Limits...
Cell elongation induces laminin alpha2 chain expression in mouse embryonic mesenchymal cells: role in visceral myogenesis.

Relan NK, Yang Y, Beqaj S, Miner JH, Schuger L - J. Cell Biol. (1999)

Bottom Line: In comparison, the expression of LM beta1 and gamma1 remains unchanged.These deficiencies were completely corrected by exogenous LM-2.The intestine, however, showed compensatory hyperplasia, perhaps related to its higher contractile activity.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.

ABSTRACT
Bronchial smooth muscle (SM) mesenchymal cell precursors change their shape from round to spread/elongated while undergoing differentiation. Here we show that this change in cell shape induces the expression of laminin (LM) alpha2 chain not present in round mesenchymal cells. LM alpha2 expression is reversible and switched on and off by altering the cell's shape in culture. In comparison, the expression of LM beta1 and gamma1 remains unchanged. Functional studies showed that mesenchymal cell spreading and further differentiation into SM are inhibited by an antibody against LM alpha2. Dy/dy mice express very low levels of LM alpha2 and exhibit congenital muscular dystrophy. Lung SM cells isolated from adult dy/dy mice spread defectively and synthesized less SM alpha-actin, desmin, and SM-myosin than controls. These deficiencies were completely corrected by exogenous LM-2. On histological examination, dy/dy mouse airways and gastrointestinal tract had shorter SM cells, and lungs from dy/dy mice contained less SM-specific protein. The intestine, however, showed compensatory hyperplasia, perhaps related to its higher contractile activity. This study therefore demonstrated a novel role for the LM alpha2 chain in SM myogenesis and showed that its decrease in dy/dy mice results in abnormal SM.

Show MeSH

Related in: MedlinePlus

Immunohistochemical detection of LM α2 chain in round and elongated cells in monocultures and in organotypic epithelial-mesenchymal cocultures. (A) mouse mesenchymal cells cultured for 24 h in 0.05% poly-l-lysine coated dishes remain round and negative for LM α2 chain. (B) Mesenchymal cells plated at high cell density remain negative for LM α2 chain after 24 h in culture. (C) Mesenchymal cells allowed to spread for 24 h synthesize LM α2 chain (red). (D) Epithelial-mesenchymal organotypic cocultures. Mesenchymal cells spread around epithelial cell spheres (e) and express LM α2 (arrow). The rest of the mesenchymal cells (m) form a monolayer of round cells and remain negative for LM α2. (Inset) Organotypic cultures after three days have well developed epithelial cysts with central lumens. More mesenchymal cells spread around the cysts and become positive for LM α2 chain. Bars: (A–D) 15 μm; (inset) 60 μm.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2168094&req=5

Figure 2: Immunohistochemical detection of LM α2 chain in round and elongated cells in monocultures and in organotypic epithelial-mesenchymal cocultures. (A) mouse mesenchymal cells cultured for 24 h in 0.05% poly-l-lysine coated dishes remain round and negative for LM α2 chain. (B) Mesenchymal cells plated at high cell density remain negative for LM α2 chain after 24 h in culture. (C) Mesenchymal cells allowed to spread for 24 h synthesize LM α2 chain (red). (D) Epithelial-mesenchymal organotypic cocultures. Mesenchymal cells spread around epithelial cell spheres (e) and express LM α2 (arrow). The rest of the mesenchymal cells (m) form a monolayer of round cells and remain negative for LM α2. (Inset) Organotypic cultures after three days have well developed epithelial cysts with central lumens. More mesenchymal cells spread around the cysts and become positive for LM α2 chain. Bars: (A–D) 15 μm; (inset) 60 μm.

Mentions: Immunohistochemical studies confirmed the absence of LM α2 chain in round mesenchymal cells and its presence in elongated cells (Fig. 2, A–C). In organotypic cultures epithelial cells rearrange into spheres and mesenchymal cells surround them forming also a surface-anchored monolayer (Schuger et al. 1993). A basement membrane is the novo assembled at the epithelial-mesenchymal interface (Schuger et al. 1998). The mesenchymal cells apposed to this new basement membrane elongate and become SM cells, while the rest remain round and undifferentiated (Yang et al. 1998). The elongated cells synthesized LM α2, whereas the rest remained negative (Fig. 2 D). Over time the mesenchymal cells formed cysts with central lumens and additional mesenchymal cells spread/elongated around them and synthesized LM α2 chain (Fig. 2, inset).


