| Structural highlights
Disease
[LRP6_HUMAN] Coronary artery disease - hyperlipidemia - hypertension - diabetes - osteoporosis. The disease is caused by mutations affecting the gene represented in this entry. [SOST_HUMAN] Defects in SOST are the cause of sclerosteosis type 1 (SOST1) [MIM:269500]. An autosomal recessive sclerosing bone dysplasia characterized by a generalized hyperostosis and sclerosis leading to a markedly thickened skull, with mandible, ribs, clavicles and all long bones also being affected. Due to narrowing of the foramina of the cranial nerves, facial nerve palsy, hearing loss and atrophy of the optic nerves can occur. Sclerosteosis is clinically and radiologically very similar to van Buchem disease, mainly differentiated by hand malformations and a large stature in sclerosteosis patients.[1] [2] [3] Defects in SOST are a cause of van Buchem disease (VBCH) [MIM:239100]. An autosomal recessive sclerosing bone dysplasia characterized by endosteal hyperostosis of the mandible, skull, ribs, clavicles, and diaphyses of the long bones. Affected patients present a symmetrically increased thickness of bones, most frequently found as an enlarged jawbone, but also an enlargement of the skull, ribs, diaphysis of long bones, as well as tubular bones of hands and feet. The clinical consequence of increased thickness of the skull include facial nerve palsy causing hearing loss, visual problems, neurological pain, and, very rarely, blindness as a consequence of optic atrophy. Serum alkaline phosphatase levels are elevated. Note=A 52 kb deletion downstream of SOST results in SOST transcription suppression causing van Buchem disease.[4] Defects in SOST are a cause of craniodiaphyseal dysplasia autosomal dominant (CDD) [MIM:122860]. A severe bone dysplasia characterized by massive generalized hyperostosis and sclerosis, especially involving the skull and facial bones. The sclerosis is so severe that the resulting facial distortion is referred to as 'leontiasis ossea' (leonine faces) and the bone deposition results in progressive stenosis of craniofacial foramina. Respiratory obstruction due to choanal stenosis compromises the clinical outcomes of affected patients. Note=Heterozygous mutations located in the secretion signal of the SOST gene prevent sclerostin secretion and can be responsible for craniodiaphyseal dysplasia.[5]
Function
[LRP6_HUMAN] Component of the Wnt-Fzd-LRP5-LRP6 complex that triggers beta-catenin signaling through inducing aggregation of receptor-ligand complexes into ribosome-sized signalsomes. Cell-surface coreceptor of Wnt/beta-catenin signaling, which plays a pivotal role in bone formation. The Wnt-induced Fzd/LRP6 coreceptor complex recruits DVL1 polymers to the plasma membrane which, in turn, recruits the AXIN1/GSK3B-complex to the cell surface promoting the formation of signalsomes and inhibiting AXIN1/GSK3-mediated phosphorylation and destruction of beta-catenin. Required for posterior patterning of the epiblast during gastrulation (By similarity).[6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [SOST_HUMAN] Negative regulator of bone growth that acts through inhibition of Wnt signaling and bone formation.[16]
Publication Abstract from PubMed
The Wnt pathway inhibitors DKK1 and sclerostin (SOST) are important therapeutic targets in diseases involving bone loss or damage. It has been appreciated that Wnt coreceptors LRP5/6 are also important, as human missense mutations that result in bone overgrowth (bone mineral density, or BMD, mutations) cluster to the E1 propeller domain of LRP5. Here, we report a crystal structure of LRP6 E1 bound to an antibody, revealing that the E1 domain is a peptide recognition module. Remarkably, the consensus E1 binding sequence is a close match to a conserved tripeptide motif present in all Wnt inhibitors that bind LRP5/6. We show that this motif is important for DKK1 and SOST binding to LRP6 and for inhibitory function, providing a detailed structural explanation for the effect of the BMD mutations.
Wnt antagonists bind through a short peptide to the first beta-propeller domain of LRP5/6.,Bourhis E, Wang W, Tam C, Hwang J, Zhang Y, Spittler D, Huang OW, Gong Y, Estevez A, Zilberleyb I, Rouge L, Chiu C, Wu Y, Costa M, Hannoush RN, Franke Y, Cochran AG Structure. 2011 Oct 12;19(10):1433-42. Epub 2011 Sep 22. PMID:21944579[17]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Balemans W, Ebeling M, Patel N, Van Hul E, Olson P, Dioszegi M, Lacza C, Wuyts W, Van Den Ende J, Willems P, Paes-Alves AF, Hill S, Bueno M, Ramos FJ, Tacconi P, Dikkers FG, Stratakis C, Lindpaintner K, Vickery B, Foernzler D, Van Hul W. Increased bone density in sclerosteosis is due to the deficiency of a novel secreted protein (SOST). Hum Mol Genet. 2001 Mar 1;10(5):537-43. PMID:11181578
