SNAT2 transceptor signalling via mTOR: a role in cell growth and proliferation?
SNAT2 transceptor signalling via mTOR: a role in cell growth and proliferation?
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DOI：
10.2741/e332
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
Jorge Pinilla;J. Aledo;Emma Cwiklinski;R. Hyde;P. Taylor;H. Hundal
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作者：
Jorge Pinilla;J. Aledo;Emma Cwiklinski;R. Hyde;P. Taylor;H. Hundal
我们研究了通过与饱和剂量的不可代谢的系统 A 氨基酸类似物 (Me-AIB) 孵育诱导的 SNAT2 (系统 A) 氨基酸 (AA) 运输的慢性竞争性抑制对完全培养基中 MCF-7 人乳腺癌细胞生长和增殖的影响。这些细胞表达 Na+ 和 pH 依赖性 SNAT2 AA 转运，饱和浓度的 Me-AIB (10 mM) 通过 SNAT2 竞争性抑制 (>90%) AA 摄取。与 Me-AIB 一起孵育长达 5 天逐渐减少细胞增殖（约 2 倍），并且不仅减少了 SNAT2 AA 底物的细胞内浓度，还减少了必需支链 AA（例如亮氨酸）的浓度。令人惊讶的是，总细胞蛋白得以维持，并且经过长期 Me-AIB 孵育的细胞表现出可检测到的细胞大小增加。 mTOR 信号传导分析表明，尽管细胞内 AA 池的大小大幅减少，Me-AIB 仍升高了 mTOR 依赖性 p70S6K1 磷酸化。 TAP 标签纯化的 SNAT2 融合蛋白的蛋白质组学分析发现了两种新型 SNAT2 相互作用蛋白，它们可能与 SNAT2 受体结合发挥作用，调节影响蛋白质周转和细胞生长的信号通路。
We have investigated the effect of chronic competitive inhibition of SNAT2 (System A) amino acid (AA) transport, induced by incubation with a saturating dose of a non-metabolisable System A amino acid analogue (Me-AIB), on growth and proliferation of MCF-7 human breast cancer cells in complete culture medium. These cells express Na+- and pH-dependent SNAT2 AA transport and a saturating concentration of Me-AIB (10 mM) competitively inhibits (>90%) AA uptake via SNAT2. Incubation with Me-AIB for up to 5 days progressively reduced cell proliferation (~2-fold) and depleted intracellular concentrations of not only SNAT2 AA substrates but of essential branched chain AAs (e.g. leucine). Surprisingly, total cellular protein was maintained and cells subjected to chronic Me-AIB incubation exhibited a detectable increase in cell size. Analysis of mTOR signalling revealed that, despite a substantial reduction in size of the intracellular AA pool, Me-AIB elevated mTOR-dependent p70S6K1 phosphorylation. Proteomic analysis of TAP-tag purified SNAT2 fusion proteins identified two novel SNAT2-interacting proteins that may potentially function in conjunction with the SNAT2 transceptor to regulate signalling pathways influencing protein turnover and cell growth.