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Laminin alpha1 chain synthesis in the mouse developing lung: requirement for epithelial-mesenchymal contact and possible role in bronchial smooth muscle development.

Schuger L, Skubitz AP, Zhang J, Sorokin L, He L - J. Cell Biol. (1997)

Bottom Line: In a set of functional studies, embryonic lung explants were cultured in the presence of monoclonal antibodies to laminin alpha1, alpha2, and beta/gamma chains.Lung explants exposed to monoclonal antibodies to laminin alpha1 chain exhibited alterations in peribronchial cell shape and decreased smooth muscle development, as indicated by low levels of smooth muscle alpha actin and desmin.Taken together, our studies suggest that laminin alpha1 chain synthesis is regulated by epithelial-mesenchymal interaction and may play a role in airway smooth muscle development.

View Article: PubMed Central - PubMed

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

ABSTRACT
Laminins, the main components of basement membranes, are heterotrimers consisting of alpha, beta, and gamma polypeptide chains linked together by disulfide bonds. Laminins-1 and -2 are both composed of beta1 and gamma1 chains and differ from each other on their alpha chain, which is alpha1 and alpha2 for laminin-1 and -2, respectively. The present study shows that whereas laminins-1 and -2 are synthesized in the mouse developing lung and in epithelial-mesenchymal cocultures derived from it, epithelial and mesenchymal monocultures lose their ability to synthesize the laminin alpha1 chain. Synthesis of laminin alpha1 chain however returns upon re-establishment of epithelial-mesenchymal contact. Cell-cell contact is critical, since laminin alpha1 chain is not detected in monocultures exposed to coculture-conditioned medium or in epithelial-mesenchymal cocultures in which heterotypic cell-cell contact is prevented by an interposing filter. Immunohistochemical studies on cocultures treated with brefeldin A, an inhibitor of protein secretion, indicated both epithelial and mesenchymal cells synthesize laminin alpha1 chain upon heterotypic cell- cell contact. In a set of functional studies, embryonic lung explants were cultured in the presence of monoclonal antibodies to laminin alpha1, alpha2, and beta/gamma chains. Lung explants exposed to monoclonal antibodies to laminin alpha1 chain exhibited alterations in peribronchial cell shape and decreased smooth muscle development, as indicated by low levels of smooth muscle alpha actin and desmin. Taken together, our studies suggest that laminin alpha1 chain synthesis is regulated by epithelial-mesenchymal interaction and may play a role in airway smooth muscle development.

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Detection of smooth muscle α actin (SM-actin) and  desmin in lung explants cultured for 3 d in the presence of monoclonal antibodies against LM chains or control IgG. There is a decrease in smooth muscle α actin and desmin proportional to the  concentration of anti-α1 chain antibody added to the lung organ  cultures (a). The inset shows a portion of the nitrocellulose membrane stained with 0.2% amido black after immunobloting to visualize the amount of protein loaded per lane. No change in  smooth muscle α actin or desmin synthesis is observed in lung explants cultured for 3 d in the presence of a mAb to LM β1/γ1  chains, a monoclonal antibody to LM-α2 chain, or normal mouse  IgG (b).
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Figure 12: Detection of smooth muscle α actin (SM-actin) and desmin in lung explants cultured for 3 d in the presence of monoclonal antibodies against LM chains or control IgG. There is a decrease in smooth muscle α actin and desmin proportional to the concentration of anti-α1 chain antibody added to the lung organ cultures (a). The inset shows a portion of the nitrocellulose membrane stained with 0.2% amido black after immunobloting to visualize the amount of protein loaded per lane. No change in smooth muscle α actin or desmin synthesis is observed in lung explants cultured for 3 d in the presence of a mAb to LM β1/γ1 chains, a monoclonal antibody to LM-α2 chain, or normal mouse IgG (b).

Mentions: To study the development of bronchial smooth muscle, we used antibodies against two different smooth muscle-specific proteins, smooth muscle α actin and desmin. Desmin is an intermediate filament expressed in all muscle tissue and, when absent, results in smooth muscle hypoplasia and degeneration (Milner et al., 1996). These antibodies recognized the two proteins in immunoblots of mouse adult gut (rich in smooth muscle) and fetal lung tissue lysates (Fig. 11). Lung explant cultured for 3 d in the presence of a monoclonal antibody against LM α1 chain showed a decrease in smooth muscle α actin and desmin proportional to the concentration of antibody (Fig. 12 a). No change in smooth muscle α actin and desmin expression was observed in lung explants cultured for 3 d in the presence of monoclonal antibodies to LM α2 chain or to LM β1/γ1 chains compared with controls (Fig. 12 b).


