GO:0034485 phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0034485 describes the enzymatic activity that removes the 5-phosphate from phosphatidylinositol-3,4,5-trisphosphate (PIP3), converting it to phosphatidylinositol-3,4-bisphosphate (PIP2).
• This activity is carried out by several distinct enzymes, including SHIP1 (INPP5D), SHIP2 (INPPL1), synaptojanin (SYNJ1/2), and the voltage-sensor protein Ci-VSP.
• By degrading PIP3, these 5-phosphatases act as negative regulators of the PI3K/AKT signaling pathway, which is central to cell growth, survival, and metabolism.
• Dysregulation of 5-phosphatase activity is linked to human diseases such as opsismodysplasia (INPPL1 mutations) and various cancers.
• Researchers study this activity using in vitro phosphatase assays, in vivo PIP3 imaging, and CRISPR-based genetic models to dissect its role in signaling.
• EDITGENE provides CRISPR knockout, point mutation, knock-in, overexpression, and library screening services to investigate genes encoding PIP3 5-phosphatases.
Description
Phosphatidylinositol-3,4,5-trisphosphate (PIP3) is a critical lipid second messenger that drives cellular responses to growth factors and hormones. The enzyme activity defined by GO:0034485, phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase activity, catalyzes the hydrolysis of PIP3 to phosphatidylinositol-3,4-bisphosphate (PIP2) and inorganic phosphate. This reaction directly opposes the action of phosphoinositide 3-kinases (PI3Ks), which synthesize PIP3, and thus serves as a key negative feedback mechanism in the PI3K/AKT signaling cascade. Researchers studying cell signaling, cancer, and metabolic disorders are intensely interested in this activity because it controls the duration and amplitude of PIP3-dependent signals.
phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase activity At A Glance
| GO ID | GO:0034485 |
|---|---|
| GO term | phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase activity |
| Ontology | molecular_function |
| Synonym | None listed in QuickGO |
| Major function | Hydrolysis of PIP3 to PIP2, terminating PI3K signaling |
| Reaction | 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol-3,4,5-trisphosphate) + H2O = 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol-3,4-bisphosphate) + phosphate |
| Substrate | Phosphatidylinositol-3,4,5-trisphosphate (PIP3) |
| Product | Phosphatidylinositol-3,4-bisphosphate (PIP2) and phosphate |
| Cofactors | Not specified in QuickGO; activity may be influenced by anionic lipids |
What Is GO:0034485?
GO:0034485 is a molecular function term describing the catalytic activity of an enzyme that removes the phosphate group at the 5-position of the inositol ring of phosphatidylinositol-3,4,5-trisphosphate. The reaction consumes water and produces phosphatidylinositol-3,4-bisphosphate and phosphate. This activity is distinct from other inositol phosphatases that act at different positions or on different substrates.
Why Is phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase activity Important in Cell Biology?
The 5-phosphatase activity defined by GO:0034485 is essential for maintaining cellular homeostasis by preventing excessive PIP3 accumulation. PIP3 is a potent activator of AKT and other downstream effectors that promote cell proliferation, survival, and migration. Loss of 5-phosphatase function can lead to hyperactivation of these pathways, contributing to cancer and developmental disorders. Conversely, excessive activity can blunt normal growth factor responses. Therefore, understanding the regulation and specificity of these enzymes is crucial for both basic cell biology and therapeutic development.
• Terminates PI3K signaling by converting PIP3 to PIP2, thereby acting as a tumor suppressor mechanism.
• Mutations in INPPL1, encoding SHIP2, cause opsismodysplasia, a rare skeletal dysplasia.
• SHIP1 (INPP5D) is a critical regulator of immune cell signaling and hematopoiesis.
• Synaptojanin (SYNJ1) is the major constitutively active PIP3 5-phosphatase in rodent brain and is implicated in synaptic vesicle recycling.
• The Ci-VSP protein from Ciona intestinalis is a model for studying voltage-dependent PIP3 5-phosphatase activity.
• Anionic lipids such as phosphatidylserine modulate SHIP2 activity, linking membrane composition to signaling output.
• Insulin regulates PIP3 5-phosphatase activity, connecting this enzyme to glucose metabolism.
• Dysregulation of 5-phosphatases is observed in cancers, neurodegeneration, and metabolic syndromes.
• These enzymes are potential drug targets for diseases driven by aberrant PI3K/AKT signaling.
• CRISPR-based models enable precise dissection of individual 5-phosphatase genes in disease contexts.
What Happens During phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase activity?
Substrate Recognition and Binding
In simple terms: The enzyme grabs onto PIP3, a lipid molecule in the cell membrane.
