In humans and other mammals the NOTCH gene family has four members, NOTCH1, NOTCH2, NOTCH3 and NOTCH4, encoded on four different chromosomes. Their transcription is developmentally regulated and tissue specific, but very little information exists on molecular mechanisms of transcriptional regulation. Translation of NOTCH mRNAs is negatively regulated by a number of recently discovered microRNAs (Li et al. 2009, Pang et al.2010, Ji et al. 2009, Kong et al. 2010, Marcet et al. 2011, Ghisi et al. 2011, Song et al. 2009, Hashimoto et al. 2010, Costa et al. 2009).
The nascent forms of NOTCH precursors, Pre-NOTCH1, Pre-NOTCH2, Pre-NOTCH3 and Pre-NOTCH4, undergo extensive posttranslational modifications in the endoplasmic reticulum and Golgi apparatus to become functional. In the endoplasmic reticulum, conserved serine and threonine residues in the EGF repeats of NOTCH extracellular domain are fucosylated and glucosylated by POFUT1 and POGLUT1, respectively (Yao et al. 2011, Stahl et al. 2008, Wang et al. 2001, Shao et al. 2003, Acar et al. 2008, Fernandez Valdivia et al. 2011).
In the Golgi apparatus, fucose groups attached to NOTCH EGF repeats can be elongated by additional glycosylation steps initiated by fringe enzymes (Bruckner et al. 2000, Moloney et al. 2000, Cohen et al. 1997, Johnston et al. 1997, Chen et al. 2001). Fringe-mediated modification modulates NOTCH signaling but is not an obligatory step in Pre-NOTCH processing. Typically, processing of Pre-NOTCH in the Golgi involves cleavage by FURIN convertase (Blaumueller et al. 1997, Logeat et al. 1998, Gordon et al. 2009, Rand et al. 2000, Chan et al. 1998). The cleavage of NOTCH results in formation of mature NOTCH heterodimers that consist of NOTCH extracellular domain (NEC i.e. NECD) and NOTCH transmembrane and intracellular domain (NTM i.e. NTMICD). NOTCH heterodimers translocate to the cell surface where they function in cell to cell signaling.
View original pathway at Reactome.
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NOTCH1 functions as both a transmembrane receptor presented on the cell surface and as a transcriptional regulator in the nucleus.
NOTCH1 receptor presented on the plasma membrane is activated by a membrane bound ligand expressed in trans on the surface of a neighboring cell. In trans, ligand binding triggers proteolytic cleavage of NOTCH1 and results in release of the NOTCH1 intracellular domain, NICD1, into the cytosol.
NICD1 translocates to the nucleus where it associates with RBPJ (also known as CSL or CBF) and mastermind-like (MAML) proteins (MAML1, MAML2 or MAML3; possibly also MAMLD1) to form NOTCH1 coactivator complex. NOTCH1 coactivator complex activates transcription of genes that possess RBPJ binding sites in their promoters.
NOTCH2 is activated by binding Delta-like and Jagged ligands (DLL/JAG) expressed in trans on neighboring cells (Shimizu et al. 1999, Shimizu et al. 2000, Hicks et al. 2000, Ji et al. 2004). In trans ligand-receptor binding is followed by ADAM10 mediated (Gibb et al. 2010, Shimizu et al. 2000) and gamma secretase complex mediated cleavage of NOTCH2 (Saxena et al. 2001, De Strooper et al. 1999), resulting in the release of the intracellular domain of NOTCH2, NICD2, into the cytosol. NICD2 traffics to the nucleus where it acts as a transcriptional regulator. For a recent review of the cannonical NOTCH signaling, please refer to Kopan and Ilagan 2009, D'Souza et al. 2010, Kovall and Blacklow 2010. CNTN1 (contactin 1), a protein involved in oligodendrocyte maturation (Hu et al. 2003) and MDK (midkine) (Huang et al. 2008, Gungor et al. 2011), which plays an important role in epithelial-to-mesenchymal transition, can also bind NOTCH2 and activate NOTCH2 signaling.
In the nucleus, NICD2 forms a complex with RBPJ (CBF1, CSL) and MAML (mastermind). The NICD2:RBPJ:MAML complex activates transcription from RBPJ binding promoter elements (RBEs) (Wu et al. 2000). NOTCH2 coactivator complexes directly stimulate transcription of HES1 and HES5 genes (Shimizu et al. 2002), both of which are known NOTCH1 targets. NOTCH2 but not NOTCH1 coactivator complexes, stimulate FCER2 transcription. Overexpression of FCER2 (CD23A) is a hallmark of B-cell chronic lymphocytic leukemia (B-CLL) and correlates with the malfunction of apoptosis, which is thought be an underlying mechanism of B-CLL development (Hubmann et al. 2002). NOTCH2 coactivator complexes together with CREBP1 and EP300 stimulate transcription of GZMB (granzyme B), which is important for the cytotoxic function of CD8+ T cells (Maekawa et al. 2008).
NOTCH2 gene expression is differentially regulated during human B-cell development, with NOTCH2 transcripts appearing at late developmental stages (Bertrand et al. 2000).
NOTCH2 mutations are a rare cause of Alagille syndrome (AGS). AGS is a dominant congenital multisystem disorder characterized mainly by hepatic bile duct abnormalities. Craniofacial, heart and kidney abnormalities are also frequently observed in the Alagille spectrum (Alagille et al. 1975). AGS is predominantly caused by mutations in JAG1, a NOTCH2 ligand (Oda et al. 1997, Li et al. 1997), but it can also be caused by mutations in NOTCH2 (McDaniell et al. 2006).
