TUSC5 Antibody

What is TUSC5 and what are its primary biological functions?

TUSC5, also known as LOST1, IFITMD3, TRARG1, or DSPB1, is a multi-pass membrane protein that belongs to the CD225 family. This protein plays several important physiological roles:

• Regulates insulin-mediated glucose uptake in adipocytes by modulating the recycling of GLUT4 (glucose transporter 4)

• Facilitates proper protein recycling during prolonged insulin stimulation, enabling complete vesicle formation

• Acts as a crucial link between the ubiquitous vesicle trafficking machinery and tissue-specific insulin-mediated glucose uptake

• May play roles in tumor suppression due to its location on chromosome 17, a region housing important tumor suppressor genes like p53 and BRCA1

Expression analysis shows TUSC5 is highly abundant in white and brown adipose tissue, mammary gland, heart, smooth and skeletal muscle, and stomach, with lower expression in lung and brain . Research has established TUSC5 as a PPARγ target gene, with knockout mice exhibiting impaired glucose disposal .

What types of TUSC5 antibodies are available for research applications?

Commercial TUSC5 antibodies come in various formats to accommodate different research needs:

These antibodies are available in multiple forms:

• Unconjugated primary antibodies for standard detection protocols

• Conjugated forms including:

  • Agarose conjugates for immunoprecipitation

  • HRP conjugates for direct Western blot detection

  • Fluorescent conjugates (PE, FITC, Alexa Fluor®) for flow cytometry and fluorescence microscopy

Different epitope targets are available, including:

• N-terminal regions (AA 1-50)

• Mid-sections (AA 78-104)

• C-terminal regions (AA 101-177)

This variety allows researchers to select antibodies optimized for their specific experimental requirements.

What laboratory applications are TUSC5 antibodies validated for?

TUSC5 antibodies have been validated for multiple research applications:

Western Blotting (WB):

• Detects TUSC5 protein in cell and tissue lysates

• Typical observed band at 19-22 kDa

• Recommended dilution ranges from 1:500-1:1000

Immunohistochemistry (IHC):

• Visualizes TUSC5 in tissue sections, particularly effective in adipose and breast tissue

• Recommended dilutions between 1:30-1:500

• May require specific antigen retrieval methods (TE buffer pH 9.0 or citrate buffer pH 6.0)

Immunofluorescence (IF) and Immunocytochemistry (ICC):

• Detects cellular localization of TUSC5

• Used for co-localization studies with GLUT4 and other trafficking proteins

• Effective for monitoring translocation during insulin stimulation

Immunoprecipitation (IP):

• Isolates TUSC5 and associated protein complexes

• Suitable for studying protein-protein interactions

• Protocols typically use 5 μg antibody with Protein G-PLUS Agarose

ELISA:

• Quantitative detection of TUSC5 protein

• Typical dilutions of 1:2000-5000

Most suppliers provide validation data showing expression in relevant positive control tissues (adipose tissue, breast cancer tissue) and specificity through knockout/knockdown models.

How should TUSC5 antibody protocols be optimized for adipose tissue analysis?

Adipose tissue presents unique challenges for immunostaining due to its high lipid content. The following optimizations are recommended based on published research:

Tissue Preparation:

• Perfuse animals with 0.9% NaCl solution prior to adipose tissue isolation to remove blood contamination

• Cut tissue into small pieces (2-4 mm) and fix with 4% paraformaldehyde

• Ensure thorough fixation but avoid overfixation, which can mask epitopes

Immunostaining Protocol:

• Permeabilization: Use PBS with 0.5% Triton-X (PBS-T) for effective permeabilization of adipocytes

• Blocking: Extended blocking (2 hours) with PBS containing 5% donkey serum, 0.05% sodium azide, 1% BSA, and 0.1% Triton-X reduces background

• Antibody incubation: For IHC/IF in adipose tissue, use primary antibodies at 1:300-1:750 dilution with overnight incubation at 4°C

• Washing: Perform multiple thorough washes (4 times, 20 minutes each) with PBS-T

Antigen Retrieval:

• Test both TE buffer pH 9.0 and citrate buffer pH 6.0 for optimal results

• For Proteintech's TUSC5 antibody, TE buffer pH 9.0 is specifically recommended

Controls:

• Include both positive controls (adipose tissue) and negative controls (tissues with minimal TUSC5 expression)

• When available, adipose tissue from Tusc5 knockout mice serves as an excellent negative control

These optimizations have been validated in published research and will help ensure specific detection of TUSC5 in adipose tissue with minimal background.

