Decoding the Cadherin Family:
From Cell Adhesion to Tissue Homeostasis and
Disease Mechanisms

1. Cadherin: A Central Hub Linking Tissue Architecture and Cell Signaling

Cadherins were originally discovered as cell–cell adhesion molecules that maintain multicellular tissue integrity. Through homophilic binding between extracellular domains on adjacent cells, cadherins form stable adhesive junctions that preserve the spatial organization of epithelial, endothelial, cardiac, and neural tissues. For this reason, cadherins have long been regarded as the "molecular glue" of tissue stability.

However, cadherins do far more than physically tether cells together. Their intracellular domains interact with p120-catenin, β-catenin, and α-catenin to form a protein complex that links adhesion to the cytoskeleton and multiple signaling pathways (Fig. 1). This enables cells to sense environmental changes and dynamically regulate proliferation, migration, differentiation, and apoptosis. Thus, cadherins function not only as structural anchors but also as critical platforms for coordinating cellular behavior.

Figure 1. Schematic of the cadherin–catenin complex at adherens junctions ^[23]

This structure–signaling coupling places cadherins at the center of tissue homeostasis. When cell–cell junctions are intact, cadherins maintain tissue polarity, restrict aberrant migration, and suppress sustained pro-proliferative signaling. When cadherin expression is reduced, mutated, or mislocalized, adhesion weakens and tissue architecture destabilizes, while multiple signaling pathways become reactivated—ultimately driving tumor invasion, fibrosis, and developmental abnormalities.

During evolution, the cadherin superfamily has diversified into distinct functional branches. Classical cadherins maintain epithelial, endothelial, and neural connections; desmosomal cadherins provide mechanical reinforcement in skin and myocardium; and non-classical cadherins primarily regulate neural circuit formation, planar cell polarity, and organ development. Despite their functional differences, all family members rely on cadherin-mediated adhesion as a common foundation for tissue homeostasis and disease regulation.

Understanding cadherin biology requires not only appreciating their adhesive functions but also recognizing how they integrate cell junctions, mechanical stimuli, and signal transduction into a unified regulatory network.

3. Classical Cadherins: Core Regulators of Tissue Homeostasis

Classical cadherins are the most extensively studied subgroup, represented by CDH1 (E-cadherin), CDH2 (N-cadherin), and CDH5 (VE-cadherin). These molecules are characterized by their involvement in tissue architecture and cell phenotype transitions, forming a regulatory axis between epithelial and mesenchymal states.

3.1 CDH1 (E-cadherin): A Tumor Suppressor Maintaining Epithelial Homeostasis

CDH1 is predominantly expressed in epithelial tissues and is the core component of adherens junctions. By linking adjacent cells to the actin cytoskeleton, CDH1 maintains cell polarity, barrier integrity, and tissue organization.

CDH1 also functions as a negative regulator of Wnt/β-catenin signaling. Under normal conditions, CDH1 anchors β-catenin to the membrane, restricting its nuclear entry. When CDH1 expression is reduced, mutated, or silenced by promoter methylation, β-catenin is released, translocates to the nucleus, and activates oncogenes such as c-Myc and Cyclin D1, while simultaneously relieving constraints on cell migration. This makes CDH1 loss a key initiating event in epithelial–mesenchymal transition (EMT) ^[3,4].

Clinically, CDH1 germline mutations are a major cause of hereditary diffuse gastric cancer, and reduced expression is frequently observed in breast, gastric, and liver cancers ^[5]. Current research on CDH1 focuses on restoring its expression, inhibiting its degradation, and utilizing soluble E-cadherin (sE-cadherin) as a disease monitoring biomarker ^[6].

3.2 CDH2 (N-cadherin): A Key Regulator of Tissue Remodeling and Cell Migration

CDH2 is primarily expressed in mesenchymal cells, neural tissues, and myocardium, where it plays important roles in tissue remodeling, synaptic formation, and cell–cell interactions. Compared to CDH1, CDH2-mediated junctions are more dynamic, facilitating cell migration and tissue reorganization.

During tumor progression, the downregulation of CDH1 and upregulation of CDH2—known as the "cadherin switch"—is a hallmark of EMT. This switch weakens stable epithelial junctions, enhances migration, invasion, and metastatic capacity, and cooperates with TGF-β and FGF signaling to promote tumor progression ^[7].

Given its direct role in tumor invasion, CDH2 has become a promising therapeutic target. ADH-1 (Exherin), a cyclic peptide antagonist targeting the CDH2 extracellular domain, is a representative drug candidate, and several function-blocking antibodies are in preclinical development for cancer and fibrotic diseases ^[8].

