PIN1 Mouse
Description
Genetic and Molecular Basis of PIN1
The PIN1 gene produces an 18 kDa enzyme that isomerizes phosphorylated Ser/Threonine-Proline motifs, regulating protein conformation and function post-phosphorylation . PIN1 knockout (Pin1 −/−) mice exhibit disrupted phosphorylation-dependent signaling pathways, impacting cell proliferation, survival, and neurodegeneration .
Key Features of PIN1 Mouse Models:
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Targeted Deletions: Complete knockout of PIN1 leads to age-dependent phenotypes, including neuronal degeneration and metabolic dysregulation .
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Substrate Specificity: PIN1 interacts with phosphorylated proteins like cyclin D1, tau, and Myc, altering their stability and activity .
Phenotypic Characteristics of PIN1 −/− Mice
Pin1 −/− mice display multisystem abnormalities, as shown below:
Role in Tau Pathology
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Pin1 −/− mice develop Alzheimer’s-like tau hyperphosphorylation at Thr231-Pro motifs, leading to neurofibrillary tangle formation .
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Overexpression of PIN1 promotes tau degradation, while its absence stabilizes pathogenic cis conformations .
Cell Cycle and Cancer
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PIN1 stabilizes oncoproteins (e.g., cyclin D1, Myc) by inhibiting ubiquitination. Pin1 −/− mice resist Myc-induced lymphomas .
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Therapeutic Target: PIN1 inhibitors (e.g., juglone, artemisinin derivatives) reduce tumor growth in prostate and breast cancer models .
Metabolic and Immune Signaling
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PIN1 modulates insulin signaling by interacting with IRS-1 and Akt, affecting adipocyte differentiation .
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In dendritic cells, PIN1 isomerizes phosphorylated IRAK3, amplifying inflammatory responses .
Research Tools and Assays
Quantitative Detection of PIN1 in Mice:
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ELISA Kits: Detect PIN1 in serum, plasma, and tissue extracts with sensitivity down to 39 pg/mL .
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Key Parameters for MBS2805945 Kit:
Therapeutic Implications
PIN1 Inhibitors in Disease Models:
Product Specs
Recombinant Mouse PIN1, expressed in E. coli, is a single, non-glycosylated polypeptide chain. It consists of 188 amino acids, with the PIN1 sequence comprising amino acids 1-165, and has a molecular weight of 20.8 kDa. The protein includes an N-terminal 23 amino acid His-tag and is purified using proprietary chromatographic techniques.
The PIN1 protein solution is provided at a concentration of 1 mg/ml in a buffer consisting of phosphate-buffered saline (pH 7.4) and 10% glycerol.
The specific activity of the PIN1 protein is greater than 1,200 nmol/min/mg. This is measured as the amount of enzyme required to cleave 1 nmole of the substrate suc-AAFP-PNA per minute at a temperature of 37°C in Tris-HCl buffer at pH 8.0 using chymotrypsin.
Peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (EC:5.2.1.8), Peptidyl-prolyl cis-trans isomerase Pin1, PPIase Pin1, Pin1, PIN1.
MGSSHHHHHH SSGLVPRGSH MGSMADEEKL PPGWEKRMSR SSGRVYYFNH ITNASQWERP SGGSTVGGSS KNGQGEPAKV RCSHLLVKHS QSRRPSSWRQ EKITRSKEEA LELINGYIQK IKSGEEDFES LASQFSDCSS AKARGDLGPF SRGQMQKPFE DASFALRTGE MSGPVFTDSG IHIILRTE.
Q&A
Here’s a structured collection of FAQs tailored for researchers studying PIN1 knockout (KO) mice, organized by complexity and grounded in experimental evidence from peer-reviewed studies:
What are the primary phenotypes observed in PIN1 KO mice?
PIN1 KO mice exhibit age-dependent neurodegenerative phenotypes, including:
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Tau pathology: Hyperphosphorylated tau aggregation, neurofibrillary tangle (NFT)-like formations, and reduced phosphatase activity toward pS/T-P motifs .
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Motor/behavioral deficits: Abnormal limb-clasping reflexes, hunched posture, and reduced mobility .
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Systemic effects: Retinal degeneration, decreased body weight (~71% of wild-type), and testicular atrophy .
Methodological insight: Use immunohistochemistry with antibodies like MPM-2 (for phospho-epitopes) and thioflavin-S (for fibrillar tau) to quantify pathology. Behavioral assays (e.g., rotarod tests) assess motor deficits .
How do PIN1 KO mice model Alzheimer’s disease (AD) pathology?
PIN1 KO mice recapitulate two hallmarks of AD:
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Aβ-independent tauopathy: Accumulation of hyperphosphorylated tau at Thr231/Ser235 and NFT-like structures .
