Phosphorylation of zona occludens-2 by protein kinase C epsilon regulates its nuclear exportation.

Departments of Physiology, Biophysics, and Neuroscience, Center for Research and Advanced Studies (CINVESTAV), Mexico, D.F., 07360, Mexico.

Molecular biology of the cell 2009 Sep

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Here, we have analyzed the subcellular destiny of newly synthesized tight junction protein zona occludens (ZO)-2. After transfection in sparse cells, 74% of cells exhibit ZO-2 at the nucleus, and after 18 h the value decreases to 17%. The mutation S369A located within the nuclear exportation signal 1 of ZO-2 impairs the nuclear export of the protein. Because Ser369 represents a putative protein kinase C (PKC) phosphorylation site, we tested the effect of PKC inhibition and stimulation on the nuclear export of ZO-2. Our results strongly suggest that the departure of ZO-2 from the nucleus is regulated by phosphorylation at Ser369 by novel PKCepsilon. To test the route taken by ZO-2 from synthesis to the plasma membrane, we devised a novel nuclear microinjection assay in which the nucleus served as a reservoir for anti-ZO-2 antibody. Through this assay, we demonstrate that a significant amount of newly synthesized ZO-2 goes into the nucleus and is later relocated to the plasma membrane. These results constitute novel information for understanding the mechanisms that regulate the intracellular fate of ZO-2.

Citation

David Chamorro, Lourdes Alarcón, Arturo Ponce, Rocio Tapia, Héctor González-Aguilar, Martha Robles-Flores, Teresa Mejía-Castillo, José Segovia, Yamir Bandala, Eusebio Juaristi, Lorenza González-Mariscal. Phosphorylation of zona occludens-2 by protein kinase C epsilon regulates its nuclear exportation. Molecular biology of the cell. 2009 Sep;20(18):4120-9