GPD1 Human

What is the genomic location and structure of the human GPD1 gene?

The human GPD1 gene is located on chromosome 12q12-q13 and encodes glycerol-3-phosphate dehydrogenase 1 . The nucleotide reference sequence can be accessed through NCBI (transcript: NM_005276.4) .

For researchers investigating the gene structure:

• Use Illustrator for Biological Sequences (IBS) software to prepare visual representations of the gene structure

• The crystal structure of human GPD1 protein is available in the Protein Data Bank (PDB ID: 1X0V)

• Visualize protein structures using PyMOL software for detailed structural analysis

• Perform variant verification through Sanger sequencing of patient and parental DNA to confirm inheritance patterns

What are the primary clinical conditions associated with GPD1 mutations?

The most well-documented condition associated with GPD1 mutations is Transient Infantile Hypertriglyceridemia (HTGTI), a rare autosomal recessive disorder characterized by:

• Hypertriglyceridemia

• Hypohepatia (reduced liver function)

• Hepatomegaly (enlarged liver)

• Hepatic steatosis (fatty liver)

• Hepatic fibrosis

Clinical studies reveal that HTGTI typically presents in infancy with a median onset age of 6.0 months (range: 0.0-7.0 years) . The condition shows a male-to-female ratio of approximately 1.6:1 based on available case reports .

For researchers conducting clinical investigations, systematic approaches should include:

• Comprehensive literature searches using multiple databases (Medline, Cochrane Library, EMBASE, PubMed, Web of Science)

• Statistical analysis using appropriate software (e.g., SPSS 18.0, R with specialized packages)

• Analysis of continuous variables using one-way ANOVA or Kruskal-Wallis tests with post-hoc tests

• Analysis of categorical variables using χ2 tests with post-hoc tests

How does GPD1 expression differ across human tissues?

To analyze GPD1 expression across human tissues, researchers should employ:

• Northern blot analysis:

  • Design radiolabeled probes specific for human GPD1 mRNA

  • Hybridize to multiple human tissue Northern blots following standard protocols

• Western blotting for protein detection:

  • Tissue preparation: Pulverize tissues under liquid nitrogen and homogenize with appropriate equipment

  • Fractionation: Centrifuge homogenate at 1000g (10 min, 4°C); spin supernatant at 100,000g (1 hr, 4°C)

  • Membrane protein isolation: Resuspend pellet in buffer containing 1% SDS

  • Remove insoluble fraction: Centrifuge at 10,000g (10 min, 4°C)

  • For total protein: Homogenize tissues/disrupt cells by sonication and remove insoluble fraction by centrifugation at 15,000g (10 min, 4°C)

How does GPD1 differ functionally from GPD1-L?

GPD1-L (Glycerol-3-Phosphate Dehydrogenase 1-Like) shares structural similarity with GPD1 but displays distinct functional properties:

• GPD1-L mutations are associated with:

  • Brugada syndrome

  • Conduction system disease

  • Sudden infant death syndrome

• Molecular mechanism:

  • GPD1-L affects trafficking of the cardiac sodium channel SCN5A to cell surface membranes

  • Mutations reduce inward Na+ current, affecting cardiac function

For experimental investigation of GPD1-L:

• Generate full-length human GPD1-L clones in appropriate expression vectors (e.g., pBKCMV)

• Create GFP-fused constructs to trace protein trafficking in transfected cells

• Perform site-directed mutagenesis (e.g., QuikChange) to engineer specific mutations

• Develop viral constructs (e.g., adeno-associated viral vectors) for gene delivery

What mechanisms underlie GPD1's role in transient infantile hypertriglyceridemia?

HTGTI is caused by inactivating mutations in the GPD1 gene, though the precise pathophysiological mechanisms remain under investigation . Research methodologies to elucidate these mechanisms include:

• Genetic analysis:

  • Comprehensive sequencing to identify novel mutations

  • Variant verification through Sanger sequencing

  • Parental testing to confirm recessive inheritance patterns

• Structural and functional analysis:

  • Map mutations onto the crystal structure of human GPD1 (PDB ID: 1X0V)

  • Predict functional consequences using bioinformatic tools

  • Express recombinant wild-type and mutant proteins for functional assays

• Statistical approach for genotype-phenotype correlations:

  • Use restricted cubic spline models to analyze the relationship between triglyceride levels and age

  • Apply appropriate statistical tests based on data distribution (parametric vs. non-parametric)

Current research indicates that GPD1 mutations disrupt glycerol metabolism and triglyceride synthesis pathways, leading to transient hypertriglyceridemia during infancy that typically resolves with age.

How does GPD1 specifically mark dormant glioma stem cells and what are the implications for brain tumor research?

Ribosome profiling analysis reveals that GPD1 is specifically expressed in brain tumor stem cells (BTSCs) but not in neural stem cells (NSCs), making it a potential marker and therapeutic target .

