| Structural highlights
Disease
[CBL_HUMAN] Defects in CBL are the cause of Noonan syndrome-like disorder with or without juvenile myelomonocytic leukemia (NSLL) [MIM:613563]. A syndrome characterized by a phenotype reminiscent of Noonan syndrome. Clinical features are highly variable, including facial dysmorphism, short neck, developmental delay, hyperextensible joints and thorax abnormalities with widely spaced nipples. The facial features consist of triangular face with hypertelorism, large low-set ears, ptosis, and flat nasal bridge. Some patients manifest cardiac defects.[1]
Function
[CBL_HUMAN] Adapter protein that functions as a negative regulator of many signaling pathways that are triggered by activation of cell surface receptors. Acts as an E3 ubiquitin-protein ligase, which accepts ubiquitin from specific E2 ubiquitin-conjugating enzymes, and then transfers it to substrates promoting their degradation by the proteasome. Recognizes activated receptor tyrosine kinases, including KIT, FLT1, FGFR1, FGFR2, PDGFRA, PDGFRB, EGFR, CSF1R, EPHA8 and KDR and terminates signaling. Recognizes membrane-bound HCK and other kinases of the SRC family and mediates their ubiquitination and degradation. Participates in signal transduction in hematopoietic cells. Plays an important role in the regulation of osteoblast differentiation and apoptosis. Essential for osteoclastic bone resorption. The Tyr-731 phosphorylated form induces the activation and recruitment of phosphatidylinositol 3-kinase to the cell membrane in a signaling pathway that is critical for osteoclast function.[2] [3] [4] [5] [6] [7] [8] [9]
Publication Abstract from PubMed
BACKGROUND: Casitas B-lineage lymphoma (Cbl or c-Cbl) is a RING ubiquitin ligase that negatively regulates protein tyrosine kinase (PTK) signalling. Phosphorylation of a conserved residue (Tyr371) on the linker helix region (LHR) between the substrate-binding and RING domains is required to ubiquitinate PTKs, thereby flagging them for degradation. This conserved Tyr is a mutational hotspot in myeloproliferative neoplasms. Previous studies have revealed that select point mutations in Tyr371 can potentiate transformation in cells and mice but not all possible mutations do so. To trigger oncogenic potential, Cbl Tyr371 mutants must perturb the LHR-substrate-binding domain interaction and eliminate PTK ubiquitination. Although structures of native and pTyr371-Cbl are available, they do not reveal how Tyr371 mutations affect Cbl's conformation. Here, we investigate how Tyr371 mutations affect Cbl's conformation in solution and how this relates to Cbl's ability to potentiate transformation in cells. RESULTS: To explore how Tyr371 mutations affect Cbl's properties, we used surface plasmon resonance to measure Cbl mutant binding affinities for E2 conjugated with ubiquitin (E2-Ub), small angle X-ray scattering studies to investigate Cbl mutant conformation in solution and focus formation assays to assay Cbl mutant transformation potential in cells. Cbl Tyr371 mutants enhance E2-Ub binding and cause Cbl to adopt extended conformations in solution. LHR flexibility, RING domain accessibility and transformation potential are associated with the extent of LHR-substrate-binding domain perturbation affected by the chemical nature of the mutation. More disruptive mutants like Cbl Y371D or Y371S are more extended and the RING domain is more accessible, whereas Cbl Y371F mimics native Cbl in solution. Correspondingly, the only Tyr371 mutants that potentiate transformation in cells are those that perturb the LHR-substrate-binding domain interaction. CONCLUSIONS: c-Cbl's LHR mutations are only oncogenic when they disrupt the native state and fail to ubiquitinate PTKs. These findings provide new insights into how LHR mutations deregulate c-Cbl.
