Laminin-2 stimulates the proliferation of epithelial cells in a conjunctival epithelial cell line.
Laminin-2 (LN-2, alpha2beta1gamma1) is a basement membrane-associated laminin isoform usually considered in the context of muscle and nerve tissues. To test the hypothesis that LN-2 can additionally modulate epithelial cell biology, an analysis of the role of LN-2 in cell adhesion, activation of signalling intermediates and proliferation was undertaken. A virally transformed human conjunctival epithelial cell line (HC0597) was utilized in this study. Adhesion assays using function-inhibiting antibodies demonstrated that alpha3beta1 integrin is essential for the rapid attachment of conjunctival epithelial cells to LN-2. Bromodeoxyuridine (BrdU) incorporation analyses revealed that, compared with LN-1 or LN-10, LN-2 significantly promotes epithelial proliferation. Phosphorylation of the signalling intermediates Erk1/2 and Akt-1 was observed within 15 min of cell adhesion to LN-2. Inhibiting alpha3beta1 integrin function decreased total cellular phosphotyrosine levels, specifically inhibited phosphorylation of Erk1/2 and Akt-1, and dampened the proliferation response of epithelial cells adherent to LN-2. Inhibition of Erk or Akt activation inhibited cell proliferation in a dose-dependent manner. However, the inhibition of Erk resulted in a stronger suppression of proliferation compared with Akt inhibition. From these results, it is concluded that human conjunctival epithelial cells adhere to immobilized LN-2 using alpha3beta1 integrin. alpha3beta1 integrin/LN-2 signalling, transduced primarily through an Erk pathway, enhances epithelial cell proliferation. These results demonstrate that LN-2 can impact on epithelial cell biology in addition to nerve and muscle, and provide information regarding the role of this isoform in ocular surface epithelial cells.
Dowgiert
J
J
Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
Sosne
G
G
Kurpakus-Wheater
M
M
D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D002450:Cell Communication / Q000187:drug effects / Q000502:physiology*; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D003228:Conjunctiva / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D039201:Integrin alpha3beta1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D007797:Laminin / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*
D004791:Enzyme Inhibitors; D039201:Integrin alpha3beta1; D007797:Laminin; D011518:Proto-Oncogene Proteins; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D020928:Mitogen-Activated Protein Kinases