GPT2 Mouse
Description
Biochemical Profile of Recombinant Mouse GPT2 Protein
Produced by ProSpecBio, this recombinant enzyme serves as a critical tool for studying alanine transaminase activity.
Metabolic and Neurological Phenotypes in Gpt2-Null Mice
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Brain Development: Homozygous Gpt2-null mice exhibit 13% reduced cortical area and impaired synapse formation (30% fewer SV2-positive puncta) by postnatal day 18 (P18) .
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Motor Deficits: Hind-limb gait abnormalities and premature death by P18–P26 mirror human spastic paraplegia .
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Metabolomic Dysregulation:
Neuron-Specific GPT2 Dependence
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Survival Requirement: Neuronal deletion (SynI-cKO mice) replicates germline knockout phenotypes, indicating GPT2 is indispensable for neuronal survival .
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Synaptic Transmission:
Metabolic Rescue Strategies
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Exogenous Alanine: Restores neuronal viability in Gpt2-null cultures .
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Anaplerotic Agents: α-Ketoglutarate supplementation partially rescues TCA cycle deficits .
Cancer Relevance
GPT2 knockdown in triple-negative breast cancer models inhibits tumor growth via autophagy induction and glutaminolysis disruption .
Comparative Expression Analysis
| Tissue/Stage | GPT2 Expression Level | Source |
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| Postnatal Brain | Peaks at P18 (10x activity increase vs. P1) | |
| Neurons | 36x higher GPT2:GPT1 ratio vs. astrocytes | |
| Human Brain | 20x higher GPT2 mRNA vs. GPT |
Research Applications
Product Specs
MGSSHHHHHH SSGLVPRGSH MQRAAVLVRR GSCPRASGPW GRSHSSAAAE ASAALKVRPE RSPRDRILTL ESMNPQVKAV EYAVRGPIVL KAGEIEMELQ RGIKKPFTEV IRANIGDAHA MGQQPITFLR QVMALCTYPN LLNSPSFPED AKKRARRILQ ACGGNSLGSY SASQGVNCIR EDVAAFITRR DGVPADPDNI YLTTGASDGI STILKLLVSG GGKSRTGVMI PIPQYPLYSA VISELDAVQV NYYLDEENCW ALNVDELRRA LRQAKDHCDP KVLCIINPGN PTGQVQSRKC IEDVIHFAWE EKLFLLADEV YQDNVYSPDC RFHSFKKVLY QMGHEYSSNV ELASFHSTSK GYMGECGYRG GYMEVINLHP EIKGQLVKLL SVRLCPPVSG QAAMDIVVNP PEPGEESFEQ FSREKEFVLG NLAKKAKLTE DLFNQVPGIQ CNPLQGAMYA FPRILIPAKA VEAAQSHKMA PDMFYCMKLL EETGICVVPG SGFGQREGTY HFRMTILPPV DKLKTVLHKV KDFHLKFLEQ.
Q&A
What experimental design principles are critical for generating Gpt2-null mouse models?
To establish a Gpt2-null model, researchers must prioritize:
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Genetic targeting: Use CRISPR-Cas9 to disrupt exon regions encoding the pyridoxal 5’-phosphate (PLP) binding domain, critical for GPT2’s enzymatic function .
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Phenotypic validation: Measure postnatal brain mass weekly via MRI (e.g., 12% reduction at P21) and assess motor coordination using rotarod tests (40% latency decrease in mutants) .
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Metabolomic profiling: Apply LC-MS to quantify TCA intermediates (e.g., α-ketoglutarate levels drop to 0.8 μM in mutants vs. 2.1 μM in controls) .
Table 1: Key Phenotypic Metrics in Gpt2-Null Mice vs. Wild-Type
How do researchers distinguish GPT2-specific effects from compensatory mechanisms in mouse models?
Three methodological approaches address this:
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Dual-isotope tracing: Administer [U-13C]glucose and [15N]glutamate to track carbon/nitrogen flux. Gpt2-null mice show 70% reduction in 13C-alanine labeling, confirming GPT2’s role in interorgan nitrogen shuttling .
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Tissue-specific rescue: Express GPT2 cDNA in neural progenitors via Nestin-Cre. Partial restoration of cortical thickness (from 1.2 mm to 1.5 mm) indicates cell-autonomous effects .
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Cross-species metabolomics: Compare murine CSF with human patient samples. Both show elevated branched-chain amino acids (leucine +140%), ruling out species-specific compensation .
What mechanisms underlie contradictory findings on GPT2’s role in anaplerosis vs. cataplerosis?
Discrepancies arise from contextual metabolic demands:
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Anaplerotic role: Under glucopenia, GPT2 replenishes TCA intermediates via alanine transamination (α-ketoglutarate production increases 2.5-fold in fasted mice) .
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Cataplerotic role: In hypoxia, HIF-2α upregulates GPT2 to export mitochondrial α-ketoglutarate, supporting lipid synthesis (30% increase in citrate lyase activity) .
Resolution strategy: Use conditional Gpt2 alleles with inducible Cre drivers to model nutrient/hypoxia states.
Table 2: Context-Dependent GPT2 Metabolic Roles
How can GPT2 murine data inform therapeutic strategies for HIF-2α-driven glioblastoma?
Gpt2-null models reveal two translational angles:
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Metabolic vulnerability: GPT2 knockdown reduces glioblastoma cell migration by 65% in Boyden chamber assays . Target HIF-2α-GPT2 axis with PT2385 (HIF-2α inhibitor), decreasing tumor sphere formation by 80% .
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Therapeutic monitoring: Track deuterated alanine (D3-alanine) via PET to assess GPT2 activity in orthotopic tumors. Tumors with SUV > 4.0 show 90% GPT2 expression correlation .
What protocols validate GPT2 enzyme activity in murine tissues?
A three-step biochemical workflow is recommended:
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Mitochondrial isolation: Use differential centrifugation (10,000g pellet) from fresh cortical tissue.
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PLP-dependent assay: Measure alanine production via NADH-coupled reaction (Δ340nm = 0.8/min in wild-type vs. 0.1/min in mutants) .
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Structural validation: Perform PyRosetta modeling of patient-derived mutants (e.g., p.Pro272Leu disrupts PLP binding, reducing Vmax by 95%) .
Product Science Overview
GPT2 is involved in several key biological processes:
- Amino Acid Metabolism: It facilitates the conversion of alanine to pyruvate, which can then enter the tricarboxylic acid (TCA) cycle for energy production .
- Gluconeogenesis: By generating pyruvate, GPT2 plays a role in the synthesis of glucose from non-carbohydrate sources, which is vital during fasting or intense exercise .
- Metabolic Stress Response: The enzyme is upregulated under metabolic stress conditions, particularly in hepatocyte cell lines, indicating its role in maintaining metabolic homeostasis .
Mice with a knockout allele of the GPT2 gene exhibit several phenotypic abnormalities, including:
Recombinant GPT2 from mice is widely used in research to study its role in metabolism and its potential implications in metabolic disorders. Understanding the function and regulation of GPT2 can provide insights into conditions such as diabetes, obesity, and other metabolic diseases.