How can TUSC5 antibodies be used to study insulin resistance mechanisms?

TUSC5 plays a critical role in insulin-stimulated glucose uptake in adipocytes, making it an important target for insulin resistance studies. The following methodological approaches are recommended:

Experimental Design Considerations:

• Include both insulin-stimulated and basal conditions (standard: 100 nM insulin stimulation)

• Implement a 3-hour serum starvation in serum-free DMEM before insulin stimulation

• Examine multiple timepoints as TUSC5's role in GLUT4 trafficking is most prominent during prolonged insulin stimulation

Co-localization Analysis:

• Perform dual immunofluorescence with TUSC5 and GLUT4 antibodies

• Fixed and permeabilized cells (4% formaldehyde, 0.18% triton for 10 minutes) show excellent results

• Use confocal microscopy to assess co-localization during insulin response

Functional Assays:

• Pair TUSC5 immunodetection with glucose uptake assays using 14C-deoxyglucose

• Protocol: Incubate cells at 37°C in Krebs–Ringer buffer containing insulin, 2 mM glucose, and 14C-deoxyglucose (200 cpm/ml)

• Compare wild-type to TUSC5 knockdown models to assess functional impact

Human Sample Analysis:

• TUSC5 expression correlates with glucose tolerance in obese individuals, independent of body weight

• When analyzing patient samples, standardize for medication status, particularly PPARγ agonists like rosiglitazone which induce TUSC5

Mechanistic Investigations:

• Focus on TUSC5's role in GLUT4 recycling rather than initial membrane fusion

• Investigate protein partner interactions through co-immunoprecipitation with TUSC5 antibodies

• Consider examining TUSC5's interactions with key trafficking proteins like VAMP2, VAMP3, and Sortilin

These approaches leverage TUSC5 antibodies to gain insights into the molecular mechanisms underlying insulin resistance in adipose tissue.

What are the optimal protocols for validating TUSC5 antibody specificity?

Rigorous validation of antibody specificity is critical for reliable research outcomes. For TUSC5 antibodies, the following comprehensive validation strategies are recommended:

Genetic Validation Approaches:

• Test the antibody in tissues/cells from Tusc5 knockout mice (should show absence of signal)

• Use shRNA or siRNA knockdown models (published protocols have used both lentiviral and adenoviral delivery systems)

• Compare signal intensity between wild-type and knockdown samples via Western blot and immunostaining

Biochemical Validation:

• Verify a single band at the expected molecular weight (19-22 kDa) in Western blot

• Perform peptide competition assays by pre-incubating the antibody with immunizing peptide (should eliminate specific signal)

• Test in multiple positive control tissues (adipose tissue, mammary gland) and negative control tissues

Application-specific Validation:

• For IHC/IF: Compare staining pattern with known expression profile

• For Western blot: Verify band migration matches predicted molecular weight

• For IP: Confirm pulled-down protein by mass spectrometry or Western blot

Cross-reactivity Assessment:

• Test antibody reactivity across species if planning cross-species studies

• Many TUSC5 antibodies are reactive with human, mouse, and rat samples, but validation in each species is recommended

• Sequence alignment of the immunogen peptide across species can predict cross-reactivity

Comparison Between Antibodies:

• Use multiple antibodies targeting different epitopes of TUSC5

• Compare staining patterns between different antibody clones

• When differences are observed, additional validation steps should be undertaken

These validation approaches will ensure the specificity and reliability of TUSC5 antibodies for research applications.

How can TUSC5 antibodies be effectively used in co-immunoprecipitation studies?

Co-immunoprecipitation (Co-IP) with TUSC5 antibodies can reveal important protein-protein interactions. Based on published protocols, the following methodology is recommended:

Antibody Selection:

• For TUSC5 pull-down, agarose-conjugated antibodies provide convenience (e.g., TUSC5 Antibody B-4 AC)

• Alternatively, use unconjugated antibodies (5 μg) coupled with Protein G-PLUS Agarose beads (60 μl)

Sample Preparation:

• Cell lysis: RIPA buffer (1% NP40 with protease inhibitors, pH 7.5) has been successfully used

• For adipocytes, use fully differentiated cells (e.g., 3T3-L1 at day 8-12 post-differentiation)

• Clear lysates by centrifugation (14,000 × g, 10 minutes, 4°C)

Co-IP Protocol (Based on Published Methods):

• Pre-clear lysate with control IgG and Protein G beads (1 hour, 4°C)

• Incubate pre-cleared lysate with 5 μg TUSC5 antibody overnight at 4°C on an overhead rotator