Key research findings and methodologies:

• BTSC dormancy characteristics:

  • GPD1+ cells represent a dormant BTSC population

  • These cells are enriched at tumor borders

  • They drive tumor relapse after chemotherapy

• Experimental approaches:

  • Ribosome profiling to analyze translational differences between BTSCs and NSCs

  • Metabolomic and lipidomic analyses to characterize cellular profiles

  • Inhibition studies to assess therapeutic potential

• Functional significance:

  • GPD1 inhibition prolongs survival in glioblastoma mouse models

  • Mechanism involves alterations in cellular metabolism and protein translation

  • GPD1 inhibition compromises BTSC maintenance

• Clinical relevance:

  • Similar GPD1 expression patterns observed in human gliomas

  • GPD1 expression has prognostic associations in patients

  • Represents a potential therapeutic target that spares resident stem cells

What methodologies are most effective for analyzing GPD1 variants in clinical samples?

For comprehensive GPD1 variant analysis in research and clinical settings:

• Genetic testing approaches:

  • Next-generation sequencing panels targeting GPD1 and related genes

  • Whole exome sequencing for novel variant discovery

  • Sanger sequencing for variant confirmation

• Variant verification workflow:

  • Amplify regions of interest using PCR

  • Perform bidirectional Sanger sequencing

  • Compare sequences with reference (e.g., NM_005276.4)

• Restriction enzyme analysis for specific variants:

  • Example: C/T base-pair change at position 899 of GPD1-L creates a Hyp188I restriction site that can be used for rapid screening

• Population screening:

  • Test variants against diverse population databases

  • Screen reference individuals of various ethnicities

  • Example methodology: Screen >1000 ethnically diverse reference alleles using WAVE denaturing high-pressure liquid chromatography followed by direct sequencing for confirmation

• Statistical analysis:

  • Excel software and SPSS 18.0 for basic statistical analysis

  • Express normally distributed data as mean ± SD

  • Express non-normally distributed variables as median M (Q1, Q3)

  • Express count data as percentages (%)

What experimental models are most appropriate for studying GPD1 function?

Researchers investigating GPD1 should consider these experimental systems:

• Cell-based models:

  • HEK 293 or COS-7 cells for transfection studies

  • Design GFP-fused GPD1 constructs to trace protein trafficking

  • Confirm fusion constructs by DNA sequencing and Western blotting

• Brain tumor models (for cancer research):

  • GPD1+ BTSCs represent a distinct population with unique metabolic profiles

  • These cells drive tumor relapse after chemotherapy

  • Animal models show prolonged survival with GPD1 inhibition

• Protein expression systems:

  • Clone full-length human GPD1 in appropriate expression vectors

  • Engineer specific mutations using site-directed mutagenesis

  • Express in mammalian or bacterial systems for functional studies

• Functional assays:

  • Western blotting for protein expression

  • Subcellular fractionation to determine localization

  • Enzyme activity assays to assess functional consequences of mutations

How do alterations in GPD1 affect cellular metabolism and lipid homeostasis?

GPD1 plays a critical role in glycerolipid metabolism, and its dysfunction impacts multiple metabolic pathways:

• Metabolomic analysis:

  • GPD1+ cells display metabolic profiles distinct from normal cells

  • This distinct profile depends on GPD1 expression

• Lipidomic analysis:

  • Comprehensive profiling of lipid species in affected tissues

  • Comparison between wild-type and mutant models

  • Quantification of triglycerides and other glycerolipids

• Functional consequences:

  • In HTGTI: Hypertriglyceridemia, hepatic steatosis, and fibrosis

  • In brain tumors: Altered metabolism supporting cancer stem cell maintenance

• Experimental approach for metabolic studies:

  • Isotope labeling to track metabolic fluxes

  • Mass spectrometry for metabolite quantification

  • Integration with transcriptomic and proteomic data

What therapeutic approaches target GPD1 in disease conditions?

Based on current research, GPD1 represents a promising therapeutic target:

• In glioblastoma:

  • GPD1 inhibition prolongs survival in mouse models

  • Mechanism: Altering cellular metabolism and protein translation

  • Specifically targets dormant cancer stem cells while sparing normal neural stem cells

• Therapeutic development strategy:

  • High-throughput screening for small molecule inhibitors

  • Structure-based drug design using GPD1 crystal structure

  • Combination approaches with standard chemotherapy

• Considerations for HTGTI:

  • Transient nature may limit need for chronic therapy

  • Supportive care during symptomatic phase

  • Dietary modifications to manage hypertriglyceridemia

• Preclinical validation:

  • Test in patient-derived xenograft models

  • Evaluate specificity using GPD1 knockout models

  • Assess potential off-target effects through comprehensive profiling