SOST: Negative regulator of bone growth that acts through inhibition of Wnt signaling and bone formation. Defects in SOST are the cause of sclerosteosis type 1 (SOST1). 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. Defects in SOST are a cause of van Buchem disease (VBCH). 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. A 52 kb deletion downstream of SOST results in SOST transcription suppression causing van Buchem disease. Defects in SOST are a cause of craniodiaphyseal dysplasia autosomal dominant (CDD). 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. Heterozygous mutations located in the secretion signal of the SOST gene prevent sclerostin secretion and can be responsible for craniodiaphyseal dysplasia. Belongs to the sclerostin family. 2 isoforms of the human protein are produced by alternative splicing.
Protein type: Secreted; Secreted, signal peptide
Chromosomal Location of Human Ortholog: 11|11 D
Cellular Component: extracellular matrix; extracellular region; extracellular space; Golgi apparatus; protein complex; proteinaceous extracellular matrix
Molecular Function: heparin binding; protein binding; transcription factor binding
Biological Process: negative regulation of BMP signaling pathway; negative regulation of ossification; negative regulation of protein complex assembly; negative regulation of Wnt signaling pathway; ossification; positive regulation of transcription, DNA-templated; Wnt signaling pathway
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