Abstract
Alteration of cytoskeletal elements of secretory cells is associated with exocytosis, presumably by regulating microfilament (actin) and microtubule structure and function. We used cytochalasins (to promote microfilament depolymerization), rhodamine-conjugated phalloidin and fluorescein-conjugated monoclonal antibodies against actin and tubulin to partially characterize the role of the cytoskeleton in surfactant secretion by Type II epithelial cells in primary culture. Surfactant pools were prelabeled with 3H-choline to follow release of tritiated phosphatidyl choline (3H-PC). Cytochalasins A,B,C, and D enhanced release 2-3-fold, EC50 of 1,1,.5, and .1 uM, respectively, but did not enhance cytosolic cyclic AMP levels. Only A caused significant cytotoxicity as determined by release of intracellular lactate dehydrogenase. Dose response of 3H-PC release by C and D was biphasic (maximum response, 1.0-0.5 uM) decreasing toward control levels >luM. D caused release by 1 hr and progressively increased release up to 3 hr. D-induced release was additive to that induced by terbutaline and forskolin. By fluorescent labeling, microfilaments were associated with lamellar bodies and D caused a change in cell morphology and microfilament/microtubule structure. Cytochalasin-induced release of 3H-PC is independent of cyclic AMP synthesis and is associated with alterations in cell morphology and organization of the cytoskeleton associated with lamellar bodies, further supporting the role of the cytoskeleton in surfactant release.
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Rice, W., Osterhoudt, K. & Whitsett, J. SURFACTANT RELEASE FROM ISOLATED TYPE II EPITHELIAL CELLS: ROLE OF MICROFILAMENTS (ACTIN). Pediatr Res 18 (Suppl 4), 144 (1984). https://doi.org/10.1203/00006450-198404001-00308
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DOI: https://doi.org/10.1203/00006450-198404001-00308