meak7 Antibody

What is mEAK7 and what cellular functions does it regulate?

mEAK-7 is the mammalian ortholog of the C. elegans EAK-7 protein. It functions as a lysosomal membrane protein that activates an alternative mTOR signaling pathway through S6K2 activation and 4E-BP1 repression . This protein regulates critical cellular processes including:

• Cell proliferation

• Cell migration

• mTOR signaling at the lysosome

mEAK-7 interacts with mTOR at the lysosome, which is essential for mTOR signaling at this cellular compartment . Unlike traditional mTORC1 or mTORC2 complexes, mEAK-7 forms an alternative mTOR complex that does not include Raptor or Rictor .

Research methodologies to study mEAK-7's functions typically include:

• RNA interference to knock down mEAK-7 expression

• Overexpression studies using HA-tagged mEAK-7 constructs

• Nutrient starvation and stimulation experiments

• Immunofluorescence microscopy for localization studies

How can I detect endogenous mEAK7 in human cell lines?

Detection of endogenous mEAK-7 requires careful selection of cell lines and antibodies. Studies have identified several cell lines that express detectable levels of mEAK-7:

For detection methods:

• Validate your antibody using positive and negative control cell lines

• For Western blotting, use NP-40 or CHAPS lysis buffers that preserve protein interactions

• For immunofluorescence, fix cells with 4% paraformaldehyde and co-stain with lysosomal markers like LAMP1/LAMP2

• Use confocal microscopy to visualize lysosomal localization of mEAK-7

Note: Studies have shown that normal embryonic stem cells and fibroblasts do not express detectable levels of mEAK-7 protein .

What epitopes are typically targeted by mEAK7 antibodies?

Commercial mEAK7 antibodies typically target specific regions of the protein:

• Common immunogens include portions of amino acids 426-456 from the human protein

• Some antibodies target the TLDc domain, which is important for V-ATPase interactions

• C-terminal directed antibodies may detect the α-helix region that forms interactions with the V-ATPase B and D subunits

When selecting an antibody, consider the specific domain you wish to study, as different domains have distinct functions in mEAK-7's interaction with mTOR and V-ATPase complexes.

How does mEAK7 modulate mTOR signaling differently from canonical pathways?

mEAK-7 establishes an alternative mTOR signaling pathway that differs from conventional mTORC1 and mTORC2 in several important ways:

• Unique Complex Formation: mEAK-7 interacts with mTOR and mLST8 but does not interact with typical components of mTORC1 (Raptor, PRAS40) or mTORC2 (Rictor, Sin1)

• Differential Substrate Activation:

  • Activates S6K2 rather than S6K1

  • When mEAK-7 is knocked down, mTOR diverts from S6K2 to S6K1, resulting in increased p-S6K1 (Thr389) levels

• Nutrient Response:

  • mEAK-7 protein levels increase after stimulation with serum, amino acids, and insulin

  • mEAK-7 is essential for both basal-level and nutrient-stimulated mTOR signaling in mEAK-7+ cells

To experimentally distinguish mEAK-7-mediated from canonical mTOR signaling:

• Monitor both S6K1 and S6K2 phosphorylation states

• Assess phosphorylation patterns of 4E-BP1 at multiple sites (Ser65, Thr37/46, Thr70)

• Perform co-immunoprecipitation experiments to determine complex constituents

• Use nutrient starvation/reintroduction protocols to assess pathway dynamics

What techniques are effective for studying mEAK7's interaction with V-ATPase?

