Brachuryとは？ブラキューリ？

カエルでの発現パターン

Comparison of Xbra reporter gene expression with that of the endogenous gene. (A) Time course of Xbra-2.1 expression compared with that of endogenous Xbra. Dorsal is upwards in all panels, except wild-type stage 9.5 (dorsal to the right). The colour reaction to detect reporter gene expression took 24 to 48 hours compared with 5 hours to detect endogenous Xbra. Reporter gene expression was restricted to the marginal zone in approximately 80% (n>150) of transgenic embryos. (B) Expression of endogenous Xbra RNA at stage 9.0. Left panel: animal pole view; right panel: side view. Embryos were cleared to visualise internal staining. Nuclear staining indicates newly transcribed zygotic RNA. Non-transgenic embryos stained for GFP RNA for the same time showed no expression (not shown). Weaker staining in the vegetal pole may be due to poor probe diffusion, but see the sectioned in situ hybridisations of Panitz et al. (1998). (C) GFP fluorescence of an embryo transgenic for Xbra-4.1. Note slightly weaker expression in the dorsal marginal zone (top right).

15 June 2000 Region-specific activation of the Xenopus Brachyury promoter involves active repression in ectoderm and endoderm: a study using transgenic frog embryos Walter Lerchner, Branko V. Latinkic, Jacques E. Remacle, Danny Huylebroeck, James C. Smit

Brachyury Knockdown Phenotype in Xenopus

Brachyury (Xbra) is a crucial gene involved in mesoderm formation and notochord differentiation in vertebrates, including Xenopus. The following synthesis presents the key findings from multiple research papers on the phenotype observed when Brachyury is knocked down in Xenopus.

Key Insights

  • Failure in Gastrulation Movements:
    • Knockdown of Brachyury in Xenopus embryos results in the failure to complete gastrulation due to the loss of convergent extension movements, which are essential for proper morphogenetic movements .
  • Down-Regulation of Downstream Genes:
    • Brachyury knockdown leads to the down-regulation of its downstream genes, including Xwnt11, which is crucial for regulating gastrulation movements via the Dishevelled pathway, but not through the canonical Wnt pathway .
  • Morphological Defects:
    • Both genetic knockout (KO) and morpholino-mediated knockdown (KD) of Brachyury in Xenopus result in virtually identical morphological defects, indicating the critical role of Brachyury in early development.
  • Off-Target Effects and Immune Response:
    • Morpholino-mediated knockdown of Brachyury can induce off-target splicing defects and a systemic immune response, which can be mitigated but not entirely eliminated by optimizing morpholino dosage and incubation conditions.

Conclusion

Knockdown of Brachyury in Xenopus leads to significant developmental issues, primarily characterized by the failure of gastrulation movements due to disrupted convergent extension. This is accompanied by the down-regulation of key downstream genes like Xwnt11. While both genetic knockout and morpholino-mediated knockdown produce similar morphological defects, the latter can also cause off-target effects and immune responses. These findings underscore the essential role of Brachyury in early vertebrate development and the complexities involved in gene knockdown studies.

(consensus.ai)

  1. Highly conserved functions of the Brachyury gene on morphogenetic movements: insight from the early-diverging phylum Ctenophora. アフリカツメガエルの胚における Brachyury のノックダウンは、収束伸展運動の喪失により胚葉形成の完了に失敗する結果となる。Developmental biology A. Yamada et al. 49 Citations 2010
  2. Innate Immune Response and Off-Target Mis-splicing Are Common Morpholino-Induced Side Effects in Xenopus 対照または標的 MO を注入された胚は、全身の GC 含有量依存性免疫応答と多くのオフターゲットスプライシング欠陥を示します。 Developmental Cell George E. Gentsch et al. 41 Citations 2018
  3. Xwnt11 is a target of Xenopus Brachyury: regulation of gastrulation movements via Dishevelled, but not through the canonical Wnt pathway. Xbra の転写活性化の妨害は、胚葉形成中の形態形成運動の阻害につながります。 Development M. Tada et al. 742 Citations 2000
  4. Cooperative non-cell and cell autonomous regulation of Nodal gene expression and signaling by Lefty/Antivin and Brachyury in Xenopus. アフリカツメガエルにおけるブラキュリ媒介転写抑制は、オーガナイザーおよび中内胚葉組織のさらなる拡大につながり、背側の特異性に影響を及ぼします。 Developmental biology Y. R. Cha et al. 33 Citations 2006
  5. The Brachyury gene encodes a novel DNA binding protein. Brachyury 変異胚は中胚葉形成が不十分で、体軸の発達が完了せず、脊索が最も影響を受けます。 The EMBO Journal A. Kispert et al. 364 Citations 1993
  6. In vivo knockdown of Brachyury results in skeletal defects and urorectal malformations resembling caudal regression syndrome. Brachyury の体内でのノックダウンは、胎児の尾部退縮症候群に似た骨格異常および尿直腸奇形を引き起こします。 Developmental biology T. Pennimpede et al. 50 Citations 2012
  7. Goosecoid and mix.1 repress Brachyury expression and are required for head formation in Xenopus. goosecoid または mix.1 の機能が阻害されると、Xbra が一時的に異所的に発現し、背前部異常や心臓および腸管の形成異常が生じます。 Development Branko V. Latinkić et al. 116 Citations 1999
  8. Expression of a xenopus homolog of Brachyury (T) is an immediate-early response to mesoderm induction Brachyury のアフリカツメガエル相同遺伝子である Xbra は、胚葉口周囲の予定中胚葉細胞で発現し、その後脊索で発現します。 Cell James C. Smith et al. 1,030 Citations 1991 本文有料