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Structure of the Grem2-GDF5 Inhibitory ComplexStructure of the Grem2-GDF5 Inhibitory Complex
Structural highlights
Disease[GDF5_HUMAN] Defects in GDF5 are the cause of acromesomelic chondrodysplasia Grebe type (AMDG) [MIM:200700]. Acromesomelic chondrodysplasias are rare hereditary skeletal disorders characterized by short stature, very short limbs, and hand/foot malformations. The severity of limb abnormalities increases from proximal to distal with profoundly affected hands and feet showing brachydactyly and/or rudimentary fingers (knob-like fingers). AMDG is an autosomal recessive form characterized by normal axial skeletons and missing or fused skeletal elements within the hands and feet.[1] Defects in GDF5 are the cause of acromesomelic chondrodysplasia Hunter-Thompson type (AMDH) [MIM:201250]. AMDH is an autosomal recessive form of dwarfism. Patients have limb abnormalities, with the middle and distal segments being most affected and the lower limbs more affected than the upper. AMDH is characterized by normal axial skeletons and missing or fused skeletal elements within the hands and feet. Defects in GDF5 are the cause of brachydactyly type C (BDC) [MIM:113100]. BDC is an autosomal dominant disorder characterized by an abnormal shortness of the fingers and toes. Note=Some BDC patients with GDF5 mutations also manifest clinical features of ASPED angel-shaped phalango-epiphyseal dysplasia (ASPED), an autosomal dominant skeletal abnormality characterized by a typical angel-shaped phalanx, brachydactyly, specific radiological findings, abnormal dentition, hip dysplasia, and delayed bone age. This suggests that BDC and ASPED are part of the same clinical spectrum (PubMed:22828468).[2] [3] Defects in GDF5 are the cause of Du Pan syndrome (DPS) [MIM:228900]; also known as fibular hypoplasia and complex brachydactyly. Du Pan syndrome is a rare autosomal recessive condition characterized by absence of the fibulae and severe acromesomelic limb shortening with small, non-functional toes. Although milder, the phenotype resembles the autosomal recessive Hunter-Thompson and Grebe types of acromesomelic chondrodysplasia.[4] [5] [6] Defects in GDF5 are a cause of symphalangism proximal syndrome (SYM1) [MIM:185800]. SYM1 is characterized by the hereditary absence of the proximal interphalangeal (PIP) joints (Cushing symphalangism). Severity of PIP joint involvement diminishes towards the radial side. Distal interphalangeal joints are less frequently involved and metacarpophalangeal joints are rarely affected whereas carpal bone malformation and fusion are common. In the lower extremities, tarsal bone coalition is common. Conducive hearing loss is seen and is due to fusion of the stapes to the petrous part of the temporal bone.[7] [8] [9] Defects in GDF5 are the cause of multiple synostoses syndrome type 2 (SYNS2) [MIM:610017]. Multiple synostoses syndrome is an autosomal dominant condition characterized by progressive joint fusions of the fingers, wrists, ankles and cervical spine, characteristic facies and progressive conductive deafness.[:][10] Defects in GDF5 are a cause of brachydactyly type A2 (BDA2) [MIM:112600]. Brachydactylies (BDs) are a group of inherited malformations characterized by shortening of the digits due to abnormal development of the phalanges and/or the metacarpals. They have been classified on an anatomic and genetic basis into five groups, A to E, including three subgroups (A1 to A3) that usually manifest as autosomal dominant traits.[11] [12] Genetic variations in GDF5 are associated with susceptibility to osteoarthritis type 5 (OS5) [MIM:612400]. Osteoarthritis is a degenerative disease of the joints characterized by degradation of the hyaline articular cartilage and remodeling of the subchondral bone with sclerosis. Clinical symptoms include pain and joint stiffness often leading to significant disability and joint replacement. Defects in GDF5 may be a cause of brachydactyly type A1 (BDA1) [MIM:112500]. Brachydactylies (BDs) are a group of inherited malformations characterized by shortening of the digits due to abnormal development of the phalanges and/or the metacarpals. They have been classified on an anatomic and genetic basis into five groups, A to E, including three subgroups (A1 to A3) that usually manifest as autosomal dominant traits.[13] Function[GREM2_MOUSE] Cytokine that inhibits the activity of BMP2 and BMP4 in a dose-dependent manner. Antagonized BMP4-induced suppression of progesterone production in granulosa cells.[14] [GDF5_HUMAN] Could be involved in bone and cartilage formation. Chondrogenic signaling is mediated by the high-affinity receptor BMPR1B.[15] [16] Publication Abstract from PubMedThe DAN family, including Gremlin-1 and Gremlin-2 (Grem1 and Grem2), represents a large family of secreted BMP (bone morphogenetic protein) antagonists. However, how DAN proteins specifically inhibit BMP signaling has remained elusive. Here, we report the structure of Grem2 bound to GDF5 at 2.9-A resolution. The structure reveals two Grem2 dimers binding perpendicularly to each GDF5 monomer, resembling an H-like structure. Comparison to the unbound Grem2 structure reveals a dynamic N terminus that undergoes significant transition upon complex formation, leading to simultaneous interaction with the type I and type II receptor motifs on GDF5. Binding studies show that DAN-family members can interact with BMP-type I receptor complexes, whereas Noggin outcompetes the type I receptor for ligand binding. Interestingly, Grem2-GDF5 forms a stable aggregate-like structure in vitro that is not clearly observed for other antagonists, including Noggin and Follistatin. These findings exemplify the structural and functional diversity across the various BMP antagonist families. Structure of Gremlin-2 in Complex with GDF5 Gives Insight into DAN-Family-Mediated BMP Antagonism.,Nolan K, Kattamuri C, Rankin SA, Read RJ, Zorn AM, Thompson TB Cell Rep. 2016 Aug 23;16(8):2077-86. doi: 10.1016/j.celrep.2016.07.046. Epub 2016, Aug 11. PMID:27524626[17] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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