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Transsulfuration Activity Can Support Cell Growth upon Extracellular Cysteine Limitation.
Cell Metabolism ( IF 27.7 ) Pub Date : 2019-10-10 , DOI: 10.1016/j.cmet.2019.09.009
Jiajun Zhu 1 , Mirela Berisa 2 , Simon Schwörer 1 , Weige Qin 2 , Justin R Cross 2 , Craig B Thompson 1
Affiliation  

Cysteine acts both as a building unit for protein translation and as the limiting substrate for glutathione synthesis to support the cellular antioxidant system. In addition to transporter-mediated uptake, cellular cysteine can also be synthesized from methionine through the transsulfuration pathway. Here, we investigate the regulation of transsulfuration and its role in sustaining cell proliferation upon extracellular cysteine limitation, a condition reported to occur in human tumors as they grow in size. We observed constitutive expression of transsulfuration enzymes in a subset of cancer cell lines, while in other cells, these enzymes are induced following cysteine deprivation. We show that both constitutive and inducible transsulfuration activities contribute to the cellular cysteine pool and redox homeostasis. The rate of transsulfuration is determined by the cellular capacity to conduct methylation reactions that convert S-adenosylmethionine to S-adenosylhomocysteine. Finally, our results demonstrate that transsulfuration-mediated cysteine synthesis is critical in promoting tumor growth in vivo.

中文翻译:

在细胞外半胱氨酸受限时,转硫活性可以支持细胞生长。

半胱氨酸既充当蛋白质翻译的构建单位,又充当谷胱甘肽合成的限制性底物,以支持细胞抗氧化剂系统。除了转运蛋白介导的摄取外,还可以通过转硫途径由蛋氨酸合成细胞半胱氨酸。在这里,我们研究了细胞外半胱氨酸受限后转硫的调控及其在维持细胞增殖中的作用,据报道,随着人类肿瘤的长大,这种情况会发生在人类肿瘤中。我们观察到一部分癌细胞系中转硫酶的组成性表达,而在其他细胞中,这些酶在半胱氨酸剥夺后被诱导。我们表明本构和诱导转硫活动有助于细胞半胱氨酸池和氧化还原稳态。转硫速率取决于细胞进行甲基化反应的能力,该甲基化反应可将S-腺苷甲硫氨酸转化为S-腺苷同型半胱氨酸。最后,我们的结果表明,转硫介导的半胱氨酸合成对于促进体内肿瘤生长至关重要。
更新日期:2019-11-09
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