Molecular balance between the regulatory and catalytic subunits of phosphoinositide 3-kinase regulates cell signaling and survival Academic Article uri icon


MeSH Major

  • Phosphatidylinositol 3-Kinases


  • Class Ia phosphoinositide (PI) 3-kinase is a central component in growth factor signaling and is comprised of a p110 catalytic subunit and a regulatory subunit, the most common family of which is derived from the p85alpha gene (Pik3r1). Optimal signaling through the PI 3-kinase pathway depends on a critical molecular balance between the regulatory and catalytic subunits. In wild-type cells, the p85 subunit is more abundant than p110, leading to competition between the p85 monomer and the p85-p110 dimer and ineffective signaling. Heterozygous disruption of Pik3r1 results in increased Akt activity and decreased apoptosis by insulin-like growth factor 1 (IGF-1) through up-regulated phosphatidylinositol (3,4,5)-triphosphate production. Complete depletion of p85alpha, on the other hand, results in significantly increased apoptosis due to reduced PI 3-kinase-dependent signaling. Thus, a reduction in p85alpha represents a novel therapeutic target for enhancing IGF-1/insulin signaling, prolongation of cell survival, and protection against apoptosis.

publication date

  • January 21, 2002



  • Academic Article



  • eng

PubMed Central ID

  • PMC133541

PubMed ID

  • 11784871

Additional Document Info

start page

  • 965

end page

  • 77


  • 22


  • 3