PTEN (gene)

Phosphatase and tensin homolog
Crystallographic structure of human PTEN. The N-terminal phosphatase domain is colored blue while the C-terminal C2 domain is colored red.
Available structures PDB Ortholog search: PDBe, RCSB List of PDB id codes 1D5R, 2KYL, 4O1V
Identifiers
Symbols	PTEN ; 10q23del; BZS; CWS1; DEC; GLM2; MHAM; MMAC1; PTEN1; TEP1
External IDs	OMIM: 601728 HomoloGene: 265 GeneCards: PTEN Gene
EC number	3.1.3.16, 3.1.3.48, 3.1.3.67
Gene ontology Molecular function • magnesium ion binding • phosphatidylinositol-3-phosphatase activity • phosphoprotein phosphatase activity • protein serine/threonine phosphatase activity • protein tyrosine phosphatase activity • platelet-derived growth factor receptor binding • protein binding • protein tyrosine/serine/threonine phosphatase activity • lipid binding • anaphase-promoting complex binding • phosphatidylinositol-3,4,5-trisphosphate 3-phosphatase activity • enzyme binding • protein kinase binding • PDZ domain binding • identical protein binding • inositol-1,3,4,5-tetrakisphosphate 3-phosphatase activity • phosphatidylinositol-3,4-bisphosphate 3-phosphatase activity Cellular component • extracellular region • nucleus • nucleoplasm • cytoplasm • mitochondrion • cytosol • plasma membrane • cytoplasmic side of plasma membrane • apical plasma membrane • PML body • myelin sheath adaxonal region • cell projection • neuron projection • dendritic spine • Schmidt-Lanterman incisure • postsynaptic membrane Biological process • regulation of cyclin-dependent protein serine/threonine kinase activity • angiogenesis • negative regulation of protein phosphorylation • regulation of B cell apoptotic process • transcription initiation from RNA polymerase II promoter • protein dephosphorylation • phospholipid metabolic process • phosphatidylinositol biosynthetic process • apoptotic process • activation of APC-Cdc20 complex activity • epidermal growth factor receptor signaling pathway • neuron-neuron synaptic transmission • synapse assembly • central nervous system development • heart development • aging • response to nutrient • learning or memory • memory • locomotory behavior • cell proliferation • positive regulation of cell proliferation • negative regulation of cell proliferation • fibroblast growth factor receptor signaling pathway • response to glucose • response to zinc ion • gene expression • regulation of neuron projection development • negative regulation of phosphatidylinositol 3-kinase signaling • cell migration • dentate gyrus development • central nervous system neuron axonogenesis • negative regulation of cell migration • adult behavior • negative regulation of myelination • regulation of protein stability • negative regulation of cyclin-dependent protein serine/threonine kinase activity involved in G1/S transition of mitotic cell cycle • regulation of synaptic transmission, GABAergic • central nervous system myelin maintenance • response to estradiol • regulation of cellular component size • regulation of myeloid cell apoptotic process • response to ATP • multicellular organismal response to stress • social behavior • peptidyl-tyrosine dephosphorylation • Fc-epsilon receptor signaling pathway • response to drug • maternal behavior • negative regulation of apoptotic process • protein kinase B signaling • endothelial cell migration • inositol phosphate metabolic process • small molecule metabolic process • innate immune response • response to ethanol • locomotor rhythm • negative regulation of cell size • negative regulation of organ growth • response to arsenic-containing substance • inositol phosphate dephosphorylation • phosphatidylinositol dephosphorylation • platelet-derived growth factor receptor signaling pathway • neurotrophin TRK receptor signaling pathway • phosphatidylinositol-mediated signaling • regulation of axon regeneration • cardiac muscle tissue development • forebrain morphogenesis • brain morphogenesis • negative regulation of epithelial cell proliferation • negative regulation of phagocytosis • negative regulation of axonogenesis • protein stabilization • T cell receptor signaling pathway • positive regulation of sequence-specific DNA binding transcription factor activity • negative regulation of focal adhesion assembly • negative regulation of protein kinase B signaling • rhythmic synaptic transmission • canonical Wnt signaling pathway • synapse maturation • prepulse inhibition • male mating behavior • long-term synaptic potentiation • long term synaptic depression • prostate gland growth • dendritic spine morphogenesis • negative regulation of dendritic spine morphogenesis • positive regulation of ERK1 and ERK2 cascade • cellular response to hypoxia • negative regulation of ribosome biogenesis • negative regulation of cell aging • negative regulation of excitatory postsynaptic membrane potential • presynaptic membrane assembly • postsynaptic density assembly • positive regulation of protein ubiquitination involved in ubiquitin-dependent protein catabolic process • negative regulation of G1/S transition of mitotic cell cycle • positive regulation of excitatory postsynaptic membrane potential • negative regulation of synaptic vesicle clustering • positive regulation of apoptotic signaling pathway Sources: Amigo / QuickGO
Orthologs
Species	Human	Mouse
Entrez	5728	19211
Ensembl	ENSG00000171862	ENSMUSG00000013663
UniProt	P60484	O08586
RefSeq (mRNA)	NM_000314	NM_008960
RefSeq (protein)	NP_000305	NP_032986
Location (UCSC)	Chr 10: 87.86 – 87.97 Mb	Chr 19: 32.76 – 32.83 Mb
PubMed search	[1]	[2]

