| First Author | Jain S | Year | 2011 |
| Journal | Biochem J | Volume | 437 |
| Issue | 2 | Pages | 289-99 |
| PubMed ID | 21545357 | Mgi Jnum | J:175095 |
| Mgi Id | MGI:5142361 | Doi | 10.1042/BJ20110587 |
| Citation | Jain S, et al. (2011) Protein kinase Czeta phosphorylates occludin and promotes assembly of epithelial tight junctions. Biochem J 437(2):289-99 |
| abstractText | Protein kinases play an important role in the regulation of epithelial tight junctions. In the present study, we investigated the role of PKCzeta (protein kinase Czeta) in tight junction regulation in Caco-2 and MDCK (Madin-Darby canine kidney) cell monolayers. Inhibition of PKCzeta by a specific PKCzeta pseudosubstrate peptide results in redistribution of occludin and ZO-1 (zona occludens 1) from the intercellular junctions and disruption of barrier function without affecting cell viability. Reduced expression of PKCzeta by antisense oligonucleotide or shRNA (short hairpin RNA) also results in compromised tight junction integrity. Inhibition or knockdown of PKCzeta delays calcium-induced assembly of tight junctions. Tight junction disruption by PKCzeta pseudosubstrate is associated with the dephosphorylation of occludin and ZO-1 on serine and threonine residues. PKCzeta directly binds to the C-terminal domain of occludin and phosphorylates it on threonine residues. Thr403, Thr404, Thr424 and Thr438 in the occludin C-terminal domain are the predominant sites of PKCzeta-dependent phosphorylation. A T424A or T438A mutation in full-length occludin delays its assembly into the tight junctions. Inhibition of PKCzeta also induces redistribution of occludin and ZO-1 from the tight junctions and dissociates these proteins from the detergent-insoluble fractions in mouse ileum. The present study demonstrates that PKCzeta phosphorylates occludin on specific threonine residues and promotes assembly of epithelial tight junctions. |
