PTEN Regulation (Homo sapiens)
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Transcription of the PTEN gene is regulated at multiple levels. Epigenetic repression involves the recruitment of Mi-2/NuRD upon SALL4 binding to the PTEN promoter (Yang et al. 2008, Lu et al. 2009) or EVI1-mediated recruitment of the polycomb repressor complex (PRC) to the PTEN promoter (Song et al. 2009, Yoshimi et al. 2011). Transcriptional regulation is also elicited by negative regulators, including NR2E1:ATN1 (atrophin-1) complex, JUN (c-Jun), SNAIL and SLUG (Zhang et al. 2006, Vasudevan et al. 2007, Escriva et al. 2008, Uygur et al. 2015) and positive regulators such as TP53 (p53), MAF1, ATF2, EGR1 or PPARG (Stambolic et al. 2001, Virolle et al. 2001, Patel et al. 2001, Shen et al. 2006, Li et al. 2016).<p>MicroRNAs miR-26A1, miR-26A2, miR-22, miR-25, miR-302, miR-214, miR-17-5p, miR-19 and miR-205 bind PTEN mRNA and inhibit its translation into protein. These microRNAs are altered in cancer and can account for changes in PTEN levels (Meng et al. 2007, Xiao et al. 2008, Yang et al. 2008, Huse et al. 2009, Kim et al. 2010, Poliseno, Salmena, Riccardi et al. 2010, Cai et al. 2013). In addition, coding and non-coding RNAs can prevent microRNAs from binding to PTEN mRNA. These RNAs are termed competing endogenous RNAs or ceRNAs. Transcripts of the pseudogene PTENP1 and mRNAs transcribed from SERINC1, VAPA and CNOT6L genes exhibit this activity (Poliseno, Salmena, Zhang et al. 2010, Tay et al. 2011, Tay et al. 2014).<p>PTEN can translocate from the cytosol to the nucleus after undergoing monoubiquitination. PTEN's ability to localize to the nucleus contributes to its tumor suppressive role (Trotman et al. 2007). The ubiquitin protease USP7 (HAUSP) targets monoubiquitinated PTEN in the nucleus, resulting in PTEN deubiquitination and nuclear exclusion. PML, via an unknown mechanism that involves USP7- and PML-interacting protein DAXX, inhibits USP7-mediated deubiquitination of PTEN, thus promoting PTEN nuclear localization. Disruption of PML function in acute promyelocytic leukemia, through a chromosomal translocation that results in expression of a fusion protein PML-RARA, leads to aberrant PTEN localization (Song et al. 2008).<p>Several ubiquitin ligases, including NEDD4, WWP2, STUB1 (CHIP), RNF146, XIAP and MKRN1, polyubiquitinate PTEN and target it for proteasome-mediated degradation (Wang et al. 2007, Van Themsche et al. 2009, Ahmed et al. 2011, Maddika et al. 2011, Lee et al. 2015, Li et al. 2015). The ubiquitin proteases USP13 and OTUD3, frequently down-regulated in breast cancer, remove polyubiquitin chains from PTEN, thus preventing its degradation and increasing its half-life (Zhang et al. 2013, Yuan et al. 2015). The catalytic activity of PTEN is negatively regulated by PREX2 binding (Fine et al. 2009, Hodakoski et al. 2014) and TRIM27-mediated ubiquitination (Lee et al. 2013), most likely through altered PTEN conformation.<p>In addition to ubiquitination, PTEN also undergoes SUMOylation (Gonzalez-Santamaria et al. 2012, Da Silva Ferrada et al. 2013, Lang et al. 2015, Leslie et al. 2016). SUMOylation of the C2 domain of PTEN may regulate PTEN association with the plasma membrane (Shenoy et al. 2012) as well as nuclear localization of PTEN (Bassi et al. 2013, Collaud et al. 2016). PIASx-alpha, a splicing isorom of E3 SUMO-protein ligase PIAS2 has been implicated in PTEN SUMOylation (Wang et al. 2014). SUMOylation of PTEN may be regulated by activated AKT (Lin et al. 2016). Reactions describing PTEN SUMOylation will be annotated when mechanistic details become available.<p>Phosphorylation affects the stability and activity of PTEN. FRK tyrosine kinase (RAK) phosphorylates PTEN on tyrosine residue Y336, which increases PTEN half-life by inhibiting NEDD4-mediated polyubiquitination and subsequent degradation of PTEN. FRK-mediated phosphorylation also increases PTEN enzymatic activity (Yim et al. 2009). Casein kinase II (CK2) constitutively phosphorylates the C-terminal tail of PTEN on serine and threonine residues S370, S380, T382, T383 and S385. CK2-mediated phosphorylation increases PTEN protein stability (Torres and Pulido 2001) but results in ~30% reduction in PTEN lipid phosphatase activity (Miller et al. 2002).<p>PTEN localization and activity are affected by acetylation of its lysine residues (Okumura et al. 2006, Ikenoue et al. 2008, Meng et al. 2016). PTEN can undergo oxidation, which affects its function, but the mechanism is poorly understood (Tan et al. 2015, Shen et al. 2015, Verrastro et al. 2016). View original pathway at:Reactome.</div>
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(EZH2) core):PTEN
geneNonendonucleolytic
RISC:PTEN mRNANonendonucleolytic
RISCNonendonucleolytic
RISC:PTEN mRNANonendonucleolytic
RISCAnnotated Interactions
(EZH2) core):PTEN
gene(EZH2) core):PTEN
geneThe MIR26A2 locus is frequently amplified in glioma tumors that retain one wild-type PTEN allele. The resulting miR-26A2 overexpression leads to down-regulation of PTEN protein level. Overexpression of miR-26A2 was shown to enhance tumorigenesis and negatively correlates with the loss of heterozygosity at the PTEN locus in a mouse PTEN +/- glioma model, based on monoallelic PTEN loss (Huse et al. 2009, Kim et al. 2010).