File:PTEN.png

Space-filling model of the PTEN protein (blue) complexed with tartaric acid (brown).

Phosphatase and tensin homolog (PTEN) is a protein that, in humans, is encoded by the PTEN gene. Mutations of this gene are a step in the development of many cancers. PTEN orthologs have been identified in most mammals for which complete genome data are available.

This gene was identified as a tumor suppressor that is mutated in a large number of cancers at high frequency. The protein encoded by this gene is a phosphatidylinositol-3,4,5-trisphosphate 3-phosphatase. It contains a tensin-like domain as well as a catalytic domain similar to that of the dual specificity protein tyrosine phosphatases. Unlike most of the protein tyrosine phosphatases, this protein preferentially dephosphorylates phosphoinositide substrates. It negatively regulates intracellular levels of phosphatidylinositol-3,4,5-trisphosphate in cells and functions as a tumor suppressor by negatively regulating Akt/PKB signaling pathway.

Function

The PTEN protein is widely expressed throughout the body. PTEN protein acts as a phosphatase to dephosphorylate phosphatidylinositol (3,4,5)-trisphosphate (PtdIns (3,4,5)P₃ or PIP₃). PTEN specifically catalyses the dephosporylation of the 3` phosphate of the inositol ring in PIP₃, resulting in the biphosphate product PIP₂ (PtdIns(4,5)P2). This dephosphorylation is important because it results in inhibition of the AKT signaling pathway.

PTEN also has weak protein phosphatase activity, but this activity is also crucial for its role as a tumor suppressor. PTEN's protein phosphatase activity may be involved in the regulation of the cell cycle, preventing cells from growing and dividing too rapidly. There have been numerous reported protein substrates for PTEN, including IRS1 and Dishevelled.

PTEN is one of the targets for drug candidates such as the oncomiR, MIRN21.

Structure

The structure of the core of PTEN (solved by X-ray crystallography, see figure to the upper right) reveals that it consists primarily of a phosphatase domain, and a C2 domain: the phosphatase domain contains the active site, which carries out the enzymatic function of the protein, while the C2 domain binds the phospholipid membrane. Thus PTEN binds the membrane through both its phosphatase and C2 domains, bringing the active site to the membrane-bound PIP₃ to de-phosphorylate it.

The two domains of PTEN, a protein tyrosine phosphatase domain and a C2 domain, are inherited together as a single unit and thus constitute a superdomain, not only in PTEN but also in various other proteins in fungi, plants and animals, for example, tensin proteins and auxilin.

The active site of PTEN consists of three loops, the TI Loop, the P Loop, and the WPD Loop, all named following the PTPB1 nomenclature. Together they form an unusually deep and wide pocket which allows PTEN to accommodate the bulky phosphatidylinositol 3,4,5-trisphosphate substrate. The dephosphorylation reaction mechanism of PTEN is thought to proceed through a phosphoenzyme intermediate, with the formation of a phosphodiester bond on the active site cysteine, C124.

Not present in the crystal structure of PTEN is a short 10 amino-acid unstructured region N-terminal of the phosphatase domain (from residues 6 to 15), known variously as the PIP2 Binding Domain (PBD) or PIP2 Binding Motif (PBM) This region is increases PTEN's affinity for the plasma membrane by binding to Phosphatidylinositol 4,5-bisphosphate, or possibly any anionic lipid.

