Abstract
We have used the pH-dependent fluorochrome fluorescein-dextran (FD) to study the acidification of prelysosomal vacuoles (endosomes) and lysosomes isolated from cultured macrophages and fibroblasts. FD was internalized by pinocytosis under conditions that allowed its selective localization in endosomes (1- to 5-min pulse) or in lysosomes (5-min pulse, 30-min chase). Fibroblasts were also exposed to FD at 20 degrees C, at which temperature endosome-lysosome fusion is inhibited. Cells were homogenized and labeled organelles were separated by centrifugation in Percoll density gradients. The addition of ATP rapidly decreased the internal pH of both endosomes and lysosomes, as indicated by a decrease in fluorescence intensity. The pH gradient was dissipated by H+ ionophores and ammonium chloride. Acidification was not affected by inhibitors of the mitochondrial F1, F0-ATPase or the Na+, K, K+-ATPase and did not require permeant anions, Na+, or K+. Of the inhibitors tested, only N-ethylmaleimide prevented the ATP-dependent acidification of both compartments. These findings provide direct support for the existence of an acidic prelysosomal compartment that may be acidified via the same type of H+ pump believed to operate in lysosomes and secretory granules.
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Selected References
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- Dunn W. A., Hubbard A. L., Aronson N. N., Jr Low temperature selectively inhibits fusion between pinocytic vesicles and lysosomes during heterophagy of 125I-asialofetuin by the perfused rat liver. J Biol Chem. 1980 Jun 25;255(12):5971–5978. [PubMed] [Google Scholar]
- Fishkes H., Rudnick G. Bioenergetics of serotonin transport by membrane vesicles derived from platelet dense granules. J Biol Chem. 1982 May 25;257(10):5671–5677. [PubMed] [Google Scholar]
- Forgac M., Cantley L., Wiedenmann B., Altstiel L., Branton D. Clathrin-coated vesicles contain an ATP-dependent proton pump. Proc Natl Acad Sci U S A. 1983 Mar;80(5):1300–1303. doi: 10.1073/pnas.80.5.1300. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Harms E., Kern H., Schneider J. A. Human lysosomes can be purified from diploid skin fibroblasts by free-flow electrophoresis. Proc Natl Acad Sci U S A. 1980 Oct;77(10):6139–6143. doi: 10.1073/pnas.77.10.6139. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Helenius A., Kartenbeck J., Simons K., Fries E. On the entry of Semliki forest virus into BHK-21 cells. J Cell Biol. 1980 Feb;84(2):404–420. doi: 10.1083/jcb.84.2.404. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Holz R. W. Measurement of membrane potential of chromaffin granules by the accumulation of triphenylmethylphosphonium cation. J Biol Chem. 1979 Jul 25;254(14):6703–6709. [PubMed] [Google Scholar]
- LaBadie J. H., Chapman K. P., Aronson N. N., Jr Glycoprotein catabolism in rat liver: Lysosomal digestion of iodinated asialo-fetuin. Biochem J. 1975 Nov;152(2):271–279. doi: 10.1042/bj1520271. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Marsh M., Bolzau E., Helenius A. Penetration of Semliki Forest virus from acidic prelysosomal vacuoles. Cell. 1983 Mar;32(3):931–940. doi: 10.1016/0092-8674(83)90078-8. [DOI] [PubMed] [Google Scholar]
- Mellman I. S., Steinman R. M., Unkeless J. C., Cohn Z. A. Selective iodination and polypeptide composition of pinocytic vesicles. J Cell Biol. 1980 Sep;86(3):712–722. doi: 10.1083/jcb.86.3.712. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Merion M., Poretz R. D. The resolution of two populations of lysosomal organelles containing endocytosed Wistaria floribunda agglutinin from murine fibroblasts. J Supramol Struct Cell Biochem. 1981;17(4):337–346. doi: 10.1002/jsscb.380170405. [DOI] [PubMed] [Google Scholar]
- Merion M., Sly W. S. The role of intermediate vesicles in the adsorptive endocytosis and transport of ligand to lysosomes by human fibroblasts. J Cell Biol. 1983 Mar;96(3):644–650. doi: 10.1083/jcb.96.3.644. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ohkuma S., Moriyama Y., Takano T. Identification and characterization of a proton pump on lysosomes by fluorescein-isothiocyanate-dextran fluorescence. Proc Natl Acad Sci U S A. 1982 May;79(9):2758–2762. doi: 10.1073/pnas.79.9.2758. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ohkuma S., Poole B. Fluorescence probe measurement of the intralysosomal pH in living cells and the perturbation of pH by various agents. Proc Natl Acad Sci U S A. 1978 Jul;75(7):3327–3331. doi: 10.1073/pnas.75.7.3327. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Reeves J. P., Reames T. ATP stimulates amino acid accumulation by lysosomes incubated with amino acid methyl esters. Evidence for a lysosomal proton pump. J Biol Chem. 1981 Jun 25;256(12):6047–6053. [PubMed] [Google Scholar]
- Rome L. H., Garvin A. J., Allietta M. M., Neufeld E. F. Two species of lysosomal organelles in cultured human fibroblasts. Cell. 1979 May;17(1):143–153. doi: 10.1016/0092-8674(79)90302-7. [DOI] [PubMed] [Google Scholar]
- Schneider D. L. ATP-dependent acidification of intact and disrupted lysosomes. Evidence for an ATP-driven proton pump. J Biol Chem. 1981 Apr 25;256(8):3858–3864. [PubMed] [Google Scholar]
- Steinman R. M., Brodie S. E., Cohn Z. A. Membrane flow during pinocytosis. A stereologic analysis. J Cell Biol. 1976 Mar;68(3):665–687. doi: 10.1083/jcb.68.3.665. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Steinman R. M., Mellman I. S., Muller W. A., Cohn Z. A. Endocytosis and the recycling of plasma membrane. J Cell Biol. 1983 Jan;96(1):1–27. doi: 10.1083/jcb.96.1.1. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Tolleshaug H., Berg T., Frölich W., Norum K. R. Intracellular localization and degradation of asialofetuin in isolated rat hepatocytes. Biochim Biophys Acta. 1979 Jun 1;585(1):71–84. doi: 10.1016/0304-4165(79)90326-x. [DOI] [PubMed] [Google Scholar]
- Tycko B., Maxfield F. R. Rapid acidification of endocytic vesicles containing alpha 2-macroglobulin. Cell. 1982 Mar;28(3):643–651. doi: 10.1016/0092-8674(82)90219-7. [DOI] [PubMed] [Google Scholar]
- van Renswoude J., Bridges K. R., Harford J. B., Klausner R. D. Receptor-mediated endocytosis of transferrin and the uptake of fe in K562 cells: identification of a nonlysosomal acidic compartment. Proc Natl Acad Sci U S A. 1982 Oct;79(20):6186–6190. doi: 10.1073/pnas.79.20.6186. [DOI] [PMC free article] [PubMed] [Google Scholar]