PREX2 is frequently overexpressed in breast and prostate cancer (Fine et al. 2009) and mutated in melanoma (Berger et al. 2012).
In response to UV induced DNA damage, PTEN transcription is stimulated by binding of the transcription factor EGR1 to the promoter region of PTEN (Virolle et al. 2001).
PTEN transcription is also stimulated by binding of the activated nuclear receptor PPARG (PPARgamma) to peroxisome proliferator response elements (PPREs) in the promoter of the PTEN gene (Patel et al. 2001), binding of the ATF2 transcription factor, activated by stress kinases of the p38 MAPK family, to ATF response elements in the PTEN gene promoter (Shen et al. 2006) and by the transcription factor MAF1 (Li et al. 2016).
NR2E1 (TLX) associated with transcription repressors binds the evolutionarily conserved TLX consensus site in the PTEN promoter. NR2E1 inhibits PTEN transcription by associating with various transcriptional repressors, probably in a cell type or tissue specific manner. PTEN transcription is inhibited when NR2E1 forms a complex with ATN1 (atrophin-1) (Zhang et al. 2006, Yokoyama et al. 2008), KDM1A (LSD1) histone methyltransferase containing CoREST complex (Yokoyama et al. 2008), or histone deacetylases HDAC3, HDAC5 or HDAC7 (Sun et al. 2007).
Binding of the transcriptional repressor SNAI1 (Snail1) to the PTEN promoter represses PTEN transcription. SNAI1-mediated repression of PTEN transcription may require phosphorylation of SNAI1 on serine residue S246. Binding of SNAI1 to the PTEN promoter increases in response to ionizing radiation and is implicated in SNAI1-mediated resistance to gamma-radiation induced apoptosis (Escriva et al. 2008). Binding of another Slug/Snail family member SNAI2 (SLUG) to the PTEN gene promoter also represses PTEN transcription (Uygur et al. 2015).
Binding of JUN to the AP-1 element in the PTEN gene promoter (Hettinger et al. 2007) inhibits PTEN transcription. JUN partner FOS is not needed for JUN-mediated downregulation of PTEN (Vasudevan et al. 2007).
Binding of the transcription factor SALL4 to the PTEN gene promoter (Yang et al. 2008) and SALL4-medaited recruitment of the transcriptional repressor complex NuRD (Lu et al. 2009, Gao et al. 2013), containing histone deacetylases HDAC1 and HDAC2, inhibits the PTEN gene transcription. SALL4-mediated recruitment of DNA methyltransferases (DNMTs) is also implicated in transcriptional repression of PTEN (Yang et al. 2012).
Binding of the transcription factor MECOM (EVI1) to the PTEN gene promoter and MECOM-mediated recruitment of polycomb repressor complexes containing BMI1 (supposedly PRC1.4), and EZH2 (PRC2) leads to repression of PTEN transcription (Song et al. 2009, Yoshimi et al. 2011).
Overexpression of PTENP1 3'UTR results in de-repression of both PTEN mRNA and protein in the presence of mature PTEN-targeting microRNAs. Knockdown of PTENP1 decreases abundance of PTEN mRNA and protein. PTENP1 therefore functions as a competing endogenous RNA (ce-RNA) in microRNA-mediated PTEN regulation. PTENP1 losses have been reported in cancer (Poliseno et al. 2010).
Overexpression of PTENP1 3'UTR results in de-repression of both PTEN mRNA and protein in the presence of mature PTEN-targeting microRNAs. Knockdown of PTENP1 decreases abundance of PTEN mRNA and protein. PTENP1 therefore functions as a competing endogenous RNA (ce-RNA) in microRNA-mediated PTEN regulation. PTENP1 losses have been reported in cancer (Poliseno et al. 2010).
Nonendonucleolytic
RISC:PTEN mRNANonendonucleolytic
RISC:PTEN mRNANonendonucleolytic
RISCNonendonucleolytic
RISC:PTEN mRNANonendonucleolytic
RISC:PTEN mRNANonendonucleolytic
RISC