Regulated assembly of tight junctions by protein kinase C.

Abstract

We have previously shown that protein phosphorylation plays an important role in the sorting and assembly of tight junctions. We have now examined in detail the role of protein kinases in intercellular junction biogenesis by using a combination of highly specific and broad-spectrum inhibitors that act by independent mechanisms. Moreover, membrane-associated PKC activity more than doubled during junction assembly, and immunocytochemical analysis revealed a pool of PKC C that appeared to colocalize with ZO-1 at the tight junction. A preformed complex containing ZO-1, ZO-2, p130, as well as 330-and 65-kDa phosphoproteins was detected by coimmunoprecipitation in both the presence and absence of cell-cell contact. Identity of the 330-and 65-kDa phosphoproteins remains to be determined, but the 65-kDa protein may be occludin. The mass of this complex and the incorporation of ZO-1 into the Triton X-100-insoluble cytoskeleton were not PKC dependent.The regulation of the assembly of intercellular junctions is poorly understood but appears to be initiated by cadherinmediated cell-cell contact, followed by formation of the adherens junction and the assembly of desmosomes. Completion of tight-junction assembly then occurs along with establishment of apical-basolateral polarity (1). In epithelial cell culture models, this entire process occurs, with impressive synchrony, over the relatively short span of a few hours (2-4); however, during the compaction stage of epithelial tissue development, these events occur over several days with considerable spatiotemporal heterogeneity.

Jian carp ( Cyprinus carpio var. Jian) intestinal immune responses, antioxidant status and tight junction protein mRNA expression are modulated via Nrf2 and PKC in response to dietary arginine deficiency

“…Chasiotis and Kelly [50] reported that high levels of cortisol can upregulate claudin 7 and occludin mRNA expression in goldfish gills. Furthermore, TJ expression can be regulated by PKC signalling pathways in terrestrial animals [25]. Yamaguchi, Kojima [53] showed that inhibition of PKC reduced claudin 7 and occludin expression in human pancreatic duct epithelial cells.…”

“…The above information indicated that arginine may have an effect on fish intestinal TJs. Furthermore, a central role for protein kinase C (PKC) in the regulation of TJ expression has emerged in terrestrial animals [25]. However, information regarding the effect of arginine on PKC signalling in fish is lacking.…”

Phosphorylation of claudin-4 by PKCε regulates tight junction barrier function in ovarian cancer cells

“…Interestingly, several studies have demonstrated the involvement of various kinases in the phosphorylation and regulation of claudin proteins [29][30][31][32][33][34][35][36][37], and we have recently shown that phosphorylation of claudin-3 by PKA can affect TJ properties in ovarian cancer cells [38]. Protein kinase C (PKC) isoforms are present in ovarian cancer and are known to modulate TJ function by phosphorylation of the proteins in the complex [24,34,[39][40][41][42][43], but it is unclear whether PKC can directly phosphorylate and regulate claudin proteins. We have previously shown that claudin-4 can be phosphorylated in ovarian cancer cells upon 12-OTetradecanoylophorbol-13-acetate (TPA) stimulation [38], but the exact PKC isoforms involved, the phosphorylation sites on claudin-4, and the consequences of this phosphorylation have remained unknown.…”

JAM-A is both essential and inhibitory to development of hepatic polarity in WIF-B cells

“…The use of specific inhibitors has implicated conventional PKC (cPKC) in regulating assembly of TJs (60). In fact, ZO-1 has been shown to be a cPKC substrate (60).…”