Recent structural and biochemical studies have revealed important interactions between mEAK-7 and V-ATPase complexes. The following methodologies have proven effective:

1. Co-immunoprecipitation approaches:

• Immunoprecipitate the B subunit of V-ATPase from cells overexpressing mEAK-7

• Use mild detergents like CHAPS or NP-40 to preserve protein interactions

• Confirm interactions by reverse IP (immunoprecipitating mEAK-7 and probing for V-ATPase subunits)

2. Structural analysis techniques:

• CryoEM has successfully revealed mEAK-7 interactions with V-ATPase subunits A, B, D, and E

• Focus on rotational state 2 of V-ATPase, where the interaction is most pronounced

3. Functional assays:

• V-ATPase activity assays measuring ATP hydrolysis

• Lysosomal pH measurements using pH-sensitive fluorescent probes

• Analysis of V-ATPase-dependent processes following mEAK-7 manipulation

The C-terminal α-helix of mEAK-7 forms a pincer-like grip around the B subunit of V-ATPase through hydrophobic interactions, while the TLDc domain interacts with subunits A, B, and E . This binding undergoes partial disruption during ATP hydrolysis, potentially enabling other proteins such as mTOR to bind to the α-helix of mEAK-7 .

How can I optimize immunoprecipitation protocols for detecting mEAK7-mTOR interactions?

Successful immunoprecipitation of mEAK7-mTOR complexes requires careful attention to experimental conditions:

Buffer selection is critical:

• NP-40 lysis buffer has been successfully used for most mEAK-7 immunoprecipitation experiments

• For certain interactions, especially with mTOR complexes, CHAPS buffer (which better preserves membrane protein interactions) may be superior

Recommended protocol:

• Grow cells to 80-90% confluence in appropriate media

• For nutrient response studies, starve cells in DMEM lacking amino acids for 2 hours, then stimulate with amino acids, insulin, or both for 30 minutes

• Lyse cells in buffer containing protease and phosphatase inhibitors

• Pre-clear lysates with appropriate control IgG and protein A/G beads

• Immunoprecipitate with validated antibodies against mEAK-7, mTOR, or HA-tag (for tagged constructs)

• Wash extensively to reduce background

• Elute and analyze by western blotting for interacting partners

Controls to include:

• IgG control immunoprecipitation

• Input samples (pre-immunoprecipitation)

• mEAK-7 knockdown controls to validate antibody specificity

• HA-tagged mEAK-7 constructs (WT and mutants) for validation

How can I design experiments to investigate the role of mEAK7 in cancer cell migration and invasion?

mEAK-7 has been demonstrated to play significant roles in cancer cell migration and invasion. Here are methodological approaches to investigate these functions:

Cell migration assays:

• Real-time migration monitoring: Use xCELLigence CIM-plates to quantify cell migration in real-time

  • This technology uses electrical impedance to measure cell movement through pores

  • Collect data at multiple time points (12, 24, 36, and 48 hours)

  • Compare mEAK-7 knockdown cells with control cells

• Scratch wound assay:

  • Create a scratch in a monolayer of cells treated with control or mEAK-7 siRNA

  • Monitor wound closure over 48 hours

  • Quantify the area of closure at multiple time points

• Transwell invasion assay:

  • Use Matrigel-coated invasion chambers

  • Seed approximately 50,000 cells (control or mEAK-7 knockdown) per chamber

  • Allow invasion for 24 hours

  • Fix, stain, and count cells that have invaded through the matrix

Molecular analysis:

• Monitor epithelial-mesenchymal transition (EMT) markers like N-cadherin

• Assess mTOR signaling components, particularly S6K2 and 4E-BP1 phosphorylation

• Analyze expression of matrix metalloproteinases (MMPs)

In published studies, mEAK-7 knockdown resulted in statistically significant reductions in real-time cell migration at 24, 36, and 48 hours across multiple cancer cell lines including H1975, MDA-MB-231, H1299, and HEK-293T .

