Modulation Of Cell-cell Adhesion Research Articles

Pathways and progress in improving drug delivery through the intestinal mucosa and blood-brain barriers.

One of the major hurdles in developing therapeutic agents is the difficulty in delivering drugs through the intestinal mucosa and blood-brain barriers (BBB). The goal here is to describe the general structures of the biological barriers and the strategies to enhance drug delivery across these barriers. Prodrug methods used to improve drug penetration via the transcellular pathway have been successfully developed, and some prodrugs have been used to treat patients. The use of transporters to improve absorption of some drugs (e.g., antiviral agents) has also been successful in treating patients. Other methods, including blocking the efflux pumps to improve transcellular delivery, and modulation of cell-cell adhesion in the intercellular junctions to improve paracellular delivery across biological barriers, are still in the investigational stage.

Polysialyltransferase expression is linked to neuronal migration in the developing and adult zebrafish

Modulation of cell-cell adhesion is crucial for regulating neuronal migration and maintenance of structural plasticity in the embryonic and mature brain. Such modulation can be obtained by the enzymatic attachment of polysialic acid (PSA) to the neural cell adhesion molecule (NCAM) by means of the polysialyltransferases STX and PST. Thus, differential expression of STX and PST is likely to be responsible for varying functions of PSA-NCAM during neuronal differentiation, maintenance, plasticity, and regeneration. We have isolated the zebrafish homologues of STX (St8sia2) and PST (St8sia4) and demonstrate that their expression in the embryonic and adult nervous system is often confined to regions of neuronal migration. Moreover, in the adult cerebellum, the complementary expression pattern of both polysialyltransferases suggests a function in regulating cerebellar neuronal plasticity. Enzymatic removal of PSA in the embryonic cerebellum results in impaired neuronal migration, suggesting that PSA-NCAM is a key regulator of motility for cerebellar neuronal progenitors.

Oriented responses of cultured cardiomyocytes by mechanical stretch is regulated by N-cadherin

Objective: Hypertrophic cardiomyopathy (HCM) is a primary myocardial disease, leading to cardiac failure. Disarray of cardiomyocytes, characteristic of HCM, has been believed to lead to arrhythmia and weakness of contraction, though little is elucidated about the mechanisms for disarray. Interestingly, it was reported that mechanical stretch induced oriented responses of cardiomyocytes. To make clear the mechanisms for oriented responses, we investigated the functional significances of N-cadherin in cyclic stretch model. Methods: Neonatal rat cardiomyocytes cultured on silicone chambers were subjected to linear cyclic stretch. Mechanical stimulation was started at various times (3, 24, or 72h) after seeding and continued for 24h. Results: Three hours after cultivation, cardiomyocytes exhibited round-shape, attaching to the chamber, and stretch stimulation promoted cell orientation. In contrast, cells did not show oriented responses 72 hours after cultivation with the upregulation of its protein. Thus we replated the cardiomyocytes cultured for 72 hours and exposed the culture to stretch. The modulation of cell-cell adhesion by replating enabled cells to rearrange their orientation following stretch stimulation. Adenoviral gene transfer of dominant negative N-cadherin restored the ability to align in response to stretch. Conclusion: Our results suggested that N-cadherin could be a significant molecule as regulator of oriented responses of cardiomyocytes by mechanical stretch.

Modulation of cellular adhesion in bovine brain microvessel endothelial cells by a decapeptide

The importance of cell adhesion molecules in maintaining the cellular integrity of the endothelial layer is well recognized, yet their exact participation in regulating the blood–brain barrier (BBB) is poorly understood. Both Ca 2+-dependent and Ca 2+-independent cell adhesion molecules are found in endothelial cells. In this study, we used immunofluorescence, ELISA, Western blot and cell adhesion assay to identify a Ca 2+-dependent cell adhesion molecule, E-cadherin, in bovine brain microvessel endothelial cells (BBMECs). Monoclonal anti-E-cadherin antibody specifically interacted with cultured BBMECs and decorated the cellular junctions with a series of punctate fluorescence spots as seen by indirect immunofluorescence using a confocal microscope. The intensity of these fluorescence spots increased after brief treatment with hIFN- γ or CPT-cAMP. In the cellular extract of BBMECs, a 120 kDa protein was immunoprecipitated with anti-E-cadherin antibody. BBMECs did not react with anti-N-cadherin antibody, but recognized the FITC-labeled LRAHAVDVNG-NH 2, a decapeptide generated from the EC-1 domain of N-cadherin, which decorated the lateral margins of the cells with fluorescence spots. A concentration-dependent binding of this decapeptide was also observed in the flow cytometry assay. BBMECs dissociated with trypsin plus Ca 2+ were able to reaggregate only in the presence of Ca 2+. However, such cell-cell aggregations of BBMECs were prevented by the presence of either anti-E-cadherin antibody or the decapeptide in the assay medium. These results confirm that BBMECs possess a distinct Ca 2+-dependent cell adhesion mechanism that can be modulated by the decapeptide. This modulation of cell-cell adhesion in BBMECs by the decapeptide is thought-provoking for creating channels for paracellular drug delivery across the BBB.