Hajdu-Cheney syndrome, an autosomal dominant disorder characterized by severe and progressive bone loss, is caused by NOTCH2 mutations that result in premature C-terminal NOTCH2 truncation, probably leading to increased NOTCH2 signaling (Simpson et al. 2011, Isidor et al. 2011, Majewski et al. 2011).
Similar to NOTCH1, NOTCH3 is activated by delta-like and jagged ligands (DLL/JAG) expressed in trans on a neighboring cell. The activation triggers cleavage of NOTCH3, first by ADAM10 at the S2 cleavage site, then by gamma-secretase at the S3 cleavage site, resulting in the release of the intracellular domain of NOTCH3, NICD3, into the cytosol. NICD3 subsequently traffics to the nucleus where it acts as a transcriptional regulator. NOTCH3 expression pattern is more restricted than the expression patterns of NOTCH1 and NOTCH2, with predominant expression of NOTCH3 in vascular smooth muscle cells, lymphocytes and the nervous system (reviewed by Bellavia et al. 2008). Based on the study of Notch3 knockout mice, Notch3 is not essential for embryonic development or fertility (Krebs et al. 2003).
Germline gain-of-function NOTCH3 mutations are an underlying cause of the CADASIL syndrome - cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy. CADASIL is characterized by degeneration and loss of vascular smooth muscle cells from the arterial wall, predisposing affected individuals to an early onset stroke (Storkebaum et al. 2011). NOTCH3 promotes survival of vascular smooth muscle cells at least in part by induction of CFLAR (c FLIP), an inhibitor of FASLG activated death receptor signaling. The mechanism of NOTCH3 mediated upregulation of CFLAR is unknown; it is independent of the NOTCH3 coactivator complex and involves an unelucidated crosstalk with the RAS/RAF/MAPK pathway (Wang et al. 2002).
In rat brain, NOTCH3 and NOTCH1 are expressed at sites of adult neurogenesis, such as the dentate gyrus (Irvin et al. 2001). NOTCH3, similar to NOTCH1, promotes differentiation of the rat adult hippocampus derived multipotent neuronal progenitors into astroglia (Tanigaki et al. 2001). NOTCH1, NOTCH2, NOTCH3, and their ligand DLL1 are expressed in neuroepithelial precursor cells in the neural tube of mouse embryos. Together, they signal to inhibit neuronal differentiation of neuroepithelial precursors. Expression of NOTCH3 in mouse neuroepithelial precursors is stimulated by growth factors BMP2, FGF2, Xenopus TGF beta5 - homologous to TGFB1, LIF, and NTF3 (Faux et al. 2001).
In mouse telencephalon, NOTCH3, similar to NOTCH1, promotes radial glia and neuronal progenitor phenotype. This can, at least in part be attributed to NOTCH mediated activation of RBPJ-dependent and HES5-dependent transcription (Dang et al. 2006).
In mouse spinal cord, Notch3 is involved in neuronal differentiation and maturation. Notch3 knockout mice have a decreased number of mature inhibitory interneurons in the spinal cord, which may be involved in chronic pain conditions (Rusanescu and Mao 2014).
NOTCH3 amplification was reported in breast cancer, where NOTCH3 promotes proliferation and survival of ERBB2 negative breast cancer cells (Yamaguchi et al. 2008), and it has also been reported in ovarian cancer (Park et al. 2006). NOTCH3 signaling is involved in TGF beta (TGFB1) signaling-induced eptihelial to mesenchimal transition (EMT) (Ohashi et al. 2011, Liu et al. 2014)
NOTCH3 indirectly promotes development of regulatory T cells (Tregs). NOTCH3 signaling activates pre-TCR-dependent and PKC-theta (PRKCQ)-dependent NF-kappaB (NFKB) activation, resulting in induction of FOXP3 expression (Barbarulo et al. 2011). Deregulated NOTCH3 and pre-TCR signaling contributes to development of leukemia and lymphoma (Bellavia et al. 2000, Bellavia et al. 2002).
The NOTCH4 gene locus was discovered as a frequent site of insertion for the proviral genome of the mouse mammary tumor virus (MMTV) (Gallahan and Callahan 1987). MMTV-insertion results in aberrant expression of the mouse mammary tumor gene int-3, which was subsequently discovered to represent the intracellular domain of Notch4 (Robbins et al. 1992, Uyttendaele et al. 1996).
NOTCH4 is prevalently expressed in endothelial cells (Uyttendaele et al. 1996). DLL4 and JAG1 act as ligands for NOTCH4 in human endothelial cells (Shawber et al. 2003, Shawber et al. 2007), but DLL4- and JAG1-mediated activation of NOTCH4 have not been confirmed in all cell types tested (Aste-Amezaga et al. 2010, James et al. 2014). The gamma secretase complex cleaves activated NOTCH4 receptor to release the intracellular domain fragment (NICD4) (Saxena et al. 2001, Das et al. 2004). NICD4 traffics to the nucleus where it acts as a transcription factor and stimulates expression of NOTCH target genes HES1, HES5, HEY1 and HEY2, as well as VEGFR3 and ACTA2 (Lin et al. 2002, Raafat et al.2004, Tsunematsu et al. 2004, Shawber et al. 2007, Tang et al. 2008, Bargo et al. 2010). NOTCH4 signaling can be downregulated by AKT1 phosphorylation-induced cytoplasmic retention (Ramakrishnan et al. 2015) as well as proteasome-dependent degradation upon FBXW7-mediated ubiquitination (Wu et al. 2001, Tsunematsu et al. 2004).