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Synaptic dysfunction: Dendritic spine loss in hippocampal neurons post-PIN1 ablation .
Key validation: Compare tau phosphorylation (e.g., AT8/PHF1 antibodies) and synaptic density (e.g., Golgi staining) between wild-type and KO mice .
How does PIN1 regulate tau phosphorylation and dephosphorylation?
PIN1 facilitates conformational-specific dephosphorylation by PP2A:
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Binds phosphorylated tau at pT231-pS235 motifs, enabling PP2A to dephosphorylate tau .
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Loss of PIN1 disrupts this interaction, leading to tau hyperphosphorylation and microtubule destabilization .
Experimental design:
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Use phospho-specific tau mutants (e.g., T231A) to isolate PIN1’s isomerase activity .
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Assess phosphatase activity via in vitro assays with recombinant PP2A and phospho-tau substrates .
How to resolve contradictions in synaptic plasticity findings in PIN1 KO mice?
Contradictory observations:
| Study | Finding | Method |
|---|---|---|
| Liou et al. (2003) | Impaired LTP, spine loss | Electrophysiology, AAV-Cre KO |
| Westmark et al. (2010) | Enhanced LTP, increased spines | Germline KO, spine imaging |
Resolution strategies:
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Use conditional KO models (e.g., Pin1 fl/fl + AAV-Cre) to avoid developmental compensation .
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Control for genetic background (e.g., pure C57BL/6 vs. mixed strains) .
What mechanisms underlie tissue-specific PIN1 effects (e.g., retinal vs. neuronal degeneration)?
Tissue-specific pathways:
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Retina: PIN1 loss disrupts Müller glial cell function, exacerbating oxidative stress .
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Hippocampus: PIN1 regulates CaMKII activity, impacting dendritic spine stability .
Methodological approach:
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Perform tissue-specific KO (e.g., Cre-Lox under GFAP or CaMKIIα promoters).
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Profile phosphoproteomes (e.g., LC-MS/MS) to identify unique PIN1 substrates in affected tissues .
Why do some studies report neuroprotection while others show neurodegeneration in PIN1 KO models?
Key variables:
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Tau isoform: PIN1 deletion reduces pathogenic tau (e.g., P301L) but exacerbates wild-type tau aggregation .
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Developmental compensation: Germline KO mice may upregulate other prolyl isomerases (e.g., Par14) .
Recommendations:
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Use inducible KO systems to bypass developmental effects.
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Crossbreed PIN1 KO mice with tau transgenic lines (e.g., JNPL3) to isolate context-dependent outcomes .
Methodological Framework Table
| Research Goal | Techniques | Key Biomarkers |
|---|---|---|
| Assess tau pathology | Western blot, immunohistochemistry | pT231-tau, MPM-2, AT8 |
| Quantify synaptic loss | Dendritic spine imaging (DiI), electron microscopy | Spine density, PSD-95 |
| Model tissue-specific PIN1 loss | AAV-Cre delivery, tissue-specific Cre lines | GFP-Cre recombination, Pin1 mRNA in situ |
| Profile phosphatase activity | In vitro dephosphorylation assay | PP2A activity, pNPP substrate |
Product Science Overview
PIN1 is a member of the peptidyl-prolyl cis/trans isomerase (PPIase) family, which is known for its ability to catalyze the isomerization of peptide bonds at proline residues . This specific isomerase interacts with phosphorylated serine/threonine-proline motifs, inducing conformational changes in its substrates . These conformational changes are critical for regulating the activity, stability, and function of various proteins involved in cell growth, stress responses, immune response, and neuronal differentiation .
The conformational regulation catalyzed by PIN1 has profound impacts on key proteins involved in several cellular processes . For instance, PIN1 is known to play a pivotal role in the regulation of cell growth, genotoxic stress responses, and the immune response . Additionally, it is involved in the induction and maintenance of pluripotency, germ cell development, and neuronal survival .
PIN1 has been implicated in the pathogenesis of several diseases, including Alzheimer’s disease and various cancers . In cancer, PIN1 is often overexpressed, driving oncogenesis by modulating the activity of oncogenes and tumor suppressors . The enzyme’s ability to regulate the post-phosphorylation conformation of its substrates makes it a potential target for therapeutic intervention .
Recent research has focused on developing specific inhibitors for PIN1 to explore its therapeutic potential . For example, a potent and specific covalent PIN1 inhibitor, Sulfopin, has been identified and shown to reduce tumor progression and increase survival in mouse models of cancer . This highlights the potential of targeting PIN1 in cancer therapy and other diseases where PIN1 plays a critical role .
