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The p110δ isoform of PI 3‐kinase negatively controls RhoA and PTEN
Author(s) -
Papakonstanti Evangelia A,
Ridley Anne J,
Vanhaesebroeck Bart
Publication year - 2007
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7601763
Subject(s) - rhoa , pten , pi3k/akt/mtor pathway , biology , microbiology and biotechnology , protein kinase b , effector , kinase , small gtpase , cancer research , phosphorylation , signal transduction
Inactivation of PI 3‐kinase (PI3K) signalling is critical for tumour suppression by PTEN. This is thought to be a unidirectional relationship in which PTEN degrades the lipids produced by PI3K, thus controlling cell proliferation, survival and migration. We now show that this relationship is in fact bidirectional, whereby PI3K reciprocally controls PTEN. We report that the p110δ PI3K negatively regulates PTEN, through a pathway involving inhibition of RhoA. Inactivation of p110δ in macrophages led to reduced Akt and Rac1 activation, but paradoxically to increased RhoA and PTEN activity. Partial inactivation of p190RhoGAP and a reduced binding of cytoplasmic RhoA to the cyclin‐dependent kinase inhibitor p27 both contributed to the increased RhoA‐GTP levels upon p110δ inactivation. Pharmacological inhibition of ROCK, a downstream effector kinase of RhoA, restored all signalling and functional defects of p110δ inactivation, including Akt phosphorylation, chemotaxis and proliferation. This work identifies the RhoA/ROCK pathway as a major target of p110δ‐mediated PI3K signalling, and establishes for the first time that PI3K controls itself, via a feedback loop involving PTEN.