The 5-phosphatase enzyme specifically binds phosphatidylinositol-3,4,5-trisphosphate (PIP3) at the membrane interface. This binding is mediated by conserved domains, such as the SH2 domain in SHIP2, which can also interact with phosphotyrosine motifs to localize the enzyme to activated receptors. The anionic lipid environment, including phosphatidylserine, can influence substrate binding and catalytic efficiency.
Catalytic Hydrolysis
In simple terms: The enzyme cuts off a phosphate group from PIP3, turning it into PIP2.
Once bound, the enzyme catalyzes the hydrolysis of the phosphate ester bond at the 5-position of the inositol ring. This reaction consumes one water molecule and releases inorganic phosphate, converting PIP3 to phosphatidylinositol-3,4-bisphosphate (PIP2). The catalytic mechanism involves conserved residues in the 5-phosphatase domain, and the reaction is highly specific for the 5-position.
Product Release and Signal Termination
In simple terms: The newly made PIP2 is released, and the signal that PIP3 was sending is shut off.
After hydrolysis, PIP2 is released from the enzyme. Because PIP3 is a key activator of downstream effectors like AKT, its conversion to PIP2 terminates these signals. This step is crucial for resetting the signaling pathway and preventing sustained activation that could lead to uncontrolled cell growth.
Regulation by Insulin and Growth Factors
In simple terms: Hormones like insulin can turn this enzyme activity up or down.
Insulin has been shown to regulate PIP3 5-phosphatase activity, providing a feedback mechanism to modulate PI3K signaling in response to metabolic cues. Similarly, interleukin-3 receptor signaling associates with a novel PIP3 5-phosphatase, indicating that cytokine receptors can recruit and regulate these enzymes. This dynamic regulation ensures appropriate cellular responses to external stimuli.
Key Genes Involved in GO:0034485 phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase activity
The following genes encode enzymes or associated proteins that exhibit phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase activity or regulate it.
| Gene | Major Role | Research Relevance |
|---|---|---|
| INPP5D (SHIP1) | Hydrolyzes PIP3 to PIP2; negative regulator of immune cell signaling | Studied in leukemia, lymphoma, and immune disorders |
| INPPL1 (SHIP2) | Hydrolyzes PIP3; regulates insulin signaling and cytoskeleton | Mutations cause opsismodysplasia; linked to type 2 diabetes |
| SYNJ1 | Major constitutively active PIP3 5-phosphatase in brain; synaptic vesicle recycling | Implicated in Parkinson's disease and neurodegeneration |
| SYNJ2 | PIP3 5-phosphatase; regulates actin dynamics | Studied in cancer cell migration and invasion |
| OCRL | PIP3 5-phosphatase; Golgi and endosomal trafficking | Mutations cause Lowe syndrome and Dent disease |
| INPP5B | PIP3 5-phosphatase; testis-specific functions | Investigated in male fertility and signaling |
| INPP5E | PIP3 5-phosphatase; ciliary signaling | Mutations cause Joubert syndrome and retinal degeneration |
| INPP5J | PIP3 5-phosphatase; regulates AKT signaling | Studied in cancer and metabolic disorders |
| INPP5K | PIP3 5-phosphatase; ER stress and insulin signaling | Linked to congenital muscular dystrophy |
| FIG4 | PIP3 5-phosphatase; endosomal trafficking | Mutations cause Charcot-Marie-Tooth disease and ALS |
| PIP5K1A | Synthesizes PIP2, indirectly affects PIP3 levels | Studied in cancer and cell motility |
| PTEN | Dephosphorylates PIP3 at 3-position, not 5-phosphatase | Tumor suppressor; often mutated in cancers |
| PIK3CA | Kinase that produces PIP3 | Oncogene; mutations drive many cancers |
| PIK3R1 | Regulatory subunit of PI3K | Mutations cause immune dysregulation and cancer |
| AKT1 | Downstream effector of PIP3 | Oncogene; target of therapies |
| MTOR | Kinase activated by PIP3 signaling | Central regulator of growth; drug target |
| INSR | Insulin receptor; activates PI3K | Regulates PIP3 5-phosphatase via insulin |
| IL3RA | Interleukin-3 receptor; associates with PIP3 5-phosphatase | Studied in hematopoietic signaling |
How Is phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase activity Regulated?
