The nuclear pore proteins Nup88/214 and T-cell acute lymphatic leukemia–associated NUP214 fusion proteins regulate Notch signaling (original) (raw)
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Nrarp is a novel intracellular component of the Notch signaling pathway
Genes & Development, 2001
The Lin12/Notch receptors regulate cell fate during embryogenesis by activating the expression of downstream target genes. These receptors signal via their intracellular domain (ICD), which is released from the plasma membrane by proteolytic processing and associates in the nucleus with the CSL family of DNA-binding proteins to form a transcriptional activator. How the CSL/ICD complex activates transcription and how this complex is regulated during development remains poorly understood.
Cell Death Discovery, 2020
Cell survival is one of the many cellular processes regulated by Notch family of proteins. A comparison of human breast cancer cell lines, which differ in the levels of endogenous Notch4, implicated the protein in regulating susceptibility to apoptosis triggered by genomic damage. In agreement with this observation, increased susceptibility to genotoxic damage was observed following siRNA ablations of Notch4 in two breast cancer cell lines. Further, overexpressing Notch4 intracellular domain (NIC4) tagged to GFP (NIC4-GFP), protected cells from apoptosis triggered by genotoxic drugs. In cells immune-stained for endogenous Notch4, protein was detected in the nucleolus and nucleoplasm, which was also confirmed by the co-localization of NIC4-GFP with RFP-tagged nucleolar proteins in breast cancer cells or the unrelated HEK cell line. Linking functional outcomes to nucleolar localization, NIC4-GFP protection from apoptosis, required the nucleolar proteins Nucleolin and Fibrillarin. Cons...
RITA, a novel modulator of Notch signalling, acts via nuclear export of RBP-J
The EMBO Journal, 2011
The evolutionarily conserved Notch signal transduction pathway regulates fundamental cellular processes during embryonic development and in the adult. Ligand binding induces presenilin-dependent cleavage of the receptor and a subsequent nuclear translocation of the Notch intracellular domain (NICD). In the nucleus, NICD binds to the recombination signal sequence-binding protein J (RBP-J)/CBF-1 transcription factor to induce expression of Notch target genes. Here, we report the identification and functional characterization of RBP-J interacting and tubulin associated (RITA) (C12ORF52) as a novel RBP-J/CBF-1-interacting protein. RITA is a highly conserved 36 kDa protein that, most interestingly, binds to tubulin in the cytoplasm and shuttles rapidly between cytoplasm and nucleus. This shuttling RITA exports RBP-J/CBF-1 from the nucleus. Functionally, we show that RITA can reverse a Notch-induced loss of primary neurogenesis in Xenopus laevis. Furthermore, RITA is able to downregulate Notch-mediated transcription. Thus, we propose that RITA acts as a negative modulator of the Notch signalling pathway, controlling the level of nuclear RBP-J/CBF-1, where its amounts are limiting.
Journal of Biological Chemistry, 2001
The Notch signaling pathway is essential in many cell fate decisions in invertebrates as well as in vertebrates. After ligand binding, a two-step proteolytic cleavage releases the intracellular part of the receptor which translocates to the nucleus and acts as a transcriptional activator. Although Notch-induced transcription of genes has been reported extensively, its endogenous nuclear form has been seldom visualized. We report that the nuclear intracellular domain of Notch1 is stabilized by proteasome inhibitors and is a substrate for polyubiquitination in vitro. SEL-10, an F-box protein of the Cdc4 family, was isolated in a genetic screen for Lin12/Notchnegative regulators in Caenorhabditis elegans. We isolated human and murine counterparts of SEL-10 and investigated the role of a dominant-negative form of this protein, deleted of the F-box, on Notch1 stability and activity. This molecule could stabilize intracellular Notch1 and enhance its transcriptional activity but had no effect on inactive membrane-anchored forms of the receptor. We then demonstrated that SEL-10 specifically interacts with nuclear forms of Notch1 and that this interaction requires a phosphorylation event. Taken together, these data suggest that SEL-10 is involved in shutting off Notch signaling by ubiquitin-proteasomemediated degradation of the active transcriptional factor after a nuclear phosphorylation event.
