6mac

Structural highlights

Disease

[TGFR1_HUMAN] Defects in TGFBR1 are the cause of Loeys-Dietz syndrome type 1A (LDS1A) [MIM:609192]; also known as Furlong syndrome or Loeys-Dietz aortic aneurysm syndrome (LDAS). LDS1 is an aortic aneurysm syndrome with widespread systemic involvement. The disorder is characterized by arterial tortuosity and aneurysms, craniosynostosis, hypertelorism, and bifid uvula or cleft palate. Other findings include exotropy, micrognathia and retrognathia, structural brain abnormalities, intellectual deficit, congenital heart disease, translucent skin, joint hyperlaxity and aneurysm with dissection throughout the arterial tree.^{[1] [2] [3] [4] [5]} Defects in TGFBR1 are the cause of Loeys-Dietz syndrome type 2A (LDS2A) [MIM:608967]. An aortic aneurysm syndrome with widespread systemic involvement. Physical findings include prominent joint laxity, easy bruising, wide and atrophic scars, velvety and translucent skin with easily visible veins, spontaneous rupture of the spleen or bowel, diffuse arterial aneurysms and dissections, and catastrophic complications of pregnancy, including rupture of the gravid uterus and the arteries, either during pregnancy or in the immediate postpartum period. LDS2 is characterized by the absence of craniofacial abnormalities with the exception of bifid uvula that can be present in some patients. Note=TGFBR1 mutation Gln-487 has been reported to be associated with thoracic aortic aneurysms and dissection (TAAD) (PubMed:16791849). This phenotype, also known as thoracic aortic aneurysms type 5 (AAT5), is distinguised from LDS2A by having aneurysms restricted to thoracic aorta. It is unclear, however, if this condition is fulfilled in individuals bearing Gln-487 mutation, that is why they are considered as LDS2A by the OMIM resource. Defects in TGFBR1 are the cause of multiple self-healing squamous epithelioma (MSSE) [MIM:132800]. A disorder characterized by multiple skin tumors that undergo spontaneous regression. Tumors appear most often on sun-exposed regions, are locally invasive, and undergo spontaneous resolution over a period of months leaving pitted scars.^[6]

Function

[GDF11_HUMAN] Secreted signal that acts globally to specify positional identity along the anterior/posterior axis during development. Play critical roles in patterning both mesodermal and neural tissues and in establishing the skeletal pattern. [TGFR1_HUMAN] Transmembrane serine/threonine kinase forming with the TGF-beta type II serine/threonine kinase receptor, TGFBR2, the non-promiscuous receptor for the TGF-beta cytokines TGFB1, TGFB2 and TGFB3. Transduces the TGFB1, TGFB2 and TGFB3 signal from the cell surface to the cytoplasm and is thus regulating a plethora of physiological and pathological processes including cell cycle arrest in epithelial and hematopoietic cells, control of mesenchymal cell proliferation and differentiation, wound healing, extracellular matrix production, immunosuppression and carcinogenesis. The formation of the receptor complex composed of 2 TGFBR1 and 2 TGFBR2 molecules symmetrically bound to the cytokine dimer results in the phosphorylation and the activation of TGFBR1 by the constitutively active TGFBR2. Activated TGFBR1 phosphorylates SMAD2 which dissociates from the receptor and interacts with SMAD4. The SMAD2-SMAD4 complex is subsequently translocated to the nucleus where it modulates the transcription of the TGF-beta-regulated genes. This constitutes the canonical SMAD-dependent TGF-beta signaling cascade. Also involved in non-canonical, SMAD-independent TGF-beta signaling pathways. For instance, TGFBR1 induces TRAF6 autoubiquitination which in turn results in MAP3K7 ubiquitination and activation to trigger apoptosis. Also regulates epithelial to mesenchymal transition through a SMAD-independent signaling pathway through PARD6A phosphorylation and activation.^{[7] [8] [9] [10] [11] [12] [13]} [AVR2B_RAT] Transmembrane serine/threonine kinase activin type-2 receptor forming an activin receptor complex with activin type-1 serine/threonine kinase receptors (ACVR1, ACVR1B or ACVR1c). Transduces the activin signal from the cell surface to the cytoplasm and is thus regulating many physiological and pathological processes including neuronal differentiation and neuronal survival, hair follicle development and cycling, FSH production by the pituitary gland, wound healing, extracellular matrix production, immunosuppression and carcinogenesis. Activin is also thought to have a paracrine or autocrine role in follicular development in the ovary. Within the receptor complex, the type-2 receptors act as a primary activin receptors (binds activin-A/INHBA, activin-B/INHBB as well as inhibin-A/INHA-INHBA). The type-1 receptors like ACVR1B act as downstream transducers of activin signals. Activin binds to type-2 receptor at the plasma membrane and activates its serine-threonine kinase. The activated receptor type-2 then phosphorylates and activates the type-1 receptor. Once activated, the type-1 receptor binds and phosphorylates the SMAD proteins SMAD2 and SMAD3, on serine residues of the C-terminal tail. Soon after their association with the activin receptor and subsequent phosphorylation, SMAD2 and SMAD3 are released into the cytoplasm where they interact with the common partner SMAD4. This SMAD complex translocates into the nucleus where it mediates activin-induced transcription. Inhibitory SMAD7, which is recruited to ACVR1B through FKBP1A, can prevent the association of SMAD2 and SMAD3 with the activin receptor complex, thereby blocking the activin signal. Activin signal transduction is also antagonized by the binding to the receptor of inhibin-B via the IGSF1 inhibin coreceptor (By similarity).