The activity of phosphatidylinositol-3,4,5-trisphosphate 5-phosphatases is regulated at multiple levels. Insulin signaling can modulate PIP3 5-phosphatase activity, providing a feedback loop to control PI3K output. Cytokine receptors such as the interleukin-3 receptor recruit specific 5-phosphatases to attenuate signaling. Additionally, the lipid environment, particularly anionic lipids like phosphatidylserine, can directly influence the catalytic activity of SHIP2. Post-translational modifications and protein-protein interactions further fine-tune these enzymes in a cell-type-specific manner.
phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| INPPL1 | Opsismodysplasia | Knockout or point-mutation knock-in in chondrocyte cell lines |
| INPP5D | Leukemia, immune dysregulation | Knockout in hematopoietic stem cells or Jurkat T cells |
| SYNJ1 | Parkinson's disease, synaptic dysfunction | Knockout in iPSC-derived neurons or SH-SY5Y cells |
| OCRL | Lowe syndrome, Dent disease | Knockout in renal epithelial cells or fibroblasts |
| FIG4 | Charcot-Marie-Tooth disease, ALS | Knockout in motor neurons or Schwann cells |
Opsismodysplasia and Skeletal Dysplasia
Biallelic mutations in INPPL1, which encodes the 5-phosphatase SHIP2, cause opsismodysplasia, a rare autosomal recessive skeletal dysplasia characterized by delayed bone maturation and severe short stature. This highlights the critical role of PIP3 5-phosphatase activity in bone development and growth plate signaling.
Cancer and PI3K/AKT Hyperactivation
Loss of 5-phosphatase function leads to PIP3 accumulation and hyperactivation of the PI3K/AKT pathway, which is a hallmark of many cancers. For example, reduced expression of SHIP1 (INPP5D) has been observed in hematological malignancies, and synaptojanin (SYNJ1) dysregulation is linked to cancer cell invasion. Targeting these enzymes is an active area of therapeutic research.
Neurodegeneration and Synaptic Dysfunction
Synaptojanin 1 (SYNJ1) is the major constitutively active PIP3 5-phosphatase in rodent brain, and its dysfunction impairs synaptic vesicle recycling. Mutations in SYNJ1 have been associated with early-onset Parkinson's disease and other neurodegenerative conditions, underscoring the importance of PIP3 turnover in neuronal health.
From phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of INPP5D increase PIP3 levels and AKT activation? | CRISPR knockout in immune cell lines (e.g., Jurkat) |
| How does the INPPL1 mutation affect SHIP2 catalytic activity? | Point-mutation knock-in of patient variants in HEK293 cells |
| Can wild-type SHIP2 rescue the opsismodysplasia phenotype? | Knock-in of wild-type INPPL1 in patient-derived iPSCs |
| Where is SYNJ1 localized in neurons? | Tagged knock-in of SYNJ1 with GFP in iPSC-derived neurons |
| Does overexpression of INPP5D suppress tumor growth? | Overexpression in cancer cell lines and xenograft models |
| Which genes modulate sensitivity to PIP3 5-phosphatase inhibition? | CRISPR library screening in cancer cell lines |
How to Study the phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| In vitro phosphatase assay | Enzymatic hydrolysis of PIP3 to PIP2 | Kinetic analysis of recombinant SHIP2 |
| PIP3 biosensor imaging | Real-time PIP3 levels in cells | Monitoring insulin response |
| CRISPR knockout screening | Gene essentiality and pathway modifiers | Identifying synthetic lethal partners |
| Lipidomics | Quantification of phosphoinositides | Assessing PIP3/PIP2 ratios |
| Phosphoproteomics | AKT and downstream phosphorylation | Evaluating pathway activation |
| Co-immunoprecipitation | Protein-protein interactions | Identifying receptor-5-phosphatase complexes |
| qRT-PCR | mRNA expression of 5-phosphatases | Validating knockout or overexpression |
| Western blot | Protein levels and phosphorylation | Confirming SHIP2 knockdown |
In Vitro Phosphatase Assays
Direct measurement of PIP3 5-phosphatase activity can be performed using radiolabeled or fluorescent PIP3 substrates followed by chromatographic separation of products. These assays are essential for determining kinetic parameters and inhibitor sensitivity.
In Vivo PIP3 Imaging
Genetically encoded PIP3 biosensors, such as GFP-tagged PH domains, allow real-time monitoring of PIP3 levels in living cells. This approach can reveal how 5-phosphatase activity shapes PIP3 dynamics in response to stimuli.
CRISPR-Based Genetic Screens
Pooled CRISPR knockout libraries can be used to identify genes that modulate PIP3 5-phosphatase activity or its downstream effects. Such screens are powerful for discovering novel regulators and therapeutic targets.
Phosphoproteomics and Lipidomics
Mass spectrometry-based lipidomics can quantify PIP3 and PIP2 levels, while phosphoproteomics can assess AKT activation status. These methods provide a systems-level view of signaling changes caused by altered 5-phosphatase activity.
