Regulation of PTEN stability and activity

Regulation of PTEN stability and activity PTEN protein stability is regulated by ubiquitin ligases, such as NEDD4, WWP2, STUB1 (CHIP), XIAP, MKRN1 and RNF146, which polyubiquitinate PTEN in response to different stimuli and thus target it for proteasome-mediated degradation (Wang et al. 2007, Van Themsche et al. 2009, Maddika et al. 2011, Ahmed et al. 2012, Lee et al. 2015, Li et al. 2015). Several ubiquitin proteases, such as USP13 and OTUD3, can remove polyubiquitin chains from PTEN and rescue it from degradation (Zhang et al. 2013, Yuan et al. 2015). TRIM27 (RFP) is an E3 ubiquitin ligase that polyubiquitinates PTEN on multiple lysines in the C2 domain of PTEN using K27 linkage between ubiquitin molecules. TRIM27 mediated ubiquitination inhibits PTEN lipid phosphatase activity, but does not affect PTEN protein localization or stability (Lee et al. 2013).
PTEN phosphorylation by the tyrosine kinase FRK (RAK) inhibits NEDD4 mediated polyubiquitination and subsequent degradation of PTEN, thus increasing PTEN half life. FRK mediated phosphorylation also increases PTEN enzymatic activity (Yim et al. 2009). Casein kinase 2 (CK2) mediated phosphorylation of the C-terminus of PTEN on multiple serine and threonine residues increases PTEN protein stability (Torres and Pulido 2001) but results in ~30% reduction in PTEN lipid phosphatase activity (Miller et al. 2002).
PREX2, a RAC1 guanine nucleotide exchange factor (GEF) can binds to PTEN and inhibit its catalytic activity (Fine et al. 2009).