PTTG's C-terminal PXXP motifs modulate critical cellular processes in vitro

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@article{9dc80885bdb0455b8492a4af4d8dd0ed,
title = "PTTG's C-terminal PXXP motifs modulate critical cellular processes in vitro",
abstract = "Human pituitary tumor-transforming gene (PTTG), known also as securin, is a multifunctional protein implicated in the control of mitosis and the pathogenesis of thyroid, colon, oesophageal and other tumour types. Critical to PTTG function is a C-terminal double PXXP motif, forming a putative SH3-interacting domain and housing the gene's sole reported phosphorylation site. The exact role of phosphorylation and PXXP structure in the modulation of PTTG action in vitro remains poorly understood. We therefore examined the mitotic, transformation, proliferation and transactivation function of the C-terminal PXXP motifs of human PTTG. Live-cell imaging studies using an EGFP-PTTG construct indicated that PTTG's regulation of mitosis is retained regardless of phosphorylation status. Colony-formation assays demonstrated that phosphorylation of PTTG may act as a potent inhibitor of cell transformation. In proliferation assays, NIH-3T3 cells stable transfected and overexpressing mutations preventing PTTG phosphorylation (Phos-) showed significantly increased [3H]thymidine incorporation compared with WT, whereas mutants mimicking constitutive phosphorylation of PTTG (Phos+) exhibited reduced cell proliferation. We demonstrated that PTTG transactivation of FGF-2 in primary thyroid and PTTG-null cell lines was not affected by PTTG phosphorylation but was prevented by a mutant disrupting the PXXP motifs (SH3-). Taken together, our data suggest that PXXP structure and phosphorylation are likely to exert independent and critical influences upon PTTG's diverse actions in vitro.",
author = "Kristien Boelaert and R Yu and Lesley Tannahill and Anna Stratford and Farhat Khanim and Margaret Eggo and Jasbir Moore and Lawrence Young and Neil Gittoes and Jayne Franklyn and S Melmed and Christopher McCabe",
year = "2004",
month = jan,
day = "1",
doi = "10.1677/jme.1.01606",
language = "English",
volume = "33",
pages = "663--677",
journal = "Journal of Molecular Endocrinology",
issn = "0952-5041",
publisher = "BioScientifica",

}

RIS

TY - JOUR

T1 - PTTG's C-terminal PXXP motifs modulate critical cellular processes in vitro

AU - Boelaert, Kristien

AU - Yu, R

AU - Tannahill, Lesley

AU - Stratford, Anna

AU - Khanim, Farhat

AU - Eggo, Margaret

AU - Moore, Jasbir

AU - Young, Lawrence

AU - Gittoes, Neil

AU - Franklyn, Jayne

AU - Melmed, S

AU - McCabe, Christopher

PY - 2004/1/1

Y1 - 2004/1/1

N2 - Human pituitary tumor-transforming gene (PTTG), known also as securin, is a multifunctional protein implicated in the control of mitosis and the pathogenesis of thyroid, colon, oesophageal and other tumour types. Critical to PTTG function is a C-terminal double PXXP motif, forming a putative SH3-interacting domain and housing the gene's sole reported phosphorylation site. The exact role of phosphorylation and PXXP structure in the modulation of PTTG action in vitro remains poorly understood. We therefore examined the mitotic, transformation, proliferation and transactivation function of the C-terminal PXXP motifs of human PTTG. Live-cell imaging studies using an EGFP-PTTG construct indicated that PTTG's regulation of mitosis is retained regardless of phosphorylation status. Colony-formation assays demonstrated that phosphorylation of PTTG may act as a potent inhibitor of cell transformation. In proliferation assays, NIH-3T3 cells stable transfected and overexpressing mutations preventing PTTG phosphorylation (Phos-) showed significantly increased [3H]thymidine incorporation compared with WT, whereas mutants mimicking constitutive phosphorylation of PTTG (Phos+) exhibited reduced cell proliferation. We demonstrated that PTTG transactivation of FGF-2 in primary thyroid and PTTG-null cell lines was not affected by PTTG phosphorylation but was prevented by a mutant disrupting the PXXP motifs (SH3-). Taken together, our data suggest that PXXP structure and phosphorylation are likely to exert independent and critical influences upon PTTG's diverse actions in vitro.

AB - Human pituitary tumor-transforming gene (PTTG), known also as securin, is a multifunctional protein implicated in the control of mitosis and the pathogenesis of thyroid, colon, oesophageal and other tumour types. Critical to PTTG function is a C-terminal double PXXP motif, forming a putative SH3-interacting domain and housing the gene's sole reported phosphorylation site. The exact role of phosphorylation and PXXP structure in the modulation of PTTG action in vitro remains poorly understood. We therefore examined the mitotic, transformation, proliferation and transactivation function of the C-terminal PXXP motifs of human PTTG. Live-cell imaging studies using an EGFP-PTTG construct indicated that PTTG's regulation of mitosis is retained regardless of phosphorylation status. Colony-formation assays demonstrated that phosphorylation of PTTG may act as a potent inhibitor of cell transformation. In proliferation assays, NIH-3T3 cells stable transfected and overexpressing mutations preventing PTTG phosphorylation (Phos-) showed significantly increased [3H]thymidine incorporation compared with WT, whereas mutants mimicking constitutive phosphorylation of PTTG (Phos+) exhibited reduced cell proliferation. We demonstrated that PTTG transactivation of FGF-2 in primary thyroid and PTTG-null cell lines was not affected by PTTG phosphorylation but was prevented by a mutant disrupting the PXXP motifs (SH3-). Taken together, our data suggest that PXXP structure and phosphorylation are likely to exert independent and critical influences upon PTTG's diverse actions in vitro.

UR - http://www.scopus.com/inward/record.url?scp=19944427069&partnerID=8YFLogxK

U2 - 10.1677/jme.1.01606

DO - 10.1677/jme.1.01606

M3 - Article

C2 - 15591026

VL - 33

SP - 663

EP - 677

JO - Journal of Molecular Endocrinology

JF - Journal of Molecular Endocrinology

SN - 0952-5041

ER -