A protein turnover.

Animals↗
PubMed2002

[Effects of Notch and its ligands on the differentiation of 32D cell].

OBJECTIVE: To explore the mechanism of Notch signaling transduction system and its effects on hematopoietic system. METHODS: Notch ligands transfected CHO cells were added into Notch1 and Notch2 transfected CHO cells, which were transiently transfected with reporter gene TP1. PGL-100 was used as substrate to test the interaction between Notch and Notch ligands. CHO, Jagged2-CHO and Delta 4-CHO cells were seeded in the petri dish containing G-CSF, and then Notch 1-32D cells were added in it to observe the differentiation of Notch1-32D cell after incubation and staining. RESULTS: All of the five Notch ligands binding to Notch1 could induce TP1 activity, it increased significantly the Jagged2-CHO, Delta 4-CHO1-4 and Delta 4-CHO1-5 cells. For Notch2, the TP1 activity induced by the five ligands in these cells was much higher than that of CHO. At the presence of G-CSF, Notch1-32D could differentiate to mature granulocyte. Jagged2 could inhibit G-CSF induced Notch1-32D cell differentiation, but Delta 4 could not. CONCLUSION: Jagged2 and Delta 4 are the ligands of Notch1. Jagged2 can inhibit G-CSF induced Notch1-32D cell differentiation, but Delta 4 can not.

Animals↗
PubMed2003

Fine-tuning Notch1 activation by endocytosis and glycosylation.

Recent studies have shown that disruption of Notch1 signaling in lymphocyte progenitors (LP) inhibits T cell development and promotes B cell development in the thymus. Conversely, inappropriate activation of Notch1 in LP inhibits B cell development and causes ectopic T cell development in the bone marrow. These observations imply that Notch1 activation must be spatially regulated to ensure that LP generate B cells in the bone marrow and T cells in the thymus. However, Notch ligands are expressed in both tissues. Studies in flies and worms have revealed that Notch activation is extremely sensitive to small changes in the amount of receptor or ligand expressed, and defined multiple mechanisms that limit Notch activation to discrete cells at specific times during development. Here, we describe how some of these mechanisms might regulate Notch activity in LP during the T/B lineage decision.

Animals↗
PubMed2002

Inactivation of Notch1 impairs VDJbeta rearrangement and allows pre-TCR-independent survival of early alpha beta Lineage Thymocytes.

Notch proteins influence cell fate decisions in many developmental systems. During lymphoid development, Notch1 signaling is essential to direct a bipotent T/B precursor toward the T cell fate, but the role of Notch1 at later stages of T cell development remains controversial. We have recently reported that tissue-specific inactivation of Notch1 in immature (CD44(-) CD25(+)) thymocytes does not affect subsequent T cell development. Here, we demonstrate that loss of Notch1 signaling at an earlier (CD44(+)CD25(+)) developmental stage results in severe perturbation of alpha beta but not gamma delta lineage development. Immature Notch1(-/-) thymocytes show impaired VDJ beta rearrangement and aberrant pre-TCR-independent survival. Collectively, our data demonstrate that Notch1 controls several nonredundant functions necessary for alpha beta lineage development.

Animals↗
PubMed2002

Pax5 promotes B lymphopoiesis and blocks T cell development by repressing Notch1.

The B lineage commitment factor Pax5 (BSAP) is exclusively expressed in B lymphocytes of the blood system. To study the effect of Pax5 on the development of other hematopoietic lineages, we generated a heterozygous knockin mouse carrying a Pax5 minigene under the control of the Ikaros locus. Conditional and constitutive activation of the Ik(Pax5) allele demonstrated that precocious Pax5 expression in hematopoietic stem cells and progenitors failed to interfere with myeloid development and only weakly affected erythroblast formation. Instead, pan-hematopoietic Pax5 expression strongly promoted B cell development at the expense of T lymphopoiesis. Pax5 thereby interfered with T lineage commitment and early thymocyte development by repressing the transcription of the T cell specification gene Notch1.