How CRISPR Can Be Used to Study GO:0034485 phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase activity
Knockout
CRISPR knockout of genes encoding PIP3 5-phosphatases (e.g., INPP5D, INPPL1, SYNJ1) allows researchers to study the consequences of losing enzymatic activity. For example, INPP5D knockout in immune cells leads to increased PIP3 and enhanced AKT signaling. These models are invaluable for dissecting the specific roles of each 5-phosphatase in cellular processes.
Point Mutation
Introducing patient-specific point mutations (e.g., in INPPL1) via CRISPR base editing or homology-directed repair can recreate disease-causing alleles in cell lines. Such models help determine whether a mutation affects catalytic activity, substrate binding, or protein stability.
Knock-in
Knock-in of tagged versions (e.g., GFP, HA) of 5-phosphatases enables live-cell imaging and proteomic studies. For instance, tagging endogenous SYNJ1 allows tracking its localization in neurons. Knock-in of wild-type or mutant alleles can also rescue or exacerbate phenotypes.
Overexpression
CRISPR activation (CRISPRa) or lentiviral overexpression of 5-phosphatases can be used to test whether increased activity suppresses PIP3 signaling. Overexpression of INPP5D in cancer cells reduces AKT phosphorylation and inhibits proliferation. This approach is useful for validating tumor suppressor functions.
How EDITGENE Supports phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase activity Research
Researchers studying phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase activity-related genes often need to determine whether a candidate gene is causally involved in a specific signaling pathway or disease phenotype. EDITGENE provides a comprehensive suite of CRISPR-based services to generate precisely engineered cell models, enabling rigorous functional studies.
Contact EDITGENE today to design your custom CRISPR model for phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase activity research.
Frequently Asked Questions About phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase activity
What is phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase activity?
It is the enzymatic activity that removes the 5-phosphate from PIP3, converting it to PIP2 and inorganic phosphate, as defined by GO:0034485.
What genes are involved in phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase activity?
Key genes include INPP5D (SHIP1), INPPL1 (SHIP2), SYNJ1, SYNJ2, OCRL, INPP5B, INPP5E, INPP5J, INPP5K, and FIG4.
How does phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase activity affect cancer?
By degrading PIP3, these enzymes act as negative regulators of the PI3K/AKT pathway; loss of their activity can lead to hyperactivation of AKT and promote cancer.
What diseases are associated with mutations in PIP3 5-phosphatase genes?
Mutations in INPPL1 cause opsismodysplasia, SYNJ1 is linked to Parkinson's disease, and OCRL mutations cause Lowe syndrome.
How is phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase activity measured?
It can be measured using in vitro phosphatase assays with radiolabeled PIP3, or in vivo using PIP3 biosensors and lipidomics.
What is the difference between SHIP1 and SHIP2?
SHIP1 (INPP5D) is primarily expressed in hematopoietic cells and regulates immune signaling, while SHIP2 (INPPL1) is ubiquitously expressed and involved in insulin signaling and bone development.
Can CRISPR be used to study PIP3 5-phosphatase activity?
Yes, CRISPR knockout, point mutation knock-in, and overexpression models allow precise manipulation of genes encoding these enzymes to study their function.
What is the role of synaptojanin in the brain?
Synaptojanin (SYNJ1) is the major constitutively active PIP3 5-phosphatase in rodent brain and is essential for synaptic vesicle recycling.
How does insulin regulate PIP3 5-phosphatase activity?
Insulin signaling can modulate PIP3 5-phosphatase activity, providing a feedback mechanism to control PI3K output and glucose metabolism.
What are the therapeutic implications of targeting PIP3 5-phosphatases?
Inhibiting these enzymes could boost PIP3 signaling in conditions where it is deficient, while activating them might suppress cancer driven by PI3K/AKT hyperactivation.
Conclusion
Phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase activity (GO:0034485) is a fundamental molecular function that controls the lifetime of the critical lipid second messenger PIP3. Through the action of enzymes such as SHIP1, SHIP2, and synaptojanin, this activity shapes diverse cellular processes including immune responses, insulin signaling, and synaptic transmission. Its dysregulation is implicated in skeletal dysplasia, cancer, and neurodegeneration, making it a compelling target for both basic research and therapeutic development. Leveraging CRISPR-based models and advanced screening technologies will continue to illuminate the precise roles of individual 5-phosphatases in health and disease.
References
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- 6. Woscholski R et al.. 1997. Synaptojanin is the major constitutively active phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase in rodent brain.. J Biol Chem 272(15):9625-8 PMID: 9092489
- 7. Pesesse X et al.. 1998. The SH2 domain containing inositol 5-phosphatase SHIP2 displays phosphatidylinositol 3,4,5-trisphosphate and inositol 1,3,4,5-tetrakisphosphate 5-phosphatase activity.. FEBS Lett 437(3):301-3 PMID: 9824312
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