ERLIN2 Antibody

What is ERLIN2 and why is it significant in cancer research?

ERLIN2 is an endoplasmic reticulum (ER) membrane protein containing an evolutionarily conserved stomatin/prohibitin/flotillin/HflK/C (SPFH) domain. The gene encoding ERLIN2 is located on chromosome 8p11.2, a region frequently altered in human breast cancers and several childhood-onset autosomal recessive motor neuron diseases . Significantly, ERLIN2 functions as a spatially and temporally regulated ER–microtubule-binding protein with an important role in cell cycle progression through interactions with mitosis-promoting factors . Its amplification and overexpression in aggressive breast cancers make it a valuable target for oncology research, particularly as it confers stress resistance and survival advantages to cancer cells .

What are the key technical specifications to consider when selecting an ERLIN2 antibody?

When selecting an ERLIN2 antibody, researchers should consider several critical specifications:

Researchers should select antibodies validated for their specific application (e.g., Western blotting, immunohistochemistry) . For studying specific domains of ERLIN2, epitope-specific antibodies (such as C-terminal targeting) may be required .

How does ERLIN2 function in the ER stress response pathway and UPR activation?

ERLIN2 serves as a novel mediator of ER stress response, functioning downstream of the IRE1α/XBP1 axis within the unfolded protein response (UPR) pathway . Studies demonstrate that IRE1α-mediated splicing of XBP1 increases ERLIN2 protein expression without affecting mRNA levels, suggesting post-transcriptional regulation . When investigating this pathway:

• Inhibition of IRE1α RNase activity significantly reduces ERLIN2 protein levels in breast cancer cells

• Forced expression of wild-type IRE1α or spliced XBP1 increases endogenous ERLIN2 protein expression

• ERLIN2 overexpression enhances adaptation to various cellular stresses associated with oncogenesis

For comprehensive pathway analysis, researchers should employ both gain-of-function (overexpression of IRE1α or XBP1s) and loss-of-function (IRE1α RNase inhibition) approaches when studying ERLIN2's role in ER stress responses .

What is the relationship between ERLIN2 and cell cycle regulation in cancer cells?

ERLIN2 exhibits cell cycle-dependent interactions and functions, particularly during G2/M phase. Research demonstrates that:

• ERLIN2 interacts with the microtubule component α-tubulin, with this interaction peaking during G2/M phase

• ERLIN2 simultaneously interacts with the mitosis-promoting complex Cyclin B1/Cdk1

• ERLIN2 facilitates K63-linked ubiquitination and stabilization of Cyclin B1 protein in G2/M phase

• Downregulation of ERLIN2 results in cell cycle arrest and repressed cancer cell proliferation

When studying ERLIN2's role in cell cycle regulation, researchers should combine cell synchronization techniques with co-immunoprecipitation assays using ERLIN2 antibodies to capture phase-specific protein interactions .

How does ERLIN2 contribute to lipid metabolism in breast cancer cells?

ERLIN2 plays a critical role in maintaining the lipogenic phenotype of breast cancer cells through:

• Regulating activation of Sterol Regulatory Element-Binding Protein 1c (SREBP1c), the key lipogenic trans-activator

• Interacting with Insulin-induced Gene 1 (INSIG1) to modulate SREBP1c activation

• Promoting lipid droplet accumulation in breast cancer cells

Research indicates that ERLIN2-amplified breast cancer cell lines (e.g., SUM225 and SUM44) possess abundant cytosolic lipid droplets, and knockdown of ERLIN2 significantly reduces cytosolic lipid droplet and cellular triglyceride content . This metabolic function represents a novel mechanism through which ERLIN2 provides growth advantages and protection from stress-induced apoptosis.

What are the optimal protocols for ERLIN2 knockdown in breast cancer cell lines?

