Anti-PARD3 (full length) polyclonal antibody

Intestinal inflammatory diseases, four of which are discussed here, are associated with alterations of claudins. In ulcerative colitis, diarrhea and antigen entry into the mucosa occurs. Claudin-2 is upregulated but data on other claudins are still limited or vary (e.g., claudin-1 and -4). Apart from that, tight junction changes contribute to diarrhea via a leak flux mechanism, while protection against antigen entry disappears behind epithelial gross lesions (erosions) and apoptotic foci. Crohn's disease is additionally characterized by a claudin-5 and claudin-8 reduction which plays an active role in antigen uptake already befgross lesions appear. In microscopic colitis (MC), upregulation of claudin-2 expression is weak and a reduction in claudin-4 may be only passively involved, while sodium malabsorption represents the main diarrheal mechanism. However, claudin-5 is removed from MC tight junctions which may be an active trigger for inflammation through antigen uptake along the so-called leaky gut concept. In celiac disease, primary barrier defects are discussed in the context of candidate genes as PARD3 which regulate cell polarity and tight junctions. The loss of claudin-5 allows small antigens to invade, while the reductions in others like claudin-3 are rather passive events. Taken together, the specific role of single tight junction proteins for the onset and perpetuation of inflammation and the recovery from these diseases is far from being fully understood and is clearly dependent on the stage of the disease, the background of the other tight junction components, the transport activity of the mucosa, and the presence of other barrier features like gross lesions, an orchestral interplay which is discussed in this article.

Disrupted cell polarity is a feature of epithelial cancers. The partitioning defective 3 (PAR-3) protein, a key component of the PAR complex that regulates the polarization of cells, is involved in tight junction formation at epithelial cell-cell contacts. Our previous study detected a homozygous deletion of the PAR-3 gene in esophageal squamous cell carcinoma (ESCC) cell lines and frequent copy number loss of the PAR-3 gene in primary ESCC. Here, we aimed to investigate the clinicopathological relevance of altered expression of the PAR-3 protein in primary ESCC. We immunohistochemically analyzed expression of the PAR-3 protein, as well as that of other tight junction proteins, ZO-1 and claudin-1, in 74 primary ESCCs. While the PAR-3 protein was expressed in the cytoplasm of basal cells, it was localized on the plasma membrane of suprabasal cells of normal squamous epithelium of the esophagus. Of the 74 ESCC tumors, 20 (27%), 11 (15%), and 13 (18%) were negative for PAR-3, ZO-1, and claudin-1 proteins, respectively. Negative PAR-3 protein expression, but not negative ZO-1 or claudin-1 expression, was significantly associated with deeper tumor invasion (P < .01), positive lymph node metastasis (P = .03), and advanced tumor stage (P = .01). Patients with PAR-3 negative tumors showed marginally significantly shorter overall survival after surgery than those with PAR-3 positive tumors (P = .053). In conclusion, these results suggest that PAR-3 protein expression is frequently lost in primary ESCC and that loss of the PAR-3 protein is associated with aggressive clinicopathological features of ESCC. (C) 2017 Elsevier Inc. All rights reserved.