References

1. ↑ Loeys BL, Chen J, Neptune ER, Judge DP, Podowski M, Holm T, Meyers J, Leitch CC, Katsanis N, Sharifi N, Xu FL, Myers LA, Spevak PJ, Cameron DE, De Backer J, Hellemans J, Chen Y, Davis EC, Webb CL, Kress W, Coucke P, Rifkin DB, De Paepe AM, Dietz HC. A syndrome of altered cardiovascular, craniofacial, neurocognitive and skeletal development caused by mutations in TGFBR1 or TGFBR2. Nat Genet. 2005 Mar;37(3):275-81. Epub 2005 Jan 30. PMID:15731757 doi:ng1511
2. ↑ Ades LC, Sullivan K, Biggin A, Haan EA, Brett M, Holman KJ, Dixon J, Robertson S, Holmes AD, Rogers J, Bennetts B. FBN1, TGFBR1, and the Marfan-craniosynostosis/mental retardation disorders revisited. Am J Med Genet A. 2006 May 15;140(10):1047-58. PMID:16596670 doi:10.1002/ajmg.a.31202
3. ↑ Matyas G, Arnold E, Carrel T, Baumgartner D, Boileau C, Berger W, Steinmann B. Identification and in silico analyses of novel TGFBR1 and TGFBR2 mutations in Marfan syndrome-related disorders. Hum Mutat. 2006 Aug;27(8):760-9. PMID:16791849 doi:10.1002/humu.20353
4. ↑ Drera B, Ritelli M, Zoppi N, Wischmeijer A, Gnoli M, Fattori R, Calzavara-Pinton PG, Barlati S, Colombi M. Loeys-Dietz syndrome type I and type II: clinical findings and novel mutations in two Italian patients. Orphanet J Rare Dis. 2009 Nov 2;4:24. doi: 10.1186/1750-1172-4-24. PMID:19883511 doi:10.1186/1750-1172-4-24
5. ↑ Yang JH, Ki CS, Han H, Song BG, Jang SY, Chung TY, Sung K, Lee HJ, Kim DK. Clinical features and genetic analysis of Korean patients with Loeys-Dietz syndrome. J Hum Genet. 2012 Jan;57(1):52-6. doi: 10.1038/jhg.2011.130. Epub 2011 Nov 24. PMID:22113417 doi:10.1038/jhg.2011.130
6. ↑ Goudie DR, D'Alessandro M, Merriman B, Lee H, Szeverenyi I, Avery S, O'Connor BD, Nelson SF, Coats SE, Stewart A, Christie L, Pichert G, Friedel J, Hayes I, Burrows N, Whittaker S, Gerdes AM, Broesby-Olsen S, Ferguson-Smith MA, Verma C, Lunny DP, Reversade B, Lane EB. Multiple self-healing squamous epithelioma is caused by a disease-specific spectrum of mutations in TGFBR1. Nat Genet. 2011 Feb 27;43(4):365-9. doi: 10.1038/ng.780. PMID:21358634 doi:10.1038/ng.780
7. ↑ Wieser R, Wrana JL, Massague J. GS domain mutations that constitutively activate T beta R-I, the downstream signaling component in the TGF-beta receptor complex. EMBO J. 1995 May 15;14(10):2199-208. PMID:7774578
8. ↑ Eppert K, Scherer SW, Ozcelik H, Pirone R, Hoodless P, Kim H, Tsui LC, Bapat B, Gallinger S, Andrulis IL, Thomsen GH, Wrana JL, Attisano L. MADR2 maps to 18q21 and encodes a TGFbeta-regulated MAD-related protein that is functionally mutated in colorectal carcinoma. Cell. 1996 Aug 23;86(4):543-52. PMID:8752209
9. ↑ Macias-Silva M, Abdollah S, Hoodless PA, Pirone R, Attisano L, Wrana JL. MADR2 is a substrate of the TGFbeta receptor and its phosphorylation is required for nuclear accumulation and signaling. Cell. 1996 Dec 27;87(7):1215-24. PMID:8980228
10. ↑ Abdollah S, Macias-Silva M, Tsukazaki T, Hayashi H, Attisano L, Wrana JL. TbetaRI phosphorylation of Smad2 on Ser465 and Ser467 is required for Smad2-Smad4 complex formation and signaling. J Biol Chem. 1997 Oct 31;272(44):27678-85. PMID:9346908
11. ↑ Ozdamar B, Bose R, Barrios-Rodiles M, Wang HR, Zhang Y, Wrana JL. Regulation of the polarity protein Par6 by TGFbeta receptors controls epithelial cell plasticity. Science. 2005 Mar 11;307(5715):1603-9. PMID:15761148 doi:10.1126/science.1105718
12. ↑ Finnson KW, Tam BY, Liu K, Marcoux A, Lepage P, Roy S, Bizet AA, Philip A. Identification of CD109 as part of the TGF-beta receptor system in human keratinocytes. FASEB J. 2006 Jul;20(9):1525-7. Epub 2006 Jun 5. PMID:16754747 doi:fj.05-5229fje
13. ↑ Sorrentino A, Thakur N, Grimsby S, Marcusson A, von Bulow V, Schuster N, Zhang S, Heldin CH, Landstrom M. The type I TGF-beta receptor engages TRAF6 to activate TAK1 in a receptor kinase-independent manner. Nat Cell Biol. 2008 Oct;10(10):1199-207. doi: 10.1038/ncb1780. Epub 2008 Aug 31. PMID:18758450 doi:10.1038/ncb1780