NOTCH4 was reported to inhibit NOTCH1 signaling in-cis, by binding to NOTCH1 and interfering with the S1 cleavage of NOTCH1, thus preventing production of functional NOTCH1 heterodimers at the cell surface (James et al. 2014).
NOTCH4 is involved in development of the vascular system. Overexpression of constitutively active Notch4 in mouse embryonic vasculature results in abnormal vessel structure and patterning (Uyttendaele et al. 2001). NOTCH4 may act to inhibit apoptosis of endothelial cells (MacKenzie et al. 2004).
Expression of int-3 interferes with normal mammary gland development in mice and promotes tumorigenesis. The phenotype of mice expressing int-3 in mammary glands is dependent on the presence of Rbpj (Raafat et al. 2009). JAG1 and NOTCH4 are upregulated in human ER+ breast cancers resistant to anti-estrogen therapy, which correlates with elevated expression of NOTCH target genes HES1, HEY1 and HEY2, and is associated with increased population of breast cancer stem cells and distant metastases (Simoes et al. 2015). Development of int-3-induced mammary tumours in mice depends on Kit and Pdgfra signaling (Raafat et al. 2006) and on int-3-induced activaton of NFKB signaling (Raafat et al. 2017). In head and neck squamous cell carcinoma (HNSCC), high NOTCH4 expression correlates with elevated HEY1 levels, increased cell proliferation and survival, epithelial-to-mesenchymal transition (EMT) phenotype and cisplatin resistance (Fukusumi et al. 2018). In melanoma, however, exogenous NOTCH4 expression correlates with mesenchymal-to-epithelial-like transition and reduced invasiveness (Bonyadi Rad et al. 2016). NOTCH4 is frequently overexpressed in gastric cancer. Increased NOTCH4 levels correlate with activation of WNT signaling and gastric cancer progression (Qian et al. 2015).
NOTCH4 is expressed in adipocytes and may promote adipocyte differentiation (Lai et al. 2013).
During Dengue virus infection, DLL1, DLL4, NOTCH4 and HES1 are upregulated in interferon-beta (INFB) dependent manner (Li et al. 2015). NOTCH4 signaling may be affected by Epstein-Barr virus (EBV) infection, as the EBV protein BARF0 binds to NOTCH4 (Kusano and Raab-Traub 2001).
Translation of NOTCH1 mRNA is negatively regulated by MIR449 microRNAs (MIR449A, MIR449B and MIR449C), which bind to the 3'UTR of NOTCH1. Downregulation of NOTCH1 signaling by the MIR449 cluster appears to be an evolutionarily conserved mechanism involved in regulation of vertebrate multiciliogenesis. DLL1 mRNA is also a target of the MIR449 cluster.
Translation of NOTCH1 mRNA is inhibited by MIR34 microRNAs (MIR34A, MIR34B and MIR34C), which bind to the 3'UTR of NOTCH1 mRNA. Expression of MIR34 microRNAs is directly regulated by the p53 (TP53) tumor suppressor gene (Chang et al. 2007, Raver-Shapira et al. 2007), and MIR34-mediated downregulation of NOTCH1 signaling is thought to negatively regulate cell survival, motility and maintenance of an undifferentiated state.
In the endoplasmic reticulum, NOTCH receptor precursors are fucosylated on conserved serine and threonine residues in their EGF repeats. The consensus fucosylation site sequence is C2-X(4-5)-S/T-C3, where C2 and C3 are the second and third cysteine residue within the EGF repeat, and X(4-5) is four to five amino acid residues of any type. Only those fucosylation sites that are conserved between human, mouse and rat NOTCH isoforms are annotated. Two additional potential fucosylation sites exist in human NOTCH1, on threonine 194 and threonine 1321, but since they are not conserved between all three species, they are not shown. Fucosylation is performed by the endoplasmic reticulum resident O-fucosyl transferase (POFUT1). Fucosylation by POFUT1 is considered to be essential for NOTCH folding/processing and production of a fully functional receptor. In addition to Notch fucosylation, Drosophila Pofut1 (o-fut1) acts as a Notch chaperone, playing an important role in Notch trafficking (Okajima et al. 2005). The chaperone role of POFUT1 may not be conserved in mammals (Stahl et al. 2008).
Beta-1,4-galactosyltransferase 1 (B4GALT1) is a Golgi membrane enzyme responsible for galactosylation of N-acetylglucosaminyl group added by fringe enzymes to O-linked fucosyl residues on NOTCH. This results in formation of trisaccharide chains on NOTCH (Gal-beta1,4-GlcNAc-beta1,3-fucitol), and is a necessary step for fringe-mediated modulation of NOTCH signaling.
