6py8
Crystal structure of the RBPJ-NOTCH1-NRARP ternary complex bound to DNACrystal structure of the RBPJ-NOTCH1-NRARP ternary complex bound to DNA
Structural highlights
Disease[SUH_HUMAN] Defects in RBPJ are the cause of Adams-Oliver syndrome 3 (AOS3) [MIM:614814]. An autosomal dominant form of Adams-Oliver syndrome, a disorder characterized by the congenital absence of skin (aplasia cutis congenita) in combination with transverse limb defects. Aplasia cutis congenita can be located anywhere on the body, but in the vast majority of the cases, it is present on the posterior parietal region where it is often associated with an underlying defect of the parietal bones. Limb abnormalities are typically limb truncation defects affecting the distal phalanges or entire digits (true ectrodactyly). Only rarely, metatarsals/metacarpals or more proximal limb structures are also affected. Apart from transverse limb defects, syndactyly, most commonly of second and third toes, can also be observed. The clinical features are highly variable and can also include cardiovascular malformations, brain abnormalities and vascular defects such as cutis marmorata and dilated scalp veins. AOS3 patients manifest characteristic vertex scalp defects and terminal limb defects, but without congenital heart defects, other associated defects, or immune defects.[1] [NOTC1_HUMAN] Defects in NOTCH1 are a cause of aortic valve disease 1 (AOVD1) [MIM:109730]. A common defect in the aortic valve in which two rather than three leaflets are present. It is often associated with aortic valve calcification and insufficiency. In extreme cases, the blood flow may be so restricted that the left ventricle fails to grow, resulting in hypoplastic left heart syndrome.[2] Function[SUH_HUMAN] Transcriptional regulator that plays a central role in Notch signaling, a signaling pathway involved in cell-cell communication that regulates a broad spectrum of cell-fate determinations. Acts as a transcriptional repressor when it is not associated with Notch proteins. When associated with some NICD product of Notch proteins (Notch intracellular domain), it acts as a transcriptional activator that activates transcription of Notch target genes. Probably represses or activates transcription via the recruitment of chromatin remodeling complexes containing histone deacetylase or histone acetylase proteins, respectively. Specifically binds to the immunoglobulin kappa-type J segment recombination signal sequence. Binds specifically to methylated DNA.[3] [NRARP_HUMAN] Downstream effector of Notch signaling. Involved in the regulation of liver cancer cells self-renewal (PubMed:25985737). Involved in angiogenesis acting downstream of Notch at branch points to regulate vascular density. Proposed to integrate endothelial Notch and Wnt signaling to control stalk cell proliferation and to stablilize new endothelial connections during angiogenesis (PubMed:19154719). During somitogenesis involved in maintenance of proper somite segmentation and proper numbers of somites and vertebrae. Required for proper anterior-posterior somite patterning. Proposed to function in a negative feedback loop to destabilize Notch 1 intracellular domain (NICD) and downregulate the Notch signal, preventing expansion of the Notch signal into the anterior somite domain (By similarity).[UniProtKB:Q91ZA8][4] [5] [6] [NOTC1_HUMAN] Functions as a receptor for membrane-bound ligands Jagged1, Jagged2 and Delta1 to regulate cell-fate determination. Upon ligand activation through the released notch intracellular domain (NICD) it forms a transcriptional activator complex with RBPJ/RBPSUH and activates genes of the enhancer of split locus. Affects the implementation of differentiation, proliferation and apoptotic programs. May be important for normal lymphocyte function. In altered form, may contribute to transformation or progression in some T-cell neoplasms. Involved in the maturation of both CD4+ and CD8+ cells in the thymus. May be important for follicular differentiation and possibly cell fate selection within the follicle. During cerebellar development, may function as a receptor for neuronal DNER and may be involved in the differentiation of Bergmann glia. Represses neuronal and myogenic differentiation. May enhance HIF1A function by sequestering HIF1AN away from HIF1A (By similarity). Publication Abstract from PubMedCanonical Notch signaling relies on regulated proteolysis of the receptor Notch to generate a nuclear effector that induces the transcription of Notch-responsive genes. In higher organisms, one Notch-responsive gene that is activated in many different cell types encodes the Notch-regulated ankyrin repeat protein (NRARP), which acts as a negative feedback regulator of Notch responses. Here, we showed that NRARP inhibited the growth of Notch-dependent T cell acute lymphoblastic leukemia (T-ALL) cell lines and bound directly to the core Notch transcriptional activation complex (NTC), requiring both the transcription factor RBPJ and the Notch intracellular domain (NICD), but not Mastermind-like proteins or DNA. The crystal structure of an NRARP-NICD1-RBPJ-DNA complex, determined to 3.75 A resolution, revealed that the assembly of NRARP-NICD1-RBPJ complexes relied on simultaneous engagement of RBPJ and NICD1, with the three ankyrin repeats of NRARP extending the Notch1 ankyrin repeat stack. Mutations at the NRARP-NICD1 interface disrupted entry of the proteins into NTCs and abrogated feedback inhibition in Notch signaling assays in cultured cells. Forced expression of NRARP reduced the abundance of NICD in cells, suggesting that NRARP may promote the degradation of NICD. These studies establish the structural basis for NTC engagement by NRARP and provide insights into a critical negative feedback mechanism that regulates Notch signaling. Extension of the Notch intracellular domain ankyrin repeat stack by NRARP promotes feedback inhibition of Notch signaling.,Jarrett SM, Seegar TCM, Andrews M, Adelmant G, Marto JA, Aster JC, Blacklow SC Sci Signal. 2019 Nov 5;12(606). pii: 12/606/eaay2369. doi:, 10.1126/scisignal.aay2369. PMID:31690634[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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