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

Cell spreading perturbation assays using antibodies to LM α2 chain. Lung mesenchymal cells were cultured in the presence of 1 and 2 μg/ml of LM α2 antibody, IgG control, or 2 μg/ml of LM α2 antibody preincubated with LM-2. Cell spreading was measured after 24 h in culture. (A) Cells in the presence of 2 μg/ml IgG. (B) Cells in the presence of 2 μg/ml LM α2 antibody. (C) Histogram obtained by measuring the maximal cell diameters under the various treatments. The inhibition in cell spreading was statistically significant, P < 0.0001 for 2 μg/ml LM α2 antibody. (D) Immunoblot showing less SM α actin in cells exposed to the anti-LM α2 chain antibody. Bar, 40 μm.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2168094&req=5

Figure 6: Cell spreading perturbation assays using antibodies to LM α2 chain. Lung mesenchymal cells were cultured in the presence of 1 and 2 μg/ml of LM α2 antibody, IgG control, or 2 μg/ml of LM α2 antibody preincubated with LM-2. Cell spreading was measured after 24 h in culture. (A) Cells in the presence of 2 μg/ml IgG. (B) Cells in the presence of 2 μg/ml LM α2 antibody. (C) Histogram obtained by measuring the maximal cell diameters under the various treatments. The inhibition in cell spreading was statistically significant, P < 0.0001 for 2 μg/ml LM α2 antibody. (D) Immunoblot showing less SM α actin in cells exposed to the anti-LM α2 chain antibody. Bar, 40 μm.

Mentions: Cell spreading is blocked by monoclonal antibodies to LM α2 chain. Effect on SM differentiation. In functional studies, 1 and 2 μg /ml of monoclonal antibody against LM α2 chain were sufficient to block mesenchymal cell spreading in a statistically significant manner (Fig. 6, A–C). Higher concentrations of antibody did not further reduce spreading. Therefore, these studies indicated a reciprocal interaction between cell shape and LM α2 by showing that not only is the LM α2 chain induced by cell spreading, but also that cell spreading is induced by the LM α2 chain. Mesenchymal cells exposed to the anti-LM α2 chain antibodies showed a decrease in synthesis of SM-specific proteins, including SM α-actin, desmin and myosin when compared with cells exposed to control immunoglobulin (Fig. 6 D, and data not shown). Attachment assays in the presence of anti-LM α2 chain antibody or IgG control showed that the antibody also inhibited cell adhesion (64% less cells attached in the presence of 20 μg/ml of anti-LM α2 chain antibodies than in the presence of same concentration of control IgG; not shown).


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)

Cell spreading perturbation assays using antibodies to LM α2 chain. Lung mesenchymal cells were cultured in the presence of 1 and 2 μg/ml of LM α2 antibody, IgG control, or 2 μg/ml of LM α2 antibody preincubated with LM-2. Cell spreading was measured after 24 h in culture. (A) Cells in the presence of 2 μg/ml IgG. (B) Cells in the presence of 2 μg/ml LM α2 antibody. (C) Histogram obtained by measuring the maximal cell diameters under the various treatments. The inhibition in cell spreading was statistically significant, P < 0.0001 for 2 μg/ml LM α2 antibody. (D) Immunoblot showing less SM α actin in cells exposed to the anti-LM α2 chain antibody. Bar, 40 μm.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 6: Cell spreading perturbation assays using antibodies to LM α2 chain. Lung mesenchymal cells were cultured in the presence of 1 and 2 μg/ml of LM α2 antibody, IgG control, or 2 μg/ml of LM α2 antibody preincubated with LM-2. Cell spreading was measured after 24 h in culture. (A) Cells in the presence of 2 μg/ml IgG. (B) Cells in the presence of 2 μg/ml LM α2 antibody. (C) Histogram obtained by measuring the maximal cell diameters under the various treatments. The inhibition in cell spreading was statistically significant, P < 0.0001 for 2 μg/ml LM α2 antibody. (D) Immunoblot showing less SM α actin in cells exposed to the anti-LM α2 chain antibody. Bar, 40 μm.
Mentions: Cell spreading is blocked by monoclonal antibodies to LM α2 chain. Effect on SM differentiation. In functional studies, 1 and 2 μg /ml of monoclonal antibody against LM α2 chain were sufficient to block mesenchymal cell spreading in a statistically significant manner (Fig. 6, A–C). Higher concentrations of antibody did not further reduce spreading. Therefore, these studies indicated a reciprocal interaction between cell shape and LM α2 by showing that not only is the LM α2 chain induced by cell spreading, but also that cell spreading is induced by the LM α2 chain. Mesenchymal cells exposed to the anti-LM α2 chain antibodies showed a decrease in synthesis of SM-specific proteins, including SM α-actin, desmin and myosin when compared with cells exposed to control immunoglobulin (Fig. 6 D, and data not shown). Attachment assays in the presence of anti-LM α2 chain antibody or IgG control showed that the antibody also inhibited cell adhesion (64% less cells attached in the presence of 20 μg/ml of anti-LM α2 chain antibodies than in the presence of same concentration of control IgG; not shown).

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