Rabbit Anti-Human CLDN3 (C-terminal) Polyclonal antibody

Tricellulin is a tight-junction protein present at tricellular tight junctions. It has been suggested that basal cells are implicated in the blood-epididymis barrier. Basal cells express claudins, a component of tight junctions; however, there is no information regarding the potential architecture or regulation of basal cell-principal cell interactions. The present objectives were to determine the expression and localization of tricellulin in rat epididymis in relation to occludin, basal cell-principal cell interactions, and other junctional proteins. Tricellulin levels were similar in all segments of the adult epididymis, and the protein was localized to the apical region of the epithelium. Postnatal development showed that tricellulin levels increased with age and localization changed from cytoplasmic to membrane-bound as a function of age. Colocalization with occludin indicated that both proteins are in the region of the tight junction. In the initial segment, the proteins did not colocalize compared to the epididymis where they were both colocalized. Tricellulin did not colocalize with cytokeratin 5, a marker of basal cells, in any region of the epididymis, including the corpus and cauda epididymidis, where apical projections of basal cells were apparent. Tricellulin knockdown studies using small interfering RNA in rat caput epididymal principal cells resulted in decreased transepithelial resistance and was correlated with decreased levels of Cldn3, Cldn1, and occludin. Tight-junction protein1, also known as ZO-1, and cadherin1 levels were unchanged. This is the first report of tricellulin in the epididymis and on the interaction between tricellulin and other tight-junction proteins.

Background: Because human claudin-3 and claudin-4 (CLDN3 and CLDN4) are overexpressed in a variety of carcinomas, they are promising targets for cancer therapy. The aim of the present study was to generate a dual-targeting monoclonal antibody against CLDN3 and CLDN4 and evaluate its antitumour activity. Materials and Methods: BALB/c mice were immunised with CLDN4-expressing Chinese hamster ovary cells and cell-based screening was performed. The antibody-binding epitope of CLDN3 and CLDN4 and the antitumour activity of the antibody were evaluated. Results: A monoclonal antibody, KM3907 (IgG2a), which recognised CLDN3 and CLDN4, but not CLDN5, CLDN6 and CLDN9, was successfully isolated. The binding assay of KM3907 revealed that KM3907 recognised the extracellular loop 1 of CLDN3 and CLDN4. Mouse human chimeric IgG1 induced antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity in vitro, and treatment with murine KM3907 significantly inhibited tumour formation in SCID mice in vivo. Conclusion: A dual-targeting monoclonal antibody against CLDN3 and CLDN4 is a promising strategy for cancer immunotherapy.