Gjorevski N., Sachs N., Manfrin A., Giger S., Bragina M.E., Ordóñez-Morán P., Clevers H., Lutolf M.P.
Nature letters, 2016
Here the authors used modular synthetic hydrogel (cross-linked poly(ethylene glycol) (PEG)) to define the key extracellular matrix (ECM) parameters that govern intestinal stem cell (ISC) expansion and organoid formation, and show that separate stages of the process require different mechanical environments and ECM components. Fibronectin-based adhesion was sufficient for ISC survival and proliferation and high matrix stiffness significantly enhanced ISC expansion through a yes-associated protein 1 (YAP)-dependent mechanism. ISC differentiation and organoid formation, on the other hand, required a soft matrix and full-length laminin-111-based adhesion. The authors also produced mechanically dynamic matrices that were initially optimal for ISC expansion and subsequently permissive to differentiation and intestinal organoid formation.
Ritié L., Spenlé C., Lacroute J.I., Bolcato-Bellemin A-L., Lefebvre O., Bole-Feysot C., Jost B., Klein A., Arnold C., Kedinger M., Bagnard D., Orend G., Simon-Assmann P.
PLOS ONE, 2012
Laminin-511 is highly expressed in the intestine. To understand the mechanistic role of laminin-511 in tissue homeostasis, the researchers used RNA profiling of embryonic intestinal tissue of lama5 knockout mice and identified a lama5 specific gene expression signature. They show that laminin a5 plays a crucial role in both epithelial and mesenchymal (smooth muscle) cell behavior by inhibiting Wnt and activating PI3K signaling. We conclude that conflicting signals are elicited in the absence of lama5, which alter cell adhesion, migration as well as epithelial and muscle differentiation. The LMa5 deficient intestine also displays a smooth muscle defect and myogenic differentiation markers are affected. Laminin-511 supports adhesion of epithelial cells and Akt phosphorylation. Laminin-511 stimulates the spreading of epithelial and muscle cells (compared to laminin-111). Inhibition of Akt with wortmannin abolished spreading of epithelial cells on laminin-511 as evidenced by cell laminin-511 specifically activates Akt through the PI3K pathway in intestinal epithelial but not in mesenchymal cells. Cell migration was also higher on Laminin-511. Laminin-511 also protects cells against H2O2-induced apoptosis.
Mahoney Z.X., Stappenbeck T.S., Miner J.H
J Cell Sci. 2008
The villus basement membrane is rich in laminin α5. Here the authors show that diminution of laminin α5 in a mouse model led to a compensatory deposition of colonic laminins that resulted in a transformation from a small intestinal to a colonic mucosal architecture. The alteration in mucosal architecture was associated with reduced levels of nuclear p27Kip1, a cell cycle regulator, and altered intestinal epithelial cell proliferation, migration, and differentiation. The results suggest that laminin α5 plays a crucial role in establishing and maintaining the specific mucosal pattern of the mouse small intestine.
Bolcato-Bellemin A-L., Lefebvre O., Arnold C., Sorokin L., Miner J. H., Kedinger M., Simon-Assmann P.
Developmental Biology, 2003
Here, the function of the laminin a5 chain in the developing intestine was defined by analyzing laminin a5 -/- mutants and by grafting experiments. The authors show that laminin a5 plays a major role in smooth muscle organization and differentiation, as excessive folding of intestinal loops and delay in the expression of specific markers are observed in laminin a5 -/- mice. Loss of a5 expression was paralleled by ectopic or accelerated deposition of laminin a2 and a4 chains; this may explain why no obvious defects were observed in the villous form and enterocytic differentiation. Lack of the laminin a5 chain was accompanied by a decrease in epithelial a3B1 integrin receptor expression adjacent to the epithelial basement membrane and of Lutheran blood group glycoprotein in the smooth muscle cells, indicating that these receptors are likely mediating the a5 interactions. Taken together, the laminin a5 chain is essential for the normal development of the intestinal smooth muscle.
Teller I.C., Auclair J., Herring E., Gauthier R., Ménard D., Beaulieu J-F.
Developmental dynamics, 2007
Here, the expression of the five laminin a-chains was analyzed in the developing and mature human small intestine at the protein and transcript levels in order to further delineate specific involvement of individual laminins in relation to the epithelial cell state as defined along the functional crypt-villus axis. The results show that all of the a-laminins are expressed in significant amounts in the small intestine relative to a panel of other tissues and organs. Distinct epithelial and mesenchymal origins, as well as the differential occurrence in intestinal basement membranes according to developmental stage, along the crypt-villus axis and in compartment-related experimental intestinal cell models. Taken together, the data point out the prime importance of a2-, a3-, and a5-containing laminins for the development and maintenance of the functional human intestinal epithelium.
Lefebvre O., Sorokin L., Kedinger M., Simon-Assmann P.
Developmental Biology, 1999
In this study, the authors examine the expression patterns and the cellular origins of the laminin a2, a4, and a5 chains in the developing mouse intestine and in in vitro mouse/chick or chick/mouse interspecies hybrid intestines. All three a-laminin chains are highest in the fetal intestine undergoing intense morphogenetic movements. Laminin a4 is associated with mesenchyme-derived cell populations such as endothelium and smooth muscle. In contrast, laminin a2 and a5 chains participate in the structural organization of the subepithelial basement membrane and, in the mature intestine, show a complementary pattern of expression. All three laminin chains occur in the smooth muscle basement membrane. Laminin a2 was found to be deposited into the basement membrane exclusively by mesenchymal cells, and the laminin a5 chain was deposited by both epithelial and mesenchymal cells in an apparently developmentally regulated pattern.