For effective ERLIN2 knockdown, researchers have successfully employed lentiviral-based shRNA systems. A detailed methodology includes:

• Vector Selection: The Expression Arrest GIPZ lentiviral shRNAmir system has proven effective, with TurboGFP as a visual marker for successful transduction .

• Lentivirus Production:

  • Transfect 293FT cells with lentiviral expression plasmid DNA and Trans-Lentiviral packaging mix

  • Harvest viral supernatants after 24-48 hours

• Cell Infection:

  • Supplement viral supernatants with 6 μg/mL polybrene

  • Incubate target cells for 24 hours with viral supernatant

  • Select transduced cells with puromycin for 2-3 weeks for functional studies or 4-10 days for RNA extraction

• Verification of Knockdown:

  • Assess ERLIN2 mRNA levels using qRT-PCR

  • Confirm protein reduction via Western blot using anti-ERLIN2 antibodies

Notable results from previous studies show that among multiple targeted vectors, ERLIN2-shRNA vector #1 produced the most effective knockdown, with nearly complete loss of ERLIN2 protein expression in SUM-225 cells . For phenotypic assays, stable knockdown cells should be maintained under selection pressure.

What experimental approaches best demonstrate ERLIN2's role in conferring stress resistance to cancer cells?

To investigate ERLIN2's role in stress resistance, a multi-faceted experimental approach is recommended:

• Stress Challenge Assays:

  • Treat ERLIN2-overexpressing and control cells with ER stress inducers such as Tunicamycin or Thapsigargin

  • Monitor cell viability using MTT or similar assays at various timepoints post-treatment

  • Assess apoptotic markers (cleaved caspase-3, PARP) via Western blotting

• UPR Pathway Analysis:

  • Examine expression of UPR markers (BiP/GRP78, CHOP, ATF4, XBP1 splicing) in ERLIN2-modified cells

  • Compare stress-induced UPR signaling kinetics between ERLIN2-overexpressing and control cells

• ER Compartment Expansion Analysis:

  • Use ER-specific fluorescent dyes or ER-targeted GFP to visualize ER morphology

  • Quantify changes in ER volume and distribution using confocal microscopy

• Chemosensitivity Testing:

  • Assess sensitivity to anti-cancer drugs in ERLIN2-knockdown versus control cells

  • Generate dose-response curves to determine IC50 values and quantify differences

Research demonstrates that ERLIN2-amplified breast cancer cells show enhanced resistance to ER stress-inducing reagents and conventional anti-cancer drugs, with knockdown of ERLIN2 increasing sensitivity to these compounds .

How can ERLIN2 protein interactions be effectively studied using antibody-based approaches?

To study ERLIN2 protein interactions, the following antibody-based approaches have proven effective:

• Co-Immunoprecipitation (Co-IP):

  • Lyse cells in non-denaturing buffer (e.g., RIPA buffer with protease inhibitors)

  • Pre-clear lysates with protein A/G beads

  • Incubate with anti-ERLIN2 antibody (preferably 2-5 μg per mg of protein)

  • Capture antibody-protein complexes with fresh protein A/G beads

  • Wash extensively to reduce non-specific binding

  • Elute and analyze by Western blotting for interacting partners

• Proximity Ligation Assay (PLA):

  • Fix and permeabilize cells on slides

  • Incubate with primary antibodies against ERLIN2 and potential interacting partners

  • Apply PLA probes and perform ligation and amplification

  • Visualize interaction signals using fluorescence microscopy

• Cell Cycle-Specific Interaction Analysis:

  • Synchronize cells at different cell cycle phases (thymidine block for G1/S, nocodazole for G2/M)

  • Perform Co-IP with anti-ERLIN2 antibodies from cells at specific phases

  • Compare interaction patterns across cell cycle phases

This methodological approach has successfully demonstrated that ERLIN2 interacts with α-tubulin and the Cyclin B1/Cdk1 complex, with peak interaction during G2/M phase . Similarly, ERLIN2's interaction with INSIG1 for regulation of SREBP1c activation has been characterized using these techniques .

