LPS-induced depolymerization of cytoskeleton and its role in TNF-alpha production by rat pneumocytes.
Lipopolysaccharide (LPS) polymerizes microfilaments and microtubules in macrophages and monocytes. Disrupting microfilaments or microtubules with cytochalasin D (CytoD) or colchicine can suppress LPS-induced tumor necrosis factor-alpha (TNF-alpha) gene expression and protein production from these cells. We have recently demonstrated that primary cultured rat alveolar epithelial cells can produce TNF-alpha on LPS stimulation. In the present study, we found that the LPS-induced increase in TNF-alpha mRNA level and protein production in alveolar epithelial cells was not inhibited by CytoD or colchicine (1 nM to 10 microM). In fact, LPS-induced TNF-alpha production was further enhanced by CytoD (1-10 microM) and inhibited by jasplakinolide, a polymerizing agent for microfilaments. Immunofluorescent staining and confocal microscopy showed that LPS (10 microg/ml) depolymerized microfilaments and microtubules within 15 min, which was prolonged until 24 h for microfilaments. These results suggest that the effects of LPS on the cytoskeleton and the role of the cytoskeleton in mediating TNF-alpha production in alveolar epithelial cells are opposite to those in immune cells. This disparity may reflect the different roles between nonimmune and immune cells in host defense.
Isowa
N
N
Thoracic Surgery Research Laboratory, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada.
Xavier
A M
AM
Dziak
E
E
Opas
M
M
McRitchie
D I
DI
Slutsky
A S
AS
Keshavjee
S H
SH
Liu
M
M
D008841:Actin Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D003078:Colchicine / Q000494:pharmacology; D015638:Cytochalasin D / Q000494:pharmacology; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism*; D047630:Depsipeptides; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008297:Male; D008870:Microtubules / Q000187:drug effects; D010456:Peptides, Cyclic / Q000494:pharmacology; D011108:Polymers / Q000378:metabolism*; D011650:Pulmonary Alveoli / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D012333:RNA, Messenger / Q000037:antagonists & inhibitors / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism
D047630:Depsipeptides; D008070:Lipopolysaccharides; D010456:Peptides, Cyclic; D011108:Polymers; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; C057531:jasplakinolide; D015638:Cytochalasin D; D003078:Colchicine