LI-cadherin cis-dimerizes in the plasma membrane Ca(2+) independently and forms highly dynamic trans-contacts. Cell Mol Life Sci. 2012;69:3851-3862. [PMID: 22842778 DOI: 10.1007/s00018-012-1053-y]

Crystal structure of the nonclassical cadherin-17 N-terminus and implications for its adhesive binding mechanism

The cadherin superfamily of calcium-dependent cell-adhesion proteins has over 100 members in the human genome. All members of the superfamily feature at least a pair of extracellular cadherin (EC) repeats with calcium-binding sites in the EC linker region. The EC repeats across family members form distinct complexes that mediate cellular adhesion. For instance, classical cadherins (five EC repeats) strand-swap their N-termini and exchange tryptophan residues in EC1, while the clustered protocadherins (six EC repeats) use an extended antiparallel `forearm handshake' involving repeats EC1-EC4. The 7D-cadherins, cadherin-16 (CDH16) and cadherin-17 (CDH17), are the most similar to classical cadherins and have seven EC repeats, two of which are likely to have arisen from gene duplication of EC1-2 from a classical ancestor. However, CDH16 and CDH17 lack the EC1 tryptophan residue used by classical cadherins to mediate adhesion. The structure of human CDH17 EC1-2 presented here reveals features that are not seen in classical cadherins and that are incompatible with the EC1 strand-swap mechanism for adhesion. Analyses of crystal contacts, predicted glycosylation and disease-related mutations are presented along with sequence alignments suggesting that the novel features in the CDH17 EC1-2 structure are well conserved. These results hint at distinct adhesive properties for 7D-cadherins.

Diagnostic value and prognostic significance of LI-cadherin and miR-378e in colorectal cancer

Expression levels of LI-cadherin and miR-378e in the serum of patients with colorectal cancer, and the diagnostic value and prognostic significance in colorectal cancer were investigated. A total of 110 patients who were diagnosed with colorectal cancer in Weihai Central Hospital, from January 2012 to November 2014, were selected and enrolled in the experimental group, and 90 healthy subjects who underwent physical examination were enrolled in the control group. The expression level of miR-378e in serum was detected by reverse transcription-quantitative PCR and the expression of LI-cadherin in serum was detected by ELISA. ROC curves of LI-cadherin and miR-378e were drawn and the sensitivity and specificity of the diagnosis were estimated. The association of the expression levels of LI-cadherin and miR-378e with the survival of the patients was analyzed. LI-cadherin and miR-378e expression levels were significantly higher in the control group than those in the experimental group (P<0.001). LI-cadherin was significantly associated with the pathogenic site, the lymphatic metastasis, depth of infiltration, degree of differentiation and clinical stage (P<0.05). The sensitivity and specificity of the LI-cadherin combined with miR-378e detection were respectively 86 and 94%; the sensitivity of miR-378e detection was the highest, as well as the specificity of the combined detection. At the end of the follow-up period, the survival rates of the patients in the LI-cadherin high-expression group and miR-378e high-expression group were significantly higher than those in the low-expression groups (P<0.05). There was a significant positive correlation between the LI-cadherin and miR-378e expression levels in both the experimental and control group (r=0.5845 and 0.6356, respectively; P<0.05). In conclusion, LI-cadherin and miR-378e are expressed at low levels in colorectal cancer, suggesting that they have a good diagnostic value for colorectal cancer and can be used as biomarkers for colorectal cancer prognosis.

Beyond N-Cadherin, Relevance of Cadherins 5, 6 and 17 in Cancer Progression and Metastasis

Cell-cell adhesion molecules (cadherins) and cell-extracellular matrix adhesion proteins (integrins) play a critical role in the regulation of cancer invasion and metastasis. Although significant progress has been made in the characterization of multiple members of the cadherin superfamily, most of the published work continues to focus in the switch E-/N-cadherin and its role in the epithelial-mesenchymal transition. Here, we will discuss the structural and functional properties of a subset of cadherins (cadherin 17, cadherin 5 and cadherin 6) that have an RGD motif in the extracellular domains. This RGD motif is critical for the interaction with α2β1 integrin and posterior integrin pathway activation in cancer metastatic cells. However, other signaling pathways seem to be affected by RGD cadherin interactions, as will be discussed. The range of solid tumors with overexpression or "de novo" expression of one or more of these three cadherins is very wide (gastrointestinal, gynaecological and melanoma, among others), underscoring the relevance of these cadherins in cancer metastasis. Finally, we will discuss different evidences that support the therapeutic use of these cadherins by blocking their capacity to work as integrin ligands in order to develop new cures for metastatic patients.