In addition to fucosylation of NOTCH receptor precursors, glucosylation represents another crucial NOTCH processing reaction, required for full receptor function. Endoplasmic reticulum O-glucosyl transferase, POGLUT1, adds a glucosyl group to conserved serine residues within the EGF repeats of NOTCH. The consensus sequence of POGLUT1 glucosylation sites is C1-X-S-X-P-C2, where C1 and C2 are the first and second cysteine residue in the EGF repeat, respectively, while X represents any amino acid. Only those glucosylation sites that are conserved between human, mouse and rat isoforms are shown. In human NOTCH1, the consensus glucosylation site on serine at position 951 was not annotated since it is not conserved in rat NOTCH1. In human NOTCH4, glucosylation at serine 398 was not annotated because this site is not conserved in rat, and glucosylation at serine 936 was not annotated because this site is not conserved in mouse. Glucosylation of NOTCH4 serine 773 was not annotated because a proline at position 775 is not conserved in either mouse or rat.
The Fringe family (CAZy family GT31) of glycosyltransferases in mammals includes LFNG (lunatic fringe; MIM:602576), MFNG (manic fringe; MIM:602577) and RFNG (radical fringe; MIM:602578). Fringe enzymes function in the Golgi apparatus where they initiate the elongation of O-linked fucose on fucosylated peptides by the addition of a beta-1,3-N-acetylglucosaminyl group (GlcNAc) (Moloney et al. 2000). Fringe enzymes elongate conserved O fucosyl residues conjugated to EGF repeats of NOTCH, modulating NOTCH activity (Cohen et al. 1997, Johnston et al. 1997) by decreasing the affinity of NOTCH extracellular domain for JAG ligands (Bruckner et al. 2000). In developing mouse thymocytes, Lfng enhances Notch1 activation by Dll4, resulting in prolonged Notch1 signaling that promotes self-renewal of TCR-beta-expressing progenitors (Yuan et al. 2011). Since the exact preference, if any, of fringe enzymes for NOTCH O-fucose sites is not known, the extension of an O-fucosyl residue at an unknown protein position is shown.
Translation of NOTCH3 mRNA is inhibited by miR-150 microRNA which binds to the 3'UTR of NOTCH3 mRNA. miR-150 is involved in regulation of differentiation of B-cells and T-cells.
Translation of NOTCH1 mRNA is inhibited by microRNAs miR-200B and miR-200C, which bind to the 3'UTR of NOTCH1 mRNA. Levels of miR-200B and miR-200C are decreased in pancreatic cancer cells with an EMT (epithelial to mesenchymal transition) phenotype, and the EMT phenotype is reversed by exogenous overexpression of miR-200B/C microRNAs, suggesting that miR-200B and mir-200C may be acting as tumor suppressors.
The NOTCH receptor is synthesized as a precursor polypeptide (approx. 300 kDa) associated with the endoplasmic reticulum membrane. The mature NOTCH receptor is produced by proteolytic cleavage to form a heterodimer. The enzyme responsible is a furin-like convertase which cleaves the full-length precursor into a transmembrane fragment (NTM) of approximate size 110 kDa and an extracellular fragment (NEC) of approximate size 180 kDa. The mature NOTCH receptor is reassembled as a heterodimer (Blaumueller et al. 1997, Logeat et al. 1998). Both disulfide bonds and calcium-mediated ionic interactions stabilize the heterodimer (Rand et al. 2000, Gordon et al. 2009). This process takes place in the trans-Golgi network . Mammalian NOTCH is predominantly presented as a heterodimer on the cell surface. Although FURIN-mediated cleavage is evolutionarily conserved, it may not be mandatory for Drosophila Notch function (Kidd et al. 2002).
Cleavage of fringe-modified NOTCH by FURIN has not been examined directly, but since mature, plasma membrane-anchored NOTCH receptors are typically cleaved by FURIN (Blaumueller et al. 1997) and fringe-modified NOTCH functions at the cell surface (Moloney et al. 2000), it is expected that fringe-modified NOTCH is processed by FURIN cleavage. The exact order of fringe-mediated glycosylation and FURIN cleavage has not been experimentally established, but since FURIN localizes to the trans-Golgi network -TGN (Teuchert et al. 1999), while fringe has not been associated with TGN, it is likely that modification of NOTCH by fringe enzymes precedes FURIN-mediated cleavage.
NOTCH receptor precursors (Pre-NOTCH) traffic from the endoplasmic reticulum to the Golgi. Endoplasmic reticulum calcium ATPases are required for maintenance of high levels of calcium and positively regulate NOTCH trafficking, perhaps by ensuring proper NOTCH folding. Exit of NOTCH precursors from the endoplasmic reticulum is negatively regulated by SEL1L (Li et al. 2010, Sundaram et al. 1993), an endoplasmic reticulum membrane protein that is part of the ERAD (endoplasmic reticulum associated degradation) system, which performs quality control and triggers degradation of misfolded proteins (Francisco et al. 2010). NOTCH trafficking through the Golgi and trans-Golgi network is positively regulated by RAB6, a Golgi membrane GTPase.
Mature fringe-modified NOTCH usually has a tetrasaccharide attached to conserved fucosylated serine and threonine residues in EGF repeats. The chemical structure of these tetrasaccharides is Sia-alpha2,3-Gal-beta1,4-GlcNAc-beta1,3-fucitol (Moloney et al. 2000). The identity of sialyltransferase(s) that add sialic acid to galactose remains unknown in this context. Based on the type of chemical bonds in the tetrasaccharide, there are three known Golgi membrane sialyltransferases that could perform this function: ST3GAL3, ST3GAL4, ST3GAL6 (Harduin-Lepers et al. 2001).
