Laminin-311 (Laminin-6) fiber assembly by type I-like alveolar cells.
Two epithelial cell types cover the alveolar surface of the lung. Type II alveolar epithelial cells produce surfactant and, during development or following wounding, give rise to type I cells that are involved in gas exchange and alveolar fluid homeostasis. In culture, freshly isolated alveolar type II cells assume a more squamous (type I-like) appearance within 4 days after plating. They assemble numerous focal adhesions that associate with the actin cytoskeleton at the cell margins. These alveolar epithelial cells lose expression of type II cell markers including SP-C and after 4 days in culture express the type I cell marker T1alpha. Those cells that express T1alpha also deposit fibers of laminin-311 in their matrix. The latter appears to be related to their development of a type I phenotype because freshly isolated, primary type I cells also assemble laminin-311-rich fibers in vitro. A beta1 integrin antibody antagonist inhibits the assembly of laminin-311 matrix fibers. Moreover, the formation of laminin fibers is dependent on the activity of the small GTPases and is perturbed by ML-7, a myosin light chain kinase inhibitor. In summary, our data indicate that assembly of laminin-311 fibers by lung epithelial cells is integrin and actin cytoskeleton dependent, and that these fibers are characteristic of type I alveolar cells.
DeBiase
Phillip J
PJ
Division of Pulmonary Medicine, Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Tarry 8-715, 303 E. Chicago Avenue, Chicago, IL 60611, USA. j-jones3@northwestern.edu
Lane
Kimberly
K
Budinger
Scott
S
Ridge
Karen
K
Wilson
Mindy
M
Jones
Jonathan C R
JC
D008841:Actin Cytoskeleton / Q000648:ultrastructure; D000199:Actins / Q000502:physiology; D000818:Animals; D001381:Azepines / Q000494:pharmacology; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000502:physiology; D004591:Electrophoresis, Polyacrylamide Gel; D005109:Extracellular Matrix / Q000378:metabolism / Q000648:ultrastructure; D015151:Immunoblotting; D019012:Integrin beta1 / Q000502:physiology; D007797:Laminin / Q000378:metabolism* / Q000648:ultrastructure; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D020559:Monomeric GTP-Binding Proteins / Q000378:metabolism; D009219:Myosin-Light-Chain Kinase / Q000037:antagonists & inhibitors; D009218:Myosins / Q000502:physiology; D009281:Naphthalenes / Q000494:pharmacology; D011650:Pulmonary Alveoli / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D051381:Rats; D017207:Rats, Sprague-Dawley; D020545:Respiratory Mucosa / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D000098853:Podoplanin
D000199:Actins; D001381:Azepines; D019012:Integrin beta1; D007797:Laminin; D008562:Membrane Glycoproteins; D020559:Monomeric GTP-Binding Proteins; D009219:Myosin-Light-Chain Kinase; D009218:Myosins; D009281:Naphthalenes; C092025:Pdpn protein, rat; D000098853:Podoplanin; C119337:laminin 6; C070571:ML 7