Primary murine mucosal response during cephalosporin-induced intestinal colonization by Enterococcus faecium

Hospitalized patients are often administered antibiotics that perturb the gastrointestinal commensal microbiota, leading to outgrowth of antibiotic-resistant bacteria, like multidrug-resistant Enterococcus faecium, subsequent spread, and eventually infections. However, the events that occur at the initial stage of intestinal colonization and outgrowth by multidrug-resistant E. faecium within the antibiotic-treated host have not been thoroughly studied. Here, we describe and visualize that only 6 hr after cephalosporin treatment of mice, the Muc-2 mucus layer is reduced and E-cadherin junctions were altered. In contrast, the cadherin-17 junctions were unaffected in antibiotic treated mice during E. faecium colonization or in untreated animals. E. faecium was capable to colonize the mouse colon already within 6 hr after inoculation, and agglutinated at the apical side of the intestinal epithelium. During the primary stage of gastrointestinal colonization the number of IgA⁺ cells and CD11b⁺ IgA⁺ cells increased in the lamina propria of the colon and mediated an elevated IgA response upon E. faecium colonization.

Water transport through the intestinal epithelial barrier under different osmotic conditions is dependent on LI-cadherin trans-interaction

In the intestine water has to be reabsorbed from the chymus across the intestinal epithelium. The osmolarity within the lumen is subjected to high variations meaning that water transport often has to take place against osmotic gradients. It has been hypothesized that LI-cadherin is important in this process by keeping the intercellular cleft narrow facilitating the buildup of an osmotic gradient allowing water reabsorption. LI-cadherin is exceptional among the cadherin superfamily with respect to its localization along the lateral plasma membrane of epithelial cells being excluded from adherens junction. Furthermore it has 7 but not 5 extracellular cadherin repeats (EC1-EC7) and a small cytosolic domain. In this study we identified the peptide VAALD as an inhibitor of LI-cadherin trans-interaction by modeling the structure of LI-cadherin and comparison with the known adhesive interfaces of E-cadherin. This inhibitory peptide was used to measure LI-cadherin dependency of water transport through a monolayer of epithelial CACO2 cells under various osmotic conditions. If LI-cadherin trans-interaction was inhibited by use of the peptide, water transport from the luminal to the basolateral side was impaired and even reversed in the case of hypertonic conditions whereas no effect could be observed at isotonic conditions. These data are in line with a recently published model predicting LI-cadherin to keep the width of the lateral intercellular cleft small. In this narrow cleft a high osmolarity can be achieved due to ion pumps yielding a standing osmotic gradient allowing water absorption from the gut even if the faeces is highly hypertonic.

Possible roles of LI-Cadherin in the formation and maintenance of the intestinal epithelial barrier

LI-cadherin belongs to the so called 7D-cadherins, exceptional members of the cadherin superfamily which are characterized by seven extracellular cadherin repeats and a small cytosolic domain. Under physiological conditions LI-cadherin is expressed in the intestine and colon in human and mouse and in the rat also in hepatocytes. LI-cadherin was shown to act as a functional Ca²⁺-dependent adhesion molecule, linking neighboring cells and a lot of biophysical and biochemical parameters were determined in the last time. It is also known that dysregulated LI-cadherin expression can be found in a variety of diseases. Although there are several hypothesis and theoretical models concerning the function of LI-cadherin, the physiological role of LI-cadherin is still enigmatic.

Sorting out a promiscuous superfamily: towards cadherin connectomics

Members of the cadherin superfamily of proteins are involved in diverse biological processes such as morphogenesis, sound transduction, and neuronal connectivity. Key to cadherin function is their extracellular domain containing cadherin repeats, which can mediate interactions involved in adhesion and cell signaling. Recent cellular, biochemical, and structural studies have revealed that physical interaction among cadherins is more complex than originally thought. Here we review work on new cadherin complexes and discuss how the classification of the mammalian family can be used to search for additional cadherin-interacting partners. We also highlight some of the challenges in cadherin research; namely, the characterization of a cadherin connectome in biochemical and structural terms, as well as the elucidation of molecular mechanisms underlying the functional diversity of nonclassical cadherins in vivo.

Significance of expression of Li-cadherin in gastric adenocarcinoma in Xinjiang Kazakh and Han patients

AIM: To investigate the significance of expression of Li-cadherin in gastric adenocarcinoma in Xinjiang Kazakh and Han patients.

METHODS: The mRNA and protein expression of CDH17 was detected by RT-qPCR and immunohistochemisty in 30 gastric adenocarcinoma tissues and 20 normal gastric mucosal tissues from Kazakh patients, as well as 30 gastric adenocarcinoma tissues and 20 normal gastric mucosal tissues from Han patients.

RESULTS: The expression level of CDH17 mRNA was significantly higher in gastric adenocarcinoma than in normal gastric mucosal tissue in Kazakh patients (1.22 ± 0.22 vs 2.37 ± 0.30, P < 0.001). In Kakzkh patients, the positive expression rate of CDH17 protein was 70.0% in gastric adenocarcinoma, and 0 in the normal gastric mucosal tissue. No correlation was found between expression of CDH17 protein and sex, age, or tumor differentiation in gastric adenocarcinoma in Kazakh patients. There was no significant difference in the expression of CDH17 in tumor or normal tissues between Kazakh and Han patients.

CONCLUSION: The expression of CDH17 in gastric adenocarcinoma was significantly higher than that in normal gastric mucosal tissues in Kazakh patients, suggesting that CDH17 may play an important role in the occurrence and development of gastric adenocarcinoma in Xinjiang Kazakh patients. There was no significant difference in the expression of CDH17 between Kazakh and Han patients.