Circulating Ouabain Modulates Expression of Claudins in Rat Intestine and Cerebral Blood Vessels

Abstract

The ability of exogenous low ouabain concentrations to affect claudin expression and therefore epithelial barrier properties was demonstrated previously in cultured cell studies. We hypothesized that chronic elevation of circulating ouabain in vivo can affect the expression of claudins and tight junction permeability in different tissues. We tested this hypothesis in rats intraperitoneally injected with ouabain (1 μg/kg) for 4 days. Rat jejunum, colon and brain frontal lobes, which are variable in the expressed claudins and tight junction permeability, were examined. Moreover, the porcine jejunum cell line IPEC-J2 was studied. In IPEC-J2-cells, ouabain (10 nM, 19 days of incubation) stimulated epithelial barrier formation, increased transepithelial resistance and the level of cSrc-kinase activation by phosphorylation, accompanied with an increased expression of claudin-1, -5 and down-regulation of claudin-12; the expression of claudin-3, -4, -8 and tricellulin was not changed. In the jejunum, chronic ouabain increased the expression of claudin-1, -3 and -5 without an effect on claudin-2 and -4 expression. In the colon, only down-regulation of claudin-3 was observed. Chronic ouabain protected the intestine transepithelial resistance against functional injury induced by lipopolysaccharide treatment or by modeled acute microgravity; this regulation was most pronounced in the jejunum. Сlaudin-1 was also up-regulated in cerebral blood vessels. This was associated with reduction of claudin-3 expression while the expression of claudin-5 and occludin was not affected. Altogether, our results confirm that circulating ouabain can functionally and tissue-specifically affect barrier properties of epithelial and endothelial tissues via Na,K-ATPase-mediated modulation of claudins expression.

Tumor Necrosis Factor Alpha Effects on the Porcine Intestinal Epithelial Barrier Include Enhanced Expression of TNF Receptor 1

“…However, with a lack of claudin-2 expression, the TJ expression pattern of IPEC-J2 appears to be very close to Peyer's patches follicle-associated epithelium, therefore representing the main relevant epithelium involved in immune surveillance in the intestine [51,52]. Currently, many studies demonstrate the susceptibility and reliability of the non-malignant porcine epithelial cell line IPEC-J2 regarding a wide variety of mechanisms in native tissue of different species in vitro [19,53].…”

Dose and time dependence of functional impairments in rat jejunum following ionizing radiation exposure

“…As I sc reflects the intensity of ion transport through the epithelium, I sc decrease and change in sign from positive to negative probably indicates a dramatic change in the vector of ion transport between the intestinal lumen and the internal environment observed by 72 h after 10 Gy irradiation. Na,K-ATPase is known to establish a transmembrane gradient of sodium and potassium ions (Matchkov & Krivoi, 2016) and functionally interact with claudins (Markov et al, 2020). Earlier in proteomic studies, it was shown that the expression of the Atp1b3 gene, encoding one of the subunits of Na,K-ATPase, is significantly modulated in ileum epithelium of mice when exposed to ionizing radiation (Huang et al, 2019).…”

“…Previous study showed that radiation disrupts intestinal epithelial tight and adherens junctions, as well as actin cytoskeleton (Shukla at al., 2016). Na,K-ATPase, which plays a critical role in polarity and vectorial transport across epithelial cells and functionally interacts with claudins (Markov et al, 2020), is also a radiation target (Huang et al, 2019). The ability of circulating ouabain, a specific ligand of the Na,K-ATPase, to affect claudins expression and therefore epithelial barrier properties, is also most pronounced in the jejunum (Markov et al, 2020).…”

“…Na,K‐ATPase, which plays a critical role in polarity and vectorial transport across epithelial cells and functionally interacts with claudins (Markov et al, 2020), is also a radiation target (Huang et al, 2019). The ability of circulating ouabain, a specific ligand of the Na,K‐ATPase, to affect claudins expression and therefore epithelial barrier properties, is also most pronounced in the jejunum (Markov et al, 2020). These observations suggest that jejunum can serve as a convenient model for studying the molecular mechanisms of radiation‐induced disorders and approaches to their prevention.…”

Selective Role of TNFα and IL10 in Regulation of Barrier Properties of the Colon in DMH-Induced Tumor and Healthy Rats

“…TJ protein levels were analyzed in the colon segments, as described in detail earlier [ 70 ], and stain-free immunoblotting was performed, as described previously [ 71 , 72 , 73 ].…”