Cystathionine is a novel substrate of cystine/glutamate transporter: Implications for immune function implications for immune function

Sho Kobayashi, Mami Sato, Takayuki Kasakoshi, Takumi Tsutsui, Masahiro Sugimoto, Mitsuhiko Osaki, Futoshi Okada, Kiharu Igarashi, Jun Hiratake, Takujiro Homma, Marcus Conrad, Junichi Fujii, Tomoyoshi Soga, Shiro Bannai, Hideyo Sato

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

The cystine/glutamate transporter, designated as system xc-, is important for maintaining intracellular glutathione levels and extracellular redox balance. The substrate-specific component of system xc-, xCT, is strongly induced by various stimuli, including oxidative stress, whereas it is constitutively expressed only in specific brain regions and immune tissues, such as the thymus and spleen. Although cystine and glutamate are the well established substrates of system xc- and the knockout of xCT leads to alterations of extracellular redox balance, nothing is known about other potential substrates. We thus performed a comparative metabolite analysis of tissues from xCT-deficient and wild-type mice using capillary electrophoresis time-of-flight mass spectrometry. Although most of the analyzed metabolites did not show significant alterations between xCT-deficient and wild-type mice, cystathionine emerged as being absent specifically in the thymus and spleen of xCT-deficient mice. No expression of either cystathionine β-synthase or cystathionine γ-lyase was observed in the thymus and spleen of mice. In embryonic fibroblasts derived from wild-type embryos, cystine uptake was significantly inhibited by cystathionine in a concentration-dependent manner. Wild-type cells showed an intracellular accumulation of cystathionine when incubated in cystathionine-containing buffer, which concomitantly stimulated an increased release of glutamate into the extracellular space. By contrast, none of these effects could be observed in xCT-deficient cells. Remarkably, unlike knock-out cells, wild-type cells could be rescued from cystine deprivation-induced cell death by cystathionine supplementation.Wethus conclude that cystathionine is a novel physiological substrate of system xc- and that the accumulation of cystathionine in immune tissues is exclusively mediated by system xc-.

Original languageEnglish
Pages (from-to)8778-8788
Number of pages11
JournalJournal of Biological Chemistry
Volume290
Issue number14
DOIs
Publication statusPublished - 2015 Apr 3

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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    Kobayashi, S., Sato, M., Kasakoshi, T., Tsutsui, T., Sugimoto, M., Osaki, M., Okada, F., Igarashi, K., Hiratake, J., Homma, T., Conrad, M., Fujii, J., Soga, T., Bannai, S., & Sato, H. (2015). Cystathionine is a novel substrate of cystine/glutamate transporter: Implications for immune function implications for immune function. Journal of Biological Chemistry, 290(14), 8778-8788. https://doi.org/10.1074/jbc.M114.625053