Abstract
The effects of phalloidin and cytochalasin D, drugs which, respectively, stabilize and destabilize actin microfilaments, have been tested on isolated rat hepatocytes. Both drugs produced a modification of cell shape, characterized by protrusions bulging from the cytoplasm. In phalloidin-treated hepatocytes, an accumulation of actin microfilamentous network was detectable at the base of each protrusion by electron microscopy, immunofluorescence, and HMM decoration. This accumulation of microfilaments was absent in cytochalasin D-treated cells. The release of triglycerides, an index of very low density lipoprotein secretion, was inhibited by phalloidin or cytochalasin D, and accompanied by an increase in cellular triglycerides. At the electron microscope examination, triglyceride accumulation was represented by fat droplets and vesicle-enclosed, very low density lipoprotein-like particles. Total protein and albumin secretion was only very slightly modified by either one of these drugs. With the use of various phalloidin analogs, a correlation was observed between their respective ability to stabilize F-actin in vitro, and their effects on cell shape and triglyceride secretion. In conclusion, phalloidin, and cytochalasin D: (a) modify the shape of isolated hepatocytes; (b) inhibit lipoprotein secretion. These effects possibly result from a modification of actin microfilament function.
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- Bauduin H., Stock C., Vincent D., Grenier J. F. Microfilamentous system and secretion of enzyme in the exocrine pancreas. Effect of cytochalasin B. J Cell Biol. 1975 Jul;66(1):165–181. doi: 10.1083/jcb.66.1.165. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bray D., Thomas C. Unpolymerized actin in fibroblasts and brain. J Mol Biol. 1976 Aug 25;105(4):527–544. doi: 10.1016/0022-2836(76)90233-3. [DOI] [PubMed] [Google Scholar]
- GORNALL A. G., BARDAWILL C. J., DAVID M. M. Determination of serum proteins by means of the biuret reaction. J Biol Chem. 1949 Feb;177(2):751–766. [PubMed] [Google Scholar]
- Heindel J. J., Cushman S. W., Jeanrenaud B. Cell-associated fatty acid levels and energy-requiring processes in mouse adipocytes. Am J Physiol. 1974 Jan;226(1):16–24. doi: 10.1152/ajplegacy.1974.226.1.16. [DOI] [PubMed] [Google Scholar]
- Lacy P. E., Howell S. L., Young D. A., Fink C. J. New hypothesis of insulin secretion. Nature. 1968 Sep 14;219(5159):1177–1179. doi: 10.1038/2191177a0. [DOI] [PubMed] [Google Scholar]
- Le Marchand Y., Patzelt C., Assimacopoulos-Jeannet F., Loten E. G., Jeanrenaud B. Evidence for a role of the microtubular system in the secretion of newly synthesized albumin and other proteins by the liver. J Clin Invest. 1974 Jun;53(6):1512–1517. doi: 10.1172/JCI107701. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Malaisse W. J., Malaisse-Lagae F., Walker M. O., Lacy P. E. The stimulus-secretion coupling of glucose-induced insulin release. V. The participation of a microtubular-microfilamentous system. Diabetes. 1971 May;20(5):257–265. doi: 10.2337/diab.20.5.257. [DOI] [PubMed] [Google Scholar]
- Patzelt C., Brown D., Jeanrenaud B. Inhibitory effect of colchicine on amylase secretion by rat parotid glands. Possible localization in the Golgi area. J Cell Biol. 1977 Jun;73(3):578–593. doi: 10.1083/jcb.73.3.578. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Redman C. M., Banerjee D., Howell K., Palade G. E. Colchicine inhibition of plasma protein release from rat hepatocytes. J Cell Biol. 1975 Jul;66(1):42–59. doi: 10.1083/jcb.66.1.42. [DOI] [PMC free article] [PubMed] [Google Scholar]
- de Vries J. X., Schäfer A. J., Faulstich H., Wieland T. Protection of actin from heat denaturation by various phallotoxins. Hoppe Seylers Z Physiol Chem. 1976 Aug;357(8):1139–1143. doi: 10.1515/bchm2.1976.357.2.1139. [DOI] [PubMed] [Google Scholar]