How can inconsistent ERLIN2 antibody staining in tissue samples be resolved?

Inconsistent ERLIN2 antibody staining in tissue samples can be addressed through several methodological refinements:

• Fixation Optimization:

  • Test multiple fixation protocols (10% neutral buffered formalin, Bouin's solution, or paraformaldehyde)

  • Optimize fixation duration (6-24 hours) to preserve epitope accessibility

• Antigen Retrieval Comparison:

  • Compare heat-induced epitope retrieval methods:

    • Citrate buffer (pH 6.0)

    • EDTA buffer (pH 8.0-9.0)

    • Tris-EDTA buffer (pH 9.0)

  • Test microwave, pressure cooker, and water bath methods

• Antibody Validation:

  • Use positive control tissues (ERLIN2-amplified breast cancer samples)

  • Include negative controls (normal adult tissues with undetectable ERLIN2)

  • Employ peptide competition assays to confirm specificity

• Signal Amplification:

  • Implement tyramide signal amplification for weak signals

  • Optimize primary antibody concentration and incubation time (4°C overnight often yields better results than 1-2 hours at room temperature)

• Quantification Approach:

  • Use digital image analysis software to standardize interpretation

  • Establish clear scoring criteria (H-score or Allred score)

Consider that ERLIN2 expression varies by developmental stage and cellular stress status, which may account for some biological variability independent of technical factors .

What are the common pitfalls in analyzing ERLIN2's role in ER stress pathways and how can they be avoided?

When analyzing ERLIN2's role in ER stress pathways, researchers should be aware of these common pitfalls and their solutions:

• Confounding UPR Activation:

  • Pitfall: Cell culture conditions (confluency, serum starvation) can activate UPR independently

  • Solution: Maintain consistent culture conditions and include appropriate time-matched controls

• Temporal Dynamics Misinterpretation:

  • Pitfall: Single time-point measurements miss the dynamic nature of UPR signaling

  • Solution: Perform time-course experiments (0-48h) to capture the full activation and resolution profile

• IRE1α-XBP1 Axis Specificity:

  • Pitfall: Assuming ERLIN2 regulation is exclusive to IRE1α-XBP1 pathway

  • Solution: Simultaneously assess all three UPR branches (IRE1α, PERK, ATF6) when studying ERLIN2

• Knockdown Efficiency Variation:

  • Pitfall: Variable knockdown efficiency leading to inconsistent results

  • Solution: Use multiple shRNA constructs, verify knockdown by both qRT-PCR and Western blot, and consider rescue experiments

• Cell Type-Specific Effects:

  • Pitfall: Generalizing findings from one cell line to all breast cancer subtypes

  • Solution: Test effects in multiple cell lines representing different breast cancer subtypes (luminal, Her2+, triple-negative)

• ER Stress Inducer Selection:

  • Pitfall: Different ER stress inducers (tunicamycin, thapsigargin, DTT) affect distinct aspects of ER function

  • Solution: Use multiple stress inducers and compare response patterns

Research has shown that ERLIN2 regulation by the IRE1α/XBP1 axis appears to be post-transcriptional, as XBP1 overexpression increases ERLIN2 protein but not mRNA levels . This highlights the importance of examining both transcript and protein levels when studying ERLIN2 regulation.

How can researchers reconcile contradictory data regarding ERLIN2's molecular functions?