Also not present in the crystal structure is the intrinsically disordered C-terminal region (CTR) (spanning residues 353-403). The CTR is constitutively phosphorylated at various positions that effect various aspects of PTEN, including it's ability to bind to lipid membranes, and also act as either a protein or lipid phosphatase.

Additionally, PTEN can also be expressed as PTEN-L (known as PTEN-Long, or PTEN-α), a leucine initiator alternative start site variant, which adds an additional 173 amino acids to the N-terminus of PTEN. The exact role of this 173-amino acid extension is not yet known, either causing PTEN to be secreted from the cell, or to interact with the mitochondria. The N-terminal extension has been predicted to be largely disordered, although there is evidence that there is some structure in the last twenty amino-acids of the extension (most proximal to the start methionine of PTEN).

Clinical significance

Cancer

PTEN is one of the most commonly lost tumor suppressors in human cancer; in fact, up to 70% of men with prostate cancer are estimated to have lost a copy of the PTEN gene at the time of diagnosis.

During tumor development, mutations and deletions of PTEN occur that inactivate its enzymatic activity leading to increased cell proliferation and reduced cell death. Frequent genetic inactivation of PTEN occurs in glioblastoma, endometrial cancer, and prostate cancer; and reduced expression is found in many other tumor types such as lung and breast cancer. Furthermore, PTEN mutation also causes a variety of inherited predispositions to cancer.

Non-cancerous neoplasia

Researchers have identified more than 70 mutations in the PTEN gene in people with Cowden syndrome. These mutations can be changes in a small number of base pairs or, in some cases, deletions of a large number of base pairs. Most of these mutations cause the PTEN gene to make a protein that does not function properly or does not work at all. The defective protein is unable to stop cell division or signal abnormal cells to die, which can lead to tumor growth, particularly in the breast, thyroid, or uterus.

Mutations in the PTEN gene cause several other disorders that, like Cowden syndrome, are characterized by the development of non-cancerous tumors called hamartomas. These disorders include Bannayan-Riley-Ruvalcaba syndrome and Proteus-like syndrome. Together, the disorders caused by PTEN mutations are called PTEN hamartoma tumor syndromes, or PHTS. Mutations responsible for these syndromes cause the resulting protein to be non-functional or absent. The defective protein allows the cell to divide in an uncontrolled way and prevents damaged cells from dying, which can lead to the growth of tumors.

Brain function and autism

Defects of the PTEN gene have been cited to be a potential cause of autism spectrum disorders. When defective, PTEN protein interacts with the protein of a second gene known as Tp53 to dampen energy production in neurons. This severe stress leads to a spike in harmful mitochondrial DNA changes and abnormal levels of energy production in the cerebellum and hippocampus, brain regions critical for social behavior and cognition. When PTEN protein is insufficient, its interaction with p53 triggers deficiencies and defects in other proteins that also have been found in patients with learning disabilities including autism.

Patients with defective PTEN can develop cerebellar mass lesions called dysplastic gangliocytomas or Lhermitte–Duclos disease.

Cell regeneration

PTEN's strong link to cell growth inhibition is being studied as a possible therapeutic target in tissues that do not traditionally regenerate in mature animals, such as central neurons. PTEN deletion mutants have recently been shown to allow nerve regeneration in mice.

Cell lines

Cell lines with known PTEN mutations include:

• prostate: LNCaP, PC-3
• kidney: 786-O
• glioblastoma: U87MG
• breast : MB-MDA-468, BT549
• bladder: J82, UMUC-3

Interactions

PTEN (gene) has been shown to interact with:

• CSNK2A2,
• CSNK2A1,
• MAGI3
• MVP,
• NEDD4,
• NR3C4,
• P53, and
• PTK2.

See also

• Multiple hamartoma syndrome

External links

• GeneReviews/NCBI/NIH/UW entry on PTEN Hamartoma Tumor Syndrome (PHTS)
• PTEN Protein at the US National Library of Medicine Medical Subject Headings (MeSH)
• UMich Orientation of Proteins in Membranes protein/pdbid-1d5r
• Research shows gene defect's role in autism-like behavior

This article incorporates text from the United States National Library of Medicine, which is in the public domain.