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From Proteopedia
The structure of a beta propeller domain in complex with peptide S
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 PubMedThe 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
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