Researchers encountering contradictory data regarding ERLIN2's molecular functions should implement the following strategies:

• Context-Dependent Function Analysis:

  • Systematically compare experimental conditions between contradictory studies

  • Test ERLIN2 function across multiple cell types to identify cell type-specific roles

  • Examine ERLIN2 function under various stress conditions versus basal conditions

• Isoform-Specific Investigation:

  • Determine if contradictory results stem from differential isoform expression

  • Use isoform-specific antibodies or constructs to distinguish functions

  • Sequence verify all expression constructs to confirm correct isoform usage

• Protein Complex Composition Analysis:

  • ERLIN2 functions through multiple protein complexes:

    • With α-tubulin and Cyclin B1/Cdk1 for cell cycle regulation

    • With INSIG1 for SREBP1c activation

    • Within ERAD complexes for protein degradation

  • Map interaction networks under specific cellular conditions to resolve functional contradictions

• Integrated Multi-Omics Approach:

  • Combine proteomics, transcriptomics, and lipidomics data

  • Correlate ERLIN2 levels with global cellular changes

  • Identify convergent pathways across different experimental systems

For example, ERLIN2 has been implicated in both cell cycle regulation through Cyclin B1 stabilization and in ER stress adaptation through undefined mechanisms . These seemingly distinct functions may be reconciled by recognizing ERLIN2's role at the interface of ER homeostasis and cell cycle checkpoints, particularly as ER stress affects cell cycle progression.

What are the most promising approaches for targeting ERLIN2 in cancer therapeutics?

Based on current research, several promising approaches for targeting ERLIN2 in cancer therapeutics warrant investigation:

• Direct ERLIN2 Inhibition:

  • Develop small molecule inhibitors targeting ERLIN2's interaction with key partners (e.g., α-tubulin, INSIG1)

  • Design peptide mimetics that disrupt ERLIN2-mediated protein complexes

  • Explore antibody-drug conjugates targeting ERLIN2-overexpressing cells

• Synthetic Lethality Exploitation:

  • Screen for compounds selectively lethal to ERLIN2-amplified cancer cells

  • Identify pathways that become essential in ERLIN2-overexpressing contexts

  • Target compensatory mechanisms that emerge after ERLIN2 inhibition

• Combinatorial Approaches:

  • Combine ERLIN2 suppression with ER stress inducers to overwhelm adaptive capacity

  • Pair ERLIN2 targeting with cell cycle inhibitors to exploit its role in Cyclin B1 stabilization

  • Test ERLIN2 inhibition alongside lipogenesis inhibitors to target multiple cancer survival mechanisms

• Predictive Biomarker Development:

  • Establish ERLIN2 amplification/overexpression as a biomarker for specific therapeutic vulnerabilities

  • Identify patient subgroups most likely to benefit from ERLIN2-targeted approaches

Research has demonstrated that ERLIN2 knockdown increases cancer cell sensitivity to anticancer drugs, suggesting that targeting ERLIN2 could be an effective strategy to enhance conventional chemotherapy responses .

How might ERLIN2 antibodies be utilized for developing novel diagnostic tools?

ERLIN2 antibodies show significant potential for novel diagnostic applications in oncology:

• Tissue-Based Diagnostics:

  • Develop immunohistochemistry-based prognostic tests for breast cancer stratification

  • Create multiplex staining panels combining ERLIN2 with other markers of ER stress and cell cycle regulation

  • Establish digital pathology algorithms for quantitative ERLIN2 assessment

• Liquid Biopsy Applications:

  • Investigate ERLIN2 in circulating tumor cells as a marker of aggressive disease

  • Develop assays for ERLIN2-positive extracellular vesicles in patient plasma

  • Explore ERLIN2 autoantibodies as potential serological cancer biomarkers

• Functional Diagnostic Tests:

  • Create ex vivo assays using patient-derived tissues to assess ERLIN2-dependent therapeutic vulnerabilities

  • Develop ERLIN2-based companion diagnostics for future targeted therapies

• Early Detection Strategies:

  • Evaluate ERLIN2 expression in pre-malignant breast lesions for risk stratification

  • Assess ERLIN2 in high-risk populations for early cancer detection

The finding that ERLIN2 is generally undetectable in adult normal tissues but overexpressed in a subset of breast cancers makes it particularly valuable as a potential diagnostic marker with high specificity .