Fringe-modified NOTCH functions at the plasma membrane. The transport of fringe-modified NOTCH to the plasma membrane from Golgi has not been studied directly, but is assumed to share properties of transport of mature NOTCH receptors that are not modified by fringe.
Mature NOTCH translocates from the Golgi to plasma membrane. In Caenorhabditis elegans, a Golgi membrane protein sel-9, a homolog of mammalian TMED2, acts as a quality controller and prevents misfolded lin-12, a NOTCH homolog, to reach the cell surface.
The NOTCH4 gene maps to the short arm of human chromosome 6. High levels of NOTCH4 transcript are detectable in adult heart. NOTCH4 mRNA is also found in lung and placenta, and at low levels in liver, skeletal muscle, kidney, pancreas, spleen, thymus, lymph nodes and bone marrow (Li et al. 1998).
In vascular endothelium, NOTCH4 transcription is activated by c-JUN (AP-1) transcription factor. JUN, likely in complex with other transcription factors, binds AP-1 motif(s) in the NOTCH4 promoter and possibly within the first intron (Wu et al. 2005).
Transcription of microRNA MIR34A is directly induced by the tumor suppressor p53, which binds to the conserved p53 binding site located in the vicinity of the MIR34A transcription start (Chang et al. 2007, Raver-Shapira et al. 2007). Genomic loss of the chromosomal band 1p36, harboring the MIR34A gene, is a frequent event in pancreatic cancer, and MIR34A is considered to act as a tumor suppressor. Conserved p53 binding sites were also mapped to the promoter of clustered MIR34B and MIR34C genes, and the transcription of MIR34B and MIR34C microRNAs was shown to be positively regulated by p53 (He et al. 2007, Corney et al. 2007). The steps involved in processing of pri-microRNA into pre-microRNA have been omitted in this event - please refer to the diagram of Regulatory RNA Pathways for details.
The NOTCH2 gene maps to human chromosome 1. NOTCH2 gene expression is differentially regulated during human B-cell development, with NOTCH2 transcripts appearing at late developmental stages. NOTCH2 mutations are a rare cause of Alagille syndrome. Alagille syndrome is a dominant multisystem disorder mainly characterized by hepatic bile duct abnormalities, and is predominantly caused by mutations in JAG1, a NOTCH2 ligand.
Translation of NOTCH3 mRNA is negatively regulated by miR-150 (Ghisi et al. 2011) and miR-206 microRNAs (Song et al. 2009). These miRNAs bind and cause degradation of NOTCH3 mRNA, resulting in decreased level of NOTCH3 protein product.
Translation of NOTCH4 mRNA is negatively regulated by miR-181c (Hashimoto et al. 2010) and miR-302A microRNAs (Costa et al. 2009). These miRNAs bind and cause degradation of NOTCH4 mRNA, resulting in decreased level of NOTCH4 protein product.
Translation of NOTCH1 mRNA is negatively regulated by microRNAs miR-200B and miR200C (Kong et al. 2010), miR-34 (Li et al. 2009, Ji et al. 2009) and miR-449 (Marcet et al. 2011). These miRNAs bind and cause degradation of NOTCH1 mRNA, resulting in decreased level of NOTCH1 protein product.
Translation of NOTCH2 mRNA is negatively regulated by miR-34 microRNAs (Li et al. 2009). miR-34 miRNAs bind and cause degradation of NOTCH2 mRNA, resulting in decreased level of NOTCH2 protein product.
The NOTCH3 gene maps to human chromosome 19. NOTCH3 transcript is ubiquitously expressed in fetal and adult human tissues. Mutations in NOTCH3 are found in cerebral arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), an autosomal dominant progressive disorder of small arterial vessels of the brain characterized by migraines, strokes, and white matter lesions, with the onset in early adulthood (Joutel et al. 1996).
NOTCH3 gene transcription is stimulated by the NOTCH3 coactivator complex but it is not known whether this effect is direct, or indirect (Liu et al. 2009).
NOTCH3 gene transcription is directly stimulated by the NOTCH1 coactivator complex and NOTCH1-mediated regulation of NOTCH3 is involved in differentiation of esophageal squamous cells (Ohashi et al. 2009).
NOTCH3 transcription is directly stimulated by transcription factor ELF3, activated by PRKCI (protein kinase C iota)-mediated phosphorylation downstream of KRAS signaling. The PRKCI-ELF3-NOTCH3 signaling controls the tumor-initiating cell phenotype in KRAS-mediated lung adenocarcinoma (Ali et al. 2016).
NOTCH1 was cloned as a chromosome 9 gene involved in translocation t(7;9)(q34;q34.3) in several T-cell acute lymphoblastic leukemia (T-ALL) patients. The gene was found to be highly homologous to the Drosophila gene Notch and was initially named TAN-1 (translocation-associated Notch homolog). Transcripts of NOTCH1 were detected in many fetal and adult human and mouse tissues, with the highest abundance in lymphoid tissues. The translocation t(7;9)(q34;q34.3) found in a small fraction of T-ALL patients puts NOTCH1 transcription under the control of the T-cell receptor-beta (TCRB) locus, which results in expression of truncated peptides that lack the extracellular ligand binding domain and are constitutively active (reviewed by Grabher et al. 2006). Activating NOTCH1 point mutations, mainly affecting the extracellular heterodimerization domain and/or the C-terminal PEST domain, are found in more than 50% of human T-ALLs (Weng et al. 2004).