• Add 60 μl pre-washed Protein G-PLUS Agarose and incubate for 2 hours at 4°C

• Wash 5 times with modified RIPA buffer (without NP40), using 1000 g spins for 2 minutes

• Elute in 100 μl of 2× Laemmli buffer, boil for 10 minutes, and centrifuge briefly

Potential Interaction Partners to Investigate:

• GLUT4 (SLC2A4) - primary functional partner

• Vesicle-associated proteins: VAMP2, VAMP3

• Sorting proteins: Sortilin

• Vesicle proteins: Cellugyrin

Essential Controls:

• Input control: Load 5-10% of pre-IP lysate

• Negative control: Non-specific IgG from the same species

• Validation control: Lysates from TUSC5 knockdown cells

This methodology has been successfully used to identify TUSC5 interaction partners in the context of glucose uptake regulation.

What approaches can be used to investigate the relationship between TUSC5 and PPARγ signaling?

TUSC5 has been identified as a PPARγ target gene, making this regulatory relationship important for understanding metabolic regulation. The following approaches utilize TUSC5 antibodies to explore this connection:

PPARγ Response Studies:

• Treat adipocytes with PPARγ agonists (troglitazone, GW1929, rosiglitazone) in dose-response experiments

• Use TUSC5 antibodies for Western blot or immunofluorescence to quantify protein induction

• Compare dose-response curves to the known binding affinities of these agents for PPARγ

Chromatin Immunoprecipitation (ChIP) Analysis:

• ChIP experiments have confirmed that PPARγ protein binds a ~-1.1 kb promoter sequence of murine TUSC5 during adipogenesis

• This binding occurs concurrently with histone H3 acetylation

• Use this approach to study factors affecting PPARγ binding to the TUSC5 promoter

Functional Studies:

• TUSC5 is required for the full anti-diabetic effects of TZDs (PPARγ agonists)

• In the absence of TUSC5, these effects are significantly blunted

• Use TUSC5 antibodies to confirm protein levels in knockdown/knockout models when studying PPARγ agonist responses

Tissue-Specific Regulation:

• TUSC5 expression is not induced appreciably in liver preparations overexpressing PPARs

• This suggests tissue-specific factors regulate PPARγ responsiveness of the TUSC5 gene

• Comparative studies across tissues can help identify these regulatory factors

Translational Research:

• No change in TUSC5 mRNA or protein levels was evident in type 2 diabetic patients treated with pioglitazone

• This contrasts with strong responses in cellular models

• Use TUSC5 antibodies to examine protein levels in patient samples before and after TZD treatment

These approaches leverage TUSC5 antibodies to explore the complex relationship between PPARγ signaling and TUSC5 expression in metabolic regulation.

How can researchers quantify TUSC5 expression across different metabolic conditions?

Accurate quantification of TUSC5 expression under varying metabolic conditions requires careful methodological considerations:

Western Blot Quantification:

• Use digital image capture systems with linear dynamic range

• Apply ImageJ or similar software for densitometric analysis (as mentioned in published protocols)

• Include internal controls for normalization

• Run samples in biological triplicates (minimum)

Sample Preparation Considerations:

• For adipose tissue, consistent protein extraction is critical

• Consider the impact of lipid content on extraction efficiency

• Normalize by total protein methods rather than housekeeping proteins that may vary with metabolic state

Immunofluorescence Quantification:

• Standardize image acquisition settings across all samples

• For total expression: measure mean fluorescence intensity

• For subcellular localization: quantify membrane-to-cytoplasm ratio or co-localization coefficients

• Capture multiple fields (≥5) per sample for representative analysis

Metabolic Conditions to Consider:

• Insulin stimulation:

  • Standard protocol: 100 nM insulin stimulation after 3-hour serum starvation

  • Compare acute vs. prolonged insulin stimulation (TUSC5's role is more prominent during prolonged stimulation)

• PPARγ activation:

  • Treatment with TZDs (rosiglitazone, troglitazone) or non-TZD agonists (GW1929)

  • Monitor dose-response and time-course of TUSC5 induction

• Nutritional status:

  • Fasted vs. fed state

  • Normal diet vs. high-fat diet

Data Analysis:

• Use appropriate statistical methods (ANOVA with post-hoc tests for multi-condition comparisons)

• Consider data transformations if assumptions for parametric tests aren't met

• Correlate TUSC5 levels with metabolic parameters (e.g., glucose tolerance)

These quantification approaches have been validated in published TUSC5 research and provide reliable methods for investigating TUSC5 regulation under different metabolic conditions.

