PTEN regulation, a novel function for the p85 subunit of phosphoinositide 3-kinase.

Abstract

Timely regulation of phosphatidylinositol-3,4-bisphosphate [PI(3,4)P2] and phosphatidylinositol-3,4,5-trisphosphate [PI(3,4,5)P3] abundance in cells is essential for the control of cellular homeostasis. The concentrations of these lipids are low in quiescent cells but rapidly and transiently increase following growth factor receptor (GFR) stimulation, which triggers cellular metabolic changes, proliferation, survival, and motility. Class I(A) phosphatidylinositol 3-kinase (PI3K), which is composed of a p85 (regulatory) and p110 (catalytic) subunits, is the enzyme generating PI(3,4)P2 and PI(3,4,5)P3 following GFR stimulation. Although the steps in GFR-induced activation of PI3K , are relatively well known, the mechanisms for subsequent 3-polyphospho-PI down-regulation are less understood. Examination of frequent genetic alterations in human cancer showed that PTEN (phosphatase with tensin homology on chromosome 10) is the major enzyme that decreases PI(3,4)P2 and PI(3,4,5)P3 cell content. Nonetheless, interpretation of the complexity of PTEN regulation remains a matter of debate. The recent description of diminished PTEN activity in liver-conditional knockout mice lacking the p85alpha PI3K regulatory subunit reveals a previously unknown p85alpha-dependent negative-feedback pathway that controls PI(3,4)P2 and PI(3,4,5)P3 half-life by regulating PTEN.

• Authors: Domingo F Barber, Maria Alvarado-Kristensson, Ana González-García, Rafael Pulido, Ana C Carrera
• Journal: Science's STKE : signal transduction knowledge environment (Sci STKE) Vol. 2006 Issue 362 Pg. pe49 (Nov 21 2006) ISSN: 1525-8882 [Electronic] United States
• PMID: 17119157 (Publication Type: Journal Article)

Chemical References

• IRS1 protein, human
• IRS2 protein, human
• Insulin
• Insulin Receptor Substrate Proteins
• Intracellular Signaling Peptides and Proteins
• Irs1 protein, mouse
• Irs2 protein, mouse
• Phosphatidylinositol Phosphates
• Phosphoproteins
• Protein Subunits
• phosphatidylinositol 3,4,5-triphosphate
• phosphatidylinositol 3,4-diphosphate
• Phosphatidylinositol 3-Kinases
• Receptor, Insulin
• Proto-Oncogene Proteins c-akt
• PTEN Phosphohydrolase
• Glucose

Topics

• Acetylation
• Animals
• Diabetes Mellitus (metabolism)
• Glucose (metabolism)
• Humans
• Insulin (metabolism)
• Insulin Receptor Substrate Proteins
• Intracellular Signaling Peptides and Proteins (metabolism)
• Liver (metabolism)
• Oxidation-Reduction
• PTEN Phosphohydrolase (genetics, metabolism)
• Phosphatidylinositol 3-Kinases (metabolism)
• Phosphatidylinositol Phosphates (metabolism)
• Phosphoproteins (metabolism)
• Protein Processing, Post-Translational
• Protein Subunits
• Proto-Oncogene Proteins c-akt (metabolism)
• Receptor, Insulin (metabolism)
• Signal Transduction
• Transcription, Genetic