3.3 CDH5 (VE-cadherin): Maintaining Vascular Barrier Integrity and Homeostasis

CDH5 is almost exclusively expressed in vascular endothelial cells and is essential for maintaining vascular barrier integrity. Under normal conditions, CDH5 forms continuous endothelial junctions that restrict plasma leakage and inflammatory cell extravasation.

Upon VEGF stimulation, the CDH5 intracellular domain undergoes phosphorylation, weakening its interaction with catenins and transiently loosening endothelial junctions to increase vascular permeability. This is a normal physiological response during angiogenesis but becomes pathological when persistently activated in tumors, inflammation, and sepsis, leading to vascular leakage, edema, and abnormal vessel formation ^[9].

Current research on CDH5 focuses on regulating vascular permeability, improving drug delivery, and inhibiting pathological angiogenesis. Circulating endothelial cells and soluble VE-cadherin are also being explored as potential disease monitoring biomarkers ^[9].

5. Non-Classical Cadherins: Neural Development, Polarity Regulation, and Genetic Disorders

Beyond classical and desmosomal cadherins, the superfamily includes a large and structurally diverse group of non-classical members, primarily protocadherins (PCDHs), the FAT family, and the CELSR family. Most of these do not directly participate in typical cell–cell adhesion but instead regulate neural circuit formation, planar cell polarity, organ development, and tissue morphogenesis—making them major research foci in developmental biology and genetics.

5.1 Protocadherins

The protocadherin family is the largest branch of the cadherin superfamily, comprising clustered PCDHs (PCDHA, PCDHB, PCDHG) and non-clustered PCDHs. Unlike classical cadherins, PCDHs lack typical catenin-binding sites in their intracellular domains and are primarily involved in neuronal recognition and connectivity rather than stable mechanical adhesion.

Clustered PCDHs are expressed in a stochastic combinatorial manner, endowing each neuron with a unique surface identity that enables self/non-self discrimination and prevents inappropriate connections—a mechanism essential for proper neural circuit assembly ^[13].

Among PCDH family members, PCDH19 and PCDH15 are the most studied. PCDH19 mutations cause clustering epilepsy (CE), with disease mechanisms involving PCDH19–β-catenin interaction and Wnt pathway dysregulation ^[14]. PCDH15 mutations cause Usher syndrome type 1F, a leading cause of hereditary deaf–blindness, for which AAV-mediated gene therapy is now in preclinical development ^[20].

5.2 FAT Family

The FAT family comprises FAT1–FAT4, characterized by exceptionally large extracellular domains that mediate long-range cell interactions. Recent studies have shown that FAT proteins not only participate in cell adhesion but also regulate Hippo-YAP signaling and planar cell polarity, playing important roles in organ development, tissue morphogenesis, and tumorigenesis.

FAT1 is highly expressed in glioblastoma and other malignancies, where it promotes tumor progression by suppressing autophagic cell death ^[15]. FAT1 also exhibits high-frequency mutations in head and neck squamous cell carcinoma, correlating with immunotherapy resistance ^[21]. Additionally, FAT1 inactivation promotes YAP/TAZ stabilization by relieving degradation ^[22].

FAT4 functions as a tumor suppressor and is involved in neuronal migration and organ development. Germline FAT4 mutations cause Van Maldergem syndrome, underscoring the essential role of FAT family members in embryonic development.

5.3 CELSR Family

CELSR1–CELSR3 are seven-pass transmembrane proteins that serve as receptors in the planar cell polarity (PCP) pathway. Unlike classical cadherins that primarily maintain cell junctions, CELSR family members govern directional cell alignment and coordinated movement within the tissue plane, with critical roles in neural tube closure, neuronal migration, ciliary orientation, and cardiovascular development.

CELSR1 mutations have been linked to brain malformations, neurodevelopmental disorders, and epilepsy ^[16]. With advances in single-cell sequencing and spatial transcriptomics, the functional networks of CELSR family members in neural development and organogenesis continue to be refined, positioning this family as a major focus of future developmental biology research.

7. Product Support

Recent advances have revealed the expanding roles of the cadherin family in oncology, biomechanics, developmental biology, and immunology. An increasing number of cadherin members are not only serving as tools for understanding disease mechanisms but also evolving into diagnostic biomarkers and therapeutic targets.

To support cadherin-related research, CUSABIO offers a range of high-quality recombinant proteins, antibodies, and ELISA kits covering multiple family members. These products are suitable for protein expression analysis, functional mechanism studies, and biomarker detection, providing experimental support for both basic research and drug development.