Cadherin-E Human

What is the molecular structure and organization of human E-cadherin?

E-cadherin belongs to the cadherin superfamily, which comprises over 100 cell surface glycoproteins containing cadherin repeats involved in Ca²⁺-dependent cell-cell adhesion. Classical cadherins like E-cadherin contain five extracellular cadherin repeats and a conserved cytoplasmic region that interacts with the actin cytoskeleton via catenins . E-cadherin was originally named for its prominent expression in skin epithelia, while other classical cadherins include N-cadherin (neural cadherin) expressed in the central nervous system and VE-cadherin (vascular endothelial cadherin) in blood vessel endothelia .

Beyond basic cell adhesion, E-cadherin plays essential roles in:

• Epithelialization of early embryos

• Cell rearrangement

• Tissue morphogenesis

• Establishment of cell polarity

• Maintenance of tissue architecture

How does calcium dependency influence E-cadherin function in experimental settings?

E-cadherin's function is strictly Ca²⁺-dependent, which has important implications for experimental design:

• The extracellular domains of E-cadherin contain calcium-binding sites between cadherin repeats

• Calcium binding induces conformational changes necessary for functional adhesion

• Experimental calcium chelation (using EDTA or similar agents) can be used to disrupt E-cadherin-mediated adhesion

• Standard cell culture media typically contain sufficient calcium (1-2 mM) to maintain E-cadherin function

• Researchers should be aware that calcium concentration can significantly affect experimental outcomes when studying E-cadherin

What are the validated methods for quantifying E-cadherin levels in human samples?

E-cadherin can be measured in various human biological samples using standardized techniques:

Quantitative ELISA:
The Human E-Cadherin Quantikine ELISA Kit provides highly reproducible results with excellent precision as shown below:

Precision Metrics:

These values provide important reference ranges for researchers evaluating E-cadherin levels in clinical or experimental samples.

How can NMR spectroscopy be implemented to study E-cadherin interactions with potential inhibitors?

Saturation Transfer Difference (STD) NMR spectroscopy offers powerful insights into E-cadherin-ligand interactions:

• Technical approach: Experiments can be conducted using different E-cadherin constructs (e.g., wild-type E-cadherin-EC1-EC2 fragment or truncated E-cadherin-(Val3)-EC1-EC2 fragment) to identify binding epitopes

• Temperature variables: STD-NMR can be performed at multiple temperatures (typically between 300-320K) to assess temperature-dependent binding changes

• Data interpretation: Different protein constructs may reveal different binding epitopes of the ligand, suggesting involvement of specific sequences (e.g., Asp1-Trp2) in binding events

• Complementary approach: Combining NMR with computational methods like docking calculations and molecular dynamics simulations helps interpret experimental results at the atomic level

This methodology has successfully characterized peptidomimetic ligands that mimic the tetrapeptide sequence Asp1-Trp2-Val3-Ile4 of the cadherin adhesion arm and inhibit E-cadherin-mediated adhesion in epithelial ovarian cancer cells .

How does E-cadherin functionally contribute to human pluripotent stem cell maintenance?

E-cadherin plays multifaceted roles in human pluripotent stem cell (hPSC) biology beyond mere cell adhesion:

• Marker of undifferentiated state: E-cadherin is co-expressed with undifferentiated markers (SSEA4, Tra-1-60, Tra-1-81, alkaline phosphatase) and pluripotency factors (Oct4, Nanog, Sox2) in hESCs

• Active regulator: E-cadherin directly contributes to hESC survival, self-renewal, and pluripotency maintenance

• Cloning efficiency enhancer: Upregulation of E-cadherin expression markedly enhances the cloning efficiency and self-renewal capacity of hESCs

• Survival mediator: E-cadherin-mediated cell-cell contacts provide essential survival signals to prevent apoptosis in hESCs

The molecular mechanisms linking E-cadherin to pluripotency maintenance involve complex signaling networks that are still being elucidated, offering fertile ground for further research .

What are the key differences in E-cadherin function between human ESCs and mouse ESCs?

Species-specific differences in E-cadherin function have important implications for stem cell research:

Research across species must carefully account for these differences when designing experiments and interpreting results.

How do peptidomimetic ligands interact with E-cadherin's extracellular domain at the molecular level?