When should researchers choose monoclonal versus polyclonal TUSC5 antibodies?

The choice between monoclonal and polyclonal TUSC5 antibodies should be guided by specific research applications:

Monoclonal TUSC5 Antibodies (e.g., B-4 clone):

Polyclonal TUSC5 Antibodies:

Application-Specific Recommendations:

• Western Blotting:

  • Both types work effectively

  • Monoclonals typically provide cleaner backgrounds

  • Expected TUSC5 band size: 19-22 kDa

• Immunohistochemistry:

  • Polyclonals often provide stronger signals in fixed tissues

  • Recommended dilutions for TUSC5 polyclonals: 1:50-1:500

• Co-immunoprecipitation:

  • Polyclonals often perform better for pulling down native complexes

  • Consider using separate antibodies for IP and detection

• Immunofluorescence:

  • For co-localization studies with GLUT4, both antibody types have been successfully used

  • Signal amplification may be needed with monoclonals for some applications

These considerations will help researchers select the optimal TUSC5 antibody type for their specific experimental needs.

What are common troubleshooting issues with TUSC5 antibodies and their solutions?

Researchers may encounter several challenges when working with TUSC5 antibodies. Here are common issues and their solutions:

High Background in Immunostaining:

Weak or Absent Signal:

Multiple Bands in Western Blot:

Poor Co-immunoprecipitation Results:

These troubleshooting approaches have been validated in published TUSC5 research and provide solutions to common technical challenges.

How can TUSC5 antibodies be used to investigate potential roles in cancer biology?

While TUSC5 is primarily studied in metabolic contexts, its name (Tumor Suppressor Candidate 5) and genomic location in a tumor suppressor region suggest potential roles in cancer biology. Here are methodological approaches using TUSC5 antibodies:

Expression Analysis in Cancer Tissues:

• Use IHC with TUSC5 antibodies on tumor microarrays

• Compare expression between normal and malignant tissues

• Focus on cancers associated with chromosome 17p13.3 alterations

• Correlate expression patterns with clinical parameters and outcomes

Mechanistic Investigations:

• Assess TUSC5 expression in response to oncogenic signaling

• Investigate relationships with known tumor suppressors in the region (p53, BRCA1)

• Determine if TUSC5 loss affects DNA repair mechanisms

• Use TUSC5 antibodies to monitor expression changes in response to treatments

Functional Validation Studies:

• Create TUSC5 overexpression or knockdown cancer cell models

• Measure effects on proliferation, apoptosis, and migration

• Use TUSC5 antibodies to confirm expression changes

• Investigate alterations in downstream signaling pathways

Technical Approaches:

• Use multiplexed immunofluorescence to co-stain for TUSC5 and cancer markers

• Perform tissue microarray analysis across multiple cancer types

• Consider correlation with genetic alterations in the 17p13.3 region

The loss or malfunction of TUSC5 may contribute to dysregulation of important cellular pathways, highlighting its potential importance in cancer biology . TUSC5 antibodies provide valuable tools for investigating these connections.

How can TUSC5 antibodies be used in translational research connecting basic science to clinical applications?

TUSC5 research has significant translational potential, particularly in metabolism and diabetes. TUSC5 antibodies can bridge basic science discoveries with clinical applications:

Biomarker Development:

• TUSC5 expression is predictive of glucose tolerance in obese individuals, independent of body weight

• Use antibodies to develop quantitative assays for TUSC5 in patient samples

• Correlate TUSC5 levels with metabolic parameters and disease progression

Therapeutic Response Monitoring:

• TUSC5 is a PPARγ target gene, and its absence significantly blunts the anti-diabetic effects of TZDs

• Monitor TUSC5 expression in patients before and after TZD treatment

• Investigate whether TUSC5 levels predict treatment response

Drug Development Support:

• Screen compounds for their ability to modulate TUSC5 expression

• Use TUSC5 antibodies in high-content screening approaches

• Evaluate effects of novel PPARγ modulators on TUSC5 expression

Patient Stratification:

• Identify patient subgroups based on TUSC5 expression patterns

• Determine if TUSC5 expression correlates with specific metabolic phenotypes

• Use this information to guide personalized treatment approaches

Methodological Considerations:

• Standardize sample collection and processing for clinical specimens

• Develop reproducible quantification methods suitable for clinical laboratories

• Include appropriate reference standards for inter-laboratory comparison

• Consider developing simplified assays suitable for clinical applications

These translational applications leverage TUSC5 antibodies to connect fundamental research findings with potential clinical applications in metabolic disorders and beyond.