Laminin alpha1 chain synthesis in the mouse developing lung: requirement for epithelial-mesenchymal contact and possible role in bronchial smooth muscle development.

Schuger L, Skubitz AP, Zhang J, Sorokin L, He L - J. Cell Biol. (1997)

Detection of smooth muscle α actin (SM-actin) and  desmin in lung explants cultured for 3 d in the presence of monoclonal antibodies against LM chains or control IgG. There is a decrease in smooth muscle α actin and desmin proportional to the  concentration of anti-α1 chain antibody added to the lung organ  cultures (a). The inset shows a portion of the nitrocellulose membrane stained with 0.2% amido black after immunobloting to visualize the amount of protein loaded per lane. No change in  smooth muscle α actin or desmin synthesis is observed in lung explants cultured for 3 d in the presence of a mAb to LM β1/γ1  chains, a monoclonal antibody to LM-α2 chain, or normal mouse  IgG (b).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2139794&req=5

Figure 12: Detection of smooth muscle α actin (SM-actin) and desmin in lung explants cultured for 3 d in the presence of monoclonal antibodies against LM chains or control IgG. There is a decrease in smooth muscle α actin and desmin proportional to the concentration of anti-α1 chain antibody added to the lung organ cultures (a). The inset shows a portion of the nitrocellulose membrane stained with 0.2% amido black after immunobloting to visualize the amount of protein loaded per lane. No change in smooth muscle α actin or desmin synthesis is observed in lung explants cultured for 3 d in the presence of a mAb to LM β1/γ1 chains, a monoclonal antibody to LM-α2 chain, or normal mouse IgG (b).
Mentions: To study the development of bronchial smooth muscle, we used antibodies against two different smooth muscle-specific proteins, smooth muscle α actin and desmin. Desmin is an intermediate filament expressed in all muscle tissue and, when absent, results in smooth muscle hypoplasia and degeneration (Milner et al., 1996). These antibodies recognized the two proteins in immunoblots of mouse adult gut (rich in smooth muscle) and fetal lung tissue lysates (Fig. 11). Lung explant cultured for 3 d in the presence of a monoclonal antibody against LM α1 chain showed a decrease in smooth muscle α actin and desmin proportional to the concentration of antibody (Fig. 12 a). No change in smooth muscle α actin and desmin expression was observed in lung explants cultured for 3 d in the presence of monoclonal antibodies to LM α2 chain or to LM β1/γ1 chains compared with controls (Fig. 12 b).

Bottom Line: In a set of functional studies, embryonic lung explants were cultured in the presence of monoclonal antibodies to laminin alpha1, alpha2, and beta/gamma chains.Lung explants exposed to monoclonal antibodies to laminin alpha1 chain exhibited alterations in peribronchial cell shape and decreased smooth muscle development, as indicated by low levels of smooth muscle alpha actin and desmin.Taken together, our studies suggest that laminin alpha1 chain synthesis is regulated by epithelial-mesenchymal interaction and may play a role in airway smooth muscle development.

View Article: PubMed Central - PubMed

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

ABSTRACT
Laminins, the main components of basement membranes, are heterotrimers consisting of alpha, beta, and gamma polypeptide chains linked together by disulfide bonds. Laminins-1 and -2 are both composed of beta1 and gamma1 chains and differ from each other on their alpha chain, which is alpha1 and alpha2 for laminin-1 and -2, respectively. The present study shows that whereas laminins-1 and -2 are synthesized in the mouse developing lung and in epithelial-mesenchymal cocultures derived from it, epithelial and mesenchymal monocultures lose their ability to synthesize the laminin alpha1 chain. Synthesis of laminin alpha1 chain however returns upon re-establishment of epithelial-mesenchymal contact. Cell-cell contact is critical, since laminin alpha1 chain is not detected in monocultures exposed to coculture-conditioned medium or in epithelial-mesenchymal cocultures in which heterotypic cell-cell contact is prevented by an interposing filter. Immunohistochemical studies on cocultures treated with brefeldin A, an inhibitor of protein secretion, indicated both epithelial and mesenchymal cells synthesize laminin alpha1 chain upon heterotypic cell- cell contact. In a set of functional studies, embryonic lung explants were cultured in the presence of monoclonal antibodies to laminin alpha1, alpha2, and beta/gamma chains. Lung explants exposed to monoclonal antibodies to laminin alpha1 chain exhibited alterations in peribronchial cell shape and decreased smooth muscle development, as indicated by low levels of smooth muscle alpha actin and desmin. Taken together, our studies suggest that laminin alpha1 chain synthesis is regulated by epithelial-mesenchymal interaction and may play a role in airway smooth muscle development.

Show MeSH