SNAT2 transceptor signalling via mTOR: a role in cell growth and proliferation?

TY - JOUR

T1 - SNAT2 transceptor signalling via mTOR

T2 - a role in cell growth and proliferation?

AU - Pinilla, Jorge

AU - Aledo, Juan Carlos

AU - Cwiklinski, Emma

AU - Hyde, Russell

AU - Taylor, Peter M.

AU - Hundal, Harinder S.

N1 - MEDLINE® is the source for the citation and abstract of this record.

PY - 2011/6/1

Y1 - 2011/6/1

N2 - 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.

AB - 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.

KW - Amino acid transporter

KW - SLC38A2 protein

KW - Cell division

KW - Cell proliferation

KW - Human

KW - Metabolism

KW - Polyacrylamide gel electrophoresis

KW - Signal transduction

KW - Tumor cell line

KW - Western blotting

UR - https://www.scopus.com/pages/publications/80053614972

U2 - 10.2741/332

DO - 10.2741/332

M3 - Article

AN - SCOPUS:80053614972

SN - 1945-0494

VL - E3

SP - 1289

EP - 1299

JO - Frontiers in Bioscience-Elite

JF - Frontiers in Bioscience-Elite

IS - 4

ER -