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肿瘤代谢与营养电子杂志
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端粒、一碳代谢与肌肉减少
端粒的“末端复制问题”一直是生物学家研究的重点。端粒功能失调被认为是退行性疾病风险增加的原因之一。 饮食模式和包括叶酸在内的微量营养素可以影响端粒的长度和功能。叶酸缺乏会导致端粒中尿嘧啶的增加,最终导致端粒断 裂和缩短,低水平叶酸也会导致亚端粒低甲基化从而影响端粒的长度和功能。叶酸和维生素B12缺乏时,血浆同型半胱氨酸的 浓度升高,端粒长度也会缩短。叶酸在一碳单位代谢过程中发挥重要作用,是嘌呤核苷酸、胸腺嘧啶合成及同型半胱氨酸转化 为甲硫氨酸时再甲基化过程中不可或缺的物质,以上途径中断会影响 DNA 合成及稳定性,并影响染色体甲基化,导致营养缺 乏和疾病发生,包括肌肉无力、行走困难、心血管疾病、出生缺陷、癌变等。尽管一些研究表明叶酸可能对骨骼肌的发育产生积 极影响,然而,叶酸在骨骼肌发育中的精确作用仍然不清楚。肌肉减少症导致肌肉质量和力量进行性下降,而肌肉退行性变化 引起的肌肉减少会导致端粒长度缩短。但具体机制尚需深入研究。本文通过对文献资料的综述,探讨端粒调节、一碳代谢和 肌肉减少的相互关联,旨在为科学研究提供思路。
1首都医科大学附属北京世纪坛医院胃肠外科/临床营养科,北京 100038;2首都医科大学肿瘤学系,北京 100038;3中国农业大学营养与健康系,北京 100193
Telomeres, one‑carbon metabolism and sarcopenia
"Terminal replication" of telomeres has been the focus of biologists. Telomere dysfunction is believed to be one of the causes for the increased risk of degenerative diseases. Dietary patterns and micronutrients, including folic acid can affect telomere length and function. Dietary patterns and micronutrients, including folic acid, can affect telomere length and function. When folic acid and B12 are deficient, the homocysteine in plasma will increase and the telomere length will shorten as well, Folic acid deficiency leads to the increase of uracil in telomeres, which eventually results in telomere breakage and shortening. Low level of folic acid also leads to sub?telomere hypomethylation, which affects the length and function of telomeres. Folic acid plays an important role in the metabolism of one carbon unit. It is an indispensable substance in the synthesis of purine nucleotides, thymine and the remethylation of homocysteine into methionine. The interruption of these pathways will affect DNA synthesis and stability, and affect chromosome methylation, which lead to malnutrition and disease, including muscle weakness, walking difficulties, cardiovascular disease, birth defects, cancer, etc. Some studies have shown that folic acid may have a positive effect on the development of skeletal muscle development. However, the precise role of folic acid in skeletal muscle development is still unclear. Sarcopenia results in the reduction of muscle mass and strength progressively and caused by muscle degeneration shortens telomere length. Sarcopenia leads to the shortening of telomere length, but the specific mechanism needs to be further explored. In this review, the correlation among telomere regulation, one carbon metabolism and muscle loss are discussed to provide ideas for scientific research.ion, one carbon metabolism and muscle loss are discussed to provide ideas for scientific research.
1 Department of Gastrointestinal Surgery/Clinical Nutrition, Beijing Shijitan Hospital, Capital Medical University, Beijing 100038, China; 2Department of Oncology, Capital Medical University, Beijing 100038, China; 3Department of Nutrition and Health, China Agriculture University, Beijing 100193, China