Molecular investigations have revealed the dynamic nature of peptidomimetic ligand interactions with E-cadherin:

• Binding dynamics: Ligand binding to E-cadherin exhibits high variability and dynamism, explaining differences observed in ligand binding epitopes under different experimental conditions

• Temperature effects: At 300K (27°C), ligands establish stable contacts with both the hydrophobic pocket and the adhesive arm of E-cadherin, forming specific hydrogen bonds

• Structural changes: At higher temperatures (320K/47°C), these interactions are altered, with reduced contacts between the ligand and the adhesive arm

• Key interaction sites: The aromatic hydrogens of peptidomimetic ligands interact with the hydrophobic pocket residues, while NH groups form contacts with both pocket residues and the adhesive arm in a temperature-dependent manner

These findings provide crucial structural insights for the rational design of more potent and selective E-cadherin inhibitors that might prevent swap dimer formation by targeting both the Trp2 binding pocket and adhesive arm residues .

What molecular mechanisms explain the temperature-dependent binding properties of E-cadherin?

Temperature significantly influences E-cadherin's binding properties through effects on protein flexibility:

• At 300K, specific hydrogen bonds form between ligand NH groups and the E-cadherin adhesive arm with 20% population of hydrogen bonds with the backbone of Asp1

• As temperature increases to 320K, these interactions become destabilized, with adhesive arm contacts dropping to <4% population

• The NH protons lose interaction with the adhesive arm at higher temperatures

• Protein flexibility, especially at the adhesive arm level, appears to be the primary mediator of temperature-dependent binding variations

This temperature sensitivity has important implications for experimental design and interpretation, as well as for understanding the physiological behavior of E-cadherin under different conditions.

How does aberrant E-cadherin expression contribute to tumor progression mechanisms?

E-cadherin dysregulation has significant implications in cancer development:

• Abnormal E-cadherin expression correlates with different stages of tumor progression

• In epithelial ovarian cancer cells, E-cadherin mediates cell adhesion processes that influence tumor behavior

• E-cadherin's role extends beyond mechanical adhesion to influence morphogenesis, cytoskeletal organization, and cell migration - all processes relevant to cancer progression

• The rational design of small inhibitors targeting E-cadherin interactions could provide powerful tools for investigating cadherin function in tumors

What structural challenges must be overcome in developing effective E-cadherin-targeting therapeutics?

Developing E-cadherin modulators faces several complex challenges:

• The highly dynamic and reversible homo-dimerization trajectory of E-cadherin creates multiple, transient structural interfaces that are difficult to target

• Creating small drug-like molecules that effectively modulate protein-protein interactions requires overcoming inherent obstacles in binding energy and specificity

• The structural complexity of various cadherin dimerization interfaces that form and disappear during protein movement complicates drug design

• Current peptidomimetic approaches mimic the tetrapeptide sequence of the cadherin adhesion arm but achieve only millimolar potency, indicating room for improvement

Research combining spectroscopic techniques with computational methods offers promising avenues for developing novel diagnostic and therapeutic interventions for cadherin-expressing solid tumors .

How should researchers design experiments to investigate E-cadherin's role in human pluripotent stem cells?

When designing experiments to study E-cadherin in hPSCs, researchers should consider:

• Cell line selection: Using both wild-type cells and those with E-cadherin knockdown/knockout to assess functional consequences

• Expression analysis: Correlating E-cadherin expression with other pluripotency markers (Oct4, Nanog, Sox2) during maintenance and differentiation

• Functional assays: Measuring cloning efficiency, survival rates, and self-renewal capacity in response to E-cadherin modulation

• Molecular interactions: Investigating E-cadherin's interaction with other cell adhesion molecules and signaling pathways relevant to pluripotency

• Species differences: Accounting for differences between human and mouse systems when designing comparative studies

These experimental considerations will help researchers accurately characterize E-cadherin's multifaceted roles in stem cell biology.

What controls and variables must be addressed when measuring E-cadherin in clinical samples?

For reliable E-cadherin quantification in clinical research:

• Sample handling: Standardize collection, processing, and storage protocols to minimize pre-analytical variability

• Assay validation: Verify precision metrics (intra-assay CV% of 1.8-2.1% and inter-assay CV% of 5.6-6.2% should be achieved)

• Reference ranges: Compare results to established reference ranges for the specific sample type (serum: 127-492 ng/mL; plasma: 116-479 ng/mL; urine: 3.03-121 ng/mL; saliva: 21.4-278 ng/mL)

• Clinical variables: Account for potential confounding factors such as age, gender, disease stage, and concurrent medications

• Longitudinal assessment: Consider temporal variations in E-cadherin levels when designing studies with multiple timepoints