Studies of mouse Rbpj knockout embryos and zebrafish Mib (mindbomb) mutants indicate that the NOTCH1 coactivator complex positively regulates NOTCH1 transcription. The RBPJ-binding site(s) that the NOTCH1 coactivator complex normally binds have not been found in the NOTCH1 promoter, however, so this effect may be indirect and its mechanism is unknown (Del Monte et al. 2007).
CCND1 (cyclin D1) forms a complex with CREBBP and binds to the NOTCH1 promoter, stimulating NOTCH1 transcription. The involvement of CCND1 in transcriptional regulation of NOTCH1 was established in mouse retinas and the rat retinal precursor cell line R28 (Bienvenu et al. 2010).
E2F1 and E2F3 are able to bind to the NOTCH1 promoter and activate NOTCH1 transcription (Viatour et al. 2011).
NOTCH1 promoter possesses two putative p53-binding sites. Chromatin immunoprecipitation (ChIP) assays of human primary keratinocytes showed binding of endogenous p53 protein to both sites. Experiments in which p53 was downregulated or overexpressed implicate p53 as a positive regulator of NOTCH1 expression in primary human keratinocytes. It is likely that p53-mediated regulation of NOTCH1 expression involves interplay with other cell-type specific determinants of gene expression (Lefort et al. 2007). In lymphoid cells, NOTCH1 expression may be negatively regulated by p53 (Laws and Osborne 2004). Other proteins implicated in the negative regulation of NOTCH1 transcription are KLF9 (Ying et al. 2011), JARID2 (Mysliwiec et al. 2011, Mysliwiec et al. 2012), KLF4 and SP3 (Lambertini et al. 2010), and p63 (Yugawa et al. 2010).
CCND1 (cyclin D1) forms a complex with CREBBP and binds to the NOTCH1 promoter, stimulating NOTCH1 transcription. The involvement of CCND1 in transcriptional regulation of NOTCH1 was established in mouse retinas and the rat retinal precursor cell line R28 (Bienvenu et al. 2010).
TP53 (p53) binds to the conserved p53 binding site located in the vicinity of the MIR34A transcription start (Chang et al. 2007, Raver-Shapira et al. 2007). TP53 also binds to conserved p53 binding sites in the promoter of clustered MIR34B and MIR34C genes, and the transcription of MIR34B and MIR34C microRNAs is directly positively regulated by p53 (He et al. 2007, Corney et al. 2007).
NOTCH1 and RBPJ (CSL), likely in the form of the NOTCH1 coactivator complex, bind to the RBPJ response elements in the second intron of the NOTCH3 gene (Ohashi et al. 2010).
PRKCI (protein kinase C iota), activated in response to KRAS signaling, phosphorylates transcription factor ELF3 on serine residue S68. PRKCI-mediated phosphorylation of ELF3 promotes transcriptional activity of ELF3, probably by stimulating nuclear retention or import of ELF3 (Ali et al. 2016).
ELF3, phosphorylated by PRKCI (protein kinase C iota) on serine residue S68, binds multiple ELF3-binding sites in the NOTCH3 gene promoter (Ali et al. 2016).
RUNX1 binding to intron 29 of the NOTCH4 gene represses NOTCH4 transcription. RUNX1-mediated inhibition of NOTCH4 expression contributes to differentiation of human pluripotent stem cells into megakaryocytes (Li et al. 2018).
Based on studies in mice, SIRT6 deacetylates H3 histones on lysine residue 10 (removing the H3K9Ac epigenetic mark) at promoters of NOTCH1 and NOTCH4 genes (Liu et al. 2017).
Based on studies in mice, SIRT6-mediated deacetylation of lysine residue 10 of H3 histones (removal of H3K9Ac epigenetic mark) at promoters of NOTCH1 and NOTCH4 genes inhibits transcription of NOTCH1 and NOTCH4. SIRT6-mediated downregulation of NOTCH1 and NOTCH4 may protect podocytes, kidney cells involved in blood filtering, from injury. SIRT6 is downregulated in podocytes of patients with podocytopathies, such as proteinuric kidney disease, and SIRT6 levels correlate with glomerular filtration rate (Liu et al. 2017).
Based on studies in mice, histone deacetylase SIRT6 binds to histone H3 acetylated on lysine residue 10 (H3K9Ac epigenetic mark) at promoters of NOTCH1 and NOTCH4 genes (Liu et al. 2017).
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mRNA:miR-200B/C
RISCNOTCH1 receptor presented on the plasma membrane is activated by a membrane bound ligand expressed in trans on the surface of a neighboring cell. In trans, ligand binding triggers proteolytic cleavage of NOTCH1 and results in release of the NOTCH1 intracellular domain, NICD1, into the cytosol.
NICD1 translocates to the nucleus where it associates with RBPJ (also known as CSL or CBF) and mastermind-like (MAML) proteins (MAML1, MAML2 or MAML3; possibly also MAMLD1) to form NOTCH1 coactivator complex. NOTCH1 coactivator complex activates transcription of genes that possess RBPJ binding sites in their promoters.
