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

Abstract

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 alpha(+) and alpha(-) 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 alpha(+)/alpha(-) ratio increased as a result of simultaneous increase of alpha(+) and decrease of alpha(-). 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 alpha(-) 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.

Characterization of protocadherin‐1 expression in primary bronchial epithelial cells: association with epithelial cell differentiation

“…3). We confirmed the kinetics of this differentiation in our ALI cultures using the ciliated-cell-specific protein FoxJ1 (23) and the ratio of the isoforms of ZO-1 associated with differentiation (24,25) (Fig. 4A).…”

“…At time points 1, 7, 21, and 45 d after the start of ALI culture, cells were harvested both for RNA and protein in duplicate. Differentiation status was confirmed by FoxJ1 and zona occludens 1 (ZO‐1) protein expression levels, both markers of epithelial differentiation (23–25).…”

Combinatory Exposure to Urolithin A, Alternariol, and Deoxynivalenol Affects Colon Cancer Metabolism and Epithelial Barrier Integrity in vitro

“…Concerning their binary mixture effects, Uro A seems to dominate the effect toward ZO-1 protein expression. ZO-1 is a TJ protein considered as a parameter for Caco-2 (HTB-37) differentiation status (73,95). Conversely, AOH possibly dictates the overall impact on TEER and LY, both serving as measures of barrier integrity per se (Figures 4, 5).…”

Moderate Dietary Protein Restriction Optimized Gut Microbiota and Mucosal Barrier in Growing Pig Model

“…Morphological alteration of the tight junctions both in protein expression and distribution may cause intestinal disorder (Suzuki, 2013 ). Claudins have strong adhesion functionand can form intercellular connections and block the intercellular space (Ciana et al, 2010 ). It has been reported claudin molecules, not occludin, were polymerized within the membranes to reconstitute paired tight junctions and were major structural components of tight junctions (Kiuchi-Saishin et al, 2002 ).…”