Xbra

Xbra is a homologue of Brachyury (T) gene for Xenopus.[1] It is a transcription activator involved in vertebrate gastrulation which controls posterior mesoderm patterning and notochord differentiation by activating transcription of genes expressed throughout mesoderm.[2] The effects of Xbra is concentration dependent where concentration gradient controls the development of specific types of mesoderm in Xenopus. Xbra results of the expression of the FGF transcription factor, synthesized by the ventral endoderm. So while ventral mesoderm is characterized by a high concentration of FGF and Xbra, the dorsal mesoderm is characterized by a reunion of two others transcription factors, Siamois and XnR, which activates the synthesis of Goosecoid Transcription Factor. Goosecoid enables the depletion of Xbra. In a nutshell, high concentrations of Xbra induce ventral mesoderm while low concentration stimulates the formation of a back.[2]

Posterior mesoderm development presents two types of cell behaviors, cell migration and convergent extension, in prechordal mesoderm and chordamesoderm cells, respectively.[3] Cell migration is exhibited by the prechordal mesoderm cells, resulting in the formation of the future anterior end.[3] Xbra induces convergent extension which inhibits cell migration and rearranges the chordamesoderm cells into a structure that will later differentiate into notochord.[3] As a result, Xbra acts as a switch to convert between these two behaviors.[3]

Xbra is able to activate itself indirectly, specifically for dorsal mesoderm, through FGF signaling while eFGF maintains Xbra expression, creating an autoregulatory loop.[4]

Inhibition of Xbra leads to abnormal patterning of mesoderm, such as shortened trunk.[3] In a previous study, the activation domain of Xbra was replaced by repressor domain of Drosophila engrailed protein in order to form a dominant-interfering Xbra construct that would help to study the function and regulation of Xbra.[5] The injection of RNA encoding this construct has led to various birth defects such as defective blastopore closure and abnormal notochord differentiation in the developing embryo.[5]  

References

  1. ^ Saka, Y; Tada, M; Smith, JC (2000). "A screen for targets of the Xenopus T-box gene Xbra". Mechanisms of Development. 93 (1–2): 27–39. doi:10.1016/S0925-4773(00)00260-4. PMID 10781937. S2CID 9583196.
  2. ^ a b Tada, M; O’Reilly, MAJ; Smith, JC (June 1997). "Analysis of competence and of Brachyury autoinduction by use of hormone-inducible Xbra". Development. 124 (11): 2225–34. doi:10.1242/dev.124.11.2225. PMID 9187148.
  3. ^ a b c d e Kwan, Kirsten M; Kirschner, Marc W (May 1, 2003). "Xbra functions as a switch between cell migration and convergent extension in Xenopus gastrula". Development. 130 (9): 1961–1972. doi:10.1242/dev.00412. PMID 12642499. S2CID 41485337. Retrieved April 22, 2014.
  4. ^ Fletcher, Russell B; Harland, Richard M (May 2008). "The Role of FGF Signaling in the Establishment and Maintenance of Mesodermal Gene Expression in Xenopus". Developmental Dynamics. 237 (5): 1243–54. doi:10.1002/dvdy.21517. PMC 3000043. PMID 18386826.
  5. ^ a b Conlon, FL; Sedgwick, SG; Weston, KM; Smith, JC (1996). "Inhibition of Xbra transcription activation causes defects in mesodermal patterning and reveals autoregulation of Xbra in dorsal mesoderm" (PDF). Development. 122 (8): 2427–35. doi:10.1242/dev.122.8.2427. PMID 8756288. Retrieved April 22, 2014.

Content Disclaimer

Informasi ini disarikan dari Wikipedia dan disajikan kembali untuk tujuan edukasi. Konten tersedia di bawah lisensi CC BY-SA 3.0. Kami tidak bertanggung jawab atas ketidakakuratan data yang bersumber dari kontribusi publik tersebut.

  1. The information displayed on this website is sourced in part or in whole from Wikipedia and has been adapted for the purpose of restating it. We strive to provide accurate and relevant information, however:
  2. There is no guarantee of absolute accuracy. Wikipedia is an open, collaborative project that can be edited by anyone, so information is subject to change.
  3. It is not intended to constitute professional advice. The content displayed is for informational and educational purposes only. For important decisions (e.g., medical, legal, or financial), please consult a professional.
  4. Content copyright. Wikipedia is licensed under the Creative Commons Attribution-ShareAlike License (CC BY-SA). This means that content may be reused with appropriate attribution and shared under a similar license.
  5. Responsible use. Any risk arising from the use of information from this website is entirely the responsibility of the user.