Cell elongation induces laminin alpha2 chain expression in mouse embryonic mesenchymal cells: role in visceral myogenesis.

Relan NK, Yang Y, Beqaj S, Miner JH, Schuger L - J. Cell Biol. (1999)

Immunohistochemical detection of LM α2 chain in round and elongated cells in monocultures and in organotypic epithelial-mesenchymal cocultures. (A) mouse mesenchymal cells cultured for 24 h in 0.05% poly-l-lysine coated dishes remain round and negative for LM α2 chain. (B) Mesenchymal cells plated at high cell density remain negative for LM α2 chain after 24 h in culture. (C) Mesenchymal cells allowed to spread for 24 h synthesize LM α2 chain (red). (D) Epithelial-mesenchymal organotypic cocultures. Mesenchymal cells spread around epithelial cell spheres (e) and express LM α2 (arrow). The rest of the mesenchymal cells (m) form a monolayer of round cells and remain negative for LM α2. (Inset) Organotypic cultures after three days have well developed epithelial cysts with central lumens. More mesenchymal cells spread around the cysts and become positive for LM α2 chain. Bars: (A–D) 15 μm; (inset) 60 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2168094&req=5

Figure 2: Immunohistochemical detection of LM α2 chain in round and elongated cells in monocultures and in organotypic epithelial-mesenchymal cocultures. (A) mouse mesenchymal cells cultured for 24 h in 0.05% poly-l-lysine coated dishes remain round and negative for LM α2 chain. (B) Mesenchymal cells plated at high cell density remain negative for LM α2 chain after 24 h in culture. (C) Mesenchymal cells allowed to spread for 24 h synthesize LM α2 chain (red). (D) Epithelial-mesenchymal organotypic cocultures. Mesenchymal cells spread around epithelial cell spheres (e) and express LM α2 (arrow). The rest of the mesenchymal cells (m) form a monolayer of round cells and remain negative for LM α2. (Inset) Organotypic cultures after three days have well developed epithelial cysts with central lumens. More mesenchymal cells spread around the cysts and become positive for LM α2 chain. Bars: (A–D) 15 μm; (inset) 60 μm.
Mentions: Immunohistochemical studies confirmed the absence of LM α2 chain in round mesenchymal cells and its presence in elongated cells (Fig. 2, A–C). In organotypic cultures epithelial cells rearrange into spheres and mesenchymal cells surround them forming also a surface-anchored monolayer (Schuger et al. 1993). A basement membrane is the novo assembled at the epithelial-mesenchymal interface (Schuger et al. 1998). The mesenchymal cells apposed to this new basement membrane elongate and become SM cells, while the rest remain round and undifferentiated (Yang et al. 1998). The elongated cells synthesized LM α2, whereas the rest remained negative (Fig. 2 D). Over time the mesenchymal cells formed cysts with central lumens and additional mesenchymal cells spread/elongated around them and synthesized LM α2 chain (Fig. 2, inset).

Bottom Line: In comparison, the expression of LM beta1 and gamma1 remains unchanged.These deficiencies were completely corrected by exogenous LM-2.The intestine, however, showed compensatory hyperplasia, perhaps related to its higher contractile activity.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.

ABSTRACT
Bronchial smooth muscle (SM) mesenchymal cell precursors change their shape from round to spread/elongated while undergoing differentiation. Here we show that this change in cell shape induces the expression of laminin (LM) alpha2 chain not present in round mesenchymal cells. LM alpha2 expression is reversible and switched on and off by altering the cell's shape in culture. In comparison, the expression of LM beta1 and gamma1 remains unchanged. Functional studies showed that mesenchymal cell spreading and further differentiation into SM are inhibited by an antibody against LM alpha2. Dy/dy mice express very low levels of LM alpha2 and exhibit congenital muscular dystrophy. Lung SM cells isolated from adult dy/dy mice spread defectively and synthesized less SM alpha-actin, desmin, and SM-myosin than controls. These deficiencies were completely corrected by exogenous LM-2. On histological examination, dy/dy mouse airways and gastrointestinal tract had shorter SM cells, and lungs from dy/dy mice contained less SM-specific protein. The intestine, however, showed compensatory hyperplasia, perhaps related to its higher contractile activity. This study therefore demonstrated a novel role for the LM alpha2 chain in SM myogenesis and showed that its decrease in dy/dy mice results in abnormal SM.

Show MeSH
Related in: MedlinePlus