Functional evaluation of PTEN missense mutations using in vitro phosphoinositide phosphatase assay

Shuang Yin Han, Hideaki Kato, Shunsuke Kato, Takao Suzuki, Hiroyuki Shibata, Seiichi Ishii, Ken Ichi Shiiba, Seiki Matsuno, Ryunosuke Kanamaru, Chikashi Ishioka

研究成果: Article査読

121 被引用数 (Scopus)

抄録

The tumor suppressor gene PTEN is frequently mutated in diverse human cancers and in autosomal dominant cancer predisposition disorders. Recent studies have shown that the lipid phosphatase activity of PTEN is critical for its tumor suppressor function and that PTEN negatively regulates the phosphatidylinositol 3'-kinase-protein kinase B pathway. Although more than half of PTEN mutations result in protein truncation, a significant fraction of PTEN mutations are missense mutations. To examine whether tumor-derived and germ-line-derived missense mutations inactivate PTEN lipid phosphatase function, we constructed 42 distinct types of PTEN missense mutations and expressed them in Escherichia coli. The purified (His)6-tagged PTEN proteins were tested for their ability to dephosphorylate inositol 1,3,4,5- tetrakisphosphate and phosphatidylinositol 3,4,5-triphosphate. In addition, we examined the effect of mutant PTENs on the ability of PTEN to bind to the phospholipid membrane. The results revealed that the majority of PTEN missense mutations [38 of 42 (90%)] eliminated or reduced phosphatase activity and that all of the mutations examined had no effect on the membrane binding activity of PTEN. Our study indicated that phosphoinositide phosphatase activity is important for the tumor suppressor function of PTEN and that there may be other mechanisms of PTEN inactivation that are not monitored by in vitro phosphatase assay and in vitro membrane binding assay.

本文言語English
ページ(範囲)3147-3151
ページ数5
ジャーナルCancer Research
60
12
出版ステータスPublished - 2000 6 15

ASJC Scopus subject areas

  • 腫瘍学
  • 癌研究

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