Tenascin-X Induces Cell Detachment through p38 Mitogen-Activated Protein Kinase Activation

Abstract

Extracellular matrix glycoprotein tenascin-X (TNX) is the largest member of the tenascin family. In this study, we investigated the adhesive properties of TNX and the signaling pathway to be induced to mouse fibroblast L cells on TNX substrate. Approximately 45% of evaluable cells used in the cell adhesion assay were attached to purified TNX but did not spread and were rounded on TNX. The remaining 55% of cells were detached from the TNX substrate and were floating in the conditioned medium. In rounded cells on TNX, phosphorylation of focal adhesion kinase (FAK) was diminished compared with that in cells on control phosphate buffered saline (PBS). To better understand the pathways that lead to the detachment of cells on the TNX substrate, we examined phosphorylation of p38 mitogen-activated protein (MAP) kinase. Phosphorylation of p38 MAP kinase was observed in the rounded cells on TNX in a dose-dependent manner, and the maximum effect was observed at 30 min on TNX. Inhibition of p38 MAP kinase a a expression by RNA interference partially suppressed the TNX-induced cell detachment. These results suggest that the p38 MAP kinase is a major mediator of TNX-induced cell detachment.

Tenascin-X: beyond the architectural function

“…TN-X shares similar properties with the other TN molecules as it causes in vitro cell rounding 22,61 and detachment. 62 Anti-adhesive properties of TN-X are characterized by a decreased formation of focal adhesions and are correlated with an impaired phosphorylation of the Focal Adhesion Kinase (FAK) on tyrosine residue at position 397. 62 However, the mechanisms by which TN-X modulates cell adhesion are currently not known and require further investigation.…”

“…62 Anti-adhesive properties of TN-X are characterized by a decreased formation of focal adhesions and are correlated with an impaired phosphorylation of the Focal Adhesion Kinase (FAK) on tyrosine residue at position 397. 62 However, the mechanisms by which TN-X modulates cell adhesion are currently not known and require further investigation. Some matricellular proteins are able to interact directly with cell-surface receptors or other membrane-associated signaling molecules, thereby regulating intracellular pathways leading to alteration of cell adhesion.…”

Vesicoureteral reflux and the extracellular matrix connection

“…In vitro studies have shown that TNXB, like other members of the tenascin family, has anti-adhesive properties and can cause cell detachment [100, 101]. Both in vivo and in vitro studies have shown that TNXB can negatively regulate matrix metalloproteinases (MMPs), and therefore modulate ECM turnover [102, 103].…”

Tenascins and the Importance of Adhesion Modulation

“…Tenascin-R inhibits adhesion of mesenchymal and neural cells to fibronectin (Pesheva et al 1994). Osteosarcoma and bladder carcinoma cells adhere to a tenascin-X substratum, but they did not spread or assemble stress fibers (Elefteriou et al 1999) and p38 MAPK was identified as the major mediator of tenascin-X-induced cell detachment of mouse L cells (Fujie et al 2009). Addition of tenascin-W to the culture medium of cancer cells (Scherberich et al 2005;Degen et al 2007) as well as primary osteoblasts (Meloty-Kapella et al 2006;Meloty-Kapella et al 2008) stimulated their migration toward a fibronectin substratum in vitro.…”