In the nucleus, NICD2 forms a complex with RBPJ (CBF1, CSL) and MAML (mastermind). The NICD2:RBPJ:MAML complex activates transcription from RBPJ binding promoter elements (RBEs) (Wu et al. 2000). NOTCH2 coactivator complexes directly stimulate transcription of HES1 and HES5 genes (Shimizu et al. 2002), both of which are known NOTCH1 targets. NOTCH2 but not NOTCH1 coactivator complexes, stimulate FCER2 transcription. Overexpression of FCER2 (CD23A) is a hallmark of B-cell chronic lymphocytic leukemia (B-CLL) and correlates with the malfunction of apoptosis, which is thought be an underlying mechanism of B-CLL development (Hubmann et al. 2002). NOTCH2 coactivator complexes together with CREBP1 and EP300 stimulate transcription of GZMB (granzyme B), which is important for the cytotoxic function of CD8+ T cells (Maekawa et al. 2008).
NOTCH2 gene expression is differentially regulated during human B-cell development, with NOTCH2 transcripts appearing at late developmental stages (Bertrand et al. 2000).
NOTCH2 mutations are a rare cause of Alagille syndrome (AGS). AGS is a dominant congenital multisystem disorder characterized mainly by hepatic bile duct abnormalities. Craniofacial, heart and kidney abnormalities are also frequently observed in the Alagille spectrum (Alagille et al. 1975). AGS is predominantly caused by mutations in JAG1, a NOTCH2 ligand (Oda et al. 1997, Li et al. 1997), but it can also be caused by mutations in NOTCH2 (McDaniell et al. 2006).
Hajdu-Cheney syndrome, an autosomal dominant disorder characterized by severe and progressive bone loss, is caused by NOTCH2 mutations that result in premature C-terminal NOTCH2 truncation, probably leading to increased NOTCH2 signaling (Simpson et al. 2011, Isidor et al. 2011, Majewski et al. 2011).
Germline gain-of-function NOTCH3 mutations are an underlying cause of the CADASIL syndrome - cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy. CADASIL is characterized by degeneration and loss of vascular smooth muscle cells from the arterial wall, predisposing affected individuals to an early onset stroke (Storkebaum et al. 2011). NOTCH3 promotes survival of vascular smooth muscle cells at least in part by induction of CFLAR (c FLIP), an inhibitor of FASLG activated death receptor signaling. The mechanism of NOTCH3 mediated upregulation of CFLAR is unknown; it is independent of the NOTCH3 coactivator complex and involves an unelucidated crosstalk with the RAS/RAF/MAPK pathway (Wang et al. 2002).
In rat brain, NOTCH3 and NOTCH1 are expressed at sites of adult neurogenesis, such as the dentate gyrus (Irvin et al. 2001). NOTCH3, similar to NOTCH1, promotes differentiation of the rat adult hippocampus derived multipotent neuronal progenitors into astroglia (Tanigaki et al. 2001). NOTCH1, NOTCH2, NOTCH3, and their ligand DLL1 are expressed in neuroepithelial precursor cells in the neural tube of mouse embryos. Together, they signal to inhibit neuronal differentiation of neuroepithelial precursors. Expression of NOTCH3 in mouse neuroepithelial precursors is stimulated by growth factors BMP2, FGF2, Xenopus TGF beta5 - homologous to TGFB1, LIF, and NTF3 (Faux et al. 2001).
In mouse telencephalon, NOTCH3, similar to NOTCH1, promotes radial glia and neuronal progenitor phenotype. This can, at least in part be attributed to NOTCH mediated activation of RBPJ-dependent and HES5-dependent transcription (Dang et al. 2006).
In mouse spinal cord, Notch3 is involved in neuronal differentiation and maturation. Notch3 knockout mice have a decreased number of mature inhibitory interneurons in the spinal cord, which may be involved in chronic pain conditions (Rusanescu and Mao 2014).
NOTCH3 amplification was reported in breast cancer, where NOTCH3 promotes proliferation and survival of ERBB2 negative breast cancer cells (Yamaguchi et al. 2008), and it has also been reported in ovarian cancer (Park et al. 2006). NOTCH3 signaling is involved in TGF beta (TGFB1) signaling-induced eptihelial to mesenchimal transition (EMT) (Ohashi et al. 2011, Liu et al. 2014)
NOTCH3 indirectly promotes development of regulatory T cells (Tregs). NOTCH3 signaling activates pre-TCR-dependent and PKC-theta (PRKCQ)-dependent NF-kappaB (NFKB) activation, resulting in induction of FOXP3 expression (Barbarulo et al. 2011). Deregulated NOTCH3 and pre-TCR signaling contributes to development of leukemia and lymphoma (Bellavia et al. 2000, Bellavia et al. 2002).
NOTCH4 is prevalently expressed in endothelial cells (Uyttendaele et al. 1996). DLL4 and JAG1 act as ligands for NOTCH4 in human endothelial cells (Shawber et al. 2003, Shawber et al. 2007), but DLL4- and JAG1-mediated activation of NOTCH4 have not been confirmed in all cell types tested (Aste-Amezaga et al. 2010, James et al. 2014). The gamma secretase complex cleaves activated NOTCH4 receptor to release the intracellular domain fragment (NICD4) (Saxena et al. 2001, Das et al. 2004). NICD4 traffics to the nucleus where it acts as a transcription factor and stimulates expression of NOTCH target genes HES1, HES5, HEY1 and HEY2, as well as VEGFR3 and ACTA2 (Lin et al. 2002, Raafat et al.2004, Tsunematsu et al. 2004, Shawber et al. 2007, Tang et al. 2008, Bargo et al. 2010). NOTCH4 signaling can be downregulated by AKT1 phosphorylation-induced cytoplasmic retention (Ramakrishnan et al. 2015) as well as proteasome-dependent degradation upon FBXW7-mediated ubiquitination (Wu et al. 2001, Tsunematsu et al. 2004).
