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Laminin-6 assembles into multimolecular fibrillar complexes with perlecan and participates in mechanical-signal transduction via a dystroglycan-dependent, integrin-independent mechanism.

Authors: Jones, JC  Lane, K  Hopkinson, SB  Lecuona, E  Geiger, RC  Dean, DA  Correa-Meyer, E  Gonzales, M  Campbell, K  Sznajder, JI  Budinger, S 
Citation: Jones JC, etal., J Cell Sci. 2005 Jun 15;118(Pt 12):2557-66. Epub 2005 May 31.
Pubmed: (View Article at PubMed) PMID:15928048
DOI: Full-text: DOI:10.1242/jcs.02395

Mechanical ventilation is a valuable treatment regimen for respiratory failure. However, mechanical ventilation (especially with high tidal volumes) is implicated in the initiation and/or exacerbation of lung injury. Hence, it is important to understand how the cells that line the inner surface of the lung [alveolar epithelial cells (AECs)] sense cyclic stretching. Here, we tested the hypothesis that matrix molecules, via their interaction with surface receptors, transduce mechanical signals in AECs. We first determined that rat AECs secrete an extracellular matrix (ECM) rich in anastamosing fibers composed of the alpha3 laminin subunit, complexed with beta1 and gamma1 laminin subunits (i.e. laminin-6), and perlecan by a combination of immunofluorescence microscopy and immunoblotting analyses. The fibrous network exhibits isotropic expansion when exposed to cyclic stretching (30 cycles per minute, 10% strain). Moreover, this same stretching regimen activates mitogen-activated-protein kinase (MAPK) in AECs. Stretch-induced MAPK activation is not inhibited in AECs treated with antagonists to alpha3 or beta1 integrin. However, MAPK activation is significantly reduced in cells treated with function-inhibiting antibodies against the alpha3 laminin subunit and dystroglycan, and when dystroglycan is knocked down in AECs using short hairpin RNA. In summary, our results support a novel mechanism by which laminin-6, via interaction with dystroglycan, transduces a mechanical signal initiated by stretching that subsequently activates the MAPK pathway in rat AECs. These results are the first to indicate a function for laminin-6. They also provide novel insight into the role of the pericellular environment in dictating the response of epithelial cells to mechanical stimulation and have broad implications for the pathophysiology of lung injury.

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CRRD Object Information
CRRD ID: 1624263
Created: 2007-05-07
Species: All species
Last Modified: 2007-05-07
Status: ACTIVE



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RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.