Bito Tomohiro, Okamoto Naho, Otsuka Kenji, Yabuta Yukinori, Arima Jiro, Kawano Tsuyoshi, Watanabe Fumio
Department of Agricultural, Life and Environmental Sciences, Faculty of Agriculture, Tottori University, Tottori 680-8553, Japan.
The United Graduate School of Agricultural Sciences, Tottori University, Tottori 680-8553, Japan.
Metabolites. 2019 Sep 19;9(9):192. doi: 10.3390/metabo9090192.
Vitamin B deficiency leads to various symptoms such as neuropathy, growth retardation, and infertility. Vitamin B functions as a coenzyme for two enzymes involved in amino acid metabolisms. However, there is limited information available on whether amino acid disorders caused by vitamin B deficiency induce such symptoms. First, free amino acid levels were determined in vitamin B-deficient to clarify the mechanisms underlying the symptoms caused by vitamin B deficiency. Various amino acids (valine, leucine, isoleucine, methionine, and cystathionine, among others) metabolized by vitamin B-dependent enzymes were found to be significantly changed during conditions of B deficiency, which indirectly affected certain amino acids metabolized by vitamin B-independent enzymes. For example, ornithine was significantly increased during vitamin B deficiency, which also significantly increased arginase activity. The accumulation of ornithine during vitamin B deficiency constitutes the first report. In addition, the biosynthesis of spermidine from ornithine was significantly decreased during vitamin B deficiency, likely due to the reduction of -adenosylmethionine as a substrate for -adenosylmethionine decarboxylase, which catalyzes the formation of spermidine. Moreover, vitamin B deficiency also demonstrated a significant reduction in worm lifespan, which was partially recovered by the addition of spermidine. Collectively, our findings suggest that decreased spermidine is one factor responsible for reduced lifespan in vitamin B-deficient worms.
维生素B缺乏会导致多种症状，如神经病变、生长发育迟缓及不育。维生素B作为参与氨基酸代谢的两种酶的辅酶发挥作用。然而，关于维生素B缺乏引起的氨基酸紊乱是否会引发此类症状，目前可用信息有限。首先，测定了维生素B缺乏情况下的游离氨基酸水平，以阐明维生素B缺乏所致症状的潜在机制。发现在维生素B缺乏期间，多种由维生素B依赖酶代谢的氨基酸（如缬氨酸、亮氨酸、异亮氨酸、蛋氨酸和胱硫醚等）发生了显著变化，这间接影响了某些由维生素B非依赖酶代谢的氨基酸。例如，在维生素B缺乏期间鸟氨酸显著增加，这也显著提高了精氨酸酶活性。维生素B缺乏期间鸟氨酸的积累尚属首次报道。此外，在维生素B缺乏期间，由鸟氨酸合成亚精胺的过程显著减少，这可能是由于作为腺苷甲硫氨酸脱羧酶底物的S-腺苷甲硫氨酸减少，该酶催化亚精胺的形成。此外，维生素B缺乏还导致蠕虫寿命显著缩短，添加亚精胺后可部分恢复。总体而言，我们的研究结果表明，亚精胺减少是维生素B缺乏蠕虫寿命缩短的一个原因。
