Integrin‐linked kinase regulates migration and proliferation of human intestinal cells under a fibronectin‐dependent mechanism

Abstract

Integrin-linked kinase (ILK) plays a role in integrin signaling-mediated extracellular matrix (ECM)–cell interactions and also acts as a scaffold protein in functional focal adhesion points. In the present study, we investigated the expression and roles of ILK in human intestinal epithelial cells (IECs) in vivo and in vitro. Herein, we report that ILK and its scaffold-function interacting partners, PINCH-1, α-parvin, and β-parvin, are expressed according to a decreasing gradient from the bottom of the crypt (proliferative/undifferentiated) compartment to the tip of the villus (non-proliferative/differentiated) compartment, closely following the expression pattern of the ECM/basement membrane component fibronectin. The siRNA knockdown of ILK in human IECs caused a loss of PINCH-1, α-parvin, and β-parvin expression, along with a significant decrease in cell proliferation via a loss of cyclin D1 and an increase in p27 and hypophosphorylated pRb expression levels. ILK knockdown severely affected cell spreading, migration, and restitution abilities, which were shown to be directly related to a decrease in fibronectin deposition. All ILK knockdown-induced defects were rescued with exogenously deposited fibronectin. Altogether, our results indicate that ILK performs crucial roles in the control of human intestinal cell and crypt–villus axis homeostasis—especially with regard to basement membrane fibronectin deposition—as well as cell proliferation, spreading, and migration. J. Cell. Physiol. 222: 387–400, 2010. © 2009 Wiley-Liss, Inc.

ILK mediates the effects of strain on intestinal epithelial wound closure

“…We (9 -11, 39, 50) and others (51-53) have previously described changes in cell migration and signaling in intestinal epithelial cells of similar magnitudes in response to various stimuli. Interestingly, Gange and colleague (20) recently observed that knockdown of ILK expression inhibits human intestinal crypt cells (HIEC) cell spreading and migration and Caco-2/15 monolayer restitution (20), and the magnitude of their result in Caco-2 cells is comparable to ours. Finally, such small changes in the rate of cell migration may well be biologically important in determining whether a mucosal wound heals or fails to heal in vivo, since the tightly regulated intestinal epithelium is constantly injured and repaired, and a small change in the equilibrium between injury and repair may make the difference between an intact mucosa and a failed barrier (54 -58).…”

“…For instance, it has only recently been reported that ILK is implicated in the formation/assembly of mature focal adhesion points in human intestinal epithelial cells (20). Our observations here demonstrate that the silencing ILK in Caco-2 cells blocked the promotion of migration in response to strain.…”

“…ILK has previously been implicated in the regulation of intestinal epithelial proliferation (2,20), while certain bacteria modulate intestinal epithelial ILK to prevent infected epithelial cell detachment (34). Furthermore, ILK knockdown in vivo inhibits fibronectin deposition (20), further emphasizing the importance of the fibronectin-dependent and ILK-dependent promotion of migration by strain studied here. ILK could prove an important target to modulate the maintenance, renewal, and healing of the intestinal epithelium under pathophysiologic conditions that alter natural patterns of deformation.…”

“…Thus ILK is of particular interest as a candidate to mediate strain-stimulated intestinal epithelial migration across fibronectin because it is required for migration in some other cell types and because of its interaction with PI3K, Akt, and MLC. Interestingly, Gange et al (20) recently reported that the small interfering RNA (siRNA) knockdown of ILK in human intestinal cells severely affected cell migration, which was rescued with exogenously deposited fibronectin.…”

HIPPO–Integrin-linked Kinase Cross-Talk Controls Self-Sustaining Proliferation and Survival in Pulmonary Hypertension

“…Because HIPPO/LATS1 inactivation is linked with ECM composition, we next tested whether mechanistic link exists between LATS1 and fibronectin, increased levels of which are linked with pulmonary vascular remodeling (33)(34)(35). We found that PAH-derived PAVSMCs produce and secrete higher levels of fibronectin than control subjects ( Figures 4A, 4B, 4D, and 4E).…”