Casitas B-lineage lymphoma linker helix mutations found in myeloproliferative neoplasms affect conformation.,Buetow L, Tria G, Ahmed SF, Hock A, Dou H, Sibbet GJ, Svergun DI, Huang DT BMC Biol. 2016 Sep 8;14:76. doi: 10.1186/s12915-016-0298-6. PMID:27609087[10]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Martinelli S, De Luca A, Stellacci E, Rossi C, Checquolo S, Lepri F, Caputo V, Silvano M, Buscherini F, Consoli F, Ferrara G, Digilio MC, Cavaliere ML, van Hagen JM, Zampino G, van der Burgt I, Ferrero GB, Mazzanti L, Screpanti I, Yntema HG, Nillesen WM, Savarirayan R, Zenker M, Dallapiccola B, Gelb BD, Tartaglia M. Heterozygous germline mutations in the CBL tumor-suppressor gene cause a Noonan syndrome-like phenotype. Am J Hum Genet. 2010 Aug 13;87(2):250-7. doi: 10.1016/j.ajhg.2010.06.015. Epub, 2010 Jul 8. PMID:20619386 doi:10.1016/j.ajhg.2010.06.015
- ↑ Joazeiro CA, Wing SS, Huang H, Leverson JD, Hunter T, Liu YC. The tyrosine kinase negative regulator c-Cbl as a RING-type, E2-dependent ubiquitin-protein ligase. Science. 1999 Oct 8;286(5438):309-12. PMID:10514377
- ↑ Howlett CJ, Robbins SM. Membrane-anchored Cbl suppresses Hck protein-tyrosine kinase mediated cellular transformation. Oncogene. 2002 Mar 7;21(11):1707-16. PMID:11896602 doi:10.1038/sj.onc.1205228
- ↑ Miyazaki T, Sanjay A, Neff L, Tanaka S, Horne WC, Baron R. Src kinase activity is essential for osteoclast function. J Biol Chem. 2004 Apr 23;279(17):17660-6. Epub 2004 Jan 22. PMID:14739300 doi:10.1074/jbc.M311032200
- ↑ Kaabeche K, Lemonnier J, Le Mee S, Caverzasio J, Marie PJ. Cbl-mediated degradation of Lyn and Fyn induced by constitutive fibroblast growth factor receptor-2 activation supports osteoblast differentiation. J Biol Chem. 2004 Aug 27;279(35):36259-67. Epub 2004 Jun 9. PMID:15190072 doi:10.1074/jbc.M402469200
- ↑ Bonaventure J, Horne WC, Baron R. The localization of FGFR3 mutations causing thanatophoric dysplasia type I differentially affects phosphorylation, processing and ubiquitylation of the receptor. FEBS J. 2007 Jun;274(12):3078-93. Epub 2007 May 17. PMID:17509076 doi:10.1111/j.1742-4658.2007.05835.x
- ↑ Dufour C, Guenou H, Kaabeche K, Bouvard D, Sanjay A, Marie PJ. FGFR2-Cbl interaction in lipid rafts triggers attenuation of PI3K/Akt signaling and osteoblast survival. Bone. 2008 Jun;42(6):1032-9. doi: 10.1016/j.bone.2008.02.009. Epub 2008 Feb 29. PMID:18374639 doi:10.1016/j.bone.2008.02.009
- ↑ Wehrle C, Van Slyke P, Dumont DJ. Angiopoietin-1-induced ubiquitylation of Tie2 by c-Cbl is required for internalization and degradation. Biochem J. 2009 Oct 12;423(3):375-80. doi: 10.1042/BJ20091010. PMID:19689429 doi:10.1042/BJ20091010
- ↑ Severe N, Miraoui H, Marie PJ. The Casitas B lineage lymphoma (Cbl) mutant G306E enhances osteogenic differentiation in human mesenchymal stromal cells in part by decreased Cbl-mediated platelet-derived growth factor receptor alpha and fibroblast growth factor receptor 2 ubiquitination. J Biol Chem. 2011 Jul 8;286(27):24443-50. doi: 10.1074/jbc.M110.197525. Epub 2011, May 19. PMID:21596750 doi:10.1074/jbc.M110.197525
- ↑ Buetow L, Tria G, Ahmed SF, Hock A, Dou H, Sibbet GJ, Svergun DI, Huang DT. Casitas B-lineage lymphoma linker helix mutations found in myeloproliferative neoplasms affect conformation. BMC Biol. 2016 Sep 8;14:76. doi: 10.1186/s12915-016-0298-6. PMID:27609087 doi:http://dx.doi.org/10.1186/s12915-016-0298-6
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