カエルが私たちの腸について教えてくれること(What Frogs Can Tell Us About Our Intestines)

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2024-02-22 ノースカロライナ州立大学(NCState)

人間の腸は約15フィートありますが、そのほとんどは身長が6フィート以下の人でも収まります。これは、胚発生中に腸がループして回転することで可能になります。しかし、このプロセスがうまくいかない場合があり、その理由はまだわかっていません。発生生物学者のNanette Nascone-Yoderは、腸の回転異常のモデルとしてカエルを研究しており、最新の研究成果を紹介しました。

<関連情報>

腸の伸長と回転には細胞代謝の発生制御が必要であることを発見 Developmental regulation of cellular metabolism is required for intestinal elongation and rotation

Julia K. Grzymkowski,Yu-Chun Chiu,Dereje D. Jima,Brent H. Wyatt,Sudhish Jayachandran,Whitney L. Stutts,Nanette M. Nascone-Yoder
Development  19 February 2024
DOI:https://doi.org/10.1242/dev.202020

Exposure to atrazine causes intestinal shortening and malrotation. (A,C) Schematics illustrating normal counterclockwise (CCW) intestine rotation in wild-type (WT) Xenopus embryos (A), and the abnormal clockwise (CW) malrotation seen in ATR-exposed embryos (C). The midgut (future intestine) is yellow. Red (WT) and blue (ATR) arrowheads indicate the intestinal apex (NF 44, establishes the initial direction of rotation), and red (WT) and blue (ATR) spirals illustrate the final rotation direction of the intestinal coil (NF 46). (B,D) In situ stereo-microscope images of DMSO or ATR-treated NF 46 intestines (ventral view). DMSO control embryos develop elongated intestines that rotate normally (B), whereas ATR-exposed embryos develop intestine coils that are both short and malrotated (D). (E) The frequency of abnormal gut phenotypes increases with increasing concentrations of ATR, from predominantly normal (norm.) length (2+ intestine loops) and CCW rotation (rot.) to increasingly short (1.5 or fewer intestine loops) and/or CW malrotated (malrot.) configurations.

ABSTRACT

Malrotation of the intestine is a prevalent birth anomaly, the etiology of which remains poorly understood. Here, we show that late-stage exposure of Xenopus embryos to atrazine, a widely used herbicide that targets electron transport chain (ETC) reactions, elicits intestinal malrotation at high frequency. Interestingly, atrazine specifically inhibits the cellular morphogenetic events required for gut tube elongation, including cell rearrangement, differentiation and proliferation; insufficient gut lengthening consequently reorients the direction of intestine rotation. Transcriptome analyses of atrazine-exposed intestines reveal misexpression of genes associated with glycolysis and oxidative stress, and metabolomics shows that atrazine depletes key glycolytic and tricarboxylic acid cycle metabolites. Moreover, cellular bioenergetics assays indicate that atrazine blocks a crucial developmental transition from glycolytic ATP production toward oxidative phosphorylation. Atrazine-induced defects are phenocopied by rotenone, a known ETC Complex I inhibitor, accompanied by elevated reactive oxygen species, and rescued by antioxidant supplementation, suggesting that malrotation may be at least partly attributable to redox imbalance. These studies reveal roles for metabolism in gut morphogenesis and implicate defective gut tube elongation and/or metabolic perturbations in the etiology of intestinal malrotation.

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生物化学工学
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