NOTCH4 was reported to inhibit NOTCH1 signaling in-cis, by binding to NOTCH1 and interfering with the S1 cleavage of NOTCH1, thus preventing production of functional NOTCH1 heterodimers at the cell surface (James et al. 2014).
NOTCH4 is involved in development of the vascular system. Overexpression of constitutively active Notch4 in mouse embryonic vasculature results in abnormal vessel structure and patterning (Uyttendaele et al. 2001). NOTCH4 may act to inhibit apoptosis of endothelial cells (MacKenzie et al. 2004).
Expression of int-3 interferes with normal mammary gland development in mice and promotes tumorigenesis. The phenotype of mice expressing int-3 in mammary glands is dependent on the presence of Rbpj (Raafat et al. 2009). JAG1 and NOTCH4 are upregulated in human ER+ breast cancers resistant to anti-estrogen therapy, which correlates with elevated expression of NOTCH target genes HES1, HEY1 and HEY2, and is associated with increased population of breast cancer stem cells and distant metastases (Simoes et al. 2015). Development of int-3-induced mammary tumours in mice depends on Kit and Pdgfra signaling (Raafat et al. 2006) and on int-3-induced activaton of NFKB signaling (Raafat et al. 2017). In head and neck squamous cell carcinoma (HNSCC), high NOTCH4 expression correlates with elevated HEY1 levels, increased cell proliferation and survival, epithelial-to-mesenchymal transition (EMT) phenotype and cisplatin resistance (Fukusumi et al. 2018). In melanoma, however, exogenous NOTCH4 expression correlates with mesenchymal-to-epithelial-like transition and reduced invasiveness (Bonyadi Rad et al. 2016). NOTCH4 is frequently overexpressed in gastric cancer. Increased NOTCH4 levels correlate with activation of WNT signaling and gastric cancer progression (Qian et al. 2015).
NOTCH4 is expressed in adipocytes and may promote adipocyte differentiation (Lai et al. 2013).
During Dengue virus infection, DLL1, DLL4, NOTCH4 and HES1 are upregulated in interferon-beta (INFB) dependent manner (Li et al. 2015). NOTCH4 signaling may be affected by Epstein-Barr virus (EBV) infection, as the EBV protein BARF0 binds to NOTCH4 (Kusano and Raab-Traub 2001).
Annotated Interactions
mRNA:miR-200B/C
RISCmRNA:miR-200B/C
RISCIn vascular endothelium, NOTCH4 transcription is activated by c-JUN (AP-1) transcription factor. JUN, likely in complex with other transcription factors, binds AP-1 motif(s) in the NOTCH4 promoter and possibly within the first intron (Wu et al. 2005).
NOTCH3 gene transcription is stimulated by the NOTCH3 coactivator complex but it is not known whether this effect is direct, or indirect (Liu et al. 2009).
NOTCH3 gene transcription is directly stimulated by the NOTCH1 coactivator complex and NOTCH1-mediated regulation of NOTCH3 is involved in differentiation of esophageal squamous cells (Ohashi et al. 2009).
NOTCH3 transcription is directly stimulated by transcription factor ELF3, activated by PRKCI (protein kinase C iota)-mediated phosphorylation downstream of KRAS signaling. The PRKCI-ELF3-NOTCH3 signaling controls the tumor-initiating cell phenotype in KRAS-mediated lung adenocarcinoma (Ali et al. 2016).
Studies of mouse Rbpj knockout embryos and zebrafish Mib (mindbomb) mutants indicate that the NOTCH1 coactivator complex positively regulates NOTCH1 transcription. The RBPJ-binding site(s) that the NOTCH1 coactivator complex normally binds have not been found in the NOTCH1 promoter, however, so this effect may be indirect and its mechanism is unknown (Del Monte et al. 2007).
CCND1 (cyclin D1) forms a complex with CREBBP and binds to the NOTCH1 promoter, stimulating NOTCH1 transcription. The involvement of CCND1 in transcriptional regulation of NOTCH1 was established in mouse retinas and the rat retinal precursor cell line R28 (Bienvenu et al. 2010).
E2F1 and E2F3 are able to bind to the NOTCH1 promoter and activate NOTCH1 transcription (Viatour et al. 2011).
NOTCH1 promoter possesses two putative p53-binding sites. Chromatin immunoprecipitation (ChIP) assays of human primary keratinocytes showed binding of endogenous p53 protein to both sites. Experiments in which p53 was downregulated or overexpressed implicate p53 as a positive regulator of NOTCH1 expression in primary human keratinocytes. It is likely that p53-mediated regulation of NOTCH1 expression involves interplay with other cell-type specific determinants of gene expression (Lefort et al. 2007). In lymphoid cells, NOTCH1 expression may be negatively regulated by p53 (Laws and Osborne 2004). Other proteins implicated in the negative regulation of NOTCH1 transcription are KLF9 (Ying et al. 2011), JARID2 (Mysliwiec et al. 2011, Mysliwiec et al. 2012), KLF4 and SP3 (Lambertini et al. 2010), and p63 (Yugawa et al. 2010).