Glycobiology Advance Access published online on March 30, 2007
Glycobiology, doi:10.1093/glycob/cwm037
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Mgat5 and Pten interact to regulate cell growth and polarity
1 Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Ave. R988, Toronto, ON, Canada M5G 1X5
2 Department of Molecular and Medical Genetics, University of Toronto
3 Department of Laboratory Medicine and Pathology, University of Toronto
Phone: 416-586-8233, FAX: 416-586-8588. Email: Dennis{at}mshri.on.ca
Received on January 23, 2007; revised on March 15, 2007; accepted on March 20, 2007
Phosphatase and tensin homologue (Pten) phosphatase opposes intracellular PI3K/Akt signaling and is a potent tumor suppressor, while Golgi ß1,6N-acetylglucosaminyltransferase V (Mgat5) is positively associated with cancer progression and metastasis. ß1,6GlcNAc-branched N-glycans on receptor glycoproteins promote their surface residency and sensitizes cells to growth factor signaling. Here we demonstrate that Pten heterozygosity in mouse embryonic fibroblasts (MEFs) enhances cell adhesion-dependent PI3K/Akt signaling, cell spreading and proliferation, while Pten/Mgat5 double mutant cells are normalized. However, planar asymmetry typical of fibroblasts and invasive carcinomas is not fully rescued suggesting that Mgat5 and Pten function together to regulate the membrane dynamics of PI3K/Akt signaling typical of motile cells. Pten heterozygosity was associated with increased surface ß1,6GlcNAc-branched N-glycans suggesting positive feedback from PI3K signaling to N-glycan branching. In vivo, Mgat5–/–Pten+/– and Mgat5+/–Pten+/– mutant mice showed a small but significant increase in longevity compared to Pten+/– mice. Taken together, our results reveal that Mgat5 and Pten interact in an opposing manner to regulate cellular sensitivities to extracelluar growth cues.
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