What are the optimal methods for investigating mEAK7's role in radiation and chemotherapy resistance?

mEAK-7 has been implicated in promoting cisplatin and radiation resistance in cancer cells. To investigate these functions:

Radiation resistance studies:

• Clonogenic survival assay:

  • Treat cells with control or mEAK-7 siRNA for 48 hours

  • Expose to varying doses of X-ray irradiation (e.g., 2 Gy, 6 Gy)

  • Seed 2,500-5,000 cells into tissue culture plates

  • Allow colony formation for 10 days

  • Quantify surviving fraction and colony numbers

• Spheroid formation assay:

  • Particularly important for cancer stem cell (CSC) populations

  • After siRNA treatment and irradiation, seed cells in ultra-low attachment dishes

  • Culture for 1 week and assess spheroid size and number

DNA damage response analysis:

• Assess DNA damage markers (γH2AX foci) after irradiation

• Examine interactions between mEAK-7 and DNA-PKcs using co-immunoprecipitation

• Monitor DNA damage-mediated mTOR signaling through S6 and 4E-BP1 phosphorylation

Cell population studies:

• Analyze CD44+/CD90+ cancer stem cell populations, which show elevated mEAK-7 levels

• Compare mEAK-7 expression, S6K2 activation, and resistance phenotypes between stem and non-stem populations

• Use flow cytometry to isolate and characterize these populations

Research has shown that CD44+/CD90+ NSCLC cells (representing approximately 1% of the total cell population) exhibit elevated protein levels of mEAK-7, S6K2, N-cadherin, and phosphorylated S6 and 4E-BP1, indicating activated mTOR signaling with higher invasive potential compared to CD44-/CD90- cells .

How can I investigate the relationship between mEAK7 and microRNA regulation in cancer?

MicroRNA regulation of mEAK-7 represents an emerging area of research with potential therapeutic implications:

Experimental approaches:

• microRNA target validation:

  • Use luciferase reporter assays with the mEAK-7 3'UTR

  • Include both wild-type and mutated binding site constructs

  • Transfect with microRNA mimics or inhibitors

  • The Exiqon miRSearch V3.0 algorithm identified microRNA-1911-3p as regulating mEAK-7 translation

• Functional assessment:

  • Transfect cells with microRNA-1911-3p mimic

  • Assess changes in:

    • mEAK-7 protein levels (Western blot)

    • mTOR signaling (S6 and 4E-BP1 phosphorylation)

    • mTOR localization to lysosomes (co-localization with LAMP2)

    • Cell proliferation and migration

• Correlation studies in clinical samples:

  • Analyze paired expression of mEAK-7 and potential regulatory microRNAs

  • Stratify patient outcomes based on expression patterns

  • Consider cell-type specific regulation patterns

Technical considerations:

• Include appropriate controls for microRNA transfection efficiency

• Use multiple cell lines to ensure reproducibility of findings

• Validate microRNA effects at both protein and functional levels

• Consider the influence of microRNA-mediated regulation on mEAK-7's interaction with mTOR and V-ATPase

Studies have shown that MicroRNA-1911-3p targets mEAK-7 mRNA at the 3'UTR and decreases mEAK-7 protein levels, leading to suppressed mTOR signaling evidenced by significantly decreased mTOR-dependent S6 and 4E-BP1 phosphorylation in NSCLC cell lines .

What are common challenges in detecting mEAK7 with antibodies and how can they be addressed?

Researchers frequently encounter challenges when working with mEAK7 antibodies:

Challenge 1: Low endogenous expression

• Solution: Select appropriate cell lines known to express mEAK7 (H1975, MDA-MB-231, H1299)

• Use enrichment techniques like immunoprecipitation before detection

• Consider examining cancer stem cell populations (CD44+/CD90+) which show higher expression

Challenge 2: Antibody specificity issues

• Solution: Validate antibodies using mEAK-7 knockdown controls

• Include positive control lysates from cells with confirmed mEAK-7 expression

• Compare results across multiple antibodies targeting different epitopes

Challenge 3: Membrane protein solubilization

• Solution: Test multiple lysis buffers (NP-40, CHAPS, RIPA)

• Include appropriate detergent concentrations to solubilize membrane proteins without disrupting interactions

• Consider using specialized membrane protein extraction kits

Challenge 4: Storage and stability

• Solution: Aliquot antibodies to avoid repeated freeze-thaw cycles

• Store at -20°C or colder as recommended by manufacturers

• Follow manufacturer guidelines for reconstitution and buffer conditions

Some commercial antibodies have been successfully used at the following dilutions:

• Flow cytometry: 1:25 (1×10^6 cells)

• Western blot: 1:500-1:2000

• Immunohistochemistry (FFPE): 1:25

How can I design effective mEAK7 knockdown or knockout experiments?

