Characterization of the tight junction protein ZO-2 localized at the nucleus of epithelial cells.
ZO-2 is a MAGUK protein that in confluent epithelial sheets localizes at tight junctions (TJ) whereas in sparse cultures accumulates in clusters at the nucleus. Here, we have characterized several nuclear properties of ZO-2. We observe that ZO-2 is present in the nuclear matrix and co-immunoprecipitates with lamin B(1) and actin from the nuclei of sparse cultures. We show that ZO-2 presents several NLS at its amino region, that when deleted, diminish the nuclear import of the ZO-2 amino segment and impair the ability of the region to regulate the transcriptional activity of promoters controlled by AP-1. Several RS repeats are detected in the ZO-2 amino segment, however, their deletion does not preclude the display of a speckled nuclear pattern. ZO-2 displays two putative NES. However, only the second one appears to be functional, as when conjugated to ovalbumin (OV), it is able to translocate this protein from the nucleus to the cytoplasm in a leptomycin B-sensitive way.
Jaramillo
Blanca Estela
BE
Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (CINVESTAV), Mexico D.F., 07000, Mexico.
Ponce
Arturo
A
Moreno
Jacqueline
J
Betanzos
Abigail
A
Huerta
Miriam
M
Lopez-Bayghen
Esther
E
Gonzalez-Mariscal
Lorenza
L
D000199:Actins / Q000378:metabolism; D021581:Active Transport, Cell Nucleus / Q000235:genetics; D020816:Amino Acid Motifs / Q000235:genetics; D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism* / Q000648:ultrastructure; D004285:Dogs; D004847:Epithelial Cells / Q000378:metabolism* / Q000648:ultrastructure; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D005809:Genes, Regulator / Q000235:genetics; D034921:Lamin Type B / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D015530:Nuclear Matrix / Q000378:metabolism / Q000648:ultrastructure; D010047:Ovalbumin / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D021381:Protein Transport / Q000187:drug effects / Q000235:genetics; D019108:Tight Junctions / Q000378:metabolism* / Q000648:ultrastructure; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000378:metabolism; D018911:Trinucleotide Repeats / Q000235:genetics; D062827:Zonula Occludens-2 Protein
D000199:Actins; D005231:Fatty Acids, Unsaturated; D034921:Lamin Type B; D008565:Membrane Proteins; D018808:Transcription Factor AP-1; D062827:Zonula Occludens-2 Protein; D010047:Ovalbumin; C038753:leptomycin B