AKT and 14-3-3 Regulate Notch4 Nuclear Localization
Scientific Reports, 2015
Members of the Notch family of transmembrane receptors, Notch1-4 in mammals, are involved in the regulation of cell fate decisions and cell proliferation in various organisms. The Notch4 isoform, which is specific to mammals, was originally identified as a viral oncogene in mice, Int3, able to initiate mammary tumors. In humans, Notch4 expression appears to be associated with breast cancer stem cells and endocrine resistance. Following ligand binding, the Notch4 receptor undergoes cleavage at the membrane and the Notch4-intracellular domain (ICD), translocates to the nucleus and regulates gene transcription. Little is known on the mechanisms regulating Notch4-ICD and its nuclear localization. Here, we describe the identification of four distinct AKT phosphorylation sites in human Notch4-ICD and demonstrate that AKT binds Notch4-ICD and phosphorylates all four sites in vitro and in vivo. The phosphorylation in cells is regulated by growth factors and is sensitive to phosphatidyl inositol-3 kinase (PI3K) inhibitors. This phosphorylation generates binding sites to the 14-3-3 regulatory proteins, which are involved in the regulation of nucleocytoplasmic shuttling of target proteins, restricting phosphorylated Notch4-ICD to the cytoplasm. Our findings provide a novel mechanism for Notch4-ICD regulation, suggesting a negative regulatory role for the PI3K-AKT pathway in Notch4 nuclear signaling. T he evolutionarily conserved Notch family of transmembrane receptors are involved in the regulation of cell fate decisions and cell proliferation via their activity as transcriptional regulators 1. Canonical Notch signaling is mediated by the transcription factor CSL (CBF-1, Suppressor of Hairless, Lag-1), also known as RBP-Jk. Mammals express four Notch genes, Notch1-4, with distinct functions and regulation, though there is some functional redundancy 2,3. Notch4, which is specific to mammals, was initially identified as a truncated oncogenic form in mice, Int3, able of initiating mammary tumors 4,5. The oncogenic activity of Notch4-ICD in transgenic mice has been shown to be independent of CSL, and thus presumably requires a yet to be identified non-canonical signaling pathway 6. In humans, Notch4 overexpression is associated with breast cancer stem cells and with endocrine resistance in estrogen-receptor a (ERa)-positive breast cancer 7,8. In normal development, Notch4 expression appears to be restricted to endothelial cells 9-11 , where it regulates vascularization during development, as well as endothelial cell function and response to inflammation 11-14. It has also a role in tumor angiogenesis and blood vessel perfusion 15,16. Activation of Notch receptors is initiated by the binding of transmembrane ligands on adjoining cells, such as Delta and Serrate/Jagged families to the Notch receptor, leading to its sequential cleavage and the release of the intracellular domain, designated Notch-ICD 17. This fragment translocates to the nucleus and participates in the formation of specific transcriptional complexes 1,18,19. Much of what is known about Notch signaling derives from studies of Notch1 and Notch2, the most conserved paralogs. Non-canonical, non-nuclear signaling has been described for Notch1 in T-cells. Specifically, Notch1 has been reported to signal through AKT via mTORC2 and to NF-kB via the IKK signalosome and nuclear IKKa 20-23. Notch-ICD is a relatively short-lived protein and undergoes rapid degradation through an ubiquitin-mediated pathway. The pathways that regulate the stability of Notch-ICDs other than Notch1 as well as the protein complexes they form are still poorly defined. Specifically, the regulation of Notch4-ICD by phosphorylation or other post-translational modifications or by interaction with adapter proteins, which are key regulators of many other transcription modulators, is largely unknown 24. A recent
Journal of Cell …, 2011