Designing effective mEAK7 suppression experiments requires careful planning:

siRNA approach:

• Multiple studies have successfully used siRNA for mEAK7 knockdown

• Use at least two different siRNA sequences to control for off-target effects

• Typical transfection protocol: treat cells for 48 hours before analysis

• Verify knockdown efficiency by Western blot

shRNA/lentiviral approach for stable knockdown:

• Useful for long-term studies and in vivo experiments

• Select appropriate promoters (e.g., U6, H1) for consistent expression

• Include puromycin or other selection markers

• Verify knockdown stability over multiple passages

CRISPR/Cas9 knockout considerations:

• Target conserved, functionally important exons

• Design guide RNAs with minimal off-target potential

• Verify knockout by sequencing and protein expression analysis

• Be aware that complete knockout may not be achievable in all cell lines

Rescue experiments:

• Include wild-type mEAK7 expression constructs to validate phenotype specificity

• Consider domain mutants (ΔTLDc, ΔC-terminal) to investigate specific functions

• Use inducible expression systems to control timing of rescue

Important controls to include:

• Non-targeting control siRNA/shRNA

• Wild-type cells without treatment

• Partial knockdown samples to assess dose-dependency of phenotypes

• Cell viability assessments to rule out non-specific toxicity

What are promising approaches for targeting mEAK7 in cancer therapy?

Based on current research, several approaches show promise for targeting mEAK7 in cancer therapy:

Direct inhibition strategies:

• Development of small molecule inhibitors targeting the interaction between mEAK-7 and mTOR

• Peptide-based inhibitors mimicking the binding interface between mEAK-7 and V-ATPase

• Structure-based drug design focusing on the TLDc domain or C-terminal α-helix

Indirect targeting approaches:

• MicroRNA-based therapies (e.g., microRNA-1911-3p mimics) to suppress mEAK-7 translation

• Combined inhibition of mEAK-7 and DNA-PKcs for enhanced radiation sensitivity

• Lysosome-targeted drug delivery systems to disrupt mEAK-7 function at its primary localization

Biomarker potential:

• Use mEAK-7 expression as a predictor of response to mTOR inhibitors

• Stratify patients based on mEAK-7 levels for personalized treatment approaches

• Combine with other markers of mTOR pathway activation

The elucidation of the mEAK-7 protein structure and its interaction with V-ATPases presents an opportunity for developing specific inhibitors that could minimize adverse effects compared to general mTOR inhibitors . Since mEAK-7 expression is largely restricted to cancer cells, targeting this protein may potentially offer a therapeutic window that spares normal tissues .

How might mEAK7 function differ between cancer types and cellular contexts?

Understanding the context-specific roles of mEAK7 is crucial for therapeutic development:

Cancer type variations:

• Non-small cell lung cancer (NSCLC): Well-established role in proliferation, migration, and radiation resistance

• Breast cancer: Expressed in multiple lines (MDA-MB-231, HCC1937, MDA-MB-436)

• Head and neck cancer: Detected in multiple UM-SCC lines

Cellular context considerations:

• Cancer stem cells: Enhanced expression in CD44+/CD90+ populations

• Metabolic state: Function may vary depending on nutrient availability and cellular stress

• Microenvironment: Potential role in adaptation to hypoxia and acidic tumor environments

Methodological approaches to study context-dependency:

• Comparative analysis across cancer cell panels

• Single-cell analysis to identify heterogeneity within tumors

• 3D organoid cultures to better recapitulate tumor microenvironment

• In vivo models with tissue-specific manipulation of mEAK-7

While mEAK-7 consistently regulates mTOR signaling across contexts, its exact molecular partners and downstream effects may vary. Research suggests that mEAK-7 may contribute to V-ATPase-mediated mTORC1 activation in some contexts, while forming an alternative mTOR complex in others .