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A dynamic ratio of the α + and α − isoforms of the tight junction protein ZO‐1 is characteristic of Caco‐2 cells and correlates with their degree of differentiation
Author(s) -
Ciana Annarita,
Meier Katharina,
Daum Nicole,
Gerbes Stefan,
Veith Michael,
Lehr ClausMichael,
Minetti Giampaolo
Publication year - 2010
Publication title -
cell biology international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.932
H-Index - 77
eISSN - 1095-8355
pISSN - 1065-6995
DOI - 10.1042/cbi20090067
Subject(s) - tight junction , gene isoform , occludin , biology , cellular differentiation , microbiology and biotechnology , caco 2 , messenger rna , cell culture , cytoskeleton , actin , in vitro , cell , biochemistry , gene , genetics
ZO‐1 is a peripheral protein that plays a central role in the macromolecular assembly of tight junctions by interacting with integral proteins (occludin, claudins, JAMs) of the membrane of adjoining cells, with the actin cytoskeleton, and with nuclear factors. Human ZO‐1 is expressed in all epithelia and some specialized endothelia as variable amounts of two related isoforms, which originate from the alternatively spliced mRNA transcripts α + and α − and whose specific differential role is still unknown. Moreover, little is known about the timing of expression of ZO‐1 isoforms at the protein and mRNA level. This study shows that during growth of freshly plated Caco‐2 cells, the α + /α − ratio increased as a result of simultaneous increase of α + and decrease of α − . Differences in the isoform ratio also correlated with differences in epithelium differentiation. This was determined by aminopeptidase N measurements of cells grown on conventional substrates and on modified, micro/nano‐patterned surfaces. A comparable shift of ZO‐1 isoforms was not observed in other tumour cell lines of non‐intestinal origin (A549, Calu‐3). Pancreatic stem cells, propagated without exogenous differentiation stimuli, displayed a slight, stable prevalence of the α − isoform. Of the intestinal cell lines examined (Caco‐2 and T84), only Caco‐2 cells displayed a dramatic shift in isoform expression. This suggests that this tumour cell line retains to a higher degree a developmental programme related to the dynamic of enterocytic differentiation in vivo .