- ↑ Brunkow ME, Gardner JC, Van Ness J, Paeper BW, Kovacevich BR, Proll S, Skonier JE, Zhao L, Sabo PJ, Fu Y, Alisch RS, Gillett L, Colbert T, Tacconi P, Galas D, Hamersma H, Beighton P, Mulligan J. Bone dysplasia sclerosteosis results from loss of the SOST gene product, a novel cystine knot-containing protein. Am J Hum Genet. 2001 Mar;68(3):577-89. Epub 2001 Feb 9. PMID:11179006
- ↑ Piters E, Culha C, Moester M, Van Bezooijen R, Adriaensen D, Mueller T, Weidauer S, Jennes K, de Freitas F, Lowik C, Timmermans JP, Van Hul W, Papapoulos S. First missense mutation in the SOST gene causing sclerosteosis by loss of sclerostin function. Hum Mutat. 2010 Jul;31(7):E1526-43. doi: 10.1002/humu.21274. PMID:20583295 doi:10.1002/humu.21274
- ↑ Balemans W, Patel N, Ebeling M, Van Hul E, Wuyts W, Lacza C, Dioszegi M, Dikkers FG, Hildering P, Willems PJ, Verheij JB, Lindpaintner K, Vickery B, Foernzler D, Van Hul W. Identification of a 52 kb deletion downstream of the SOST gene in patients with van Buchem disease. J Med Genet. 2002 Feb;39(2):91-7. PMID:11836356
- ↑ Kim SJ, Bieganski T, Sohn YB, Kozlowski K, Semenov M, Okamoto N, Kim CH, Ko AR, Ahn GH, Choi YL, Park SW, Ki CS, Kim OH, Nishimura G, Unger S, Superti-Furga A, Jin DK. Identification of signal peptide domain SOST mutations in autosomal dominant craniodiaphyseal dysplasia. Hum Genet. 2011 May;129(5):497-502. doi: 10.1007/s00439-011-0947-3. Epub 2011 Jan, 9. PMID:21221996 doi:10.1007/s00439-011-0947-3
- ↑ Semenov MV, Tamai K, Brott BK, Kuhl M, Sokol S, He X. Head inducer Dickkopf-1 is a ligand for Wnt coreceptor LRP6. Curr Biol. 2001 Jun 26;11(12):951-61. PMID:11448771
- ↑ Mao B, Wu W, Li Y, Hoppe D, Stannek P, Glinka A, Niehrs C. LDL-receptor-related protein 6 is a receptor for Dickkopf proteins. Nature. 2001 May 17;411(6835):321-5. PMID:11357136 doi:10.1038/35077108
- ↑ Li X, Zhang Y, Kang H, Liu W, Liu P, Zhang J, Harris SE, Wu D. Sclerostin binds to LRP5/6 and antagonizes canonical Wnt signaling. J Biol Chem. 2005 May 20;280(20):19883-7. Epub 2005 Mar 18. PMID:15778503 doi:10.1074/jbc.M413274200
- ↑ Zeng X, Tamai K, Doble B, Li S, Huang H, Habas R, Okamura H, Woodgett J, He X. A dual-kinase mechanism for Wnt co-receptor phosphorylation and activation. Nature. 2005 Dec 8;438(7069):873-7. PMID:16341017 doi:10.1038/nature04185
- ↑ Swiatek W, Kang H, Garcia BA, Shabanowitz J, Coombs GS, Hunt DF, Virshup DM. Negative regulation of LRP6 function by casein kinase I epsilon phosphorylation. J Biol Chem. 2006 May 5;281(18):12233-41. Epub 2006 Mar 2. PMID:16513652 doi:10.1074/jbc.M510580200
- ↑ Wei Q, Yokota C, Semenov MV, Doble B, Woodgett J, He X. R-spondin1 is a high affinity ligand for LRP6 and induces LRP6 phosphorylation and beta-catenin signaling. J Biol Chem. 2007 May 25;282(21):15903-11. Epub 2007 Mar 30. PMID:17400545 doi:10.1074/jbc.M701927200
- ↑ Mi K, Johnson GV. Regulated proteolytic processing of LRP6 results in release of its intracellular domain. J Neurochem. 2007 Apr;101(2):517-29. Epub 2007 Feb 26. PMID:17326769 doi:10.1111/j.1471-4159.2007.04447.x
- ↑ Piao S, Lee SH, Kim H, Yum S, Stamos JL, Xu Y, Lee SJ, Lee J, Oh S, Han JK, Park BJ, Weis WI, Ha NC. Direct inhibition of GSK3beta by the phosphorylated cytoplasmic domain of LRP6 in Wnt/beta-catenin signaling. PLoS One. 2008;3(12):e4046. doi: 10.1371/journal.pone.0004046. Epub 2008 Dec 24. PMID:19107203 doi:10.1371/journal.pone.0004046
- ↑ Chen M, Philipp M, Wang J, Premont RT, Garrison TR, Caron MG, Lefkowitz RJ, Chen W. G Protein-coupled receptor kinases phosphorylate LRP6 in the Wnt pathway. J Biol Chem. 2009 Dec 11;284(50):35040-8. doi: 10.1074/jbc.M109.047456. Epub 2009, Oct 2. PMID:19801552 doi:10.1074/jbc.M109.047456
- ↑ Wu G, Huang H, Garcia Abreu J, He X. Inhibition of GSK3 phosphorylation of beta-catenin via phosphorylated PPPSPXS motifs of Wnt coreceptor LRP6. PLoS One. 2009;4(3):e4926. doi: 10.1371/journal.pone.0004926. Epub 2009 Mar 18. PMID:19293931 doi:10.1371/journal.pone.0004926
- ↑ Semenov M, Tamai K, He X. SOST is a ligand for LRP5/LRP6 and a Wnt signaling inhibitor. J Biol Chem. 2005 Jul 22;280(29):26770-5. Epub 2005 May 20. PMID:15908424 doi:10.1074/jbc.M504308200
- ↑ Bourhis E, Wang W, Tam C, Hwang J, Zhang Y, Spittler D, Huang OW, Gong Y, Estevez A, Zilberleyb I, Rouge L, Chiu C, Wu Y, Costa M, Hannoush RN, Franke Y, Cochran AG. Wnt antagonists bind through a short peptide to the first beta-propeller domain of LRP5/6. Structure. 2011 Oct 12;19(10):1433-42. Epub 2011 Sep 22. PMID:21944579 doi:10.1016/j.str.2011.07.005
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