Animals↗
PubMed2001

Notch1 and T-cell development: insights from conditional knockout mice.

Notch proteins influence cell-fate decisions in many developmental systems. Gain-of-function studies have suggested a crucial role for Notch1 signaling at several stages during lymphocyte development, including the B/T, alphabeta/gammadelta and CD4/CD8 lineage choices. Here, we critically re-evaluate these conclusions in the light of recent studies that describe inducible and tissue-specific targeting of the Notch1 gene.

Animals↗
PubMed1998

A full-length Notch1 allele is dispensable for transformation associated with a provirally activated truncated Notch1 allele in Moloney MuLV-infected MMTV(D)/myc transgenic mice.

The Notch1 gene was previously found to be targetted by provirus insertion in a high proportion of T-cell lymphomas arising in Moloney MuLV-inoculated MMTV(D)/myc transgenic mice. Proviral activation of Notch1 was associated with overexpression of truncated Notch1, deleted of the sequences coding for the extracellular domain. The high levels of truncated Notch1 RNA and proteins in these tumors are thought to be involved in the oncogenic transformation. However, in addition to these truncated RNA and proteins, high level expression of full-length Notch1 RNA and proteins was also observed in several tumors, suggesting that they could also contribute to the transformation process. To test this hypothesis, we used a genetic approach and studied MMTV(D)/myc transgenic mice in which one of the Notch1 alleles was mutated by targeted mutagenesis (Notch1+/- mice). Heterozygote (Notch1+/-) and wild-type (Notch1+/+) transgenic mice were inoculated with Moloney MuLV and the frequency of Notch1 rearrangements was compared between both groups. Notch1 was rearranged at similar frequencies in both groups, indicating that the full-length Notch1 allele is dispensable in tumors harboring an activated Notch1 allele.

Alleles↗
PubMed2003

Glycoprotein 130 signaling regulates Notch1 expression and activation in the self-renewal of mammalian forebrain neural stem cells.

Glycoprotein130 (gp130) and Notch signaling are thought to participate in neural stem cell (NSC) self-renewal. We asked whether gp130 regulates Notch activity in forebrain epidermal growth factor (EGF)-responsive NSCs. Disruption of Notch1 using antisense or a gamma-secretase inhibitor demonstrated a requirement for Notch1 in the maintenance and proliferation of NSCs. Ciliary neurotrophic factor (CNTF) activation of gp130 in NSCs rapidly increased Notch1 expression. NOTCH1 activation, indicated by tumor necrosis factor alpha-converting enzyme (TACE)- and presenilin-mediated processing, also increased. Infusion of EGF+CNTF into adult forebrain lateral ventricles increased periventricular NOTCH1 compared with EGF alone. Neither Hes1 (hairy and enhancer of split) nor Hes5 appeared to mediate gp130-enhanced NOTCH1 signaling that regulates NSC maintenance. This is the first example of a link between gp130 signaling and NOTCH1 in regulating NSC self-renewal.

Amyloid Precursor Protein Secretases↗
PubMed2000

Radial glial identity is promoted by Notch1 signaling in the murine forebrain.

In vertebrates, Notch signaling is generally thought to inhibit neural differentiation. However, whether Notch can also promote specific early cell fates in this context is unknown. We introduced activated Notch1 (NIC) into the mouse forebrain, before the onset of neurogenesis, using a retroviral vector and ultrasound imaging. During embryogenesis, NIC-infected cells became radial glia, the first specialized cell type evident in the forebrain. Thus, rather than simply inhibiting differentiation, Notch1 signaling promoted the acquisition of an early cellular phenotype. Postnatally, many NIC-infected cells became periventricular astrocytes, cells previously shown to be neural stem cells in the adult. These results suggest that Notch1 promotes radial glial identity during embryogenesis, and that radial glia may be lineally related to stem cells in the adult nervous system.

Animals↗