T-box transcription factor TBX5 is a protein that in humans is encoded by the TBX5gene.[1][2][3]
This gene is a member of a phylogenetically conserved family of genes that share a common DNA-binding domain, the T-box. T-box genes encode transcription factors involved in the regulation of developmental processes. This gene is closely linked[clarification needed] to related family member T-box 3 (ulnar mammary syndrome) on human chromosome 12.
The encoded protein may play a role in heart development and specification of limb identity. Mutations in this gene have been associated with Holt-Oram syndrome, a developmental disorder affecting the heart and upper limbs. Skeletally there may be abnormally bent fingers, sloping shoulders, and phocomelia. Cardiac defects include ventral and atrial septation and problems with the conduction system.[4] Several transcript variants encoding different isoforms have been described for this gene.[3]
Clinical significance
In studies done in mutant mice without the TBX5 gene it has been shown that the homozygous mice did not survive gestation due to the heart not developing past E9.5. Also the heterozygous mice were born with morphological problems such as enlarged hearts, atrial and ventral septum defects, and limb malformations similar to those found in the Holt-Oram Syndrome.[5] Supporting the essential role of TBX5 in the heart development.
Tbx5 is a gene that is located on the long arm of chromosome 12.[8] Tbx5 produces a protein called T-box 5 that acts as a transcription factor.[9] The Tbx5 gene is involved with forelimb and heart development. This gene impacts the early development of the forelimb by triggering FGF-10 (Fibroblast Growth Factor 10).[10] Tbx5 is involved with the development of the four chambers in the heart, the electrical conducting system, and the septum separating the right and left sides of the heart.[11] A mutation in this gene can cause Holt-Oram syndrome or Amelia syndrome. Holt-Oram syndrome can cause several different defects. One effect of Holt-Oram syndrome is a hole in the septum.[12] Another symptom of this syndrome is bone abnormalities in the fingers, wrists, or arms.[13] An additional defect that Holt-Oram syndrome can cause is a conduction disease leading to abnormal heart rates and arrhythmias.[14] Amelia syndrome is a condition where forelimb malformation occurs because FGF-10 is not triggered due to Tbx5 mutations.[15] This condition can lead to the absence of one or both forelimbs.
References
↑Basson CT, Bachinsky DR, Lin RC, Levi T, Elkins JA, Soults J, Grayzel D, Kroumpouzou E, Traill TA, Leblanc-Straceski J, Renault B, Kucherlapati R, Seidman JG, Seidman CE (January 1997). "Mutations in human TBX5 [corrected] cause limb and cardiac malformation in Holt-Oram syndrome". Nat Genet. 15 (1): 30–5. doi:10.1038/ng0197-30. PMID8988165.
↑Terrett JA, Newbury-Ecob R, Cross GS, Fenton I, Raeburn JA, Young ID, Brook JD (September 1994). "Holt-Oram syndrome is a genetically heterogeneous disease with one locus mapping to human chromosome 12q". Nat Genet. 6 (4): 401–4. doi:10.1038/ng0494-401. PMID8054982.
↑Packham EA, Brook JD (2003). "T-box genes in human disorders". Hum. Mol. Genet. 12 (Spec No 1): R37–44. doi:10.1093/hmg/ddg077. PMID12668595.
↑Takeuchi JK, Ohgi M, Koshiba-Takeuchi K, Shiratori H, Sakaki I, Ogura K, Saijoh Y, Ogura T (2003). "Tbx5 specifies the left/right ventricles and ventricular septum position during cardiogenesis". Development. 130 (24): 5953–64. doi:10.1242/dev.00797. PMID14573514.
↑ 6.06.1Garg V, Kathiriya IS, Barnes R, Schluterman MK, King IN, Butler CA, Rothrock CR, Eapen RS, Hirayama-Yamada K, Joo K, Matsuoka R, Cohen JC, Srivastava D (July 2003). "GATA4 mutations cause human congenital heart defects and reveal an interaction with TBX5". Nature. 424 (6947): 443–7. doi:10.1038/nature01827. PMID12845333.
↑Hiroi Y, Kudoh S, Monzen K, Ikeda Y, Yazaki Y, Nagai R, Komuro I (July 2001). "Tbx5 associates with Nkx2-5 and synergistically promotes cardiomyocyte differentiation". Nat. Genet. 28 (3): 276–80. doi:10.1038/90123. PMID11431700.
↑Jhang, W. K.; Lee, B. H.; Kim, G.; Lee, J. & Yoo, H. "Clinical and molecular characterisation of Holt–Oram syndrome focusing on cardiac manifestations". Cardiology in the Young. 25 (6): 1093–1098. doi:10.1017/s1047951114001656.
↑Jhang, W. K.; Lee, B. H.; Kim, G.; Lee, J. & Yoo, H. "Clinical and molecular characterisation of Holt–Oram syndrome focusing on cardiac manifestations". Cardiology in the Young. 25 (6): 1093–1098. doi:10.1017/s1047951114001656.
Simon H (1999). "T-box genes and the formation of vertebrate forelimb- and hindlimb specific pattern". Cell Tissue Res. 296 (1): 57–66. doi:10.1007/s004410051266. PMID10199965.
Packham EA, Brook JD (2003). "T-box genes in human disorders". Hum. Mol. Genet. 12 (Spec No 1): R37–44. doi:10.1093/hmg/ddg077. PMID12668595.
Li QY, Newbury-Ecob RA, Terrett JA, et al. (1997). "Holt-Oram syndrome is caused by mutations in TBX5, a member of the Brachyury (T) gene family". Nat. Genet. 15 (1): 21–9. doi:10.1038/ng0197-21. PMID8988164.
He ML, Chen Y, Peng Y, et al. (2002). "Induction of apoptosis and inhibition of cell growth by developmental regulator hTBX5". Biochem. Biophys. Res. Commun. 297 (2): 185–92. doi:10.1016/S0006-291X(02)02142-3. PMID12237100.
Garg V, Kathiriya IS, Barnes R, et al. (2003). "GATA4 mutations cause human congenital heart defects and reveal an interaction with TBX5". Nature. 424 (6947): 443–7. doi:10.1038/nature01827. PMID12845333.
Huang T, Lock JE, Marshall AC, et al. (2003). "Causes of clinical diversity in human TBX5 mutations". Cold Spring Harb. Symp. Quant. Biol. 67: 115–20. doi:10.1101/sqb.2002.67.115. PMID12858531.
Collavoli A, Hatcher CJ, He J, et al. (2004). "TBX5 nuclear localization is mediated by dual cooperative intramolecular signals". J. Mol. Cell. Cardiol. 35 (10): 1191–5. doi:10.1016/S0022-2828(03)00231-1. PMID14519429.