Notch is a highly conserved transmembrane receptor that performs a key role in the determination of cell fate, differentiation, adult cell self-renewal, cancer, neurodegenerative disease, wound healing, and inflammation (Artavanis-Tsakonas et al., 1995; Egan et al., 1998; Lai, 2004; Weinmaster, 1998). The Notch1 receptor plays the role of a membrane-bound transcription factor. Notch1 is processed by furin in the endoplasmic reticular Golgi complex (S1 cleavage) during transport to the cell surface, where it is expressed in heterodimeric form (Lieber et al., 2002; Pan and Rubin, 1997). Upon binding to the specific ligands, Jagged and Delta, the transmembrane C-terminal fragment of Notch is generated via proteolytic cleavage (S2 cleavage) (Brou et al., 2000; Mumm and Kopan, 2000). Cleavage of this fragment by -secretase (S3 cleavage) induces the release of the Notch intracellular domain (Notch-IC) from the membrane, and induces the nuclear translocation of Notch-IC, thus resulting in the formation of a complex with the CSL transcription factor family [CBF1/RBP-Jk/KBF2 in mammals, Su(H) in Drosophila and Xenopus, and Lag2 in Caenorhabditis elegans]
Journal of Biological Chemistry, 2002
§ These authors contributed equally to the manuscript 1 The abbreviations used are: AP-1, activator protein-1; CBF1, C promoter binding factor 1; CMV cytomegalovirus; CSL, CBF1/RBP-J κ, Su(H), and L ag-1; EMSA, electrophoretic mobility shift assay; ERK, extracellular regulated kinase; IF, indirect immunofluorescence; IL-8, interleukin-8 JNK, c-Jun amino terminal kinase; luc, luciferase; MMP1, matrix metalloproteinase 1; NIC -Notch intracellular domain; NES, nuclear export signal; NLS, nuclear localization signal; PBS, phospha buffered saline; RAM, RBP-J κ-associated molecule; RLU, relative light units; SDS-PAGE, SDS polyacrylamide gel electrophoresis ABSTRACT Developmental decisions that control cell fate are commonly regulated by the Notch signaling pathway. Activation of transmembrane Notch receptors results in proteolytic liberation of the intracellular domain of Notch (NIC), which translocates into the nucleus, binds a repressor (CSL),
Journal of Cell Science, 2002
Notch/RBP-Jκ and nuclear factor-κB (NFκB) complexes are key mediators of the progression of many cellular events through the activation of specific target gene transcription. Independent observations have shown that activation of Notch-dependent transcription generally correlates with inhibition of differentiation. In contrast, activated NFκB complexes are required for progression of differentiation in several systems. Although some interactions between both pathways have been observed, the physiological significance of their connection is unclear. We have now demonstrated that the increase in p65-NFκB protein levels enhances Notch-mediated activation of the Hes1 promoter up to three-fold. This effect does not require NFκB transcriptional activity, and it is independent of the previously described interaction between Notch and p50-NFκB. Furthermore, we show that p65-NFκB can modulate subcellular localization of the transcriptional corepressor N-CoR, abrogating N-CoR mediated repress...
The role of epigenetic mechanisms in Notch signaling during development
Journal of cellular physiology, 2015
The Notch pathway is a highly conserved cell-cell communication pathway in metazoan involved in numerous processes during embryogenesis, development, and adult organisms. Ligand-receptor interaction of Notch components on adjacent cells facilitates controlled sequential proteolytic cleavage resulting in the nuclear translocation of the intracellular domain of Notch (NICD). There it binds to the Notch effector protein RBP-J, displaces a corepressor complex and enables the induction of target genes by recruitment of coactivators in a cell-context dependent manner. Both, the gene-specific repression and the context dependent activation require an intense communication with the underlying chromatin of the regulatory regions. Since the epigenetic landscape determines the function of the genome, processes like cell fate decision, differentiation, and self-renewal depend on chromatin structure and its remodeling during development. In this review, structural features enabling the Notch pat...